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NOTE ON THE RIGIDITY OF THE PECTORAL FIN OF

MAKAIRA INDICA (CUVIER)*

Mary-LouisE WAPENAAR & FRANK HAMILTON TALBOT

South African Museum

(With 1 plate and 7 figures in the text)

ABSTRACT

It has been known for a long time that the pectoral fin of the black marlin, Makaira indica,

cannot be folded flat against the side of the body as it can in all other istiophorid fishes. The

anatomy of the pectoral girdle of the black marlin is here compared with that of the striped

marlin, MM. audax, to determine the mechanism of the rigid joint. The osteology and musculature

of the pectoral girdle of both species is described and discussed, with particular reference to the

articular region. It is concluded that the bony structure of the joint and the strength and

disposition of its fibrous connective tissue sheath together ensure the rigidity of the pectoral fin

in M. indica. It is suggested that the rigid pectoral fin of M. indica is used as a plane of elevation.

I. INTRODUCTION

Ever since Nakamura (1938) and, more particularly, Gregory & Conrad

(1939) showed that the black marlin Makaira indica (Cuvier) has a rigid

pectoral fin which cannot be folded flat against the body, while all other

istiophorids have a folding pectoral fin, the reason for such a difference, and

the structural features that prevent the fin from folding in the black marlin,

have been a source of speculation among ichthyologists.

The pectoral fin of marlins is in the main an inflexible, sickle-shaped

structure with a narrow leading edge formed by the sharp edge of the strong

marginal ray, and a small movable posterior lobe formed by the last ten rays

or actinosts. In all marlins it is set at an angle of about 35° to the horizontal,

so that when extended at right angles to the body it acts as a plane of eleva-

tion by presenting a horizontal or oblique surface to the direction of flow of

the water rather than a vertical surface as in many teleosts. In all istiophorids

other than M. indica the fin can be rotated from the extended position to

lie flat against the side of the body, but in M. indica the fin is permanently

extended and cannot be folded against the body without structural damage,

for which considerable force must be used.

An anatomical study was undertaken in which the pectoral girdle of

M. indica was compared with that of the striped marlin, /. audax (Philippi), to

* This paper formed part of the Oceanography Symposium held during the 61st Annual

Congress of the South African Association for the Advancement of Science at Durban, July 1963.

The association has kindly given permission for publication here.

167 TT rT Bus

peer MAY 2 5 1064

Ann. S. Afr. Mus. 48 (6), 1964, 167-180, pl. IL., 7 figs.

168 ANNALS OF THE SOUTH AFRICAN MUSEUM

determine the reason for the rigidity of the pectoral fin in M. indica. The

articular regions of the pectoral girdles of M. albida (Poey) and M. nigricans

(Lacépéde) were also examined.

Nakamura (1938), Gregory & Conrad (1939), LaMonte & Marcy (1941),

LaMonte (1955), J. L. B. Smith (1956), Robins (1957), Robins & de Sylva

(1961), and Talbot & Penrith (1962) and others have referred to the rigidity

of the pectoral fin of . indica, but only one attempt to investigate this feature

on an anatomical basis has been made (Morrow, 1957).

Morrow states that the rigidity of the fin in M. indica is due to three bony

pads associated with the articular surface of the marginal ray of the fin, giving

it a rigid three-point suspension and thus preventing it from being rotated and

folded back as occurs in the other species. In our opinion this explanation is

untenable, for reasons which are given below.

II. MATERIAL

Makaira indica (Cuvier)

(a) Two loose girdles, fresh, of a 600 Ib. fish, length 2,935 mm., taken

aboard the fishing vessel Karimona by longline west of Slangkop, Cape Peninsula,

30/1/1962. S.A.M. Reg. No. 23194.

(b) Anterior half, fresh, of an 800 Ib. fish, length 3,210 mm., taken aboard

the fishing vessel Walvis Pioneer by longline 40 miles west of Cape Point,

28/1/1962. S.A.M. Reg. No. 23193.

and line 25 miles west-north-west of Cape Point, 25/2/1962. S.A.M. Reg. No.

23244.

(d) Prepared girdle of a 1,028 lb. fish taken by longline south-west of

Hout Bay, March 1961. S.A.M. Reg. No. 23054.

Makara audax (Philippi)

(a) Anterior half, fresh, of a 130 lb. fish, length 2,120 mm., taken aboard

the fishing vessel Overberg by longline west of Cape Point, 2/2/1962. S.A.M.

Reg. No. 23197.

(b) Prepared girdle of small specimen taken west of Hout Bay by longline,

March 1961. S.A.M. Reg. No. 23052. ,

Makaira nigricans (Lacépéde)

(a) Prepared girdle of large specimen taken aboard the fishing vessel

Cape Point by longline 45 miles north-west of Dassen Island, 29/6/1961. S.A.M.

Reg. No. 23104.

Makaira albida (Poey)

(a) Prepared girdle of specimen taken by longline south-west of Hout

Bay, March 1961. S.A.M. Reg. No. 23053.

RIGIDITY OF PECTORAL FIN OF MAKAIRA INDICA (CUVIER) 169

III. OsTEOLOGY OF THE PECTORAL GIRDLE OF M/. audax AND M. indica

The pectoral girdle of marlins (figs. 1, 2) is suspended from the skull by

a three-pronged post-temporal and a long, flat supra-cleithrum, and is typical

in consisting of a complex of three bones. There is an anterior cleithrum which

has medial and lateral flanges or arms, a rod-like ventral process which meets

that of the opposite side in the mid-ventral line, and two dorsal processes, an

anterior, rod-like one and a posterior expanded process. The posterior bone

of the complex is the coracoid, which is roughly triangular. From its antero-

dorsal corner a ridge runs ventro-caudally. Above the ridge is the dorsal

process of the coracoid; the ventral process of the coracoid meets the cleithrum

just above the ventral process of that bone. Dorso-medially between the

cleithrum and the coracoid lies the scapula, a fairly small semicircular bone

perforated by the scapular foramen, through which the nerves supplying the

abductor musculature of the fin pass. The scapula bears the articular surfaces

for the pectoral fin.

No bony pads such as those described by Morrow (1957) were found in

any of the South African specimens of M. indica. If they are not present in all

specimens it seems unlikely that those found by Morrow are of any significance

in the mechanism of the rigid joint.

The pectoral complex is very similar in M. indica and M. audax, with a

major difference in the articulation of the fin (described below in section V),

anterior dorsal process

of cleithrum

posterior dorsal process

of cleithrum

articular surface for

rsal marginal ray

dorsal process

of coracold

scapula

dorsal process of coracoid

scapular foramen

medial arm of cleithrum

coracoid

| lateral arm of cleithrum

ventral process speciale ‘

of cleithrum

)

Hh}

{

ventral process of coracoid

Lateral view

Medial view

Fic. 1. Pectoral girdle of Makaira indica.

170 ANNALS OF THE SOUTH AFRICAN MUSEUM

anterior dorsal

process of cleithrum

posterior dorsal process

of cleithrum

articular surface for

marginal ray + cleithrum

articular surface for

marginal ray

scapula

coracold ridge

dorsal process of coracold scapular foramen

dorsal process of coracoid

medial arm of cleithrum

lateral arm of cleithrum

coracold *

~ ventral process of

cleithrum

"ventral process of

coracol

Fic. 2. Pectoral girdle of Makaira audax.

and other minor differences. In MM. audax the anterior edge of the cleithrum is

concave, while in M. indica this edge is almost straight, with the ventral process

of the cleithrum somewhat backwardly directed. The coracoid ridge is shorter

and heavier in M. indica than in M. audax, and the dorsal process of the coracoid.

is pointed in the former and rounded in the latter. The scapular foramen is

relatively larger in M. audax than in M. indica.

IV. MuscuLATURE OF THE PECTORAL GIRDLE OF MW. indica AND M. audax

(figs. 3, 4, 5)

The musculature of the pectoral girdle of M. indica and M. audax was

investigated. The body muscles and the muscles between the pectoral girdle

and the head and visceral skeleton were found to be identical in M. indica

and M. audax and will not be included here.

The musculature of the pectoral girdle consists as in all fishes of adductor

and abductor portions (Shann, 1919), which draw the fin towards and away

from the body respectively. Both portions are more or less divided into superficial

and deep parts, although these are often not easily separable. The abductor

musculature arises from the lateral surface of the scapula and the coracoid,

and the lateral surface of the medial flange of the cleithrum, and inserts on

the marginal ray and the bases of the remaining rays of the fin. For most of

their length from their fleshy origin the superficial and deep fibres are not clearly

separable, but towards their insertion they become more distinct and have a

separate tendinous insertion on the bases of the rays, the deep fibres inserting

on the ventral extremities of the bases of the rays while the superficial fibres

insert on a slight ridge a short distance above the bases of the rays. The last

ten rays are movable in relation to the rest of the fin and have a fairly specialized

musculature, some of which inserts on the radials supporting them (described

below, section V). The adductor musculature arises from the medial surface

_ marginal ray

cleithrum

ventral lobe of fin

lateral arm of cleithrum

coracoid

Superficialis

marginal ray

cleithrum

fateral arm of cleithrum ventral lobe of fin

coracoid

Profundus

Fic. 3. Abductor musculature of Makaira indica.

172 ANNALS OF THE SOUTH AFRICAN MUSEUM

of the cleithrum, scapula, and coracoid, and also has a tendinous insertion

on the bases of the rays on the medial side of the fin. As in the case of the abduc-

tor musculature, the adductors of the last ten rays are separate and very well

developed. An additional adductor, present in many fishes, the coracoradialis

marginal ray

cleithrum

ventral lobe of fin

coraco-radialis muscle

coracoid

Superficialis

marginal ray

scapula

cleithrum

* ventral lobe of fin

Profundus

Fic. 4. Adductor musculature of Makaira audax.

RIGIDITY OF PECTORAL FIN OF MAKAIRA INDICA (CUVIER) 173

marginal ray

cleithrum

ventral lobe of fin

coraco-radialis muscle

toracoid

Fic. 5. Adductor superficialis musculature of Makaira indica.

muscle, arises from the medial surface of the coracoid and inserts on the last

two radials.

In general the abductor and adductor portions are very similar in M.

indica and M. audax (figs. 3, 4, 5). In M. indica the superficial and the deep

abductor of the marginal ray form a bundle clearly separated from the abductors

of the remaining fin rays, while in M/. audax the abductors for the marginal ray

are not distinct. In both species the last ten rays form a distinct lobe witha

separate and well-defined musculature; the abductor portions of the muscula-

ture of this lobe are identical in the two species.

There are certain differences in the adductor musculature of the two

species (figs. 4, 5); again in M. indica the adductors of the marginal ray are

clearly defined and in addition have a slightly different origin, arising from

the posterior dorsal process of the cleithrum rather than from the medial arm

of the cleithrum. In general the adductor muscles in M. audax are arranged

so that the fibres are relatively longer than in M. indica. The greatest difference

is in the adductor musculature of the ventral lobe, with which the present

174 ANNALS OF THE SOUTH AFRICAN MUSEUM

discussion is not concerned as it has no bearing on the mechanism of the rigid

joint. This lobe clearly has important hydrodynamic effects on the fin, however,

and one would expect its mode of action to differ in two species in which the

action of the fin as a whole differs strongly.

The adductor and abductor muscles then are responsible for the movements

of the pectoral fin. By contraction of the abductors other than those of the

ventral lobe the antero-ventral tip of the fin-base is pulled forward and down-

ward. In M. audax (pl. II) this movement causes the fin to be pulled away from

the body into the extended position. This actually involves two movements, the

drawing downwards of the antero-ventral tip of the fin base and the drawing

forwards of the fin as a whole so that the direction of the fin tip is at right angles

to the direction of the body, but both movements occur simultaneously in

M. audax. In the extended position in M. audax either movement can be

carried out; by twisting, the plane of the fin to the water can be altered by

about 10°, and the leading edge can move through any arc between the fully

extended position and the folded position.

Fic. 6. Range of movement of fin in Makaira indica.

In M. indica (fig. 6), where the fin is permanently extended, two limited

movements are possible, and are also brought about by the abductor and

adductor muscles. The angle of incidence of the fin plane to the water can be

altered within an arc of about 4°, brought about by the pulling down by the

abductors of the antero-ventral tip of the marginal ray base; the fin is also

capable of an antero-posterior movement in a horizontal plane through an

RIGIDITY OF PECTORAL FIN OF MAKAIRA INDICA (CUVIER) 175

angle of 12°. It can thus be seen that the range of movement is far more limited

in M. indica than in M. audax.

It would be anatomically unusual if the rigidity of the fin were dependent

on the musculature. This would imply continual sustained muscle activity to

hold the fin rigid during forward movement of the fish; that is, during most

of its life. The total extension of a muscle group is never limited by its own

action alone (Professor L. H. Wells, personal communication). The maximum

extension 1s normally limited by the structure (ligament, cartilage and bone) of

the joint itself. If they were not limited in this way, the structure of muscle

fibres is such that on relaxation they could expand until damaged. If muscles

held the fin rigid in the black marlin it would also follow that in a freshly

dead specimen the fin should be able to move back against the body, even if

the muscle fibres were damaged in so doing. This is not the case. As would be

expected, therefore, the structure of the joint itself and not the muscles is the

limiting factor to further backward movement. In any joint the arrangement

of the muscles will depend on the amount of movement allowed by the arrange-

ment of the bones and ligaments of the joint. Thus in M. audax, where the

range of possible movement of the fin is more extensive, the muscle fibres are

longer than in M. indica.

The fin musculature of M. indica is very well developed in spite of the small

range of movement of the fin. It is suggested that while the fin of MM. audax

encounters little water resistance in the initial stages of its extension, water

pressures render considerable muscular effort necessary for moving the fin

when it is extended. It is these latter movements with which the muscles of

M. indica are concerned, so that they must be well developed, as well developed

as in M. audax, in fact. Short fibres are adequate for these short-range

movements, however.

The main point arising from the study of the pectoral musculature is that,

if the abductors of MM. audax are contracted, the pectoral fin can be maintained

in the same position as that of M. indica, but in M. indica the fin is maintained

in this position even when the abductor muscles are relaxed and the adductors

contracted. The muscles do not assist in rendering the joint rigid; as would be

expected, M. indica has developed some method of maintaining the rigid

position of the fin other than by sustained muscular contraction.

V. ARTICULATION OF THE PECTORAL FIN (fig. 7)

The most significant difference in the pectoral complex lies in the arrange-

ment and shape of the articular surfaces for the pectoral fin. In M. audax,

M. nigricans, and M. albida the articular surface for the base of the marginal ray

lies on the dorsal edge of the scapula; its surface is markedly convex and curves

smoothly from the lateral to the medial surface of the bone; in other words it

is saddle-shaped. The base of the marginal ray in these species is concave to

correspond with its articular surface on the girdle. In M. indica the articular

176 ANNALS OF THE SOUTH AFRICAN MUSEUM

surface for the marginal ray, although close to the dorsal edge of the scapula,

lies entirely on the lateral surface and is flat, so that a limited amount of

sliding but no rolling movement is possible. The base of the marginal ray in

this species is correspondingly flat. The dorsal edge of the scapula above the

articular surface (which surface is occupied by the inner half of the saddle-

shaped articular surface in M. audax) is here extremely rugose and pitted for

the attachment of connective tissue.

In all four species there is at the posterior end of the articular surface for

the marginal ray a shallow trough, which receives a downward process of the

articular surface of the marginal ray base. This trough lies mainly on the dorsal

edge of the scapula.

Posterior to the articular surface for the marginal ray are the articular

surfaces for the radials (fig. 7). The radials are very similar in all four species.

They are four in number, the first two being short and cubical, and the posterior

two rather long and slender and forming the base of the posterior lobe of the fin.

Their articulation lies mainly on the dorsal edge of the scapula; that of the

anterior dorsal

process of cleithrum

marginal ray

posterior dorsal process

of cleithrum Hae ee.

articular surface

scapula

articular surface for

/ marginal ray radials bases of fin rays

dorsal process of coracoid

coracoid ridge

lateral arm of cleithrum

medial arm of cleithrum

Fic. 7A. Articular region of pectoral girdle of Makaira indica.

RIGIDITY OF PECTORAL FIN OF MAKAIRA INDICA (CUVIER) Lyi]

anterior dorsal process posterior dorsal process

of cleithrum of cleithrum

marginal ray

articular surface

articular surface for

marginal ray

scapula

radials

dorsal process of coracoid

lateral arm of cleithrum coracoid ridge

medial arm of cleithrum

Fic. 7B. Articular region of pectoral girdle of Makaira audax.

first two is an area of attachment rather than articulation, most movement

taking place between their distal ends and the bases of the rays. The third and

fourth radials are slightly more movable, and movement is possible between

the second and third radials in all species. The distal ends of the first two radials

are smoothly curved in M. audax, allowing free movement of the rays over them,

but are strongly rugose and pitted in M. indica for the attachment of connective

tissue. The last ten rays are movably articulated on the distal ends of the third

and fourth radials in both species.

In both M. audax and M. indica the pectoral fin is held to its articular

surfaces by a connective tissue sheath, but this sheath shows significant differ-

ences in the two species. In M. audax the ligaments are elastic and loosely

arranged so as to allow maximum movement of the joint, but in M. indica a very

strong sheath of interwoven fibrous tissue is developed which holds the fin

strongly to its articular surfaces; the fibres are short and their area of attach-

ment to the bone is more extensive than in M. audax.

bases of fin rays

178 ANNALS OF THE SOUTH AFRICAN MUSEUM

VI. Discussion

No features of the osteology of the pectoral girdle other than the articular

region suggested a mechanism for maintaining the rigidity of the fin. The muscu-

lar system, although showing differences connected with the movements

carried out by the fin in the two species compared, is not adapted to hold the fin

away from the body in ™. indica.

It is suggested that the only difference between the pectoral girdles in

M. indica and the other species studied which is large enough to be of significance

in the functioning of the joint of the pectoral fin lies in the position and confor-

mation of the articular surfaces of the fin, in particular that for the marginal

ray, and in the development of the connective tissue of the joint.

Owing to the flat, lateral articular surface for the marginal ray base of the

fin of M. indica, the fin cannot roll back so that its base rests on the dorsal edge

of the scapular, without leaving its articular surface; to prevent it from being

forced off its articular surface by the pressures it encounters in the extended

position, a very strong connective tissue sheath is developed around the joint.

This tough connecting sheath prevents the fin from lying back against the body.

If the fin is forced back against the body in a dead specimen, an operation

requiring considerable force, the connective tissue sheath is torn. The bones,

including the radials, are undamaged, suggesting that there can be no bony

locking or strutting device for maintaining the rigidity of the fin.

After the ligaments have been broken the fin can fold back considerably

farther than before, but not completely as in the other species; it is stopped by

the dorsal expansion of the marginal ray being jammed against the posterior

edge of the posterior dorsal process of the cleithrum, which is slightly thickened

in this species. Unless the ligamentous sheath is torn this position is not reached,

so this is not a mechanism for holding the pectoral fin rigid.

It is suggested that at some time and for some reason in its evolutionary

history M. indica or its ancestors found it necessary to maintain the fin in a

laterally extended position. This was presumably accomplished at first by

muscular contraction sustained over long periods, but in time the tension was

taken by greatly strengthening the connective tissue sheath attaching the fin to

the girdle, and the inner portion of the girdle’s articular surface, which is used

only when the fin lies against the side, was lost.

The pectoral fin of the black marlin appears to act either as a stabilizer,

or as a plane of elevation. The body is very large and deep, and it may be that

some stabilizing factor is necessary during forward movement. The broadbill

swordfish, Xiphias gladius, of similar body shape, also has rigid pectoral fins.

However, if this is the reason for the modification, it is surprising that the blue

marlin, Makaira nigricans, also a large, deep-bodied marlin, does not have rigid

pectoral fins.

The other possibility, that the fin acts as a plane of elevation during forward

movement, deserves consideration.

RIGIDITY OF PECTORAL FIN OF MAKAIRA INDICA (CUVIER) 179

It is interesting to speculate on the possible reasons for the necessity of such

continuous lifting force. In pelagic surface teleosts very small marine species

usually possess a well-developed closed swim bladder, but among many medium

and large sized species, particularly in the Scombridae, it is variable or absent

(Jones & Marshall, 1953). For example, in many species of the genus Thunnus, it

is variably reduced or rudimentary; in Aatsuwonus pelamis, Sarda lineolata,

S. chiliensis, the genus Auxis, the genus EKuthynnus and most species of the genus

Scomberomorus, it is absent. It is probable that in fast-swimming forms which

change depth rapidly a large swim bladder is a liability because of its necessarily

slow change of volume. The absence or reduction of the swim bladder would

necessitate some upward thrust to counteract the tendency to sink because of

increased density. In such powerfully swimming fishes as the tunas and the

marlins where forward movement may be continuous this presents little

difficulty, and presumably the increased effort has not been too great to offset

the advantage gained in vertical manoeuvrability.

Preliminary examination (dissection of one black marlin and one striped

marlin) showed that the swim bladder structure is very different between the

two species, and that the black marlin seems to have a relatively smaller swim

bladder. This work is being continued.

It is therefore tentatively suggested that the black marlin has a reduced

swim bladder, and that some upward thrust is supplied by the rigid pectoral fins.

Comparison may be made here with the sharks. In this group the pelagic

surface forms are large, and in the absence of a swim bladder upward thrust

is obtained by the broad and rigid pectorals.

ACKNOWLEDGEMENTS

We are indebted to the manager and skippers of the Atlantic Tuna

Corporation and to Mr. F. Slack and Mr. W. Gilmore of the South African

Marlin & Tuna Club for the specimens; to Dr. N. A. H. Millard of the Zoology

Department of the University of Cape Town and Mr. M. J. Penrith of the

South African Museum for advice and help; to Professor L. H. Wells of the

Department of Anatomy, University of Cape Town, for advice on joints; and

to all those who helped with the conveying and handling of the material.

The Trustees of the South African Museum gratefully acknowledge the

grant-in-aid towards the cost of publishing this paper made by the Council

for Scientific and Industrial Research.

REFERENCES

Grecory, W. K., & Conran, G. M. 1939. Body forms of the black marlin and the striped

marlin of New Zealand and Australia. Bull. Amer. Mus. nat. Hist. 76: 443-456.

Jones, F. R. H., & Marsuatt, N. B. 1953. The structure and functions of the teleostean swim-

bladder. Biol. Rev. 28: 16-83.

LaMonte, F. R. 1955. A review and revision of the marlins, genus Makaira. Bull. Amer. Mus.

nat. Hist. 107: 323-365.

180 ANNALS OF THE SOUTH AFRICAN MUSEUM

LaMonte, F. R., & Marcy, D. E. 1941. Swordfish, sailfish, marlin, and spearfish. Ichthyol.

Contr. internat. Game Fish Assoc. & (2): 1-24. (Not seen. Information from Morrow, 1957.)

Morrow, J. E. 1957. On the morphology of the pectoral girdle in the genus Makaira. Bull.

Bingham oceanogr. Coll. 16 (2): 88-105.

Nakamura, H. 1938. Report of an investigation of the spear-fishes of Formosan waters. U.S.

Fish & Wildlife Serv., Spec. Sci. Rpt. Fisheries, 153, 1955 : 1-46.

Rosins, C. R. 1957. Charles F. Johnson Oceanic Gamefish Investigations, Progress Rpt. 4.

Rosins, C. R., & DE Sytva, D. P. 1961. Description and relationships of the longbill spearfish,

Tetrapturus belone, based on western North Atlantic specimens. Bull. Mar. Sci. Gulf and

Caribbean. 10 (4): 383-413.

Suann, E. W. 1919. The comparative myology of the shoulder girdle and pectoral fin of fishes.

Trans. Roy. Soc. Edinb. 52: 531-570.

Smiru, J. L. B. 1956. Swordfish, marlin and sailfish in South and East Africa. Ichthyol. Bull. 2,

25-33:

Tatsot, F. H. & Penritu, M. J. 1962. Tunnies and marlins of South Africa. Nature. 193,

no. 4815: 558-559.

Ann. S. Afr. Mus., Vol. XLVIII Plate II

(6) Extended position.

Range of movement in Makaira audax.

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REFERENCES

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Volume number in arabic numerals (without prefix ‘vol.’), with wavy underlining (black type).

Part number, only if separate parts of one volume are independently numbered. Page numbers,

first and last, preceded by a colon (without prefix ‘p’). Thus:

Smiru, A. B. 1956. New Plonia species from South Africa. Ann. Mag. nat. Hist. (12) 9: 937-945.

When reference is made to a separate book, give in this order: Author’s name; his initials;

date of publication; title, underlined; edition, if any; volume number, if any, in arabic numerals,

with wavy underlining; place of publication; name of publisher. Thus:

Brown, X. Y. 1953. Marine faunas. 2nd ed. 2. London: Green.

When reference is made to a paper forming a distinct part of another book, give: Name of

author of paper, his initials; date of publication; title of paper; ‘In’, underlined; name of

author of book; his initials; title of book, underlined; edition, if any; volume number, if any,

in arabic numerals, with wavy underlining; pagination of paper; place of publication; name

of publisher. Thus:

SmirH, C. D. 1954. South African plonias. Jn Brown, X. Y. Marine faunas. 2nd ed. 3: 63-95.

London: Green.

SYNONYMY

Arranged according to chronology of names. Published scientific names by which a species

has been previously designated (subsequent to 1758) are listed in chronological order, with

abbreviated bibliographic references to descriptions or citations following in chronological

order after each name. Full references must be given at the end of the paper. Articles and

recommendations of the International code of zoological nomenclature adopted by the XV International

congress of zoology, London, July 1958, are to be observed (particularly articles 22 and 51).

Examples: Plonia capensis Smith, 1954: 86, pl. 27, fig. 3. Green, 1955: 23, fig. 2.

When transferred to another genus:

Euplonia capensis (Smith) Brown, 1955: 259.

When misidentified as another species:

Plonia natalensis (non West), Jones, 1956: 18.

When another species has been called by the same name:

[non] Plonia capensis: Jones, 1957: 27 (= natalensis West).