i
tel Bessie
BOIEEE TIN OF
THE BRITISH MUSEUM
(NATURAL HISTOR Y )
ZOOLOGY
Wolle7
1960-1962
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM (NATURAL HISTORY)
LONDON: 1962
DATES OF PUBLICATION OF THE PARTS
No. 1. 4 November 1960
No. 2. 22 July 1960
No. 3. 24 February 1961
No. 4. 3 February 1961
No. 5. 30 March 1961
No. 6. 18 April 1961
No. 7: 30 May 1961
No. 8. 23 June 1961
No. 9. 20 February 1962
PRINTED IN
GREAT BRITAIN
AT THE y
BARTHOLOMEW PRESS
DORKING
BY
ADLARD AND SON LTD.
NS
CONTENTS
ZOOLOGY VOLUME 7
Hearing in Cetaceans. By F. C. Fraser and P. E. Purves (Pls. 1-53)
Les types d’Harpagophoridae de R. I. Pocock conservés au British
Museum (Natural History) (Myriapodes, Diplopodes). By J. M.
Demange
A proposed reclassification of the Gastropod family Vermetidae.
By A. Myra Keen (Pls. 54-55)
A revision of the genus Dinotopterus Blgr. (Pisces, Clariidae). By
P. H. Greenwood
The taxonomy and identification of Pipits (genus Anthus). By B. P.
Hall (Pls. 56-67)
Free-living Nematodes from South Africa. By William G. Inglis
The species of Rhabditis (Nematoda) found in rotting seaweed on
British beaches. By William G. Inglis and John W. Coles.
The Dealfishes (Trachipteridae) of the Mediterranean and north east
Atlantic. By G. Palmer (Pl. 62)
A young Macristium and the Ctenothrissid fishes. By N. B. Marshall
The distribution of pelagic Polychaetes across the north Pacific. By
Norman Tebble
Index to Volume 7
PAGE
372
493
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_ HEARING IN CETACEANS
PLUTON OFTHE , ACCESSORY AIR. SACS
YD THE STRUCTURE AND FUNCTION OF
E OUTER AND MIDDLE EAR IN RECENT
CETACEANS
? (= 7Ua a Se
cc i A ~ Se ’
PRESENTED Pilecct
BULLETIN’ OF
BRITISH MUSEUM (NATURAL HISTORY)
LOGY Vol. 7 Noga
LONDON: 1960
PTS(PR)
PT
PTS(PO)
FRONTISPIECE.—SKULL OF A YOUNG PILOT WHALE IN WHICH THE AIR SINUS SYSTEM
AND ITS VASCULAR NETWORK HAVE BEEN INJECTED WITH POLYESTER RESIN.
AM —Mandibular artery.
AMI—Internal maxillary artery.
apt—Pterygoid artery and arterial branches
to internal pterygoid muscle
ET —Eustachian tube.
FVp—Fibro-venous plexus.
ms —Middle sinus.
PBS —Peribullary sinus.
PT —Pterygoid bone.
PTS —Pterygoid sinus.
PTS (PR)—Preorbital lobe of pterygoid sinus.
PTs (PO)—Postorbital lobe of pterygoid
sinus
TB —Tympanic bulla.
By Courtesy of ‘ ENDEAVOUR”.
HEARING IN CETACEANS
EVOLUTION OF THE ACCESSORY AIR SACS AND THE
SIRUCTURE AND FUNCTION OF THE OUTER AND
MIDDLE EAR IN RECENT CETACEANS _
PRESENTED
BY
F, C. FRASER and P. E. PURVES
British Museum (Natural History)
Pp. 1-140; Plates 1-53; 34 Text-figures
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 1
LONDON : 1960
THE BULLETIN OF THE BRITISH MUSEUM ¥
(NATURAL HISTORY), instituted in 1949, ts i
issued in five series corresponding to the Departments .
of the Museum, and an Historical Series.
Parts appear at irregular intervals as they become
ready. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No. 1 of the Zoological series.
© Trustees of the British Museum, 1960
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM
Issued September, 1960 Price Eighty Shillings
HEARING IN CETACEANS
EVOLUTION OF THE ACCESSORY AIR SACS AND THE
STRUCTURE AND FUNCTION OF THE OUTER AND
MIDDLE EAR IN RECENT CETACEANS
By F. C. FRASER AND P. E. PURVES
CONTENTS
Page
HISTORY . : : : : : d : : ee
BASICRANIAL ANATOMY 0 9 3 Sy
PTERYGOID AND NASOPHARYNGEAL MUSCLES a : 6 (a
DELPHINUS . C ¢ 5 ° 6 : 0 . oO |
MESOPLODON . : > : 5 : : 2 E 22
BALAENOPTERA 5 5 , 0 : ¢ : ee
VASCULAR SYSTEM . < ° 6 , f , E 5 2
ARTERIAL SUPPLY . ° fs : 5 5 cl : 23
VENOUS DRAINAGE ¢ 6 z C 26
CONTENTS OF THE AIR SACS AND HISTOLOGY 3 4 = 30
OSTEOLOGY c 5 cl : 6 0 a : : o 33
MYSTICETI : ‘ c 3 0 ° < 4 ° eS 4
BALAENOPTERIDAE . 5 5 6 b 4 r = 134)
BALAENIDAE . : f . F 6 g 6 F 35
ESCHRICHTIDAE : i : , _ . : : é 39
ODONTOCETI . 5 ; : 2 2 : 5 z - 39
ZIPHIOIDEA . a - 5 Z < : 3 5 E 39
PHYSETEROIDEA ‘ , : 2 ° 7 ; c 41
PLATANISTOIDEA . : = < ‘ Z 5 5 : 43
MONODONTOIDEA . A 5 5 5 5 : 47
DELPHINOIDEA c 6 . 5 c 5 a 3 - 49
PHOCAENIDAE . = : 5 : : “ : e 49
DELPHINIDAE . : : Fi 5 i i - 2 49
“ DISTRIBUTION OF AIR SPACES . 0 : S : 0 “ 61
ODONTOCETI : : 5 0 3 7 F a : Or
Stenodelphis blainvillei —. c : : z : 5 LO?)
Inia geoffrensis 5 2 : : é a a 5 = 163
Phocaena phocoena . ° é 0 : 0 o E o |
Lagenorhynchus albivostris : : : E : - 66
Globicephala melaena F : ; 0 0 3 5 POT)
Grampus griseus. 0 0 : c : 0 = (33)
Tursiops truncatus . : : : . : . . . 7o
Delphinus delphis . : : : oO : 5 5 oft
Mesoplodon bidens . 5 : 5 : : - 2
MYSTICETI : 5 5 . 0 6 6 z 7S
Balaenoptera acutorostrata.. 6 ° ¢ : : 3 Ss 95}
ZOOL. 7, I
4 HEARING IN CETACEANS
Page
EVOLUTION OF THE AIR SACS é 75
DISSOCIATION OF THE TYMPANO- PERIOTIC BONES FROM
THE SUEL : Wil
THE INVASION OF THE PTERYGOID BONE BY THE MIDDLE
EAR CAVITY . : ; a : 3 3 3 6 80
SYSTEMATIC ARRANGEMENT 5 2 5 : : 0 = od
MYSTICETI i . 6 . ; : é ; F F 85
ODONTOCETI. : 0 5 5 6 : : 2 87
ZIPHIOIDEA . - 9 P : : 4 : 5 87
MONODONTOIDEA . j 3 : : 2 ° “ ee
PHYSETEROIDEA : : : d p a : : ¢ 89
PLATANISTOIDEA . : : : : : : : - 89
DELPHINOIDEA : A : 5 “ = : 5 0) 6B
FUNCTION . : 5 : : 0 - 108
EXTERNAL AUDITORY MEATUS Q f 5 . a - 108
TYMPANIC MEMBRANE . 5 : 6 : : é 2 eZ
MIDDLE EAR . 5 0 0 : : 5 0 Bent
MALLEUS 5 F : ci : : 2 : 6 ali/
Incus . . : = 5 c 3 : é Gg tthiy/
STAPES . 9 ; é : és é Gains)
MUSCLES OF THE Minor EAR > 118
THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVI
DENCE . : b : fs 7 LES
HYDRODYNAMIC FUNCTIONS OF THE "AIR Sacs z 0 . «118
Acoustic FUNCTION OF THE AIR SACS. c 123
EXPERIMENTAL EVIDENCE OF THE SOUND Conpuerivity OF THE
MEatTus . 5 6 ze
EXPERIMENTAL EvIpENcE OF Acousric Matcurne 0 5 = L277,
DISCRIMINATION AND DIRECTIONALITY ; < a : a gO)
THEORIES OF CETACEAN HEARING F 0 4 A ) etg2
CONCLUSIONS . c c 5 : 5 : g » 135
ACKNOWLEDGMENTS ; : : . 6 5 c 5 =) 136
KEY . 0 5 é a rs 5 : : . ‘ 6 7 Se,
“
Notes. In the diagrams referred to in Figs. 16-21 as “ transverse section ’”’ the
plane of the section is through the foramen ovale and pterygoid hamulus. Owing to
the progressive displacement forward of the hamuli from the foramen a varying
degree of obliquity is introduced.
In relating Diagrams 22-25 to the skulls figured in Plates 5-47, it should be
remembered that the latter represent ventro-lateral views of the skull.
Contractions used in the text-figures are to be found in the Key, Page 137.
HISTORY
In their previous paper (Fraser and Purves 1954) the writers made reference to
the subject of pressure equalization and adjustment on either side of the tympanic
membrane in the Cetacea. It was shown that Beauregard was the first to suggest
a hypothesis which appeared to satisfy all the anatomical and physical requirements
of the conditions encountered by cetaceans in their natural environment. Beauregard
was however by no means the first to recognize the existence of the accessory air
sinuses of the middle ear, and as a preliminary to the writers’ own observations a
brief historical summary of the earlier work on this subject is required.
HEARING IN CETACEANS 5
Camper (1777) gives reference to Joh. Dan Major as the discoverer of the peribul-
lary sinus in the year 1672, quoting the latter’s paper he states ‘“‘ one should know
that the petrous bones are not tightly attached to the cranium, but are lying loosely
between the flesh and the fat close to the base of the brain and the occiput, at the
side of the head, in a sinus, which is formed by two processes which do not touch
each other’’. Dan Major thus antedates Tyson (1680) who in his Anatomy of the
Porpoise made much the same observation.
Hunter’s (1787) description is a little more detailed. It is as follows :
“The Eustachian tube opens on the outside of the upper part of the fauces ;
in some higher in the nose than in others ; highest I believe, in the Porpoise. From
the cavity of the tympanum, where it is largest, it passes forwards and inwards,
and near its termination is very much sacculated, as if glandular’.
“The Eustachian tube and tympanum communicate with several sinuses, which
passing in various directions surround the bone of the ear. Some of these are cellular,
similar to the cells of the mastoid process in the human subject, although not bony.
There is a portion of this cellular structure of a particular kind, being white, liga-
mentous, and each part rather rounded than having flat sides. One of the sinuses
passing out of the tympanum close to the membrana tympani goes a little in the
same direction and communicates with a number of cells’.
“The whole function of the Eustachian tube is perhaps not known; but it is
evidently a duct from the cavity of the ear, or a passage for the mucus of these
parts ; the external opening, having a particular form would incline us to believe
that something is conveyed to the tympanum ’’.
Monro (1785) from the results of the dissection of a porpoise appears to have been
the only writer to suggest the relationship of the air sinuses with the frontal, sphenoidal
and maxillary sinuses of terrestrial mammals and it is noteworthy that these sinuses
as such are totally absent in cetaceans.
Home (1812) found in Balaena mysticetus that the Eustachian tube had a
similar glandular and sacculated appearance to that seen by Hunter in the porpoise.
Rapp (1837) made a review of the existing information about the cetacean ear
and demonstrated in the porpoise the relation of the air sacs to adjacent bones.
He stated that the anterior end of the tympanum was open and extended into a
branching sinus. In front of the cavity of the tympanum lay a membranous, ovoid
cavity over an inch long and wide enough for the insertion of a finger. Its upper and
inner wall lay immediately against the bony surface of the skull. Branches extended
further out, one forward, ending in the cavity of the pterygoid bone. Another went
somewhat higher and forward to the outer side of the ascending branch of the palatine,
and ended blindly, immediately behind the tooth row of the upper jaw. Still another
branch went upwards, and passed into a bony canal which was found in the bone
of the upper jaw, ascending on the outer side of the nasal cavity, until it reached
the frontal bone and ended blindly. An extension of the main sinus passed outwards
and ended under the supra-orbital process of the frontal, and finally a backward
extension passed between the ear bones and the ridge of the basioccipital bone.
All the sinuses were lined by a thin, and on the inner surface, smooth, white, glandular
membrane. He described the Eustachian tube and in addition to what was already
6 HEARING IN CETACEANS
known, noted the absence of cartilage in its structure and that it passed through
no bone. He observed the presence of crescent-shaped valves projecting into the
lumen of the tube and directed towards the nares. In his opinion the valves could
not quite close the lumen. Rapp gave a description of the pterygoid muscles and
in general Stannius’ (1849) account agrees with that of the former author.
Carte and Macalister (1868) gave an account of the dissection of a Lesser Rorqual
which, in addition to a short description of the osteology and musculature of the
pterygoid region, included a more detailed reference to a very remarkable plexus
of arteries and veins which lay in a distinct cavity bounded internally by the ptery-
goid muscle and externally by the angle of the mandible and fibro-cartilage. The
cavity was lined by an extremely delicate, glistening, membranous structure, similar
in texture and appearance to the serous lining membrane of the veins. The vascular
plexus itself extended from the coronoid process of the lower jaw to a point midway
between the angle of the latter bone and the upper border of the sternum. The
venous ramifications that partly formed the plexus gradually united as they passed
backwards and ultimately formed one trunk, the jugular vein.
In the course of his work on the anatomy of the Pilot Whale (Globicephala melaena)
Murie (1878) noted several anatomical features which he considered to be common
to cetaceans in general. ‘‘ In all the Cetacea cut up by me I have observed well
developed and separate pterygoider. The external, flat, broad, fleshy and of a quadri-
lateral shape, is fixed to the outer surface of the pterygoid plate and with a downward
and forward plane goes to the inner surface of the lower jaw chiefly to the upper
margin of the bone. The internal muscle arises from the superficies of the prominent
portion of the pterygo-palatine, passes backwards and downwards to the mandible.
Inferiorly and on its posterior border, the latter muscle sends off tendinous fibres
which join those of the articulating condylar process of the mandibular.’’ Following
a description of the tympanic bulla and neighbouring tissues which coincides with
those of earlier writers he goes on, “‘ The Eustachian canal as it leaves the tympanic
bulla, has considerable diameter and retains it more or less uniform as it passes
towards the fauces. A tough membrane and retia mirabilia lie superficial to it ’’.
Later he states: ‘‘ Of the cranial vascular distribution, circumstances did not
permit me to master it in detail. The more notable observations I could make were
chiefly regarding a great plexus situated at the inferior base of the skull and situated
with a rete occupying the proximal infundibular cavity of the mandible. I subse-
quently had an opportunity of investigating the same in Grampus and Lagenorhynchus
where it likewise obtains’.
“ The internal maxillary artery having passed deeply behind the lower jaw, and
made a bend, sends forwards a long inferior dental artery. As this pursues its course
it distributes ramifications among the fatty matters and plexus presently to be
mentioned. The mandibular cavity contains a mass of softish, marrow-like sub-
stances held together by a network of fibrous tissue. Moreover the interstices are
occupied with a maze of vascular channels partly composed of arterial and partly
of venous capillaries interwoven irregularly. Next the bone the tissue and vessels are
firmly adherent te the periosteum in some cetaceans, e.g. the great Balaena mysticetus
and Balaenoptera musculus, as I myself have been a witness to, the cavity in question
HEARING IN CETACEANS G)
possesses a perfectly enormous amount of oily material. Even in smaller genera
the quantity is by no means sparse ; so that the tissues hereabouts as a whole and
on section may be compared to blubber supercharged with blood vessels. Further
on, the internal maxillary gives off large muscular branches and others forming
pterygo-maxillary divisions. These latter were not followed into the cranium. The
inferior base of the skull, from the tympanic bone forwards to the maxillary, inter-
nally bounded by the levator and sphincter muscles of the posterior nares, represents
one continuous rete mirabile. This spongy network of vessels lies upon a thick
layer of fibroid tissue, and the vessels anastomose with the aforesaid mandibular
rete whilst they likewise appear to inter-communicate with another venous locular
network behind and at the root of the Eustachian tube. The venous capillaries collect
into a jugular channel more or less connected with the rete of the neck ”’.
Anderson (1879) in his account of the anatomy of Platanista found the situation
of the air sacs so comparable with the ‘‘ guttural pouches”’ of the Perissodactyla
that he refers to them as such.
His description reflects the highly involved and complicated arrangement of
these cavities but essentially they are a paired structure each member of which
originates from the Eustachian tube. Part of each sac lies between the stylo-hyoid
and the thyro-hyal, forming attachments to these, with its internal wall against the
the outer wall of the back of the pharynx while the roof of the sac lies below the
exoccipital and basioccipital bones. The inner surface of the sac is ‘‘ white, smooth,
glistening and tendinous in appearance and its wall has numerous deep recesses
of various dimensions formed by arching folds of the membrane constituting the
walls of the sacs—some of the recesses lead into small secondary pouches and from
from these into a labyrinth of smaller passages.”’
“A pair of diverticula from these sacs converge in front of the thyroid cartilage
where they are separated only by a thin membrane ’’.
Of the microscopical appearance of the Eustachian sacs Anderson says that they
are composed of loose folds of thick mucous membrane. “ Flat, irregular papillae
invest the surface, and everywhere, ... are small pits and minute orifices
of mucous glands. These glands are most of them superficially situated but some are
sunk deeper into the tissue, chiefly simple and tubular. Certain of them nevertheless
are slightly racemose ; and all contain cylindrical epithelium with often a central
cavity. The elevated papillae are exceedingly vascular, indeed possess a thick
network of fine capillaries the parent vessels of which are both numerous and of
considerable calibre. The free surfaces of the papillae are covered by a close-set
layer of cylindrical, fringed or ciliated epithelium. The deep connective tissue of
the submucous membrane is loose, strong fibred, but very open, some fat cells and
oily particles being mingled with the tissue, while elliptical-shaped great bundles of
striped muscular fibres course in different directions, right up almost to the glandular
layer in some instances ’’.
The contributions of Beauregard (1894) to the knowledge of the anatomy and
physiology of the organ of hearing of mammals constitute a major advance, especially
to the extent that they concern cetaceans. He was the first person to inject the
sacs of the middle ear and to give names to the component parts. In addition
8 HEARING IN CETACEANS
he puts forward a physiological hypothesis of their function which appears to be
more acceptable than those of earlier writers. Having successfully injected the
middle ear and sacs, both of Odontoceti and of Mysticeti, the following features
were noticed. In the Common Dolphin the Eustachian tube was funnel-shaped
anteriorly, its orifice a longitudinal slit in the posterior region of the nares. The tube
was about 4 mm in diameter and lay against the bony wall of that part of the nostril
formed by the pterygoid. For two centimetres from its orifice the tube passed
obliquely outwards and posteriorly along a notch formed by the sphenoid and
pterygoid. The mucous membrane of the tube was areolar throughout its length.
There was in addition on the inner wall, a longitudinal fibrous ridge which extended
to the lower wall of the tube and united with it near the entrance to the bulla.
The duct was thus divided into two parts, one external, which terminated in a cul-
de-sac, and another internal, which showed inside an orifice, joining the end of the
bulla and making communication between the Eustachian tube and a vast air cavity
emanating from the bulla. The orifice in question measured one cm long by three
mm wide and was placed in such a way that by its intermediate position it com-
municated simultaneously with the blind canal, the tympanic cavity and air sacs.
A downward extension of the squamosal, a characteristic feature of all cetaceans,
was designated the falciform process, a name by which it is now recognized. The
names employed by Beauregard for the divisions of the sinus system are so generally
applicable that they will be used as applied by Beauregard throughout this paper
with one exception. The following is a summary of Beauregard’s description. The
sacs or sinuses are as follows :
1. The Anterior Sac.
2. Pterygoid Sac.
3. Peribullary Sac.
4. Posterior Sac.
5. Medial Sac.
All of these cavities communicate with the middle ear proper.
The anterioy sac. This is very large—extending over all the ventral surface of
the cranium anterior to the falciform process, surrounding the foramina of the
cranial nerves and penetrating between the irregularities of the bone in the frontal
and preorbital regions. In the Common Dolphin it is prolonged in a deep channel
extending in the ventral surface of the maxilla for about two thirds of the latter’s
length. (As the greater part of the sac has been identified by the present writers
as belonging properly to the pterygoid sac, the use of ‘“‘ Anterior Sac’’ will be
restricted to that part of the system projecting beyond the posterior limit of the
rostrum).
The pterygoid sac. A large diverticulum, filling the deep cavity which the palatine
and pterygoid make as they fold below the sphenoid, is given the name of the
pterygoid sac. Part of the Eustachian tube in its course to its external opening
lies in close apposition to this sac.
The peribullary sac. Beauregard’s anterior sac communicates posteriorly with
a space which lies between the periotic and the bones of the cranium. This cavity,
limited mesially by the occipital crest and dorsally by the dura mater contains the
HEARING IN CETACEANS 9
ear bones. The fibrous, saccular extension from the “ anterior sac ’’ which lines the
cavity is called the peribullary sac. Beauregard pointed out that it does not extend
to the ventral surface of the bulla which is covered in this region by a thick pad of
fibrous tissue.
The posterior sac. The posterior sac communicates with the tympanic cavity
by the posterior orifice of the bulla. It occupies the concavity of the paroccipital
process. This cavity is sheathed in thick cartilage and enveloped anteriorly and
posteriorly in a strong cushion of fat.
The medial sac. The medial sac communicates with the tympanic cavity by the
petro-tympanic orifice and is situated under the concave surface of the zygomatic
process, internal and posterior to the glenoid fossa. It is prolonged into the groove
formed in this region and is limited anteriorly by the curved and concave border
of the falciform process. The present writers will refer to the concavity in the
squamosal in which the medial sac is lodged as the tympano-squamosal recess.
All the sacs are distinguished by the presence of numerous trabeculae which divide
their cavities into complicated air pockets. Blood vessels, especially veins, form
a rete of great richness. From the superior wall of the great “anterior sac”’ a thick,
prominent ridge of mucous membrane protrudes, which is areolar and very vascular
and gains access to the bulla by which it penetrates the tympanic cavity. This fold,
reduced to very nearly a cylindrical cord when it enters the cavity, is there developed
into a spongy mass which passes along the whole length of the bulla. Beauregard
goes on to say that it is attached by its concave border to the anterior process of
the external lip of the bulla, then to the body of the malleus near the tubercle to
which is attached the ligament of the tympanic membrane. It terminates by an
enlarged extremity near the fenestra rotunda, fixing itself to the base of the mastoid
process.
According to Beauregard, the relationship of this spongy mass with the hammer
and the anterior orifice of the bulla gives rise to the supposition that it acts as a
muscle for the malleus; but on microscopic examination he was unable to find
any trace of muscle fibres. (For discussion of this see page 29).
He injected the vessels of the region of the ear of a foetal dolphin 110 cm long.
He found that the internal carotid artery accompanied by the (internal) jugular
vein passed along the deep notch separating the basi-occipital from the mastoid
region. It penetrated the tympanic cavity in the space which limits the internal
lip of the bulla and the groove which separates the posterior promontory of the
bulla from the periotic. In this first part of its course the internal carotid artery
was a neighbour of the facial nerve. In the tympanic cavity it occupied the long
axis of the spongy mass and measured not less than 3 mm in diameter. Its course
was sinuous. It made a curve towards the dorsal convexity, another towards the
ventral convexity, and then made straight towards the anterior extremity of the
tympanic cavity. It emerged from that extremity and penetrated the great
“anterior air sac’’, crossing the latter obliquely before entering the carotid orifice
of the cranium. During its passage across the tympanic cavity the carotid artery
was found to be enveloped in a voluminous venous plexus, the varicose ramifications
of which measured from 1-5 mm in diameter. This plexus, mixed with fibrous
10 HEARING IN CETACEANS
tissue is the enigmatic spongy organ. Beauregard considered the spongy organ, in
common with all the other venous retia in the pterygoid region, to be erectile, but
this aspect of his hypothesis will be discussed later (pages 119-120).
Beauregard continued his researches by injecting the air sinuses of a Lesser
Rorqual. He found that the Eustachian tube, in its course rearwards, passed between
the angle formed by the inferior border of the sphenoid and the hamular process
of the pterygoid. Subsequently it connected with a large ovoid sinus occupying
the pterygoid. He considered the sinus to be an enlargement of the posterior
extremity of the Eustachian tube, and established the connection between these and
the tympanic cavity proper. He homologized a large cavity on the upper and mesial
surface of the bulla with the peribullary sac, and similarly a small diverticulum
at the posterior extremity of the bulla was recognized as the posterior sac.
Finally Beauregard identified the “ glove finger’’ of the tympanic membrane
with the medial sac, but the present writers (Fraser and Purves, 1954) suggested its
relationship with the “ pars flaccida ’’ (but see also p. I13-5).
Denker (1902) examined the ear region of cetaceans and although not dealing
with the anatomy of the air sinuses suggested a possible means by which they
function.
The work of Boenninghaus on Phocaena phocoena contained in two monographs
produced in 1902 and 1904 constitutes the most comprehensive study of the anatomy
of the throat and ear of cetaceans ever published. The earlier paper is concerned
chiefly with the musculature of the throat and nose, and the other more particularly
with the ear. Parts of the latter paper are more relevant to the subject of the air
sinuses but it is necessary in the survey of them which follows to include extracts
from the earlier work. His long, detailed description of the bones of the base of the
skull recapitulates what has been written by a number of earlier writers and need
not be repeated. Information about the morphology and relationships of bones
concerned with the air sacs can be seen on Pls. 5-47. As the musculature and
associated structures of the throat and mouth are important in the comprehension
of the evolution and function of the air sacs, a more detailed note must be made of
Boenninghaus’ findings. These will be dealt with in the following order: (1)
Musculature of the posterior nares; (2) the soft parts of the pterygoid region in
general ; (3) the fibrous supporting tissue of the skull base ; (4) the intra-mandibular
fatty body; (5) the pterygoid and palatine muscles; (6) the arteries; (7) the
veins.
1. Musculature of the posterior nares. According to Boenninghaus, the muscular
complex of the posterior nares is made up of the following elements: (@) m. con-
strictor-pharyngeus-superioris, (b) m. palato-pharyngeus, (c) m. thyro-palatinus,
(d) m. salpingo-pharyngeus, (e) m. levator palati, (f) m. tensor palati, (g) m. stylo-
pharyngeus.
(a) Constrictor-pharyngeus-superioris. “‘ The whole pars superioris of the pharynx
has been greatly drawn out by the up-turning and lengthening of the presphenoid,
thereby the form of the rear wall has become changed. In land mammals the m.
constrictor inferioris seen from behind partly covers the m. constrictor medius
and the latter partly covers the constrictor superioris. The constrictors lie like
HEARING IN CETACEANS II
the slides of a half-open telescope, one over the other. In Phocaena, however, the
m. constrictor superioris is completely withdrawn from the medius and inferioris.
The gap thus created is filled by the palato-pharyngeus ’’.
(b) M. palato-pharyngeus. ‘‘ The inner face of the muscular pharynx of Phocaena
is formed, except at the palato-pharyngeal arc, by a single, extended, thick muscle,
the fibres of which lie parallel, while they are in the posterior nares, then behind
these radiate fan-wise in sweeping lines towards the rear of the pharynx so that the
lowest fibre layers encircle the epiglottis. At their posterior extremity the fibres
merge bilaterally but do not form a raphe. This muscle is further distinguished by
the fact that near its lower end a powerful sphincter muscle 9 cm thick arises from
its inner surface and is so formed that its superior surface merges without boundary
into the m. palato-pharyngeus. Its ventral, sharper rim lies mesial to the latter
and forms the mesial boundary of a pair of lateral pockets open dorsally. This
sphincter lies underneath the swelling of the mucous membrane known as the arcus
pharyngeus which tightly encloses the upper part of the epiglottis and arytenoid
cartilage.”’
(c) M. thyro-palatinus. ‘‘ From the ventral rim of this constrictor some bundles
(of muscle fibre) emerge which do not encircle the epiglottis but proceed laterally
and ventrally to be inserted into the thyroid cartilage. This extension of the pars
interna of the m. palato-pharyngeus is known otherwise only in man and the horse
and is named the thyro-palatinus.”’
(d) M. salpingo-pharyngeus. ‘‘ From the ventral extremity of the bony nares
a muscle originates, which, like the constrictor superioris passes obliquely and medially
downwards. Having emerged from the nares it lies alongside its counterpart from
the other nostril for a short distance and eventually merges with its fellow. Only
a narrow streak of the m. salpingo-pharyngeus can be observed from the inner
aspect of the naso-pharynx but on the outer aspect of the naso-pharyngeal muscle
mass it can be seen to widen considerably and overlie the united superior constrictor
palato-pharyngeus (pars externa). At its ventral extremity the m. salpingo-pharyn-
geus unites, by means of a light inscriptio tendinea ... with the m. longitudinalis
oesophagi.”’
(e) M. levator palati. ‘‘ From the upper border of the naso-pharynx there arises
a muscle which encircles the boundary of the pterygo-palatine attachment of naso-
pharyngeal muscle mass from front to rear in a pointed curve. At the anterior narial
wall it dips downward, lying close to the septum and finally merges without visible
boundary into its respective half of the pars interna of the palato-pharyngeus.”’
“ Tn its string-like outer form, as in the delicacy and lighter colouring of its fibres
it corresponds so completely with the pars interna of the m. palato-pharyngeus
and its continuation, the arcus palatinus that the whole gives the impression of
forming a combined muscle system.”’
(f) M. tensor palati. ‘ At the lower margin of the posterior nares and attaching
to the origin of the m. salpingo-pharyngeus some delicate muscle streaks leave the
region of the mouth of the Eustachian tube and radiate between the fibres of the m.
constrictor superior obliquely without our being able to follow them between these
fibres for any considerable distance.’’ Boenninghaus reports that Zuckerhandl
12 HEARING IN CETACEANS
confused the tensor palati with the internal pterygoid saying “ certainly the tensor
palati is to be found in this position in all other mammals except in the whales,
i.e. between the internal pterygoid and the Eustachian tube’’. This is discussed
in the present paper on p. 19.
(g) M. stylo-pharyngeus. ‘“‘ This is originally an unpaired muscle which springs
from the floor of the posterior nares and diverges into two limbs each of which is
attached to the rear part of its respective styloid. The free outer face of the muscle
is streaked longitudinally and without a raphe, on the inner face the fibres lack
any definite direction and are firmly fused with the ventral face of the m. palato-
pharyngeus.”’
2. The soft parts of the pterygoid region. Boenninghaus dissected the pterygoid
region in three stages, shown in PI. 1, figs. a, 6, and c (corresponding to his Pl. 12,
figs. 3, 4 and 5). The first, the most superficial stage, shows the following structures
(fig. a). The bony nasopharynx is filled by the naso-pharyngeal muscle mass which
rises into the nose through the “‘ false choanae’’ (Pl. 1, fig. a). The whole lateral
part of the skull base is covered by the m. pterygoideus internus (2) under which
posteriorly can be seen the eminence of the tympanic bulla (17). The m. pterygoideus
internus and the pharynx are separated by the pterygoid ligament (5’). When the
attachment of the pterygoid muscle is separated from this ligament, and the muscle
reflected, one sees that the ligament forms the ventral edge of a mass of tissue,
smooth and membranous posteriorly, and anteriorly pierced by large holes. The
holes give entry to the vena pterygoidea (16) and to the pterygoid fibro-cavernous
venous plexus. Laterally the m. mylo-hyoideus is reflected over the jaw. Boenning-
haus’ next figure (PI. 1, fig. b) depicts a dissection made one cm more dorsally than
that of fig. a and from which the naso-pharyngeal muscle mass has been removed.
As seen in the figure, the following structures are to be distinguished. Laterally
from the pterygoid (18) the Eustachian tube is open at its distal end and leads into
the vestibulum pneumaticum (8), this in turn leads into the bulla (17) in which is
a conspicuous body (17’) the corpus cavernosum tympanicum. Beside the tube one
sees the pterygoid fibro-cavernous venous plexus (5’). The massive fatty body of
the lower jaw (6), as well as the jaw itself, can be seen. The third dissection (fig. c)
is again one cm deeper than the previous one. The pterygoid bone, the lower jaw,
fatty body and the pterygoid muscle have been removed. The anterior pneumatic
cavities (9, 10, II) are seen to be connected with the vestibulum pneumaticum
(8). Overlying this is the pterygoid fibro-cavernous venous plexus (5’).
In the figure there are probes from space to space.
3. The fibrous supporting tissue at the skull base. The skull base of the toothed
whales has a supporting tissue which is not found in any land mammals. From this,
continues Boenninghaus, it may be assumed that it plays some important role in
these aquatic mammals One can distinguish posteriorly a smooth, flatter, non-
perforate part from an anterior portion which is thicker and pierced by many veins.
The rear part covers the bulla while the anterior part lies in front of it. The fossa
of the skull base which contains the tympano-periotic bones is closed ventrally
by a fibrous membrane which covers the ventral surface of the tympanic bulla, and
_ Is attached to the cartilaginous ventral edges of the basi-occipital, the paroccipital
HEARING IN CETACEANS 13
and the zygomatic process of the squamosal. This tissue bridges the paroccipital
fissure and is penetrated by the meatus and facial nerve. Boenninghaus makes the
important indication that he regarded the tissue as the perichondrium or the perio-
steum of the bones just referred to. The tissue round the bulla is up to I cm thick
and is strongly attached to the roughened, ventral surface of the latter, acting as
a support ventrally for the bulla.
From the posteriorly directed tip of the ala palatina (19) and from the adjacent
plate of the pterygoid (8) there originates a wide, reticular, ventral membrane. It
is directed posteriorly towards the supporting tissue of the bulla and merges with it.
Mesially it covers the Eustachian tube (7, fig. 6) and the vestibulum pneumaticum
(8) and ends ventrally in a ligament-like edge, the pterygoid ligament (5, fig. a).
Laterally the membrane has a wide attachment to the falciform process. Part of
the membrane in this region does not fasten on to the wide line of attachment but
runs more posteriorly and laterally, surrounding the bulla, and merging with the
thickened periosteum of the zygomatic process. This membranous tissue is traversed
by many large and small intercommunicating, venous cavities which appear oval
in transverse section. It has extensions which pass round the median aspect of the
Eustachian tube and through the gaps in the skull to the dura mater. There is
also an extension from the zygomatic process of the squamosal to the post-orbital
process of the frontal ( fig. 22c,) which closes the otherwise incomplete orbit ventrally.
4. The intra-mandibular fatty body. On the inner surface of the lower jaw of
toothed whales is a fatty body of considerable size (Pl. 1, fig. 6). An interesting
peculiarity of the lower jaw is that the posterior half of the median wall is completely
absent. The anterior half ends in a posteriorly open arcuate edge which forms the
entrance to the wide mandibular hiatus corresponding to the mandibular foramen
of other mammals. The wide, bony trough at the hinder end of the lower jaw is
occupied by the fatty body. Boenninghaus considers this to be the bone marrow
of the posterior half of the lower jaw, and states that it is covered by a strong fibrous
tissue continuous with the periosteum of lateral aspect of the lower jaw, and forms
an attachment for the pterygoid and mylo-hyoid muscles (see fig. 0). The fatty
body is traversed by the mandibular vessels and nerves and a strong fibrous tissue
with a wide mesh. The marrow lying in this tissue mesh is not of the usual con-
sistency but is semi-liquid and oil-like. It has a tendency to hypertrophy since it
sends out extensions covered by periosteum in various directions. It forces its
way to the mylo-hyoid (PI. 1, fig. 6, 5) and grows forward over the edge of the hiatus
mandibularis for some distance, lifting the pterygoid muscles from the ventral
border of the jaw. Also a further extension lies in the deep trough adjacent to the
ventro-lateral aspect of the bulla and, according to Boenninghaus, is continuous
with the supporting fibrous tissue of the latter.
5. The pterygoid muscles. According to Boenninghaus the internal pterygoid
muscle (2 in Pl. 1, figs. a and 6) covers the whole of the ventro-lateral skull base.
It originates from the lateral edge of the maxilla, from the lateral edge of the palatine,
from the palatine process of the pterygoid, from the pterygoid ligament and from
the basioccipital process. From these attachments the fibres stretch obliquely
backwards and outwards and are inserted into the mesial periosteal wall of the lower
14 HEARING IN CETACEANS
jaw fatty body. Posteriorly it is attached to the fibrous sheath of the bulla and
anteriorly to the bony part of the mandible (but see p. 18).
The external pterygoid lies dorsally and laterally to the internal pterygoid and
has a similar but more dorsally situated origin. Its insertion is also partly on the
periosteum of the marrow and on the narrow dorsal edge of the posterior portion
of the lower jaw. Its course is obliquely outwards and more horizontal than that
of the internal pterygoid (but see p. 17-18).
6. Arterial supply. Boenninghaus describes the vascular system of the base of
the cranium in great detail, but only certain features of his account are relevant to
the present paper. His main concern is with the course and atrophy of the internal
carotid artery and with the alternative cranial blood supply through the spinal
meningeal arteries. Nevertheless, the diagram which he uses to illustrate the first
of these features is useful for showing the external carotid and its extensions, although
Boenninghaus regarded it as unnecessary of mention in his text. The figure (Text-fig.
1) shows the very short innominate artery giving rise soon to the internal and external
carotids. The external carotid curves slightly round the lateral aspect of the tym-
panic bulla after having given off a branch labelled “external maxillary ’’ by
Boenninghaus but more correctly to be interpreted as the transverse cervical, it
passes forward lateral to the air sacs and gives off a plexus of vessels supplying
the fibro-cavernous venous plexus; at about the same point the temporal artery
originates. The main stem continues anteriorly as the internal maxillary.
7. Venous drainage. As with arterial supply so with the venous drainage system
Boenninghaus’ account is very involved and difficult to follow. It is perhaps best
understood, for the purpose of later discussion (p. 29) by reference to his schematic
diagrams (Text-fig. 2) reproduced here. Although his identification of the main
venous trunks, coincides with that of the present writers his interpretation of some
of the details is open to criticism.
Hanke (1914) examined the foetuses of several whalebone whales and was able
only to identify the peribullary and medial sinuses. “‘ The largest of the pneumatic
cavities the sinus pterygoideus seems to develop at rather a later stage and its
size and position is influenced by the position of the tympano-periotic.’’ He further
noted that while in the embryo the pterygoid is in contact with the anterior margin
of the bulla, in the adult there is a gap of as much as 10 cm between the two.
Brazier Howell (1930) observes that ‘‘ in the whalebone whales (at least in Balaen-
optera) the anterior part of the bulla projects into a fossa the size of one’s two fists
and in freshly killed specimens this is entirely filled with a coarse foam of albuminous
rather than greasy texture. ... There is free communication between this
fossa and the choanae. In the odontocetes there is a different but analogous system
of air sinuses adjoining the middle ear, and connecting with an intricate labyrinth
of ducts. Authors have been very vague and cautious about describing these ducts,
and with good reason, for without the injection of a suitable coloured mass into this
part of the freshly killed specimen their proper definition is utterly impossible as
their finer ramifications are otherwise not to be distinguished from adjoining blood
vessels and oil ducts. It must therefore suffice to say that this system of air sinuses
communicates with the choanae and apparently sends trabeculated branches rami-
HEARING IN CETACEANS
4
atl Wn hy
Ht Nie
AWN
HOA
Vig
Fic. 1. Boenninghaus’ (1903) figure of the course of the internal carotid artery, right
side ventral view, of Phocaena, 116 cm. long.
1. Paroccipital process. 2. Basioccipital. 3. Tympanic bulla. 4. Periotic.
5. Eustachian tube (= Boenninghaus’ vestibulum pneumaticum). 6. Tympanic cavity.
7. Posterior aperture of the tympanic cavity. 8. Anterior entrance of the same.
9. Paroccipital notch. 10. Corpus cavernosum. 11. Aortic arch. 12. Innominate
artery. 13. Subclavian artery. 14. Internal carotid artery. 15. External carotid
artery. 16. External maxillary artery. 17. Internal maxillary artery. 18. Pterygo-
palatine artery (or plexus). 19. Deep temporal artery. 20. Occipital artery.
15
16 HEARING IN CETACEANS
fying through the peculiar fatty tissue that occurs in odontocetes within the angle
of the lower jaw.”
Anthony & Coupin (1930) appear to be the first to have described the air sacs
of a ziphioid, Mesoplodon bidens. The extent of their observations is limited by
lack of material. Comparison is made between the guttural pouch of various Peris-
sodactyls and the Beaked Whales’ air sacs. ‘‘In Mesoplodon the gutteral pouch
consists of a large bag of which the two expansions, one superior and posterior
(the smaller), and the other inferior and anterior, are lodged on the external face of
the pterygoid bone.”
—> 13
15 —~ 75
Fic. 2. Boenninghaus’ (1903) figure of the venous drainage of the base of the cranium
in Phocaena.
1. Cavernous sinus. 2. Superior petrosal sinus. 3. Inferior petrosal sinus. 4.
Transverse sinus. 5. Longitudinal sinus. 6. Internal jugular vein. 7. Common
jugular vein. 8. Emissary vein from the foramen lacerum medium. 9. Bulbous
venosus epibularis of Boenninghaus. 10. Fibro-venous plexus of the pterygoid.
11. Pterygoid vein. 12. Corpus cavernosum. 13. Ramus bulbi venosi ad jugularem
internam of Boenninghaus. 14. Ramus bulbi venosi ad jugularem externam of
Boenninghaus. 15. External jugular vein of Boenninghaus. 16. Spinal venous
plexus. a. Periotic, b. tympanic bulla.
Scholander (1940) in his classic paper on the respiratory function in diving animals
and birds states ‘‘ On the inner rear side of the lower jaw of the Bottlenose on each
side, is an air recess, each with a maximal capacity of about 11. The recesses are in
open connection with the nasal cavity and can be completely collapsed.”’
Finally Yamada (1953) figures, but does not describe in detail, the arrangement
of air sacs in Berardius bairdi and Kogia breviceps.
The foregoing historical account of the structure of the accessory air sinuses in
cetaceans is in general agreement with the writers’ own finding, with certain
reservations which will be discussed in the following sections.
HEARING IN CETACEANS 17
BASICRANIAL ANATOMY
PTERYGOID AND NASOPHARYNGEAL MUSCLES
(1) DELPHINUS
In his dissections of Phocaena phocoena Boenninghaus described a supporting
tissue of the skull base which is fully referred to on p. 12. The present writers have
found that this tissue is present in all the odontocetes examined by them—Phocaena
phocoena, Lagenorhynchus albirostris, Globicephala melaena, Grampus griseus, Tursiops
truncatus and Delphinus delphis. A dissection of the last species is shown in Text-
MTP PA PTH Mpe
Fic. 3. Dissection of the right half of the head of Delphinus delphis, after removal of
mandible and posterior part of palatal musculature, to show inter-relationship of
muscles and periosteal sheet.
fig. 3. The “wide reticular, ventral membrane (Ps) directed posteriorly towards and
merging with the supporting tissue of the bulla ’’ is more extensive than Boenning-
haus suggests. In fact it constitutes the whole lateral wall of the air sinus system
and its histology will be described in the next section. In Pl. 4A it will be seen that
voluntary, striped muscle (mrs) is attached to the outermost layer of fibrous tissue
(rr). This voluntary muscle is a small part of the pterygoid musculature now to be
described.
External pterygoid muscle. The external pterygoid muscle (MEP) in Delphinus
delphis (Text-figs. 3 and 4) is similar in position and extent to that described by
Boenninghaus for Ph. phocoena but in the former, attachments were observed which
were not described by this author. As noted by him there is an attachment to the
ZOOL. 7, I. 2
18 HEARING IN CETACEANS
narrow dorsal edge of the posterior portion of the mandible (mp). In addition there
is a more ventral attachment (vTEP) to the fibro-cartilaginous articulation of the lower
jaw (Mb), which is homologous with the insertion of the pterygoid muscle of man
into the articular capsule. On its mesial aspect the muscle is attached at its anterior
extremity to the lateral aspect of the tip of the posteriorly directed lateral lamina
of the palatine bone, but its greater part on this aspect is attached to the fibrous
external wall of the air sinus.
Internal pterygoid muscle. The present writers do not agree with Boenninghaus
in his identification of the internal pterygoid muscle (mip). The ventro-lateral
FVP MEP
MPP
Fic. 4. Dissection of the left half of the head of Delphinus delphis to show inter-
relationships of palatal and pterygoid muscles. (Only the proximal end of the
mandible is shown im situ, the remainder being indicated in outline.)
muscle mass identified by him as the internal pterygoid is, in D. delphis, clearly
divisible into two distinct portions separated by fascia. Only the more anterior
portion has the attachments normally associated with the internal pterygoid muscle,
namely—as in man—palatine, pterygoid, maxilla, and inner face of lower jaw.
This muscle is attached to the ossified palatine bone and to membranous, unossified
portions of the air sinus system in the neighbourhood of the other three bone elements.
These membranous areas are derived from pterygoid, maxilla and mandible. The
position of the internal pterygoid in relation to the external, is such that the qualifica-
tions used are misnomers. The internal pterygoid muscle is displaced anteriorly
so that it lies entirely in front of, and not alongside, the external pterygoid. In man
the internal pterygoid is described as a thick, quadrilateral muscle whereas in the
~~
HEARING IN CETACEANS 19
Common Dolphin it is elliptical in shape, the longer axis lying parallel to the long
axis of the lower jaw.
Tensor palati muscle. The other portion of the ventro-lateral muscle mass referred
to above is roughly of an acute angular shape, one side of the triangle lying along
and overlapping the angular lateral edge of the pterygoid hamulus. Anteriorly
it is attached along the whole posterior ventral margin of the palatine bone ; poster-
iorly to the lateral wall of the Eustachian tube and to the styloid near its junction
with the tympanic bulla. Along the ventro-lateral edge of the pterygoid hamulus
its muscle fibres run antero-mesially and merge into a strong, fibrous, glistening
aponeurosis (PA) which covers the ventral surface of the palate and merges with the
muscle of the opposite side. According to Boenninghaus, Zucherhandl wrongly
identified this muscle as the tensor palati, but the present writers consider the latter
author to be right (see p. 11). In Delphinus delphis the part of the mesial aspect of
this muscle (MTP) is attached to the lateral wall of the pterygoid air sac posterior
to the posterior margin of the lateral lamina of the pterygoid hamulus, whereas
in Mesoplodon bidens the fascia of this muscle forms nearly the whole of the lateral
wall of the pterygoid sac.
Between the postero-dorsal margin of this muscle and the postero-ventral margin
of the external pterygoid muscle is a triangular space closed mesially by the fibrous
supporting tissue previously mentioned, and pierced by the tensor palati and ptery-
goid branches of the mandibular nerve (NM).
According to Boenninghaus the tensor palati muscle is restricted to a few, small,
inconspicuous, vestigial muscle fibres in the posterior nares close to the opening of
the Eustachian tube. It may be pointed out that the muscle identified by the present
writers and Zucherhandl as the tensor palati is innervated by a branch of the mandi-
bular nerve, i.e. the conventional innervation of this muscle. The tensor palati of
Boenninghaus is remote from this nerve and separated from it by the lateral wall
of the posterior nares, the pterygoid air space and the lateral muscle mass.
Temporal muscle. Consideration of the temporal muscle (MT) is not within the
scope of the present investigation. It need merely be said that it originates in the
temporal fossa and passes through that portion of the zygomatic arch formed by the
squamosal, to an insertion on the dorsal edge of the mandible posteriorly. Closely
associated with, and situated ventrally to this muscle is another muscle mass which
originates from the fibrous covering of the tympano-squamosal recess on the zygo-
matic process of the squamosal. It is inserted into the lateral face of the mandible
and in its general position its identification as the masseter muscle (MM) seems
reasonable.
Nasopharyngeal muscles. In order to demonstrate the manner in which the air
sinus system has profoundly altered the arrangement of the muscles of the soft
palate, it is necessary to review the inter-relationship of the components of the
naso-pharyngeal muscle mass using Delphinus delphis (Text-figs. 3-6) as the subject.
But before doing so it is well to recall the disposition in a typical mammal, for
example man. According to Gray’s Anatomy (1946) “ the palatine aponeurosis
(tendon of the tensor palati) forms a central sheet enclosing the uvular muscles
near the median plane; the levator palati and the palato-pharyngeus are inserted
20 HEARING IN CETACEANS
into its upper surface, the two strands of the latter muscle lying in the same plane
respectively in front of and behind the levator palati.’’ In Cetaceans, the dorsal
and ventral surfaces of the palatine aponeurosis are widely separated by the expanded
and distended hamular portions of the pterygoid bones and their associated air
sinuses and venous plexuses (FvP). Thus in their narial portions the palato-pharyngeus
and levator palati muscles (MPP) are separated from the ventral aspect of the palatine
aponeurosis by the interval formed by the pterygoid air spaces. As a result of the
development of these air spaces and the modifications of the pterygoid bones enclos-
ing them, profound alterations of the conventional orientation of the naso-pharyngeal
FR
MSP
7M1//
A
ET S202 ~
Coes On)
ipoaee
Co: < Ay
MLO
Mx
MPP (I)
s
ir mppP (S)
Fic. 5. Bisected head of Delphinus delphis, right side, showing
naso-pharyngeal muscle mass in situ.
“ ”
muscles have ensued. The “soft palate’’ is invaded by the pterygoid bones and
is thus no longer soft, and the palato-pharyngeal muscle mass is largely enclosed
within the bony nares (see Text-fig. 14g). The arrangement of this muscle mass in
Delphinus delphis is almost identical with that so adequately described by Boenning-
haus in Phocaena phocoena (see p. 11). Thus the partes interna and externa of the
palato-pharyngeus muscles (MPP(I)) (MPP(E)) form the greater part of the thick mass
of tissue which covers the anterior wall and floor of the posterior narial aperture,
whilst the constrictor pharyngeus (Msc), salpingo-pharyngeus (Msp) and longitudinalis
oesophagi (MLO) form the posterior portion of its roof. The ventral extremities of all
these muscles encircle the glottis in a powerful palato-pharyngeal sphincter (MPP (s)).
HEARING IN CETACEANS 21
In Text-fig. 6. the whole palato-pharyngeal muscle mass has been removed from the
nares to show that the individual muscles overlap in a manner similar to their
arrangement in terrestrial mammals. The present writers, however, do not concur
with Boenninghaus in his identification of the levator palati muscle, and consider
that the muscle he so identified is merely a portion of the pars interna of the palato-
so
MPP (1)
S
SS mpP (e)
BSS ———s
Fic. 6. Bisected head of Delphinus delphis left side, with
naso-pharyngeal muscle mass reflected.
pharyngeus. Indeed, Boenninghaus himself found it difficult to establish a differen-
tiation of the two muscles. In Delphinus delphis (Text-figs. 4 and 6) there is a
muscle (MLP) which arises from the junction of the styloid with the tympanic bulla,
lies along the medial wall of the Eustachian tube, and after passing within the
upper, concave border of the superior constrictor, runs dorsally between the partes
interna and externa of the palato-pharyngeus ; thereafter it spreads out into the
palatine glandular surface near the narial opening of the Eustachian tube. This
22 HEARING IN CETACEANS
disposition of the muscle coincides in all its relationships with that identifying the
levator palati in man.
(2) MESOPLODON
In the Ziphiidae the size and disposition of the lateral muscle mass are correlated
with the enormously enlarged pterygoid hamuli (see Text-fig. 14c). It will be seen
later that the air sinus system is almost wholly confined to this region, thus whilst
the tensor palati muscle is expanded in correspondence with the enlargement of
the hamuli, the expansion of each hamulus has apparently been at the expense
of the remaining portion of the pterygoid, which is reduced to a long, narrow shelf,
situated immediately above the hamular fossa. The “‘external’’ and “‘ internal ”’
pterygoid muscles extend from the upper surface of this shelf to the dorsal edge of
the mandible and are consequently restricted to the narrow interval which separates
these two attachments. The muscles are also flattened dorso-ventrally and in general
are very much reduced in size, and presumably in function, compared with those of
the Delphinidae. The temporal fossa, and with it the temporal muscle, is also
reduced in size as compared with those of the Delphinidae.
(3) BALAENOPTERA
In order to complete the description of the musculature of the air sinus system,
it is necessary to describe the arrangement in the baleen whales. Before doing so
it may be noted that Beauregard (1894) identified in Balaenoptera acutorostrata
a sheet of fibrous tissue covering the lower surface of the cranium, and closing the
pterygoid sinus ventrally. This sheet is undoubtedly homologous with that described
above (p. 12) in the Odontoceti.
With regard to the lateral muscle mass the writers have little to add to the descrip-
tion provided by Carte & Macalister (1869). They state “the pterygoid muscle
was small and flat ; it arose fleshy from the external surface of the pterygoid plate,
which formed the outer wall of the posterior nares ; the muscle ran downwards
and backwards, and was inserted into the internal border of the lower jaw near its
angle, sending some of the posterior fibres to be inserted into the interarticular
fibro-cartilage. This muscle was evidently the representative of the external ptery-
goid ; no muscle corresponding to the internal pterygoid was found.”’ In a dissection
of a foetal fin whale the present writers were similarly unable to distinguish positively
the internal pterygoid, but a small slip of muscle inserted into the mesial aspect
of the lower jaw, approximately at the level of the coronoid process, appeared to
have its origin in the lower part of the temporal fossa near or on the pterygoid bone.
Its position relative to the lateral pterygoid suggested that it might be the internal
pterygoid muscle.
The arrangement of the muscles in the naso-pharyngeal mass is precisely as in
the Odontoceti except that the muscles are not enclosed within the bony nares
(see Text-fig. 140). This is related to the fact that the pterygoid hamuli do not
extend towards the middle line and are not enormously enlarged as in the Odontoceti,
a true soft palate persisting. It will be seen, from Carte & Macalister’s description
HEARING IN CETACEANS 23
of the deep fibres of the masseter muscle which follows, that this muscle agrees in
position and attachments with that tentatively so identified in D. delphis (p. 19 supra).
They state ‘‘ The deeper set of fibres arose tendinous from the margin of the glenoid
cavity, extending as far forward as the posterior edge of the orbit ; the fibres of this
plane ran downwards and a little forwards, and were inserted into the base of the
lower jaw about three inches in front of its angle, and occupied by its insertion
about three inches of the outer surface of this bone.”’
VASCULAR SYSTEM
The modification from the conventional arrangement of soft structures at the
skull base with the development of air sinuses is particularly well demonstrated by
the distribution of the blood vessels in this region. Anatomists such as Murie,
Boenninghaus, Carte & Macalister have, with justification, described the blood vessels
only in very general terms, because the ramifications of the finer branches are
exceedingly complex and form extensive retia mirabilia which are associated with the
air spaces. In order to relate their investigations with those of previous authors
the present writers examined the vascular systems of five species of odontocete.
Use was made of the recently developed polyester resins in order to obviate the
necessity of making very laborious and less satisfactory dissections. The arterial
and venous systems were injected with coloured plastic through the common carotid
artery and jugular vein respectively. Freshly killed animals being unavailable,
use was made of stranded specimens, the venous system of which naturally contained
varying amounts of congealed blood. As a consequence the injection of this system
was in some instances not complete, but sufficient information has been obtained by
considering the injected specimens together to build up a composite impression.
This impression is possible because inspection of the preparations of the heads
of the five species injected, namely Phocaena phocoena, Grampus griseus (Text-fig. 7),
Tursiops truncatus (Text-fig. 8), Globicephala melaena (frontispiece and Text-fig. 9)
and Lagenorhynchus albirostris (Text-fig. 10) showed that the vascular system as
a whole was very similar in each.
The general impression of the vascular system in the region of the base of the skull
is of an elaborate plexus of vessels investing the whole of the air sac system, and
apparently entirely subservient to the proper functioning of the latter. It is well
known that the blood supply to the brain of cetaceans is by way of spinal meningeal
arteries which are greatly increased in calibre and, correspondingly, the internal
carotid is known to be reduced and apparently atrophied.
ARTERIAL SUPPLY
The external carotid (ACE) (Text-fig. 8) divides in the neighbourhood of the tym-
panic bulla into an external and internal maxillary artery, the former of these being
irrelevant to the subject of this paper. The internal maxillary (AMI, Text-figs. 7,
8, 9, 10) can be referred to under the three sub-divisions recognized in terrestrial
mammals.
24 HEARING IN CETACEANS
The first part forms a sinuous curve and is enveloped in the superior portion of
the intra-mandibular fatty tissue (ImFB); laterally it gives off the mandibular
artery (AM) (Text-figs. 7, 8, 9) which is distributed to the ramus of the lower jaw.
—- 4
boty
——
PTH
gic,
Co 5
= ‘
= ;
TB
Fic. 7.
Grampus griseus. Ventral aspect of the head showing
distribution of air sinuses, arteries and veins.
Further forward it gives off, mesially, pterygoid arteries (apt) and laterally the
deep temporal (AT) (Text-figs. 7, 8). The pterygoid arteries form a rich plexus of
vessels which is distributed to the submucosa of the air sacs as well as to the
external pterygoid and tensor and levator palati muscles. The plexus communicates
HEARING IN CETACEANS
APTMB
PAL (LL)_AS
VIM AO re
AM! PTS (PR)
ol
IMFB FR
PTS (Po)
AT PTS
FOI
APT. ET
VPT. ace
AM FP
VM SQ
ACE
TB
IJ
. POS
Fic. 8. Tursiops truncatus. Ventral aspect of the head showing
distribution of air sinuses, arteries and veins.
25
26 HEARING IN CETACEANS
with the vascular envelope of the air sac system in the position of the angle formed
by the tensor palati and lateral pterygoid muscles. The arteries supplying the
internal pterygoid muscle (Text-figs. 7, 8, 9, Io, APTMB), although originating in
approximately the same position as those supplying the external pterygoid, extend
forward on a course approximately parallel with that of the parent (internal maxil-
lary) vessel in conformity with the forward displacement of the internal pterygoid
muscle (see p. 18).
In terrestrial mammals the middle meningeal artery is a conspicuous branch of
the first portion of the internal maxillary, and anastomoses with the internal carotid.
In at least one of the injected specimens evidence of an intra-cranial blood supply
from this source has been established ; and it cannot be assumed that this artery has
atrophied, notwithstanding the apparent atrophy of the internal carotid and the
proliferation of the spinal meningeal supply.
The second part is not enclosed within any alisphenoid canal and indeed it is
displaced from the lateral wall of the cranium by the whole width of the pterygoid
air sinus. The vessels (Ao and AL) stemming from this portion of the internal maxil-
lary go to supply the orbital muscles, the lachrymal gland and upper eyelid (Text-figs.
7, 8, 9); their distribution is not relevant to the present paper but it may be noted
that a considerable extent of main vessel separates the origins of the orbital and
lachrymal branches.
The third part commences immediately anteriorly to the lachrymal branch (AL)
of the Second Part (Text-fig. 9). It immediately turns mesially and dorsally to
pass through the infra-orbital foramen. Before doing so it gives off vessels, which
penetrate the palatine base (Text-figs. 8, 9, APPB) presumably to supply the palato-
pharyngeal muscle mass, and the roof of the mouth. Another branch ramifies on
the ventro-lateral surface of the rostrum (Text-figs. 7, 9). The maxillary artery
passes forward within the rostrum after giving off branches to the nasal cavity and
the musculature of the blowhole. It is interesting to note that, as in the orbital
region where the cranial foramina are crowded together, in the preorbital region the
infra-orbital, spheno-palatine and posterior palatine foramina are all in juxtaposition.
VENOUS DRAINAGE
The venous drainage of the base of the skull is extremely complex and anastomoses
freely with that of the cranial cavity. It is mainly characterized by the development
of an extensive fibro-venous plexus which lines the whole of the lateral and mesial
walls of the air sinuses. In spite of the profusion of retia, however, certain conven-
tional features of the venous drainage can be recognized.
Internal maxillary vein. This vein (Text-fig. 8, vim) can be said to commence
at the posterior extremity of the zygomatic arch and pass forward parallel with the
latter as far as the posterior margin of the jugal. It then passes over the dorsal
edge of the ramus of the mandible and runs posteriorly in company with the artery
(AMI) of the same name. In the temporal region it merges with the massive venous
plexus of the intra-mandibular fatty body (1mFs), and is joined by the deep temporal
vein.
HEARING IN CETACEANS 27
Mandibular vein. Boenninghaus’ identification of the intra-mandibular fatty
body with the bone marrow of the lower jaw seems to be justified. A full description
of its situation and extensions is given on Pp. 13. The venous plexus which ramifies
extensively in the fatty body ultimately drains into a large vessel which can be
recognized as the mandibular vein (Text-figs. 8, 9, 10, vm). The plexus consists
primarily of a network of vessels of small calibre, the walls of which are extremely
JIN
y \ vi
FVP
AMI
Ma
AM
Yoffa
Y i} iG H IMFB
an |] Hi Gj A
NW Bh ATR bare)
\ Ni WH), yy) vm
— agi
TIN
ye
vPT
sQ
PAQ
Fic. 9. Globicephala melaena. Ventral aspect of the head showing
distribution of air sinuses, arteries and veins.
28 HEARING IN CETACEANS
thin and intimately associated with the adipose tissue of the marrow. Boenning-
haus points out the tendency of the fatty body to hypertrophy beyond the natural
boundaries of the mandible, and it is a significant fact that among the toothed
cetaceans, even those with a reduced number of teeth, for example Grampus griseus,
PTH
PAL
JU
PTS (PR)
or
ZA
FR pt(Lt)
PTS (Po)
AMI
SQz
aes Es
VM
|
VPT
POS
Fic. 10. Lagenorhynchus albirostyis. Ventral aspect of the head
showing distribution of air sinuses, arteries and veins.
HEARING IN CETACEANS 29
have a greatly enlarged fatty body. The large size of the mandibular vein can be
correlated with that of the large plexus it drains. It continues posteriorly beyond
the postero-lateral border of the skull to join the internal jugular (v1j).
Internal jugular vein. Like the internal carotid artery the internal jugular vein
(Text-fig. 8) is short, sharply tapered and presumably reduced in function. It
emerges from the paroccipital notch and accompanies the internal carotid artery
posteriorly.
Pterygoid vein. Unlike that of terrestrial mammals the pterygoid vein (Text-,
figs. 7, 8, 9, 10, vpT) in the Cetacea is not limited to the drainage of the pterygoidea.
It is continuous with the great fibro-venous plexus of the air sacs so that its ramifica-
tions are co-extensive with the distribution of the sacs themselves. Thus there are
portions of this plexus to be found in the post-orbital, orbital and pre-orbital regions
of the head and in some species, e.g. Delphinus delphis, the plexus extends towards
the tip of the rostrum. On the mesial aspect of the cranial portions of the air sac
system the fibro-venous plexus communicates freely with extensions from the intra-
cranial venous system, through the optic foramen, and by way of the cavernous,
superior and inferior petrosal sinuses. As a result of the displacement of the tympano-
periotic from participation in the wall of the cranium, the petrosal and cavernous
sinuses are divested of their bony cranial protection and are anastomosed with the
fibro-venous plexus (but see Capevea pp. 77-79). In the terrestrial mammals the
internal carotid artery passes through the cavernous sinus within the cranial cavity. In
the Cetacea it passes through the so-called cavernous tissue body within the tympanic
cavity. It seems therefore that the problematical cavernous tissue body or spongy
mass of Beauregard in the cetacean ear is the homologue of the cavernous sinus of
terrestrial mammals. At the angle made by the tensor palati and lateral pterygoid
muscles, the lateral portion of the fibro-venous plexus anastomoses extensively with
the plexus of the intra-mandibular fatty body. The pterygoid vein passes posteriorly
along the ventral margin of the basioccipital crest (Boc) and, according to Boenning-
haus, at the level of the tympanic bulla (TB) is joined by small tributaries from the
inferior petrosal sinus. Still further posteriorly it unites with the mandibular and
internal jugular veins.
The schematic representation of the venous system described by Boenninghaus
and reproduced in Text-fig. 2 agrees in the main with the arrangement found in the
more recently injected specimens figured in the present paper. There are, however,
certain modifications which are embodied in the diagram. Thus the vessel labelled
“internal jugular ’’ (6) is shown with a relatively wide lumen, whereas the injected
specimens show that it is very attenuated at its cranial end (see Text-fig. 8). The
vessel labelled ‘“‘ external jugular ’’ (15) lies on the mesial side of the mandible and
is more properly designated as the mandibular vein. As previously stated it is
embedded in the plexus of the intra-mandibular fatty body. The vessel labelled
“ramus bulbi venosi ad jugularem externam’’ (14) in the injected specimens con-
sists of a mass of small vessels connecting the vascular plexus of the fatty tissue
body to the “corpus fibro-cavernosum pterygoideum’”’ (Io) i.e. the fibro-venous
plexus of the air sacs. No vessel corresponding to the “ramus bulbi-venosi ad
jugularem internam’’ (13) could be found unless it be the deep temporal vein in
30 HEARING IN CETACEANS
which case it is not in direct communication with the fibro-venous plexus, since it
drains the temporal muscle.
At the points of attachment of the pterygoid muscles to the walls of the air sacs.
the vessels of the fibro-venous plexus are much smaller than those in areas where
no muscles are attached.
No detailed dissection was made of the nervous system in the region involving
the air sacs, but it might be expected that since the air sac system covers the ventro-
lateral aspect of part of the cranium the air sacs would be penetrated by the cranial
nerves in this region. However, the paths of the nerves concerned are restricted to
three exits, that associated with the optic infundibulum, that of the infundibulum
of the foramen ovale and that of the “‘ cranial hiatus’’ in the vicinity of the periotic.
CONTENTS OF THE AIR SACS AND HISTOLOGY
FoAM
With reference to the contents of the pterygoid fossa, Brazier Howell (1930)
writes “in freshly killed specimens this is entirely filled with a coarse foam of
albuminous, rather than greasy texture. Whether this is so in living specimens
cannot be demonstrated, but presumably it is, and the foam may have some function
in determining the quality of sound reception.”
One of us (P.E.P.) examined the pterygoid sinuses of approximately fifty pilot
whales stranded at Dunbar (1950) and found that each one contained a similar
type of foam.
Mr. D. E. Sergeant of the Newfoundland Fisheries Research Station, who had
been asked to look out for this phenomenon, also noted its occurrence in a Globicephala
melaena only 1 hrs. after death.
Dr. R. M. Laws, National Institute of Oceanography, to whom a similar request
had been made, reported that in no whale examined for this purpose was the foam
lacking.
Dr. Robert Clarke of the same Institute, while at the Azores in 1955 examined a
number of Sperm Whales in which foam was found to fill the pterygoid air sacs.
HIsTOLOGY
If the surface of the wall of the air sac is examined with the naked eye it is seen
to be of a light brown colour and matt texture. This texture is the macroscopic
expression of the presence of the openings of innumerable, minute ducts closely
adjacent to one another with a separating, membranous network, the trabeculae of
which are ca. 0-025 mm wide. PI. 2, fig. A, shows a section cut in the plane of the
surface of the mucous membrane. The ducts (pMUv) are fairly uniform in size, their
openings of a roughly oval shape and measuring approximately 0-2 mm at their
widest diameter. In the thick part of the same section each duct is filled by a layer
of inwardly projecting columnar cells (Eco), mucus and foreign particles. The longi-
tudinal section (Pl. 2, fig. B) of the pterygoid sac lateral wall shows that these
ducts communicate with an elaborate system of mucous glands (GMU) some simple,
some racemose, some deeper than others. The glands are lined by a thick layer of
HEARING IN CETACEANS 31
columnar epithelium with goblet cells (Pl. 2, fig. c, Goc). The free surface of the
interglandular areas of the mucous membrane is covered by ciliated epithelium
(ect). The whole glandular area is extremely vascular being equipped with an intri-
cate network of capillaries and larger vessels.
The mucous membrane (mum) is supported by a thick layer of fibrous tissue (PI. 3,
fig. A, TF) with here and there small clusters of fat cells (Pl. 3, fig. c, cF). The
fibrous layer may also contain elastic tissue. Disposed at random throughout the
tissue are circular spaces of small size, each bounded by a fine layer of brown, un-
stainable substance (Pl. 3, fig. c, FG), which presumably represent fat globules. A
number of larger irregularly shaped spaces (Pl. 3, fig. B, Ls) contain a filling of
translucent, emulsoid texture (Pl. 3, fig. D).
Deep to the fibrous layer is an open network of large venous spaces (FVP) with
interspersed arteries (A), and connected by strands of fibrous tissue (TF) and patches
of fatty tissue (FT) (Pl. 3, fig. A). The boundaries of the venous spaces appear to
be composed of the interlaced fibrous strands, no well-defined endothelium being
present.
Another fibrous layer TF lies deep to the vascular plexus, attached to which can
be seen many striped muscle fibres (mFs) (Pl. 3, fig. A) parallel with and closely
adherent to the last named fibrous layer. In Plate 4, fig. A which is at right angles
to the previous one a much larger area of this striped muscle (mFS) can be seen in
transverse section, the peripheral regions of the individual muscle bundles being
separated by fasciae originating from the fibrous layer (TF). The muscle involved
is the external pterygoid.
The mucous membrane lining the mesial wall of the air sinus is identical in structure
with that of the lateral wall. The photomicrograph of the sections (Pl. 3, fig. B)
shows the membrane and its underlying structures. The crypts are rather more
racemose than those of the lateral wall and, as in the latter, the sub-mucous layer is
highly vascular, the cut ends of the vessels being seen in the sections. The circular
and irregularly shaped spaces are also present. Below the mucous membrane, as
in the lateral section, is a continuous layer of fibro-elastic tissue. Deep to this is
a reticulation of the fibrous tissue containing very large venous spaces (FVP) with
here and there arteries. This fibro-venous plexus is continuous with the haversian
system of the mesial lamina of the pterygoid bone which is not represented in the
sections.
In Fraser & Purves 1954 it is stated that the fibro-venous plexus referred to in the
two previous sections was supplied by an arterial plexus which emerges from the
_ internal maxillary artery immediately anterior to the tympanic bulla. The plexus
is partially drained by an intricate plexus of small veins which penetrates the
fibrous covering of the sinus at the angle formed by the lateral pterygoid and tensor
palati muscles. This plexus is very dense and ramifies throughout the mass of fatty
tissue which lies on the mesial aspect of the lower jaw. The section (PI. 4, fig. B) is
through the lateral wall of the air sac in this region. It is composed of mucous
membrane (muM) which as in the previous sections is provided with racemose
crypts. The sub-mucous fibrous tissue (TF) contains considerable aggregations of
elastic fibres arranged in sinuous folds. There are also numerous arterial capillaries
32 HEARING IN CETACEANS
(A) and lymphatics. Deeper is a network of fibrovenous spaces (FvP) containing
many large and small arterioles shown in transverse section. In places the fibrous
interstices of the venous plexus are replaced by fat. Further laterally the fibro-
venous plexus is continuous with a system of smaller venioles which penetrate a
mass of adipose tissue, i.e. the fatty body of the lower jaw. The walls of these
venioles are extremely thin.
Pl. 4, fig. c is a section from the intra-mandibular fatty body on the mesial aspect
of the lower jaw showing reticulations of large venous spaces (vN). Open fat cells
Fic. 11. Diagram to show formation of air sacs and fibro-venous plexus.
and lymph ducts are present. The section is lined at one side by a thin layer of
fibrous tissue (TF)—mandibular periosteum (see p. 13 supra). It is interesting to
compare this section with one taken from the fat layer on the lateral aspect of the
lower jaw. In this section Pl. 4, fig. D the large venous spaces are absent, although
normal arteries and veins are represented. The whole mass of tissue is streaked by
parallel patches of striped muscle (MFs).
From these descriptions it can be seen that the lateral wall of the air sac is composed
of four main layers :
. Surface mucous membrane.
. Thick layer of fibrous tissue.
. Open plexus of veins and arteries.
. A second band of fibrous tissue.
WN H
HEARING IN CETACEANS 33
The foregoing histological description applies to the wall of the air sac however
extensive the latter may be, so that the fibrous tissue sheet and vascular network
mentioned by Boenninghaus reaches beyond the limits defined by him. It allows
conclusions about its origin to be drawn. It will be seen in the next chapter that the
sinus system is derived from a great extension of the limits of the pterygoid bone,
and it is clear that the tissue sheet and vascular system are derived from the perio-
steum and osteo-vascular system of that bone in the manner shown in Text-fig. 11.
Starting with a sinus (s) adjacent to a bone, which can be assumed to be the ptery-
goid (Text-fig. 11a) the principal features are a vascular system (v) in a bony matrix
(Bc) covered by a layer of periosteum (P), with, external to this again, the mucous
membrane (mum) which contributes the lining of an incipient air sinus system (s).
A number of striped muscular fibres (M) are inserted into the lateral wall of the bone.
In Text-fig. 11d an invagination of the pterygoid bone has commenced, with resorp-
tion of the calcified element (BC) of the bone. Laterally, where resorption has proceeded
as far as the lateral aspect of the bone, a vascular system remains between two sheets
of periosteum, the mesial component of which is lined by mucous membrane, and the
lateral supporting the previously mentioned muscle fibres (M). Mesially in the sinus,
resorption (BR) of the calcified element has not proceeded to the mesial limit of the
bone so that the component parts of the wall of the sinus consist of a vascular network
which is continuous with that of the bone, and covered laterally by a single sheet of
periosteum and a layer of mucous membrane. The extent to which this process
has developed in various cetaceans can be judged from the next chapter.
OSTEOLOGY
There are some features of the cetacean skull to which very little reference has
been made in the relevant literature. As a preliminary to a description of these
features in the various forms of cetacean it will be necessary to draw attention to
basic aspects of the skull. Various descriptions exist of the more or less elongated
rostrum, the overlapping extension of the maxillaries above or below the frontal,
the elevation and enormous extension of the supra-occipital with the partial or
complete exclusion of the frontal and parietal bones from the external surface of
the cranium, the diminutive size of the nasal bones and the associated change in
direction of the nasal passages from a horizontal to a dorso-ventral situation. The
features which concern this paper however are to be found on the ventral aspect of
the skull. They are:
1. The ventral displacement of the tympano-periotic bones and their dissociation
from the adjacent bones of the cranium.
2. The presence of a falciform process of the squamosal.
3. The basioccipital crests which form a longitudinal arcade for the accommoda-
tion of the larynx and naso-pharyngeal muscle complex.
4. The disproportionate enlargement of the pterygoid with overriding of and
intrusion into the palatine.
ZOOL. 7, I. 3
34 HEARING IN CETACEANS
5. The splitting of the pterygoid, and sometimes of the alisphenoid and squamosal
also, into lateral and mesial laminae, connected to a greater or lesser extent by
superior and inferior laminae.
6. The excavation of the zygomatic process of the squamosal to form the tympano-
squamosal recess.
In the descriptions of the skulls which follow, the osteological features will be
discussed in the foregoing numerical order and the specimens will be considered
in the following sequence—the Mysticeti including the Balaenopteridae, Balaenidae
and Eschrichtidae ; and the Odontoceti including the Ziphioidea, Physeteroidea,
Platanistoidea, Monodontoidea, Delphinoidea.
MYSTICETI
BALAENOPTERIDAE
In the Mysticeti the arrangement of the bones in the region under discussion in
the present paper are described and figured by Lillie (Ig10) who says “‘ The Cetacea
have a remarkable depression on the base of the cranium on each side of the median
line (Lillie’s fig. 71). In Balaenoptera these depressions are bounded posteriorly
by the projecting edge of the exoccipital, externally by the base of the zygomatic
process of the squamosal, on the inner side behind by the prominent edge of the
basioccipital. The anterior portion of the inner side of this depression and the front
of the recess are bounded by the pterygoid and alisphenoid bones which are fused
together ; the latter also form the roof of the anterior half of the depression. Thus
the anterior portion of the cavity is bounded on three sides by the pterygoid and
externally by the squamosal, and is known as the pterygoid fossa. In this recess
the united tympanic and periotic bones lie.”’
Ridewood (1922) gives an extensive account of the pterygoid region of Megaptera
and Balaenoptera in which he points out that Lillie’s interpretation of the pterygoid
fossa as being components of the pterygoid and alisphenoid was wrong, and that he
confused it with the pterygoid fossa in man. In the latter the “ lateral pterygoid
plate’’ is the descending wing of the alisphenoid. Ridewood is in agreement with
Van Kampen (1905) that the pterygoid fossa in mysticetes is contained within
the pterygoid bone alone. This also is the interpretation accepted by the present
writers and is substantiated by the evidence obtained from the Odontoceti.
The Mysticeti differ from the Odontoceti in that the tympano-periotic is not
completely extruded from the cranial wall—thus there is no cranial hiatus. The
pyramidal pro-otic portion projects into a cavity in the squamosal bone; the dorsal
surface of the otic portion is a component of the ventral wall of the cranium ; the
opisthotic part forms a long thin extension which is the fused mastoid part of the
periotic and tympanic. It lies in a deep groove between the exoccipital and the
squamosal, its anterior face forming part of the boundary of the meatal groove.
Ridewood’s (1922) description of the falciform process of Megaptera summarizes
the condition found in Balaenopteridae generally (see Pl. 7, Fp). He says “ The
front of the squamous portion (of the squamosal) is prolonged forward, inward
and slightly downward as the bifid pterygoid process, the upper part of which
HEARING IN CETACEANS 35
overlaps the upper part of the pterygoid bone near, but behind and below the ala
temporalis ; the lower part of the fork, the processus falciformis, overlaps, i.e.
lies external to the part of the pterygoid that forms the external boundary of the
pterygoid fossa (or sinus). Between the two parts of the pterygoid just mentioned
is a broad notch opening backward, which, in conjunction with the notch in the
squamosal bone immediately above the processus falciformis, constitutes the foramen
ovale ’’ (see Pl. 7, FO). Later he states “‘ It is unusual in mammals for the squamosal
to extend so far forward as to reach the pterygoid; the whales are exceptional
in this respect as they also are in having the foramen ovale in the form of a cleft
between the squamosal and the pterygoid.’’ It should be pointed out however
that this cleft represents the external opening of the foramen ovale and communicates
with a bony infundibulum as will be described in the Odontoceti. The cranial
aperture of the infundibulum is formed by a notch in the alisphenoid, again as in
the Odontoceti and emphasized in the Physeteridae.
The basioccipital crests (Boc), as shown in Balaenoptera acutorostrata (Pl. 7), are
low and stout in comparison with the skull as a whole and with the condition found
in the Odontoceti. They are insignificant in size. The paroccipital processes (PAO)
on the other hand are very prominent and greatly extended laterally. The mesial
part of the anterior margin of the process forms the posterior wall of a laterally
directed groove, which is bounded anteriorly by the recessed posterior face of the
mastoid process of the tympano-periotic (MAS).
In none of the Mysticeti does the pterygoid attain the proportions observed in
odontocetes. The mesial (PT (ML)), superior (PT (SL)) and lateral laminae (PT (LL))
of the bone (see p. 34 supra) are complete, bounding the pterygoid fossa already
referred to. The bony bridge which the lateral lamina of the pterygoid makes
between the squamosal (sQ) and the palatine (PAL) is intact, so that the lateral wing
of the alisphenoid is concealed except for a small part of its distal extremity in the
temporal fossa. There is no extension of the pterygoid beyond the orbital region
as in the Odontoceti.
The pterygoid hamuli (PTH) are very small, widely separated and not excavated.
Because of this condition the palatine bones form an extensive part of the palate.
They are long, broad laminae which posteriorly partly overlap the pterygoid.
There is no evidence of the presence of a tympano-squamosal recess (see p. 9
supra).
The extent to which the pterygoid process of the squamosal overlaps the pterygoid
bone varies in different balaenopterids (Text-fig. 12a-e). In B. physalus and B.
acutorostrata a broad width of pterygoid separates the pterygoid process of the
squamosal from the palatine. This width is progressively narrowed by the extension
of the pterygoid process of the squamosal, in the order B. borealis, Megaptera
novaeanglhiae, B. brydei, to B. musculus in which the process makes broad contact
with the posterior margin of the palatine, so that in this last species the pterygoid
is divided into two areas respectively ventral and lateral. It is interesting to note
that the contact between squamosal and palatine achieved in Balaenoptera musculus
is also to be seen in the odontocete Pseudorca crassidens.
BaLaENIDAE. This family is represented by the two genera Caperea and Balaena.
HEARING IN CETACEANS
36
‘snjarysdu nuavjog "J “snjnosnu ga “waphéqg’g “Pp ‘avysuvavaou py °9 ‘syvadeq “{@ “4 ‘snyoskyd vaajqouavyg “e
‘sojoorjsAtm snorea ur souoq yueoelpe 0} prosf10qzd oy} yo drysuoyzeper moys OF sueiseiq “ZI ‘SIq
HEARING IN CETACEANS 37
In respect of the parts under discussion in the present paper it shows the least
degree of specialization. Referring to Capevrea marginata first (Pl. 5 and 6), the skull
as a whole shows more primitive features than any other mysticete. Neither the
orbital process of the frontal nor the zygomatic process of the squamosal is very
greatly extended laterally, the bony narial passages are elongated and there is a
well-defined cribriform plate. The pterygoid hamuli (PTH) are inconspicuous and
are separated from each other by nearly the total width of the choanae. The channel
for the Eustachian tube from the tympanic cavity to the choanae is not merely
a notch in the pterygoid but a deep antero-mesially-directed bony groove on the
ventral aspect of the latter bone.
The tympano-periotic bones (TB and PE) are not entirely excluded from the wall
of the cranium, a portion of the superior face of the periotic participating in the
formation of the cranial cavity. The tympanic bulla is disproportionately large
compared with the periotic and is itself relatively much larger than that found
in any other mysticete. It is flattened ventrally to conform with the general level
of adjacent bones and constitutes an appreciable part of the base of the skull in
this region.
The mastoid processes of the tympanic and periotic are fused together, the relatively
massive combined process extending to the lateral limit of the skull where it forms
a roughly oval facet of considerable area between the basioccipital and squamosal.
The mastoid process, although inserted between the bones just mentioned, is freely
movable in the macerated skull.
With Ridewood’s description of the falciform process of Megaptera in mind (see
Pp. 34 supra) it should be noted that in Caperea the pterygoid process of the squamosal
is not bifid and only that part of it corresponding to the falciform process (FP) is
developed to any extent. It does not appreciably overlap the pterygoid bone except
posteriorly and does not approximate to the external opening of the infundibulum
of the foramen ovale (Fo). This infundibulum is formed by a transverse, dorsally-
directed bifurcation, the two branches of which meet dorsal to the infundibulum.
The basioccipital crests (BOC) are robust and unexcavated and approximate very
closely to, but are not, as in terrestrial mammals, in contact with the mesial face
of the bulla (see p. 77). The paroccipital process on each side is bounded mesially
by a conspicuous semicircular notch which is much larger than, but corresponds in
position with, the channel which conducts the gth, roth and 11th nerves as well as
the internal carotid artery and the internal jugular vein. It communicates with a
wide postero-lateral extension of the cranial cavity superior to the periotic. The
paroccipital process is recessed on its anterior face to form the posterior limiting
wall of an infundibulum, the anterior wall of which is provided by the posterior face
of the mastoid process (MAS).
As in cetaceans, generally, the pterygoid bone of Caperea is split into a mesial
(PT (ML)) and a lateral lamina (PT (LL)) but in addition, superior (pT (sL)) and inferior
(PT (1L)) laminae are present so that the cavity so formed is only open posteriorly.
The limited distention of the pterygoid sinus is indicated by (a) the antero-posterior
width of the falciform process (FP), (b) the position of the mandibular branch of the
5th nerve (NM) which is anterior to the sinus of the pterygoid (see Text-fig. 15).
38 HEARING IN CETACEANS
It will be recalled that in Balaenoptera the infundibulum of the 5th nerve passes
above, and posterior to the anterior limit of this sinus.
The pterygoid hamuli (Pru), in addition to being but poorly developed and widely
separated, are quite remote from the excavated part of the pterygoids.
The pterygoid (pr) and palatine (PAL) bones meet in a simple edge-to-edge suture,
there being no over-lapping of the pterygoid by the palatine as in the Balaenopteridae,
and of the palatine by the pterygoid as in the Odontoceti.
There is a deep fissure between the glenoid process and the pterygoid which is
comparable in position with the tympano-squamosal recess of odontocetes, but
its association, as in odontocetes, with the system of tympanic air spaces seems
unlikely. It evidently appears to be related to the close proximity of the elongated
glenoid process with the distended lateral lamina of the pterygoid.
The members of the genus Balaena although, generally speaking, not as specialized
as the Balaenopteridae, still show a considerable advance on the conditions found
in Caperea. Both the orbital process of the frontal and the zygomatic process of
the squamosal are greatly extended laterally. The paroccipital process shows less
lateral extension than in the Balaenopteridae. The hard palate is extended
posteriorly, the palatine bones being squamous over the pterygoid hamuli to an
extent that the latter are sometimes completely hidden in the ventral view of the
skull (Text-fig. 12f). (The Balaenidae in this condition thus demonstrate exactly
the reverse of the condition found in Platanista in which the greatly extended ptery-
goids completely cover the palatines). The hamuli themselves are better developed
than in Capevea. Their greatly flattened ventral surfaces are in apposition to the
overlying palatine bones and the posterior portions of their mesial borders extend
towards the middle line.
The tympano-periotic bones are withdrawn in a ventral direction from the cranial
cavity, being separated from the latter by a long, narrow, antero-mesially directed
infundibulum (Text-fig. 13c). The combined tympanic and periotic pars mastoidea
is more attenuated than in Caperea but considerably shorter than in any of the Balaen-
opterids, this being associated with the state of development of the paroccipital
process. It bears a facet which is a component part of the external surface in this
region. The pyramidal pro-otic portion of the periotic is widely exposed and not
partly overlapped by the squamosal as in the Balaenopteridae. The tympanic
bullae are relatively large and are flattened dorso-ventrally as in Caperea. As in
the latter their ventral faces form an important portion of the postero-ventral
surface of the skull. Their mesial borders approximate closely to the lateral margins
of the basioccipital crests.
The pterygoid process of the squamosal is bifid as in the Balaenopteridae but is
directed postero-ventrally instead of antero-ventrally as in the latter family. The
process overlaps the pterygoid and bifurcates round the external aperture of the
foramen ovale forming posteriorly a well defined falciform process (Text-fig. 12/, FP).
The infundibulum of the foramen ovale (FO) is incomplete posteriorly since the
superior lamina of the pterygoid bone is not extended posteriorly as in the
Balaenopteridae.
The basioccipital crests are very stout and roughly pyramidal in shape, and are
HEARING IN CETACEANS 39
overriden to some extent anteriorly by squamous extensions of the otherwise equally
robust mesial laminae of the pterygoids. Each paroccipital process, as previously
stated, is relatively short. At the mesial end of its antero-ventral surface is a short,
elongated, oval concavity which is in juxtaposition with a similar concavity on
the postero-dorsal face of the ‘‘ pars mastoidea’’’ of the tympano-periotic.
The pterygoid bones, as in other cetaceans, are split into mesial and lateral laminae
to form the so-called pterygoid fossa. The two laminae are continuous ventrally
and anteriorly, but the superior lamina is deficient posteriorly so that part of the
alisphenoid adjacent to the path of the mandibular branch of the fifth nerve is
visible in the roof of the pterygoid fossa. The orbital portions of the pterygoid
bones are for the most part concealed by a dorso-lateral extension of the palatine.
A small slip of the pterygoid can, however, be seen adjacent to the alisphenoid-
squamosal suture. The pterygoid hamuli, already described, are not excavated.
The squamosal has an even wider contact with the palatine than in Balaenoptera
musculus (Text-fig. 12f). Between the pterygoid process of the squamosal and the
glenoid process (the latter of which is greatly extended ventrally) is a deep con-
cavity which is in the position of the tympano-squamosal recess of the Odontoceti
but it is not to be considered homologous with the latter.
EScHRICHTIDAE. In Eschrichtius, as in other cetaceans, the tympano-periotic
bone is dissociated from the remainder of the skull and its relation to the cranial
cavity is as in Balaenoptera. The thin, laminate mastoid process is inserted between
the squamosal and basioccipital and extends to the lateral limit of the latter bone.
The falciform process is slender and more attenuated than in Balaenoptera,
resembling in this respect Balaena, but it is directed antero-ventrally as in Balaen-
optera. The infundibulum of the mandibular branch of the 5th nerve is open to the
tympanic cavity and occupies the same position as in Balaena.
The basioccipital crests are not very prominent but extremely robust with little
excavation of their lateral faces. As in Balaena the paroccipital notch is very wide,
and a smooth area in its proximity suggests excavation of the bone in this region.
The laminae of the pterygoid are complete but the superior lamina does not extend
posteriorly under the 5th nerve infundibulum as it does in Balaenoptera. The
pterygoid fossa does not extend anteriorly as far as in Balaenoptera but the pterygoid
hamuli are similar in shape to those of the latter species, being unexcavated and not
dorso-ventrally compressed as in Balaena. The amount of backward extension of
the palatine bones in Eschrichtius is midway between Balaenoptera and Balaena.
It will thus be seen that Eschrichtius occupies an intermediate position between
Balaena and Balaenoptera as far as the pterygoid sinus system is concerned.
ODONTOCETI
ZIPHIOIDEA
The following species of ziphioid whale have been examined—Hyperoodon ampul-
latus, Berardius arnuxt, Berardius bairdi, Ziphius cavirostris, Mesoplodon bidens
(Pls. 8-12). Two general features emerge from the examination, the first being the
distinctive difference between the Ziphioids and the Delphinids of the regions under
40 HEARING IN CETACEANS
discussion in this paper, the second being the general homogeneity and smoothness
of structure of this region in all the ziphioids, there being little or no evidence of
progressive changes between individual species.
The tympano-periotic bones of the Ziphioids are excluded from the wall of the
cranial cavity, but unlike that of delphinids the mastoid process of the tympanic
(MAS) is relatively larger and interdigitates with the pars mastoidea of the squamosal.
This interdigitation has been described by many authors as an actual fusion of the
bones concerned but in no specimen examined by the present writers has fusion been
observed ; in the macerated skull, whatever the age of the animal concerned, the
mastoid process of the tympanic is always freely moveable. In very young specimens
there is a cranial hiatus dorsal to the periotic but this is soon occluded by extensions
of the bones adjacent to the hiatus.
The falciform process (FP) is invariably in the form of a stout spine curving round
the anterior margin of the tympanic bulla (TB) and in close approximation to the latter.
The process in Ziphius cavirostris is distinctive in being stouter, more robust and
more flattened meso-laterally than in the remainder of the species examined.
A considerable portion of the proximal part of the infundibulum of the foramen
ovale (Fo) is present as a lamelliform shelf forming the ventral wall of the channel.
The basioccipital crests (BOC) are massive and show no cavitation of their lateral
aspect. The interval between the tympanic bulla and crest is very narrow. The
peribullary space as a whole is extremely restricted, and there is none of the excavation
round the dorsal margin of the foramen ovale which occurs in the Delphinoidea.
The paroccipital processes are massive, unexcavated tubercles. The extensive
interdigitation of the mastoid process of the periotic with the paroccipital process
is probably associated with the absence of excavation of the anterior face of the
latter.
The pterygoid bones are conspicuously large, their length being about one third
that of the skull. The general form of the pterygoids is such as to suggest a funda-
mental difference in the process of modification of these bones in the Ziphioidea
from that of all other cetaceans in the disproportionate development of the hamulus
(pTH). It will be seen below that in Platanista each pterygoid bone is split longi-
tudinally, and more or less equally, into a mesial and a lateral lamina, and that the
process of modification from this simple form throughout the series of skulls des-
cribed, consists of a gradual distention and elaboration of the inter-laminar space,
together with the formation of a superior lamina.
In the absence of intermediate stages between the primitive form of pterygoid
and the more or less uniform resultant form found in recent ziphioids, the writers’
interpretation of the mode of formation of the pterygoid bones is as follows. There
appears to have been an initial splitting of the pterygoids, but thereafter this has
progressed very asymmetrically, so that the mesial lamina is enormously enlarged
whilst the lateral lamina is relatively inconspicuous and compressed ventro-dorsally,
and is horizontally instead of vertically disposed. In this condition it overlaps
the alisphenoid (ALS), orbitosphenoid (os) and part of the palatine (PAL). The result
of the great exaggeration of the mesial lamina is that the pterygoid hamulus (PTH)
is disproportionately enlarged and distended posteriorly and anteriorly. The great
HEARING IN CETACEANS 41
fossa on the lateral aspect of the pterygoid bone can be said to be made up almost
entirely of the hamular part of the bone, the posterior tip of which is extended
backwards to the level of the anterior margin of the basioccipital crest, emphasizing
the acuity of the pterygoid notch. Anteriorly the pterygoid bone extends forward
over the palatine to make contact with the maxilla (mx) thus dividing the palatine
into mesial and lateral portions. In this region the lateral and dorsal parts of the
pterygoid are frequently of extreme thinness and in places the bone as such has
altogether disappeared, exposing the underlying palatine in macerated specimens
(see Pl. 9). The asymmetrical evolution of the pterygoid fossa probably accounts
for the greater robustness of the hamuli as compared with those of the delphinoids.
In the specimens of Berardius bairdi and B. arnuxi examined, that part of the ptery-
goid overlying the alisphenoid is also rarified so that part of the ventral surface of
the latter bone is exposed.
The tympano-squamosal recess (TSQR) is of the form found generally in other
odontocetes but its boundaries are not as well defined. It consists of a posterior
portion which occupies the region behind the glenoid fossa and an anterior extension
which lies mesial to the latter fossa and along the anterior margin of the zygomatic
process of the squamosal.
PHYSETEROIDEA
In Kogia (PI. 16) as in the ziphioid whales the tympano-periotic bones are excluded
from the wall of the cranial cavity, and the mastoid process of the periotic (mAs)
is much larger than in the delphinoids. The tympano-periotic bones are apparently
disproportionately small, but the mastoid process of the periotic is relatively much
larger than in the ziphioids and does not interdigitate with the pars mastoidea of
the squamosal. It is a stout, roughly pyramidal tubercle of which the apex points
towards, and is attached to, the periotic, and of which the base forms its external
aspect. On its squamosal face the bone is marked by a series of deep, radiating
channels which appear to be connected with the peculiar cancellated structure of
the bone. Its paroccipital aspect forms a smooth, triangular facet. There are no
marks on the squamosal nor on the paroccipital process which would suggest a
close articulation. On the contrary, the mastoid process appears to lie quite loosely
between the bones adjacent to it. When the pars mastoidea of the periotic is dis-
sociated from the latter it is extremely light in weight, is translucent and floats
in water as if pneumatized. The mamillated appearance of the external surface
of the bone is extremely reminiscent of that of the pneumatized squamosal of other
mammals (e.g. adult gorilla). It may also be noted that in the ziphioids generally,
as well as in Kogia, the bone in the mastoid region has a peculiar, crevassed appearance
quite distinct from the bone adjacent to it.
There appears to be no trace of a falciform process, the articulation of the squa-
mosal (sQ) with the alisphenoid (ALs) being more like that found in terrestrial mam-
mals. The foramen ovale (FO) is also in the position typical of terrestrial mammals,
that is, within the alisphenoid bone, and there is no trace of a bony infundibulum
such as is found in most of the delphinids,
42 HEARING IN CETACEANS
The basioccipital crests (Boc) are stout and prominent, and the paroccipital
processes are very large and their concavities of a size commensurate with that of
the massive mastoid processes of the periotic.
The pterygoid bones are very greatly enlarged, their length being between a half
and two-thirds that of the skull. The constitution of the pterygoid bone is inter-
pretable in terms comparable with those used in connection with the ziphioids,
that is to say the splitting of the pterygoid plate appears to have taken place asym-
metrically, the mesial lamina (pT (ML)) being greatly enlarged. The ventro-dorsally
compressed superior lamina (pT (SL)) is represented only by a short shelf of bone
extending laterally below the orbito-sphenoid. It will be recalled that in the
ziphioids the greater part of the pterygoid distention was in the hamular region.
The reverse is the case in Kogia, the hamulus (PTH) being relatively insignificant
and not at all distended, whilst the mesial lamina is grossly enlarged and extended
posteriorly, partially to override the basioccipital crest. The effect of this on the
position of the foramen ovale is discussed in the section below dealing with Physeter.
Anteriorly the pterygoids are extended as squamations which make contact with
the maxillae (Mx) and divide the palatines (PAL) into mesial and lateral areas.
The greater part of the ventral surface of the orbital process of the frontals (FR),
as well as the preorbital portions of the maxillae have a characteristic smoothness.
The tympano-squamosal recess is poorly developed, consisting of a single lobe
which lies along the posterior border of the zygomatic process of the squamosal
and terminates at the mesial limit of the ill-defined glenoid fossa.
Flower (1868) remarks on the small size of the tympano-periotic bones of Physeter
catodon. He goes on to draw attention to the development of a large mass of
curiously laminated bone which he says extends from the posterior and outer end of
the tympanic, close to its attachment to the periotic, and thicker at its distal than
at its proximal end. He states that it is composed of a large number of distinct,
thin plates held together only by their common attachment to the tympanic. The
present writers have been able to distinguish only two such plates which they regard
as the tympanic and periotic elements of the mastoid process. This condition can
be homologized with that found in the Delphinioidea, in which, to quote Flower
himself : ‘‘ This process resembles in its relations the mastoid of ordinary mammals,
but in young cetaceans it may be seen to be composed of two nearly equal parts,
in close apposition with each other, the inferior being derived from the tympanic
and the superior from the periotic so that the latter alone can represent the pars
mastoidea of other mammals.’’ As Flower says, referring again to the Sperm Whale :
“The whole mass partly overlaps and embraces the hinder edge of the squamosal
and partly fits into a groove between the latter and the exoccipital.’’ He goes on
“Tt evidently corresponds to the strong tenon-like process of corresponding situation
and function in the Whalebone Whales’. “ The contiguous edge of the squamosal
has a laminated character, the ridges and grooves on its surface exactly fitting those
of the appendage of the tympanic ”’ [1.e. tympano-periotic].
In the skull of a female sperm whale examined, the mastoid process is not firmly
wedged, but freely movable between the bones adjacent to it. The ventral edge of
the process is strongly involuted so as to form a bony canal for the external meatus,
HEARING IN CETACEANS 43
The tympano-periotic bones are excluded from the wall of the cranium and in
the specimen examined, no trace of the cranial hiatus remains.
The falciform process is moderately well developed, in this respect differing from
Kogia. The foramen ovale is displaced anteriorly from the process by a considerable
distance, a feature to which reference will be made below, and in which Physeter
and Kogia differ from all other cetaceans.
The basioccipital crests are massive tuberosities and are very short antero-
posteriorly. The paroccipital processes are relatively small and the ventral margin
of the lateral border is strongly involuted to form an infundibulum, the inner end
of which is continued in a groove giving access to the peribullary space. As in Kogia
the pterygoid bones are relatively large and appear to have undergone the same
process of asymmetrical splitting observed in the ziphioids. The lateral lamina is
extremely compressed ventro-dorsally and squamated over the alisphenoid, orbito-
sphenoid and frontal bones. The distention of the pterygoid hamulus is slightly
greater than in Kogia but this part is relatively insignificant as compared with the
mesial lamina. The lateral lamina is extended ventrally and posteriorly so that it
overrides and partially envelops the basioccipital bone. By the same process the
pterygoid notch is deepened but diminished in size. This process of exten-
sion posteriorly seems to have involved the posterior margin of the alisphenoid
bone.
In the foetal specimen of this species the foramen ovale is situated at the end of
a conspicuous longitudinal notch in the posterior margin of the alisphenoid. In
the adult specimen the foramen ovale is still more anteriorly situated, and even
although it appears to penetrate the lateral wing of the alisphenoid, its true relation-
ship is with the closed up, re-entrant portion of the posterior margin of the latter
bone, as in the above-mentioned foetal specimen and in cetaceans generally. The
longitudinal notch in the posterior border of the alisphenoid is clearly visible in
adult specimens of Kogza.
The pterygoid bones are not squamated over the palatines to the same extent as
in Kogia, the latter bones not being divided into mesial and lateral areas. The whole
of the base of the cranium external to the pterygoids shows extensive squamation
and rarification of the bones involved.
The glenoid fossa is ill-defined, to say the least, so that it is impossible to delineate
the boundaries of the tympano-squamosal recess, but most of the ventral aspect
of the zygomatic process of the squamosal is of a characteristic smoothness and has
its antero-mesial margin squamated over the alisphenoid.
PLATANISTOIDEA (Pls. 17-23)
Contrary to the view of Hyrtl (1845), repeated by Yamada (1955), the tympano-
periotic of Platanista (Pls. 17, 18) is not fused to adjacent elements of the cranium
in any of the specimens in the British Museum collections, and the series includes
old as well as juvenile skulls. The mastoid process (MAS) of the periotic is intimately
interdigitated with the squamosal so that after maceration the tympano-periotic
Temains 77 situ but is freely movable in its interlocked position, The combined
44 HEARING IN CETACEANS
elements are displaced ventrally and somewhat laterally from the cranial cavity
and the hiatus in the cranial cavity thus formed is partially filled by osteosclerosis of
the squamosal, parietal and occipital.
The falciform process (FP) is a stout, bony plate which passes antero-ventrally
round the posterior border of the foramen ovale (Fo,) almost covering over the ali-
sphenoid and making contact with the posterior border of the lateral lamina (PT (LL))
of the pterygoid bone. There is thus a complete bony bridge extending from the
maxilla (Mx) to the squamosal (sq).
The basioccipital crests (Boc), although not very prominent, are stout in structure
and on their lateral (tympano-periotic) aspect are profusely cavitated in a manner
reminiscent of the mastoid region of terrestrial mammals. Posteriorly to the crests
the paroccipital processes (PAO) are deeply excavated by narrow, dorsally-directed
concavities.
The palatines are completely obliterated from view by the forward extension of
the laminae of the pterygoids. External to the basioccipital arcade, the anterior
portion of the squamosal, the alisphenoid and pterygoid bones are split into two
distinct laminae with an interval between which is crossed by bony trabeculae and
is continuous with the tympanic cavity. The passage of the mandibular branch
of the trigeminal nerve through the foramen ovale traverses the inter-laminar space
in the form of a bony tube. There is reason to believe that the inter-laminar space
(ILs) communicates with another similar inter-laminar space occupying the whole of
the mesial aspect of the massive maxillary crests (Mxc) which characterize the
gangetic Dolphin.
In all the British Museum specimens of Platanista except that shown in Pl. 18
the hamular processes of the pterygoids (PTH) are missing and skulls are generally
depicted without them. Pl. 18 shows that well-defined processes are present in the
juvenile and that they meet in the middle line. They are excavated like the remainder
of the pterygoid bones and the ventral surfaces show extensive fenestration. It
seems likely that the processes persist in the adult but that they are usually lost in
maceration.
In the posterior, proximal part of the zygomatic process of the squamosal there
is a ventrally situated, deep, triangular recess the posterior angle of which is adjacent
to, and confluent with, the petro-tympanic fissure, the tympano-squamosal recess
(tsgR). The ventral angle occupies the mesial aspect of the glenoid process which
is deeply excavated. The lateral borders of this recess are strongly involuted. The
position and extent of the recess and its contiguity with the petro-tympanic fissure
recall the pneumatic extension of the tympanic cavity of Macropus as described
by Owen (Anat. of Vert. Vol. II, p. 341).
In the specimen of Stenodelphis figured (Pl. 19), the tympano-periotic is missing
but its absence serves to demonstrate the process of exclusion from the cranial
cavity already referred to in Platanista. The large hiatus (CRH) in the cranial wall
can be seen to be partially filled in by osteosclerotic extensions of the alisphenoid
(ALS) and parietal (PAR) bones.
As in Platanista, the falciform process (FP) is wide, overlaps the alisphenoid and
anteriorly makes contact with the posterior border of the pterygoid bone,
HEARING IN CETACEANS 45
The downward extension of the basioccipital crests (BOC) is more emphasized than
in Platanista. The bone substance does not show the characteristic cavitation seen
in Platanista except in the region of the paroccipital processes (PAO) which are
excavated in a manner comparable with that in the last named genus.
The pterygoid bones do not quite cover the palatine bones (Pl. 19, PAL) but
laterally they have an anterior extension below the orbit as far as the jugal (pT and
ju). Anteriorly to the tympanic cavity the interlaminar space of the pterygoids is
more distended than that of Platanista. The bony connection between the lateral
and mesial openings of the foramen ovale (FO) is deficient ventrally and laterally.
The lateral lamina of the pterygoid (pT (LL)) shows extensive fenestration and
antero-laterally the interlaminar space continues into the mesial end of the orbit.
The two pterygoid hamuli (pTH) are distended meso-laterally but unlike those of
Platanista their mesial borders are not in contact but form a wide angle. Anteriorly
the dorsal and ventral extensions of each pterygoid are separated by a wide, plate-like
process of the maxillary bone (Mx).
The orbital extension of the pterygoid bone is of great significance in the inter-
pretation of the distribution of the air sacs in other cetaceans.
The tympano-squamosal recess (TSQR) in the vicinity of the glenoid fossa is more
extensive in Stenodelphis than in Platanista. It can be associated morphologically
with the latter by regarding the anterior angle as being much extended anteriorly
along the mesial border of the zygomatic process of the squamosal (sgz). In its
course this part of the recess curves round, and in part overlies, the glenoid fossa.
Its anterior extremity is situated slightly anterior to the notch formed by the
junction of the zygomatic process with the lateral wall of the cranium.
In the genus Jia resorbtion of the bones under discussion has proceeded to such
an extent that interpretation of their arrangement has had to be arrived at with
reference to X-ray photographs of the air sinuses. In Pl. 21 the tympano-periotic
is wanting but its absence permits to be seen the same process of exclusion of the
ear-bones from cranial contact that was observed in the previously described genus.
The osteosclerotic parts of the squamosal, parietal and basioccipital can be seen
in the figure forming the anterior margin of the cranial hiatus (cRH).
The falciform process (FP) is reduced to a low, acutely-ridged eminence extending
posteriorly from the squamoso-alisphenoidal suture.
At the anterior border of the foramen ovale (Fo) an acutely-pointed, laterally-
directed process represents the remaining vestige of the bony tube? which in
Platanista connects the cranial and external apertures of the foramen.
The basioccipital crests (Boc) are moderately prominent but rather thin and plate-
like. This condition in Jmia may be interpreted as being due to the merging of
numerous cavities like those observed in this region in Platanista. The same explana-
tion would account for the deep, re-entrant angle that the plane of the crest makes
with the portion of the basioccipital in the vicinity of the tympano-periotic.
Of the hollow which occupied the paroccipital process (PAO) of Platanista and
Stenodelphis only the posterior boundary remains in Ima. The anterior and mesial
1In the succeeding references to the bony tube it should be noted that in the plates the presence
of its osseous remnants is usually obscured by the falciform process.
46 HEARING IN CETACEANS
delimitations have completely disappeared so that the cavity persists only as part of
the peribullary space.
The condition of the pterygoid bone can best be interpreted by regarding it in
relation to that found in Platanista and Stenodelphis. In Imia the whole of the
lateral and superior laminae of the pterygoid has disappeared so that the great
wing of the alisphenoid (ats), which in the other two genera was hidden by the
pterygoid, is completely exposed. In the posterior narial region the pterygoid is
reduced so that only the mesial lamina (pT (ML)) of the pterygoid hamulus remains,
except at the posterior border where fenestrated vestiges of the inferior lamina
(pr(1L)) still persist. Asa result of the extensive resorption of the mesial lamina, the
lateral aspect of the palatine (PAL) is largely exposed, and posteriorly to the palatine
a wide lacuna gives entrance to the nares. Because of the reduction of the pterygoid
bone there is no osseous evidence of its extension into the orbital region as in Steno-
delphis but radiographs (see p. 70) show that the air sacs primarily associated with
the pterygoid protrude into the orbital region (see Pl. 22). As in Stenodelphis there
is a posteriorly projecting, but in this genus much fenestrated, maxillary plate. This
plate was considered by Flower (1889) to be a portion of the palatine fused anteriorly
to the maxilla, but the lateral suture between the palatine and the maxillary plate is
situated in the deep fossa formed between the aforementioned plate and the palatine.
It should be noted that in the post-orbital region of the majority of the specimens
of Inia examined, the maxillary is exposed to view on its ventral aspect owing to
resorption of the frontal (FR).
The greater wing of the sphenoid, part of the parietal and the greater part of the
ventral aspect of the frontal present a smooth, polished appearance. It will be
demonstrated later that this smoothness is associated with the proximity of the
bones to air sacs.
The tympano-squamosal recess (TSQR) is much shallower than in the other two
River Dolphins. The anterior angle extends as far as the border of the squamo-cranial
notch but does not extend along the mesial margin of the zygomatic process (SQZ)
as in Stenodelphis. The borders of the recess are not strongly involuted as in the
other two genera.
In the only available specimen of Lipotes (Pl. 23) the tympano-periotic bones are
in situ so that the hiatus and the recesses in the paroccipital process cannot be seen,
but the general impression which is possible suggests considerable separation of the
tympano-periotic bones from the adjacent bones of the skull.
The falciform process has completely disappeared as has also the bony infundibulum
of the foramen ovale (Fo.) The foramen ovale in this species appears to form a discrete
perforation of the alisphenoid but is in fact a re-entrant of that bone, the distal
borders being in close apposition in a manner comparable with the condition found
in Physeter and Kogia.
The basioccipital crests (BoC) are more prominent than in Jia, but as in the latter
are rather thin and plate-like.
The condition of the pterygoids is similar to that in Inia but the hamuli (PTH) do
not project posteriorly to the same extent as in that species. On the other hand the
postero-lateral borders of the pterygoids extend ventrally beyond those of the basi-
HEARING IN CETACEANS 47
occipital crests so that a deep notch is formed in the crest at the point of junction
of the two bones. The lateral lamina is almost as completely resorbed as in Inia
and the mesial lamina (PT(ML)) is absent anterior to its junction with the posterior
edge of the palatine (pAt.) There is no trace of the superior or lateral lamina in the
orbital and post-orbital regions and the great wing of the alisphenoid (ALS) is com-
pletely exposed. The post-orbital process of the frontal is greatly widened as com-
pared with Jnza and its ventral surface is smooth as in that genus.
The development of the tympano-squamosal recess (TSQR) shows a considerable
advance on Inia, its anterior process projecting halfway along the mesial border
of the zygomatic process of the squamosal (SQ).
MONODONTOIDEA
Except in the lesser prominence of the falciform process Monodon monoceros
shows a less advanced state of resorption of the bones associated with the air sinuses
than Delphinapterus and therefore will be dealt with first.
In the figure of the skull of an adult Monodon (Pl. 13) it will be seen that the
tympano-periotic bones are missing, but the figure of that of a very young specimen
(Pl. 14) shows the position which they occupy and how their ventral surfaces are
level with the basioccipital crest (Boc). It will be noted that the mastoid process
(mAs) is completely dissociated from the adjacent bones of the skull. In the juvenile
specimen there is a wide hiatus in the cranial cavity above the tympano-periotic
bone but in the adult (Pl. 13) this has been largely filled in by extensions from the
squamosal, parietal and alisphenoid.
The falciform process (FP) is a low, rather stout tubercle (Pl. 13). Of the bony
tube of the foramen ovale (FO) which transmits the mandibular branch of the trigemi-
nal nerve the anterior, dorsal and ventral walls of its mesial portion remain, Monodon
in this respect being unlike Zmza in which only a very small, spike-like portion of
the wall persists (see p. 46 supra).
The basioccipital crests are more prominent and the laryngeal arcade between
them more heightened than in the River Dolphins. The crests themselves are stouter
and show a condition of excavation of their lateral aspect similar to that of Steno-
delphis. The excavation of the paroccipital process (PAO) consists of a saucer-like
depression with an anterior communication into the peribullary space; there is
no evidence of a ventral closing wall as in Platanista.
The space between the mesial (PT (ML)) and lateral laminae (PT (LL)) of the ptery-
goid, which involves palatine and alisphenoid bones, is considerably more distended
than in any of the River Dolphins. Posteriorly the superior lamina (pT (SL)) of
the pterygoid has disappeared exposing to view most of the greater wing of the ali-
sphenoid, as in Jmia. In this respect the posterior region of the pterygoid shows a
more advanced state of resorption than that of the anterior region. The pterygoid
hamuli (PTH) are only slightly excavated and their mesial borders are widely separated
anteriorly and approximately but not touching posteriorly.
The lateral laminae of the alisphenoid, pterygoid and palatine on each side, form
a bony bridge extending posteriorly from the anterior border of the orbital process
48 HEARING IN CETACEANS
of the frontal to the squamosal. The greater part of the ventral portions of these
laminae has disappeared leaving a wide, gaping, irregular concavity on the ventro-
lateral aspect of the skull.
The overgrowth of the palatines by the pterygoids is less conspicuous than in the
River Dolphins, large areas of the palatine bones being visible on the ventral aspect
of the skull.
The tympano-squamosal recess (TSQR) is wide by comparison with that of any of
the River Dolphins. Its anterior border is ill-defined, its mesial and lateral borders
slightly involuted.
In the figured specimen (Pl. 15) of the skull of Delphinapterus leucas the tympano-
periotic bone is wanting, showing the dissociation of these bones from the adjacent
bones of the skull. The cranial hiatus (cRH) is seen in the figure as are the osteo-
sclerotic extensions of the basioccipital (Bo), parietal (PAR), alisphenoid (ats)
and squamosal (sQ). An examination of a number of skulls of adult specimens
shows that the hiatus eventually becomes almost entirely obliterated by such
extensions.
The falciform process (FP) is much more prominent in this species than in
Delphinapterus and bears, on its mesial surface proximally, a residual part of
the wall of the bony tube of the foramen ovale. Remnants of the mesial part
of this tube are also found in the same relative position and in the same form as in
Monodon.
The basioccipital crests (Boc) are robust and prominent. The paroccipital excava-
tions like those of Monodon are open ventrally to expose a shallow depression com-
municating anteriorly with the peribullary space.
As in Mondon, the posterior portion of the superior lamina (PT (SL)) of the pterygoid
has disappeared exposing a part of the alisphenoid (As) ; the state of development
of the anterior portion is also very similar to the condition found in Monodon,
there being no lateral extension of the pterygoid inter-laminar space in the orbital
region. The pterygoid hamuli (PTH) are more excavated and the juvenile specimen
figured shows considerable fenestration of their ventral surfaces.
Of the bony bridge, which in Monodon extends posteriorly from the anterior
border of the supra-orbital process of the frontal to the squamosal, very little remains.
The alisphenoidal portion of this lateral lamina is wanting. The pterygoid portion
(pT (LL)) is fragmentary and irregularly bordered, with a slender extension posteriorly
to the squamosal. Its anterior border is separated from the lateral lamina of the
palatine (PAL (LL)) by a short gap, The lateral concavities in the ventral aspect of
the skull are thus still delineated mesially by the basioccipital ridges and laterally
by the above-mentioned bony bridges. It should be noted that the anterior end of
the concavities excavate the palatine bones to a greater extent than in Monodon.
The pterygoids do not override the palatines anteriorly but make deep invaginations
into the posterior borders of the latter. The hamuli are similar to those of Monodon,
being separated mesially from each other, their mesial borders being wider apart
anteriorly than posteriorly.
As in Mondon the tympano-squamosal recess is shallow and ill-defined, with
almost no involution of any of the borders.
HEARING IN CETACEANS 49
DELPHINOIDEA
PHOCAENIDAE (Pls. 26, 27, 28). The tympano-periotic in the specimen of Phocaena
phocoena figured (Pl. 26) is missing, being dissociated from the remainder of the skull.
The cranial hiatus (cRH) dorsal to the ear bones is partly filled by osteosclerotic
extensions of the basioccipital (Bo) and parietal (PAR).
The falciform process (FP) is reduced to a low, rounded, ventro-mesially projecting,
thin blade. Of the bony tube of the foramen ovale (FO) only a minute fragment of
the mesial portion remains and the foramen itself is very much enlarged.
The basioccipital crests (BOC) are very prominent but very thin, being fenestrated
in the region mesial to the peribullary space. Posteriorly and mesially to the tym-
panic bulla the edge of the crest is strongly involuted so that it forms a partial floor
to the peribullary space. The paroccipital processes are deeply excavated on the
anterior face and bear a shallow depression on their antero-ventral aspect.
The whole of the superior lamina of the pterygoid has disappeared so that the
wing of the alisphenoid (ars) and the ventral face of the orbito-sphenoid (0s) are
exposed. The mesial lamina (PT(ML)) and the sphenoid wing form a deep, trough-
like fossa anterior to the peribullary space. The lateral lamina of the pterygoid
(PT (LL)) remains as a narrow, perforated, irregularly-edged strip of bone connected
anteriorly to the palatine and posteriorly to the alisphenoid (PI. 26).
Although no bony remnants of an orbital distention of the pterygoid bone remain,
it is known that an extension of the air sinus system passes dorsally and posteriorly
into a deep cavity, the walls of which are formed by the anterior face of the frontal
and the ventral face of the maxillary bones (Mx). A great part of the mesial wall
of this cavity is formed by a portion of the mesial lamina of the pterygoid.
The pterygoid hamuli (PTH) are more extensively excavated than in the Mono-
dontidae and are frequently fenestrated on their ventral surface. The hamuli are
widely separated, with their mesial borders divergent caudally.
The tympano-squamosal recess is extended laterally in front of the glenoid fossa.
Its lateral border is involuted.
The arrangement of the bones under discussion in Neomeris phocaenoides (Pl. 28) is
essentially as in Phocaena phocoena with, however, some noteworthy differences. The
basioccipital crests (BOC) are more robust but not so strongly involuted in the
region of the tympanic bulla. The fossae formed by the mesial lamina of the
pterygoid (pT (ML)) and the greater wing of the sphenoid, and that on the anterior
face of the cranium, are enlarged. The bony bridge formed by the lateral lamina of
the alisphenoid, which is reduced to a minute promontory, extends anteriorly to
the postero-dorsal angle of the pterygoid bone.
DELPHINIDAE (Pls. 29-35). Pseudorca crassidens, so far as the region of the skull
under consideration is concerned, shows the most primitive arrangement existing
in any of the Delphinidae. In the plates (Pls. 29, 30) the tympano-periotic is
missing so that the great extent to which the cranial hiatus has been obliterated by
secondary osteosclerosis is well-demonstrated ; only the foramina for the transmission
of blood vessels and nerves persist.
The falciform process (FP) is a broad, irregularly-outlined, robust plate the posterior
margin of which, proximally, follows the contour of the tympanic bulla situated
ZOOL. 7, I. 4
50 HEARING IN CETACEANS
immediately behind it. The bony tube which transmits the mandibular branch
of the fifth nerve is represented by spicular, bony elements involving the pterygoid
and alisphenoid. They extend from the cranial wall obliquely and caudally to make
contact with the inner aspect of the falciform process.
The basioccipital crests (BoC) are very stout and extensively cavitated on their
lateral aspect. They are not very prominent so that the laryngeal arcade is correspond-
ingly shallow as compared with that of other Delphinids. The depressions on the
ventral aspect of the paroccipital processes (PAO) are rather ill-defined.
Pseudorca cvassidens shares with Balaenoptera musculus the distinction from other
forms of having the falciform process in contact with the posterior border of the
palatine. Thus there is a continuous bony bridge, as in certain species previously
described, but it is deficient in bony elements of the pterygoid and alisphenoid,
the lateral bony lamina consisting solely of extensions of the palatine (PAL (LL)) and
squamosal (sg). A considerable portion of the superior lamina of the pterygoid
(PT(SL)) is still present but it does not cover the alisphenoid to any great extent.
Laterally the ventral border of the mesial lamina of the pterygoid (PT(ML)) is deeply
excavated by numerous, and for the most part longitudinally-directed, indentations
which continue for a distance into the posterior nares. At their terminus there
originates a posteriorly directed bony groove which lies along the mesial aspect of
the ventral border of the pterygoid. As in the River Dolphins, notably Stenodelphis,
there is an extension of the pterygoid above the plate of the palatine which has a
distinct horizontal, laterally-directed flexure in this area. This orbital extension is
much better defined and more strongly developed than that of the River Dolphins,
and, owing to the presence of a large optic nerve, is divided into two distinct lobes,
the one passing round the anterior margin of the optic foramen, the other posterior
to the foramen. In the amount of osseous content remaining in the prepared skull
there is considerable individual variation within the species. In the specimen shown
in Plate 29, the inferior, mesial and lateral laminae of the orbital extension of the
pterygoid are complete, so that the inter-laminar space is enclosed in an unper-
forated bony case, whereas in the specimen shown in PI. 30, the bony laminae are
so rarified that only a cage-like remnant persists.
On the palatal surface the palatine bones (PAL) are widely exposed, but their
posterior face is deeply invaginated by the forward extension of the cavity of the
pterygoid hamuli (pTH). The hamuli are strongly excavated and their mesial borders
are in close apposition in the middle line.
The tympano-squamosal recess (TSQR) is wide, shallow and ill-defined, but its
anterior extension reaches almost to the anterior tip of the zygomatic process.
The tympano-periotic bones are absent in the specimen of Orcinus orca figured
(Pl. 31). The cranial hiatus (cRH) shows dimensions consonant with the juvenile
condition of the skull, there being little osteosclerosis of the marginal bones.
The falciform process (FP) is more attenuated than in Pseudorca, being a sickle-
shaped, narrow plate with irregularly pointed extremity. The bony tube of the
foramen ovale (FO) is represented by a small flange projecting from the cranial
wall. On the mesial face of the falciform process there is a small tuberosity which
apparently represents the last vestige of the distal end of the tube.
HEARING IN CETACEANS 51
The basioccipital crests are moderately thin and prominent, with a small amount of
cavitation of their lateral aspect. The depressions of the paroccipital processes
(PAO) like those of Pseudorca are rather ill-defined.
The lateral lamina and the greater part of the superior lamina of the pterygoid
bone, except in the hamular region, have disappeared. A large area of the ali-
sphenoid (ALs) is exposed. A small portion of the superior lamina (PT (SL)) persists,
covering the mesial end of the ventral face of the orbito-sphenoid and a small part
of the adjacent alisphenoid. The mesial lamina (PT (ML)), as in Pseudorca, is scored
by a number of longitudinal grooves on the ventral margin ; they are not however, as
conspicuous as in Pseudorca crassidens. As in Pseudorca there is an extension of the
pterygoid (pr) into the pre-orbital region although it is more resorbed than in that
species. It extends anteriorly from the mesial lamina of the pterygoid as a small,
recurved, finely fenestrated plate of bone which lies alongside the lateral face of
the palatine. A feature, which is distinctive of Ovcinus, is that the fossa which
gives access to the maxillary foramen is very much enlarged relative to that
of other dolphins. It is confluent with the pre-orbital smoothed area. Parts of the
jugal and maxilla lateral to the pre-orbital smoothed area have a flattened squamous
appearance above the position of the eye. In the position occupied by the post-
orbital extension of the pterygoid in Pseudorca there is in Orca a shallow depression
on the ventral surface of the frontal, in which the bone is of a smoother texture than
that which surrounds it. The smooth area in the preorbital region is considerably
larger than the area occupied by the preorbital extension of the pterygoid in Pseudorca.
The significance of these features is referred to on p. 96.
The pterygoid hamuli (prH) are moderately excavated, their ventral aspects being
fenestrated (this latter condition is usually associated with juvenile specimens)
and their mesial borders are in contact in the middle line. The palatine bones (PAL)
are extensively exposed ventrally and laterally and their posterior faces are very
strongly invaginated.
The tympano-squamosal recess is wide and well defined ; its anterior extremity
extends about halfway along the mesial border of the zygomatic process of the
squamosal. The antero-mesial margin is involuted.
In the specimen of Orcaella figured (Pl. 32) the tympanic bulla and periotic are
absent and the infilling of the cranial hiatus (CRH) is composed of an osteosclerotic
extension of the parietal.
The falciform process (FP) is slender, curved and ventrally projecting. A very small
laterally-projecting spine on the ventral margin of the foramen ovale (Fo) represents
the last remnant of the bony tube of the fifth nerve mandibular branch.
The basioccipital crests (Boc) are thinner than those of Orcinus. The paroccipital
processes (PAO) are marked by shallow excavations of the anterior face.
Posteriorly not a vestige remains either of the superior or of the lateral lamina of
the pterygoid, nor is there a trace of the lateral lamina of the alisphenoid. The
greater wing of the sphenoid (ars) and most of the orbito-sphenoid (os) are exposed,
and a large hiatus is present in the region of the optic canal (oF). There is a small
remnant of the orbital extension of the pterygoid in the form of a narrow shelf
(pr(st)) and a slender, curved spine extending laterally from the mesial lamina of
52 HEARING IN CETACEANS
the pterygoid (pt (mML)) along the anterior border of the orbito-sphenoid. In this
position the palatine bone shows a conspicuous, horizontal, laterally-directed flexure
(PAL (LL)). As in Ovcinus there are two smoothed depressions in the ventral surface
of the frontal corresponding in position to the pre- and post-orbital extensions of
the pterygoid noted in Pseudorca. The anterior depression is much larger than the
posterior and communicates with a cavity which lies between the frontal and maxil-
lary bones on the front of the cranium. There is also a small, smoothed area on the
proximal end of the maxilla. In the relative extent of the smoothed areas Orcaella
resembles Orcinus.
The pterygoid hamuli (PTH) are excavated but not inflated and their mesial
borders are widely separated.
In Orcaella the anterior prolongation of the tympano-squamosal recess (TSQR)
extends almost to the anterior limit of the zygomatic process of the squamosal.
In the Globicephala melaena skull figured (Pl. 33) the tympano-periotic bones
are lacking. The cranial hiatus (cRH) is very largely occluded so that only the fora-
mina of the nerves remain. The falciform process (FP) is a truncated, irregular
plate, which bears no trace of the bony tube of the foramen ovale (Fo) on its mesial
aspect. A small flange on the alisphenoid (ats) represents the proximal end of this
tube.
The basioccipital crests (Boc) are moderately stout and shallowly cavitated on
their lateral aspect.
The depressions on the paroccipital processes (PAO) are separated only by a very
low ridge from the peribullary space.
The lateral lamina of the pterygoid is completely wanting, but a small remnant
of the lateral lamina of the alisphenoid remains in the form of a low, ventrally
projecting ridge at the lateral extremity. Of the superior lamina of the pterygoid
the greater part of the posterior portion is wanting, exposing the wing of the ali-
sphenoid (ars). Anteriorly however there is a fairly wide plate of the lamina (pT
(SL)) underlying the orbitosphenoid (0s). No bony vestige remains of the pre-orbital
extension of the pterygoid, but the whole of this region is deeply recessed and is
partially lined by a squamous extension of the palatine bone (PAL), the remainder
of the recess involving the maxilla (mx). An extension of the recess passes dorsally
and posteriorly, between the frontal and the maxilla. The two smoothed depressions
on the ventral aspect of the frontal bones which were observed in Orcinus and
Orcaella are also present in Globicephala but there is an enlargement of the posterior
depression corresponding with the enlargement of the anterior one, so that both are
equal in area. To this extent Globicephala differs from the other two genera just
mentioned, in which the posterior depression is relatively insignificant.
The pterygoid hamuli (prH) are entirely excavated and very widely dilated, and
in juvenile specimens there is fenestration of the ventral aspect. The mesial borders
of the two hamuli are in contact. Anteriorly the palatine bones are not extensively
overgrown by the pterygoids and the invagination of their posterior face is only
moderate.
The tympano-squamosal recess (TSQR) extends to the anterior tip of the zygomatic
process of the squamosal, as in Oycinus.
HEARING IN CETACEANS 53
The tympano-periotic bones are dissociated from the skull of the specimen of
Feresa intermedia figured (Pl. 35) and the cranial hiatus (cru) is partially obliterated
by extensions from the bones adjacent to it. The margins of the peribullary sinus
are deeply involuted, particularly in the anterior region. Here the wing of the
sphenoid is divided horizontally into two laminae by an extension of the peribullary
space.
The falciform process (FP) is broken but the remaining basal part suggests that it
consisted of a small hamate plate of bone. The fracture is such that it is impossible
to state whether any remnant of the distal end of the bony tube of the foramen
ovale remains. The proximal end of the tube is well-defined.
The basioccipital crests (Boc) are slender but quite prominent, and involuted
laterally on their ventral margin. The depression in the paroccipital process (PAO)
is moderately defined.
No vestige of the lateral and superior laminae of the pterygoid bone remains
_except for a small shelf of the superior lamina (pT (SL)) below the orbitosphenoid
(os). In both the specimens available there is secondary cavitation of the alisphenoid
(ALs) and frontal (FR). Of the pre-orbital extension of the pterygoid only part of
the mesial lamina remains and the pre-orbital region generally is recessed as in
Globicephala melaena, the recess being partially lined by a squamous extension of
the palatine bone. The recess between the frontal and maxillary is moderately
well developed on the right side but not so evident on the left. The two pre-orbital
recesses of each side are markedly asymmetrical, that on the right being much
larger than the other. The smoothed, post-orbital recesses are larger in area in
relation to the preorbital than in Globicephala.
The pterygoid hamuli (pTH) are widely dilated, and they are extensively fene-
strated on their ventral aspect. As their posterior extremities are missing it is
impossible to state whether the pterygoids meet in the middle line, but it seems
likely that they do. The palatine bones (PAL) are not extensively overgrown by
the pterygoids but their posterior faces, as well as those of the maxillae, are deeply
invaginated by an intercalation of the pterygoid cavity.
The tympano-squamosal recess (TSQR) is relatively extensive, its anterior extremity
spreading out and occupying the whole of the ventral surface of the anterior apophysis
of the zygomatic process of the squamosal.
Cephalorhynchus heavisidei and C. commersoni are sufficiently alike to be considered
together. In the figured specimen of C. heavisidei (Pl. 36) the tympano-periotic
bone is dissociated from the skull so that the very large cranial hiatus (cru) is
exposed. The falciform process (FP) is a wide, bifurcated bone with no trace of the
infundibulum of the mandibular branch of the 5th nerve on its mesial aspect. A
short length of the mesial portion of the infundibulum protrudes from the wing of
the sphenoid bone partially surrounding the foramen ovale (Fo).
The basioccipital crests (Boc) are thin, partially excavated and moderately
involuted. There is a small recess on the ventral face of each of the paroccipital
processes (PAO). The pterygoid plate and hamuli are wanting but from observation
of a complete specimen of C. commersoni no trace of the superior or lateral laminae
of the pterygoid remains,
54 HEARING IN CETACEANS
The bony orbital extensions of the pterygoid are absent and a very deep pre-
orbital recess passes between frontal and maxilla. The post-orbital recess on the
ventral aspect of the frontal is almost contiguous with the pre-orbital recess and
has a posteriorly projecting extension under the post-orbital processs of the frontal
(FR (PpO)). In this respect, and in the degree of excavation of the pterygoid hamuli,
together with the separation of the hamuli, Cephalorhynchus compares with Phocaena.
The tympano-squamosal recess (TSQR) is limited in area, extending only halfway
along the mesial border of the zygomatic process of the squamosal—another respect
in which it bears some resemblance to Phocaena.
The skull of Lagenorhynchus albirostris examined but not figured, lacks the tympano-
periotic bone and, as in Pseudorca crassidens, the cranial hiatus 1s filled by secondary
bone except for the foramina. The falciform process is a wide, irregularly-shaped,
thin plate with a slender, ventrally directed spine which makes contact with the
anterior extremity of the bulla. The remnants of the bony tube of the foramen ovale
consist of a few postero-laterally directed spicules as in Pseudorca crassidens.
The basioccipital crests are thin, plate-like, very prominent ridges. The depressions
of the paroccipital processes are shallow.
In Pl. 37 which shows the anterior portion of a cranium, the bony bridge of the
lateral lamina consists of elements of the alisphenoid (ALs), pterygoid (PT (LL))
and palatine (PAL (LL)). The pterygoid element, which is much fenestrated, is sutured
anteriorly to the lateral corner of the hamular part of the same bone (PTH), in addition
to being in contact with the palatine. Although there is no contact between the
lateral pterygoid element, and either the superior (PT (SL)) or mesial portions (PT (ML)),
its identity as part of the pterygoid bone can be deduced by reference to the con-
dition of the lateral lamina in Monodon, in which the lateral portion is joined to the
superior portion by small, extremely thin, bony connections. As in previously
described species there is, in Lagenorhynchus albivostris, an extension of the pterygoid
bone into the orbital and pre-orbital regions, but the greater part of its lateral lamina
has disappeared. Of the superior lamina of the pterygoid, only that part which
underlies the orbito-sphenoid remains.
The pre- and post-orbital depressions on the ventral surface of the frontal are
relatively smaller than in Cephalorhynchus. L. albirostris compares with that genus
in having an extension of the post-orbital depression passing posteriorly under the
post-orbital process of the frontal.
The pterygoid hamuli are deeply excavated, and elongated, each showing a sharp
keel ventrally, a feature which characterizes most of the specialized delphinids.
The mesial borders of the hamuli meet in the middle line.
The tympano-squamosal recess (TSQR) is a deep, crescent-shaped fossa bordering
the postero-mesial margin of the glenoid fossa. Its anterior extension reaches to
about half way along the anterior border of the zygomatic process. The lateral
margin is strongly involuted.
Before proceeding with a description of the ventral region of the skull of Lagenorhyn-
chus acutus, it should be noted here that the precedence of order in the descriptions
has been decided by the extent to which the lateral lamina is evident. The presence
or absence of this bony bridge in the prepared specimens is dependent upon the
HEARING IN CETACEANS 55
degree of attachment of the bridge elements to the squamosal and palatine. The
absence of the component bridge elements does not imply that such elements do not
exist, and indeed it has been observed that small fragments of the bridge are some-
times present in the fibrous connective tissue and are usually lost in the process of
maceration. The presence of such unconnected ossicles is an indication of greater
specialization in the evolution of the air sinuses than is the case when a connected
bony bridge persists.
In the figured skull of L. acutus (Pl. 39) the tympano-periotic bones are absent,
and the partial obliteration of the cranial hiatus (cru) is illustrated. In this species
the cavity occupied by the peribullary sinus is well defined and its borders involuted.
The greater extent of this involution, as compared with that present in this region
in L. albivostris, indicates that, as far as the evolution of the peribullary space is
concerned L. acutus is in an earlier phase than L. albivostris.
The falciform process (FP) is a robust, digitiform plate making contact on its
inner face with the bony tube of the foramen ovale (Fo). The bony tube is nearly
entire in this species and is a conspicuous lateral projection of the cranial wall.
The basioccipital crests are thin, prominent and involuted. The ventral depres-
sions of the paroccipital processes (PAO) are very shallow but the processes themselves
are deeply cavitated dorsally, the cavities being confluent with those of the peribullary
spaces.
Whether or not any portions of the bony bridge of the lateral lamina are present
in the living animal has not been ascertained but the state of resorption of the superior
lamina indicates that if such remnants are present they will be very small. The
superior lamina is restricted to a narrow strip bordering the mesial margin of the
orbito-sphenoid (os). The alisphenoid (ats) is completely exposed. The extension
of the pterygoid bone into the pre-orbital region is strongly reminiscent of the
condition found in the specimen of Pseudorca shown in Pl. 30. It consists, on the
right side, of a pointed, laterally projecting loop of bone (see Pl. 39) on the left side
it forms a small, flat, oblique, fenestrated projection. There is a slight lateral flexure
of the palatine bone (PAL (LL)) adjacent to it.
The pterygoid hamuli (PTH) are completely excavated and their mesial margins
meet in the middle line. The excavation of the hamuli anteriorly does not produce
a corresponding invagination of the posterior wall of the palatines as in some species
already described. On the palatal surface of the skull the palatine bones (PAL)
are exposed to a moderately conspicuous extent.
The pre- and post-orbital smoothed areas on the ventral surface of the frontal
are like those of L. albirostris.
The tympano-squamosal recess (TSQR) is small and its margins strongly involuted
like those of the peribullary space. Its anterior limit extends only a short distance
along the anterior margin of the zygomatic process.
In the Lagenorhynchus obscurus specimen figured (Pl. 40) the tympano-periotic
bones are missing and the cranial hiatus (cRH) is wide and conspicuous, although
its original extent is reduced by secondary growth of bone from the alisphenoid and
parietal. As in the previous species, there is involution of the border of the peribullary
space but not to the same extent,
56 HEARING IN CETACEANS
The falciform process (FP) is a small, roughly triangular plate. Of the bony tube
of the foramen ovale (FO) only a small portion of its cranial end remains.
The basioccipital crests (Boc) are extremely thin and delicate. The depressions
on the paroccipital processes (PAO) are more conspicuous than in L. acutus, and there
is a slight excavation of the anterior face of the processes themselves.
No part of the lateral lamina of the pterygoid and alisphenoid remains, and of the
superior lamina (PT (SL)) only a small plate extends under the orbito-sphenoid. On
the right side, this plate has a small, lateral, strap-like projection (see Pl. 40 (PT7)).
Of the orbito-pre-orbital bony extension of the pterygoid, only a minute, anteriorly
projecting spicule remains, but the pre-orbital regions of the lateral face of the palatine
and maxillary are strongly recessed, the bone in this area being of the characteristic
smoothness associated with proximity to air sacs.
The pre-orbital depressions on the ventral face of the frontal are conspicuously
larger than those of L. albirostris or L. acutus, and give indication of coalescence
with the post-orbital smoothed areas. The latter are comparable in extent to those
of the species just mentioned.
The pterygoid hamuli (PTH) are completely excavated, their mesial borders being
parallel proximally but strongly divergent distally. The excavation of the hamuli
does not involve invagination of the posterior face of the palatines (PAL), and the
latter are themselves moderately conspicuous on the palatal aspect of the skull.
The tympano-squamosal recess (TSQR) on each side is conspicuous, its margin
involuted, the anterior extremity extending as far as the anterior end of the zygomatic
process of the squamosal. This extension is obscured in Pl. 40 by the glenoid fossa.
In the figured skull (Pl. 41) of Grampus griseus the tympano-periotic bones are
missing and the cranial hiatus is obliterated by secondary bone, except for the
foramina of the auditory nerve and the foramen lacerum posterius.
The falciform process (FP) is narrow and irregularly outlined. On its mesial face
it bears a small shelf of bone which sutures with the distal end of the bony tube of
the foramen ovale, thus the ventral wall of this tube is complete. Between the mesial
face of the falciform process and the lateral edge of the bony tube of the foramen
ovale (i.e. alisphenoid) a small, irregularly triangular piece of bone is inserted. This is
the last vestige of the lateral lamina of the pterygoid bone in this region.
The basioccipital crests (BOC) are moderately stout and not cavitated.
The depressions on the paroccipital processes (PAO) merge anteriorly with the
peribullary space.
Apart from the portion of lateral lamina of the pterygoid bone mentioned above,
no other trace remains. Of the superior lamina (pT (sL)) the part underlying the
alisphenoid is wanting, but beneath the orbito-sphenoid (0s) is a wide, plate-like
remnant which extends in places beyond the lateral border of the orbito-sphenoid
and bears on its anterior border a small, laterally directed process. Of the pre-
orbital bony extension of the pterygoid only portions of the mesial lamina remain,
but in this region a wide recess excavates deeply into the lateral face of the palatine
(PAL) bone and passes postero-dorsally above the pre-orbital margin of the frontal
in a manner similar to that found in Phocaena phocoena.
The pre- and post-orbital smoothed areas on the ventral surface of the frontal
HEARING IN CETACEANS 57
(FR) are very extensive and indicate coalescence with one another. The post-orbital
extension is widely spread on the postero-ventral face of the frontal. The pre-orbital
area extends anteriorly onto the posterior end of the ventral face of the maxilla.
The pterygoid hamuli (PTH) are deeply excavated and dilated, with their ventral
aspect frequently considerably fenestrated. In the specimen figured, the palatine
bone, on the palatal surface, is partially obscured by the overgrowth of the pterygoid
bone, but in the range of specimens available for inspection there is considerable
variation in the extent to which the palatine on each side is overgrown by the ptery-
goid bone. The anterior face of the palatine is deeply invaginated by the forward
extension of the cavity of the pterygoid hamulus. The mesial borders of the hamult
meet in the middle line.
The tympano-squamosal recesses (TSQR) are extensive but ill-defined anteriorly.
In the figured specimen of Tursiops truncatus the tympano-periotic bones are
missing. Pl. 43 shows the cranial hiatus (cru) largely occluded by secondary bone so
that only the well-defined foramina of the appropriate nerves persist.
The falciform process (FP) is of the shape implied by the name given to this portion
of the squamosal. No remnants remain of the distal end of the bony tube of the
foramen ovale (Fo), but a small tuberosity on the alisphenoid (ALS) representing
the vestige of this tube is sometimes present proximally.
The basioccipital crests (Boc) are moderately prominent and robust, the posterior
portions being slightly involuted. The paroccipital processes (PAO) are excavated
anteriorly and ventrally.
The whole of the lateral lamina and the greater part of the superior lamina of the
pterygoid have disappeared so that the wing of the alisphenoid (ALs) is widely
exposed. Anteriorly a very small remnant of the superior lamina (PT (SL)) overlaps
the orbito-sphenoid (os). The orbito-preorbital extension of the pterygoid bone
is represented only by a small portion of the mesial lamina. A small lateral flexure
of the palatine (PAL (LL)) in the preorbital region is shown in PI. 43.
The pre- and post-orbital smoothed areas are very similar to those of Grampus
griseus, thus there is evidence of coalescence of the two areas lateral to the optic
foramen (oF), and of an extension of the post-orbital area onto the postero-ventral
face of the frontal (FR (Po)). Tursiops differs from Grampus in that the pre-orbital
extension of the smoothed area on the posterior end of the ventral surface of the
maxilla (Mx) is longer and much more conspicuous.
The pterygoid hamuli (PTH) are completely excavated but the inter-laminar
space is very restricted by the close approximation of the laminae. The ventral
surfaces of the lateral laminae are flattened but strongly keeled, their mesial borders
meeting in the middle line.
The palatine bones (PAL) are extensively exposed anteriorly and laterally to the
pterygoid hamuli and there is little or no excavation of their posterior face by exten-
sions of the hamular cavities.
The tympano-squamosal recess (TSQR) is well-defined; mesially the boundary
is involuted, while the forward extension ends little more than half way along the
zygomatic process.
The specimen of Stenella euphrosyne figured (Pl. 45) shows the tympano-periotic
58 HEARING IN CETACEANS
bones (TB) glued approximately in their natural position. It will be seen that the
peribullary space separates the ear-bones from the basioccipital crest (Boc) and the
paroccipital process (PAO). The ear bones have been glued by the “ mastoid
process ’’’ to the exoccipital bones (EXO) giving an appearance of contiguity with
these which is artificial. In the natural state the process is separated from the
adjacent bones by a fibrous ligament.
The falciform process (FP) is long and slender and its close relation to the tympanic
bulla is well shown in the figure. Of the bony tube of the foramen ovale (FO) only
a small vestige of the proximal part remains.
The basioccipital crests (Boc) are very slender and laminate and the paroccipitals
(PAO) much reduced in thickness, being deeply excavated on their anterior faces.
The lateral and superior laminae of the pterygoid bones have almost entirely
disappeared exposing considerable areas of the alisphenoid (ALs) and orbito-sphenoid
(os) bones. A narrow, irregular desquamation of the superior lamina (pT (SL))
occupies the mesial margin of the orbito-sphenoid. Of the pre-orbital extension of
the pterygoid only a portion of the mesial lamina is present. A conspicuous
upwardly and backwardly projecting recess in this region is bounded by the
maxilla (Mx) and the frontal (FR).
The distribution of the pre-orbital and post-orbital smoothed areas is very similar
to that of Tursiops truncatus, but there is in addition a deep fossa lateral to the orbito-
sphenoid which excavates the ventral surface of the orbital process of the frontal,
producing a stout ridge of bone along the anterior margin of the frontal in this
region. The pre-orbital recess is very deeply excavated and as in Tursiops there is
an anteriorly attenuating fossa on the hinder end of the ventral surface of the maxilla.
It may be noted that Lagenorhynchus obscurus shows the above mentioned features
although less conspicuously.
The pterygoid hamuli (pTH) are completely excavated and slightly dilated ; their
ventral laminae is of a transluscent thinness. The internal walls of the hamular
space are reinforced by trabeculae. The palatal aspect of each hamulus is bluntly
keeled and the two hamuli approximate closely to each other in the middle line.
The palatal bones (PAL) are extensively exposed anteriorly and laterally to the
pterygoid, but are deeply invaginated on their posterior faces by forward extension
of the pterygoid cavities.
The tympano-squamosal recess (TSQR) is clearly delineated, its margin being for
the most part strongly involuted.
In the adult skull of Delphinus delphis, examined but not figured, the tympano-
periotic bones were missing and the cranial hiatus was partially occluded by secondary
extensions of adjacent bones. The falciform process was comparable with that of
Stenella euphrosyne and, as in the latter species, there was only a small remnant
of the proximal end of the bony tube of the foramen ovale. The basioccipital crests
were slender, laminate and very similar to those of Stenella ewphrosyne.
The paroccipital processes were stouter and not so strongly excavated on their
anterior face as in the latter species. They showed the characteristic depression
on the ventral face which has been noted in some of the previously described species.
The lateral and superior laminae of the pterygoid had entirely disappeared, and, in
HEARING IN CETACEANS 59
the preorbital region, only the mesial lamina remained. In the distribution of the
pre-orbital and post-orbital smoothed areas Delphinus delphis differs from Stenella,
only in the maxillary region. Here, a conspicuous, deep, elongated fossa extends
on the ventral aspect of the maxilla, diminishing in depth towards its termination
near the anterior extremity of the rostrum.
The confluent aperture of the optic foramen, foramen rotundum and sphenoidal
fissure was very much enlarged by resorption of the boundary margins of the orbito-
sphenoid and alisphenoid.
The pterygoid hamuli were completely excavated and trabeculated as in Stenella
euphrosyne. The posterior margins of the lateral laminae were extensively resorbed
and the keeled ventral surfaces were fenestrated. The hamuli were in close apposition
to each other in the middle line.
The juvenile specimen figured (Pl. 46) is in the main similar to the adult but with
the following differences. There is a small remnant of the superior lamina of the
pterygoid (pr (SL)) covering the mesial part of the orbito-sphenoid (os). Of the orbital
extension of the pterygoid, considerable portions of the superior and mesial laminae
remain, and a delicate bridge of bone between these represents the last vestige
of the lateral lamina (pT (LL)). Although in this respect the juvenile appears
to be more primitive than the adult, the fenestration of the hamular laminae is of
much greater extent than in the adult.
The palatine bones (PAL) are extensively exposed anteriorly and laterally to the
pterygoid hamuli (PTH), and are quite strongly invaginated on their posterior face
by forward extension of the hamular cavities.
The tympano-squamosal recesses (TSQR) are sharply defined but their borders
are not strongly involuted as in Stenella.
STENIDAE. In the figured specimen (Pl. 24) of Steno bredanensis the tympano-
periotic bones are wanting and the widely open cranial hiatus (cru) is plainly visible.
The falciform process (FP) forms a broad, spatulate extension of the squamosal (sq).
It is nearly contiguous with cancellated remnants of the bony tube of the foramen
ovale (FO).
The basioccipital crests (Boc) are prominent, although slender and plate-like, and
the paroccipital processes (PAO) show little excavation of their anterior or ventral faces.
The lateral lamina of the pterygoid bone is wanting except in the hamular region.
The superior lamina (PT (SL)) remains as a broad, irregularly bounded plate which
partly covers the lateral wing of the alisphenoid (ats) and posterior portions of the
orbitosphenoid (0s).
Of the orbito- pre-orbital extension of the pterygoid, only the mesial lamina
remains, but there is a remnant of the lateral flexure of the palatine bone (PAL (LL))
in this region. The pre-orbital and post-orbital smoothed areas indicate coalescence
lateral to the optic foramen, with the production of a wide, shallow fossa bounded
anteriorly and posteriorly by two smoothed ridges of bone. In comparison with this
fossa, the post-orbital extension of the smoothed area below the post-orbital process
of the frontal (FR (PO)) is reduced in area. The pre-orbital smoothed area is extended
_onto the maxilla as in Tursiops and Stenella.
The pterygoid hamuli (PTH) are deeply excavated, strongly keeled ventrally and
60 HEARING IN CETACEANS
their mesial borders meet in the middle line. The palatine bones (PAL) are not
extensively covered externally by the pterygoids but their posterior faces are invagin-
ated by forward extension of the pterygoids.
The tympano-squamosal recess (TSQR) is clearly defined, the mesial and anterior
margins of the glenoid cavity being slightly involuted. The anterior extension of
the recess reaches the anterior limit of the zygomatic process of the squamosal.
The figured specimen of Sousa plumbea lacks the tympano-periotic bones (PI. 25).
The cranial hiatus (cRH) is exposed and there is little or no infilling of it by adjacent
bones.
The falciform process (FP) is a broad lamina, having a thickening on its mesial
aspect with a remnant of the distal end of the bony tube of the foramen ovale (Fo).
Considerable vestiges of the proximal end of this tube extend laterally from the
alisphenoid (Ars).
The basioccipital crests (Boc) are prominent and stout as compared with those of
Steno bredanensis, their mesial aspect not being excavated to any great extent.
The paroccipital processes (PAO) on the other hand are slender, being excavated
both anteriorly and ventrally.
The lateral and superior laminae ofthe pterygoid have entirely disappeared on
the left side, but on the right side of the specimen figured a minute vestige of the
lateral lamina persists, loosely articulated with the anterior face of the bony tube
of the foramen ovale. The lateral aspect of the bony wall of the posterior nares
is deeply recessed, the recess being formed dorsally by the ali- and orbito-sphenoid
(ALS and os) and ventrally by a strong involution of the mesial lamina of the
pterygoid (PT (ML)).
No trace of the bony orbital extension of the pterygoid remains but there is a
very deep recess extending dorsally and posteriorly between the anterior face of the
frontal (FR) and the ventral surface of the maxilla (Mx). As in Ima geoffrensis
there is marked resorption of the ventral aspect of the post-orbital process of the
frontal so that the maxilla is partially exposed in this region.
Apart from the feature just mentioned the distribution of pre-orbital and post-
orbital smoothed areas is comparable with that of Steno, Tursiops and Stenella.
The pterygoid hamuli (PTH) are much fenestrated and a great part of the outer
laminae has disappeared. The hamuli are deeply excavated ; numerous trabeculae
extend from the inner to the outer lamina between the fenestrations.
The hamuli do not meet in the middle line and their outer surfaces are rounded
rather than keeled.
The palatines (PAL) are widely visible and their posterior faces are interpenetrated
by trabeculated extensions of the pterygoid hamuli.
The tympano-squamosal recess (TSQR) is very well defined, its margins being in-
voluted both mesially and laterally. Its forward extension terminates some distance
short of the anterior end of the zygomatic process of the squamosal.
A skull of Lissodelphis borealis became available! after the main work contained in
this contribution had been completed. Distinctive features of the skull justify
inclusion of a description at this late stage.
1 By courtesy of Dr. Carl L. Hubbs, Scripps Institution of Oceanography, La Jolla, California.
HEARING IN CETACEANS 61
The tympano-periotic bones are wanting and the cranial hiatus is partially closed.
The falciform process is broad basally but extends into a much narrower, irregularly
outlined, distal portion. The bony infundibulum of the foramen ovale is of sphenoidal
composition only and is prominent.
The basioccipital crests are prominent, slender and plate-like. The paroccipital
processes on the other hand are comparatively robust in ventral aspect. The anterior
face of each of these processes is excavated by a distinctive cavity with an involuted
margin.
The lateral lamina of the pterygoid bone is absent, but the smoothed areas of
the skull base as a whole are characterized by their limited lateral extension. Thus
the lateral wing of the sphenoid is short, and the smoothed area ends before reaching
the spheno-parietal suture. The superior lamina persists as a narrow shelf in the
pre-orbital region.
Whilst there is evidence of fusion of the pre- and post-orbital smoothed areas
above the optic infundibulum there is practically no extension of the post-orbital
lobe under the post-orbital process of the frontal. The pre-orbital smoothed area
is extended onto the maxilla as in Tursiops and Stenella.
The pterygoid hamuli are deeply excavated, strongly keeled ventrally and their
mesial borders meet in the middle line. They do not completely cover the palatine
bones ventrally.
The tympano-squamosal recess is clearly defined, and the anterior extension of the
recess reaches the anterior limit of the zygomatic process of the squamosal.
DISTRIBUTION OF AIR SPACES
The preceding account of the osteological features of the ventral aspect of the
cetacean skull was undertaken on the assumption that the form of the various bones
and the distribution of smoothed areas was associated with the state of development
of the air sinuses connected with the tympanic cavity, and that these sinuses occupied
the space between mesial and lateral laminae of bones such as the pterygoid, ali-
sphenoid and palatine.
In most of the skulls examined the greater part of the lateral and superior laminae
of these bones was absent, but it has been assumed throughout the account that
at some stage in the evolution of the air sinuses the whole of all four laminae (see
PP. 33-34) was present. In order to support this hypothesis it was decided to
examine the distribution of the air sinuses in detail.
In most cases examination of the distribution of the air spaces involved injection
of the latter with a polyester resin, and complete destruction of the soft parts by
bacteriological maceration. By this method it was possible to obtain a three dimen-
sional cast of the entire system of air spaces.
ODONTOCETI
In the examination of the River Dolphins the scarcity of material prohibited the
destruction of any of the soft parts, so the sinuses of single specimens of Stenodelphis
and Ima were injected with iodized oil and radiographed.
62 HEARING IN CETACEANS
It is unfortunate that no specimen of Platanista was available, since this is the only
species in which the lateral laminae of pterygoid, alisphenoid and squamosal are
complete.
In Stenodelphis the greater part of these laminae is present, though much perfor-
ated, and it is this species which demonstrates most clearly the close association
between the distribution of the air sinuses and the various extensions of the pterygoid
bone. In addition, the sinus distribution in Stenodelphis provides a guide to the
interpretation of sinus formation in species in which no trace of a lateral lamina
can be found, and provides strong evidence that such a lamina may have been
present at an earlier stage in the evolution of these species.
STENODELPHIS BLAINVILLEI
Pl. 20 is a dorso-ventral radiograph of the head of Stenodelphis after injection of
the air sinuses with iodized oil. The opaque area shows the distribution of the air
space in the horizontal plane and its five main components have been indicated by
the names originally applied to the air sacs by Beauregard (vide supra). From the
point of view of the evolution of these air spaces it is preferable to refer to them as
sinuses.
The posterior sinus.
This can be seen as a small, opaque promontory occupying the position of the
cavity in the paroccipital process. On the left side the sinus is incompletely filled
with the injection medium so that the concavity of the paroccipital process is partly
visible as a small, rounded transparent area.
The peribullary sinus
The shadow of the tympanic bulla is completely obliterated by a conspicuous,
opaque area in the tympanic region. This opaque area marks the position of the
peribullary sinus and demonstrates the extent to which the tympano-periotic bones
are surrounded by the sinus. Most of the ventral region of this opaque area is the
shadow-graph of that part of the peribullary sinus which lies dorsal to the tympanic
bulla separating the latter from the bones of the cranium.
The pterygoid sinus
The name “‘ pterygoid sac ’’ was applied by Beauregard only to that part of the
air sinus system which occupies the pterygoid hamuli, the remainder of the system
anterior to the tympanic cavity being designated the anterior sinus. As, however,
it can be shown that nearly the whole of the anterior air sinus system is associated
with the extensions of the pterygoid bone previously described, the authors have
found it necessary to include all but the most anterior extremities of the air sinus
system in the description of the pterygoid sinus. In the radiograph this sinus is
represented by the two conspicuous, wing-like, opaque areas which lie anterior to
the tympanic region—as well as by a triangular projection which marks the position
of one of the pterygoid hamuli. It will be noted that the opacity extends and parti-
ally fills the orbital and pre-orbital parts of the skull—occupying areas normally
«
HEARING IN CETACEANS 63
filled by the optic muscles. In this region there are numerous, irregular, semi-
transparent patches. Comparing the distribution of opaque areas with the description
and figures of the osteological characters in this area, it will be seen that the pterygoid
sinus is almost exactly delineated by the boundaries of the pterygoid bone with all
its distentions. The external surface of the sinus is almost completely covered by
the thin, lateral lamina of pterygoid bone, although the latter is much perforated,
and in the orbital region trabeculated and ruptured by a number of large fenestrations.
The small, irregular, semi-transparent patches in the radiograph serve to indicate
the cavitation of bone in this region.
Laterally the pterygoid sinus extends as far as the spheno-parietal suture, covering
over the greater part of the lateral wing of the alisphenoid.
The anterior sinus
Throughout the descriptions which follow, the name anterior sinus will be applied
only to parts of the air sinus system which extend further forward than the most
anterior limits of the pterygoid bone. In Stenodelphis it is evident that no anterior
sinus is present, and that, although the pterygoid lamina is fenestrated in the pre-
orbital region, there has been little further extension of the sinus system.
The middle sinus
The radiograph shows a small, triangular, opaque protrusion extending antero-
laterally from the general opacity of the peribullary sinus. This protrusion coincides
with the position of the tympano-squamosal recess and marks the position of the
middle sinus. Its concavity is shown by the semi-transparent streak along its
central axis. Although obscured by the peribullary sinus, the point of emergence
of this sinus from the tympanic bulla lies immediately dorsal to the tympanic
membrane. It was this factor which led Beauregard to homologize it with the
“ glove finger ’’ of the Mysticeti. This matter is discussed in Part I of Hearing in
Cetaceans, Fraser & Purves (1955).
INIA GEOFFRENSIS
Pl. 22 is the dorso-ventral radiograph of the head of Inia geoffrensis—the air
sinuses of the right side having been injected with iodized oil. The left side is not
injected so that the relationship of the air spaces to the various osteological features
can be seen.
The posterior sinus
This was the sinus through which the injection was made and its outline is partly
obscured by the spillover of the injection medium. It can be seen as a small, reniform,
Opaque area occupying the position of the paroccipital process, the latter being
distinctly outlined on the left side.
The peribullary sinus
The shadow of the tympano-periotic bones is shown on the left side—and from
the right side of the radiograph it will be seen that the peribullary sinus completely
64 HEARING IN CETACEANS
surrounds this bone. As in the previously described species, the centre of the mass
represents the air space between the periotic and the skull and coincides with the
position of the cranial hiatus.
The pterygoid sinus
Passing forward from the tympanic region, two narrow, opaque areas can be seen
lying along the mesial and lateral aspects of the basi-occipital crest. The mesial
opacity demonstrates the form and direction of the Eustachian tube. The tube is
widely dilated at its emergence from the tympanic bulla but is compressed meso-
laterally as it proceeds forward in the direction of the choanae. The lateral opacity
marks the beginning of the pterygoid sinus, and at a short distance forward from
the tympanic region it widens laterally to form an irregular, opaque patch covering
the area of the wing of the sphenoid bone. Anterior to this patch the opacity increases
in dimension and divides eventually into three distinct lobes. The lateral lobe passes
forward into the pre-orbital, orbital and post-orbital regions, the last extension
continuing dorsally and posteriorly along ventral surface of the post-orbital process
of the frontal. The mesial lobe invades the triangular concavity of the pterygoid
hamulus.
The anterior sinus
The remaining lobe of the pterygoid sinus extends beyond the orbital and hamular
lobes and penetrates the bony rostrum, passing forward inside this part of the skull
for a short distance. As this extension is clearly beyond the limits of the bony part
of the pterygoid it has been designated the anterior sinus.
With the exception of the anterior sinus none of the above-mentioned air spaces
is covered laterally by a bony lamina—in this respect differing markedly from the
condition found in Stenodelphis. Reference to the description of the osteological
features on p. 45 shows that the disappearance of the lateral and superior laminae
of the pterygoid hamuli, as well as the resorption of the ventral surface of the post-
orbital process of the frontal, has occurred in close correlation with the extension
and distension of the pterygoid sinus. The continuation of the anterior sinus between
the bones of the rostrum is of interest in connection with the condition of this sinus
in Delphinus delphis (see p. 70).
The middle sinus
The rounded concavity of the tympano-squamosal recess has not been filled with
the injection medium, but on the basis of the evidence from Stenodelphis and other
species hereafter to be described, it is very probable that the recess marks the position
of the middle sinus.
PHOCAENA PHOCOENA
The air spaces of the specimen figured on Pl. 27 have been filled with polyester
resin and the soft parts removed.
HEARING IN CETACEANS 65
The posterior sinus
A small portion of this sinus can be seen protruding from the posterior aperture
of the tympanic bulla. The sinus is not completely filled and would normally occupy
the ventral concavity of the paroccipital process. Its normal outline has been indicated
on Pl. 27 by a dotted line.
The peribullary sinus
Parts of the peribullary sinus can be seen lying between the tympanic bulla and
the basioccipital crests but the greater part is concealed by the tympano-periotic.
The latter bone is completely separated from the cranium on its superior aspect by
an extension of the peribullary sinus. In the specimen figured, the deep cavity
lying anterior to the periotic and postero-ventral to the falciform process is partly
filled by a cavernous venous plexus.
The pterygoid sinus
The main mass of the Eustachian tube and the pterygoid sinus can be seen emerg-
ing from the anterior aperture of the tympanic bulla. That part which lies along
the ventral edge of the mesial lamina of the pterygoid represents the lumen of the
Eustachian tube though its outline is not clearly shown. The remaining mass passes
forward round the ventral and anterior margins of the foramen ovale, partly covering
the alisphenoid and extending into the orbital and pre-orbital regions of the skull
and the pterygoid hamuli. On the exterior face of the mass can be seen small fragments
of bone which represent respectively the remaining vestiges of the lateral laminae
of the pterygoid and alisphenoid. (In Platanista these laminae form a continuous
sheet of bone reaching from the pterygoid hamulus to the falciform process (see
p. 44)). In the post-orbital region a small extension of the pterygoid sinus passes
backwards over the alisphenoid, and dorsally and posteriorly under the post-orbital
processes of the frontal bones in a manner similar to the condition found in Inia
geoffrensis. Asin the latter species, the surface of the bone is frequently resorbed
in this area. Anteriorly the pterygoid sinus passes under the lateral lamina of the pala-
tine bone and invades the pre-orbital concavity, a small lobe of the sinus passing
ventrally for a short distance. The pre-orbital part of the pterygoid sinus gives off
a diverticulum which passes upwards between the anterior aspect of the frontal
and the ventral face of the maxilla.
The anterior sinus
There is no evidence of an extension of the pterygoid sinus beyond the pre-orbital
region.
The middle sinus
This sinus has not been completely filled but its proximal position can be seen
at its emergence from the aperture above the annulus of the tympanic bulla. The
portion of the sinus figured occupies part of the tympano-squamosal recess and in
its fully inflated state would occupy the whole of this recess.
ZOOL. 7, I. 5
66 HEARING IN CETACEANS
LAGENORHYNCHUS ALBIROSTRIS
Pl. 38 shows the cast of the air spaces of left side of a skull of Lagenorhynchus
albirostris.
The posterior sinus
Only a small portion of the posterior sinus can be seen protruding from the posterior
aperture of the tympanic bulla, but the ventral recess on the paroccipital process,
into which this sinus protrudes, can be seen in the figure. A dotted line indicates
the normal limit of the sinus in its distended state.
The peribullary sinus
The ventral border of the peribullary sinus is visible between the mesial aspect
of the tympanic bulla and the lateral aspect of the basioccipital crest. Between
the periotic and the falciform process there is a fibro-venous plexus as in Phocaena.
Close examination of the plexus shows that it contains, between the ramifications
of the veins, a reticulate mass of minute, bony trabeculae, the significance of which
will be understood when considering the progress of development of the peribullary
sinus (see p. 79).
The pterygoid sinus
This sinus emerges from the bulla as a diverticulum of the Eustachian tube, and
as the latter has not been injected, its relationship to the sinus has been indicated in
Pl. 38. Anterior to the bulla the sinus passes round the ventral margin of the falci-
form process and the ventral and anterior margins of the foramen ovale. It continues
along the lateral aspect of the mesial lamina of the pterygoid and enters the post-
orbital, orbital and pre-orbital regions as well as the pterygoid hamuli. In the ptery-
goid region a considerable vestige of the lateral lamina of the pterygoid bones
remains. In the specimen figured the vestige is limited in its backward extension
to a point about 1 cm anterior to the falciform process but in most of the specimens
examined the bony bridge is more complete although very much fenestrated. Pl. 37
shows the condition of this lamina (PT(LL)) in the majority of individuals examined.
It should be noted that the alisphenoid is only partly covered by the sinus.
It has been emphasized that in Phocaena phocoena and in this species the posterior
part of the pterygoid sinus passes ventral to the foramen ovale and round and
above the ventral tip of the falciform process. Posterior to the dorsal and proximal
parts of the latter process, the ventral concavity of the cranium is filled by a fibro-
venous plexus and the alisphenoid is partly visible. These features are of importance
in considering the progressive enlargement of the air spaces and will be referred
to in the description of other species.
In the orbital region the pterygoid sinus passes over the ventral aspect of the orbito-
sphenoid, being more laterally extended than this bone and forming the proximal
part of the ventral floor of the orbit. The wide infundibulum for the optic and
oculomotor nerves can be seen in the figure and it will be noted that its dorsal wall
is formed by the ventral wall of the orbital process of the frontal. Posterior and
HEARING IN CETACEANS 67
anterior to this infundibulum are the post-orbital and pre-orbital extensions of the
pterygoid sinus. The post-orbital extension is much more limited posteriorly than
in Inia and Phocaena and has, instead of the long attenuated diverticulum which
in the latter two species lies under the post-orbital process of the frontal, a small,
half-oval protrusion. The pre-orbital extension is also more limited than in Phocaena
and is confined to the deep concavity which surrounds the pre-orbital foramen.
There is no anterior sinus.
The middle sinus
This has been well injected and shows the typical form which the sinus takes,
with few variations, in nearly every species of cetacean. The air space is exactly
delineated by the tympano-squamosal recess and its lateral margin lies in the deep
groove formed by the involuted margin of the glenoid fossa.
GLOBICEPHALA MELAENA
The posterior sinus
No part of the posterior sinus has been injected but its position in the saucer-like
depression in the paroccipital process is marked by a dotted line (PI. 34).
The peribullary sinus
A part of the peribullary sinus lies between the tympanic bulla and the basioc-
cipital crest and shows the irregular, rugose form of its ventral edge. The significance
of this irregular outline, which is very conspicuous in some other species, e.g. Tursiops
(Pl. 44), may be seen by comparing it with the condition of the bone of the lateral
aspect of the basioccipital crest in the primitive cetacean Platanista (Pl. 17). In the
latter species the basioccipital crests are stout and the lateral aspect of the bone shows
extensive cavitations and a minutely cancellated structure. The proximity of this
finely cancellated bone to the peribullary spaces in Platanista suggests that the bone
and air spaces are intimately connected and that the cancellation is due to resorption
of bone with the progressive enlargement of the sinus. The thinness of the basioccipital
crest and the rugose surface of the air sinus cast in Globicephala indicate that the
peribullary sinus in the more specialized odontocetes has been developed at the
expense of the osseous content of the basioccipital crest (see p. 80). A forward
extension of the peribullary sinus can be seen occupying the deep cavity anterior
to the periotic and should be compared with the fibro-venous plexus which is found
in this area in Phocaena phocoena and Lagenorhynchus albirostris.
The pterygoid sinus
The relationship between the pterygoid sinus and the Eustachian tube is well
shown in Pl. 34. Both structures emerge from the involucral anterior fissure of
the tympanic bulla but diverge just anterior to the tip of the falciform process.
The connection between the lumen of the Eustachian tube and the pterygoid sinus
has been fully described by Beauregard (see p. 8). From Pl. 34 it will be seen
68 HEARING IN CETACEANS
that the Eustachian tube lies ventral to the pterygoid sinus and lateral to the
basioccipital crest until it reaches the posterior margin of the choanae, thereafter
passing by way of the deep notch in the pterygoid bone along the lateral wall of
the posterior nares. The ventral aspect of the internal cast of this tube shown in
the figure is marked by a series of obliquely-disposed, deep fissures which mark the
position of those valvular folds in the lining walls of the Eustachian tube which
have been fully described by Anderson, Beauregard, Boenninghaus and others.
Anterior to the bulla the pterygoid sinus passes, as in the previously described species,
along the mesial aspect of the ventral part of the falciform process, and round the
ventral and anterior margins of the foramen ovale. Thereafter the sinus expands
conspicuously and completely fills the angle formed by the mesial lamina of the
pterygoid bone and the external ventral wall of the cranium. In this species the
alisphenoid bone is completely covered and the pterygoid hamuli widely dilated.
There are no vestiges of the lateral lamina of the pterygoid on the external face of
the sinus. Close examination of this external face reveals that it is marked by very
numerous, minute indentations and folds, the significance of which will be understood
in relation with the histology of the sacs. As in Lagenorhynchus the hamuli are com-
pletely filled.
Further forward the arrangement of the sinus is very similar to that in Lagenorhyn-
chus albirostris. As in the latter species, there are three distinct portions in this region ;
(1) a post-orbital lobe which lies along the posterior margin of the optic infundibulum
but which does not, as in all the previously described species, give off a dorsally
directed diverticulum under the ventral face of the post-orbital process of the
frontal ; (2) an orbital part which covers the orbito-sphenoid and forms the ventral
closing wall of the optic infundibulum ; (3) a pre-orbital lobe which fills the concavity
round the pre-orbital foramen and extends laterally a short distance along the
anterior margin of the optic infundibulum. As in the previous species the dorsal
wall of this infundibulum is formed by the frontal, a considerable portion of the latter
bone being visible in Pl. 34 between the pre-orbital and post-orbital lobes of the
pterygoid sinus. There is no anterior sinus.
The middle sinus
The middle sinus has not been injected but its position is marked by a dotted
line in Pl. 34.
GRAMPUS GRISEUS
The posterior sinus
The position of this sinus, though not well injected, can be seen from Pl. 42.
The sinus occupies the concavity on the antero-ventral aspect of the paroccipital
process.
The peribullary sinus
This can be seen in Pl. 42 occupying the space between the mesial aspect of the
tympanic bulla and the lateral aspect of the basioccipital crests, as well as the
HEARING IN CETACEANS 69
concavity behind the falciform process. The rugose character of its external borders
should be noted.
The pterygoid sinus
As in previously described species, the pterygoid sinus emerges from the tympanic
bulla in conjunction with the Eustachian tube. The latter is not shown in the plate
since its internal cast was so delicate and flattened meso-laterally that it became
detached before the photographs were taken. Sufficient of the narial part of the
tube remained to indicate that its form and direction were similar to those of the
Eustachian tube of other species and have been so indicated. The sinus widens
abruptly in front of the falciform process, sweeps round the ventral and anterior
margins of the foramen ovale and covers the whole of the alisphenoid. In the region
of the foramen ovale there are numerous, posteriorly-directed, lobulated diverticulae
which pass over the dorsal margin of the foramen and become contiguous with the
anterior extremity of the peribullary sinus. As in Globicephala, the sinus is very
expansive and fills the angle between the mesial lamina of the pterygoid and the
external wall of the cranium. The pterygoid hamuli are entirely filled and even more
widely dilated than in Globicephala. In respect of the orbital extensions of the sinus
there are several major differences between the arrangement in this species and that
in all the previously described specimens. The lateral extension of the sinus which
covers the ventral aspect of the orbito-sphenoid is very much wider and more
extensive than in Globicephala and forms a greater part of the floor of the orbit.
The post-orbital lobe is also larger and has a wide diverticulum under the post-orbital
process of the frontal. The pre-orbital lobe is equally developed and is not confined
merely to the concavity which surrounds the pre-orbital foramen but continues
laterally almost as far as the lateral limit of the frontal. In Pl. 42 a narrow strip
of the frontal bone can be seen separating the post-orbital and pre-orbital lobes and
forming the roof of the optic infundibulum, but in another injected specimen (not
figured) the frontal bone is obliterated in this region by coalescence or close con-
tiguity of the two lobes. In this manner the optic nerves and muscles have been
completely surrounded in the latter specimen by a continuous band of air sinus.
The extremities of all the lobes hitherto mentioned show the peculiar lobulated
form which was noted on the diverticulae round the dorsal margin of the foramen
ovale.
The anterior sinus
It will be seen from PI. 42 that the pterygoid sinus not only fills the deep fossa on
the lateral aspect of the palatine bone (see p. 57 and Pl. 41) but extends anteriorly
‘under the maxilla for a short distance.
The middle sinus
The middle sinus is well shown in Pl. 42, partly filling the tympano-squamosal
Tecess. It will be noted that it consists of two lobes, one of which is directed laterally
round the posterior border of the glenoid fossa, and the other directed antero-
79 HEARING IN CETACEANS
laterally round the anterior margin of the same fossa and following the anterior
border of the zygomatic process of the squamosal. The whole sinus is minutely
lobulated at its external borders in a manner which is characteristic of many species
of odontocetes.
TURSIOPS TRUNCATUS
The posterior sinus
The relationship of the posterior sinus to the tympanic bulla and the depression
on the paroccipital process are well illustrated on Pl. 44, and the rugosity of the
external surface should be compared with that of the bone in this area.
The peribullary sinus
This is shown at its ventral extremities, mesially, between the lateral aspect of
the basioccipital crest and the mesial aspect of the tympanic bulla, and anteriorly
behind the curved posterior border of the falciform process. As in other species. the
surface is irregularly contoured.
The pterygoid sinus
This sinus emerges from the anterior aperture of the tympanic bulla in conjunction
with the Eustachian tube, the proximal end of which is shown in the plate. Here
again, owing to the laterally compressed state of the tube, its lumen has not been
injected but its approximate direction has been indicated. The pterygoid sinus
passes over the tip of the falciform process, round the ventral and anterior margins
of the foramen ovale, spreading out laterally, ventrally and anteriorly, filling the
angle between the mesial lamina of the pterygoid and the ventral aspect of the
cranium, and completely covering the alisphenoid. As in Risso’s Dolphin there are
posteriorly directed diverticula passing round the superior margin of the foramen
ovale so that the mandibular branch of the 5th nerve is entirely surrounded by
air space. More anteriorly the arrangement is very similar to that in Grampus
griseus, although the pterygoid hamuli are not as widely dilated as in the latter
species. The orbital, pre-orbital and post-orbital lobes are all well developed, the
orbital lobe covering the orbito-sphenoid and forming a conspicuous laterally
projecting ventral boundary to the optic infundibulum. The pre-orbital and post-
orbital lobes are well extended and the latter spreads dorsally under the post-
orbital process of the frontal. As in one of the specimens of Grampus the two lobes
are closely contiguous and partly coalesced proximally so that no part of the frontal
bone is visible between them. The optic nerve, like the mandibular branch of the
trigeminal, is thus entirely surrounded by an air cavity. The contiguous pre-orbital
and post-orbital lobes extend almost to the lateral limit of the frontal bone and their
extremities are deeply cavitated with small, irregular diverticula as in Grampus.
The anterior sinus
With respect to the anterior sinus, Tursiops truncatus shows a more advanced
state of the development of the air spaces than any of the previously mentioned
HEARING IN CETACEANS 71
species. The extent of the sinus is not fully demonstrated by the injection in Pl. 44
but its prolongation beyond the pre-orbital foramen has been indicated. The deep
recess on the ventral aspect of the maxilla marks the boundary of the sinus when
fully distended.
The middle sinus
Pl. 44 shows the form of the middle sinus and its exact point of emergence from
the tympanic bulla. It will be noted that it originates immediately dorsal to the
tympanic annulus and the sigmoid process. The sinus consists of two lobes, one
passing laterally round the posterior border of the glenoid fossa, and the other
following the course of the anterior wing of the tympano-squamosal recess.
DELPHINUS DELPHIS
The arrangement of the air sinuses in this species was figured by Anthony and
Coupin (1930), but not described in detail. A summary of Beauregard’s description
is given on p. 8.
The posterior sinus
This sinus is not fully injected but its contiguity with the depression on the
paroccipital process is demonstrated in Pl. 47.
The peribullary sinus
The ventral limits of the peribullary sinus are indicated in Pl. 47 lying between
the mesial aspect of the tympanic bulla and the basioccipital crests, and in the
cavity behind the falciform process.
The pterygoid sinus
The relationship between the pterygoid sinus and the Eustachian tube is demon-
strated. The latter widens considerably after its emergence from the bulla and
continues forward along the ventro-lateral border of the mesial lamina of the
pterygoid, becoming narrower and more compressed meso-laterally until it reaches
the notch in the latter bone. Having passed through the notch, its lumen becomes
very attenuated and passes dorsally along the mesial aspect of the lateral wall of
the posterior nares for a short distance, thereafter turning at first mesially and then
ventrally to open into the choanae. The cast is marked ventrally by a series of
oblique grooves which indicate the position of the valvular folds in the mucous
membrane of the tube, (see p. 6). The pterygoid sinus widens out in front of
the bulla, its ventral border lying mesial to the Eustachian tube and its dorsal
border passing round the ventral and anterior margins of the foramen ovale. The
alisphenoid is completely covered and there is a posteriorly directed, lobulated
diverticulum which passes round the dorsal border of the foramen ovale. The mandi-
bular nerve is thus surrounded ventrally, anteriorly and dorsally by the pterygoid
sinus and posteriorly by the peribullary sinus. The pterygoid hamulus is filled by
a ventrally directed lobe of the sinus which passes over the lateral aspect of the
72 HEARING IN CETACEANS
Eustachian tube near the latter’s entry into the pterygoid notch. This arrangement
is well shown in Pl. 34 which figures the pterygoid sinus of Globicephala. The orbital
portion is fairly prominent, covers the orbito-sphenoid and forms the ventral
boundary of the optic infundibulum. The pre-orbital and post-orbital lobes are
well extended laterally and unite above the optic infundibulum to form its dorsal
boundary. The optic nerve is therefore completely surrounded by an air space
as was observed in Tursiops truncatus and in one member of the species Grampus
griseus. The dorsally directed diverticulum which extends over the ventral aspect
of the post-orbital process of the frontal is wide, though fairly short.
The anterior sinus
In the degree of development of the anterior sinus Delphinus delphis exceeds
every other known species of cetacean, although there is evidence from its osteological
features that the recently described species Lagenodelphis hosei closely approaches
its position. The soft parts of the latter species were not available but it may be
assumed that the arrangement of the sinus would approximate to that of Delphinus.
The anterior sinus of Del/phinus takes the form of a wide, elongated sac which fills
in the whole pre-orbital region and projects forward, tapering gradually to occupy
the deep groove in the maxilla, and continuing anteriorly in the adult for about
two thirds of the length of the rostrum.
The middle sinus
A small part of the middle sinus can be seen in PI. 47, protruding from the tympanic
bulla, its shape in the fully distended state being indicated by a dotted line. It
fills the tympano-squamosal recess.
MESOPLODON BIDENS
The air sinus system of Mesoplodon bidens has been described by Anthony & Coupin
(1930) but as this description does not emphasize the striking differences between
the arrangement of the sinuses in ziphioid whales generally on the one hand, and those
of other odontocetes on the other, the authors have decided to review the structure
in the light of these differences. Anthony & Coupin distinguish several lobes of
the pterygoid sinus but as these are in no way homologous with those found in other
odontocetes their names cannot be adopted in the present work.
The posterior sinus
This is relatively inconspicuous in PI. 12 as the sinus is not fully injected. Never-
theless its extent is confined within the boundaries of a smooth area on the pars
mastoidea of the tympano-periotic. There is no evidence of the saucer-like depression
in the paroccipital process.
The peribullary sinus
In spite of the close contiguity of the tympanic bulla with the basioccipital crest
the ventral edge of a laterally compressed lobe of the peribullary sinus can be seen
HEARING IN CETACEANS 73
on Pl. 12 interposed between the above mentioned bones. It should be noted that
its outline is quite smooth and regular, showing none of the rugosities which were
seen on the edge of the sinus in many of the Delphinidae. There is no extensive
excavation of the anterior aspect of the paroccipital process, the latter being massive
and of a simple, nodular form. The falciform process is in close apposition with the
anterior border of the tympanic bulla so that no part of the peribullary sinus is
seen between the two bones, and there appears to be little distension of the anterior
parts of the sinus generally.
The pterygoid sinus
With regard to the form of the pterygoid sinus Mesoplodon bidens differs from all
the cetaceans hitherto described. It emerges with the Eustachian tube from the
anterior end of the tympanic bulla and passes round the ventral and anterior borders
of the foramen ovale. The superior margin of the latter foramen is not surrounded
by the sinus, its wall. being formed by the ventral surface of the alisphenoid bone.
This posterior part of the sinus lies against the mesial lamina of the pterygoid bone
and is insignificant in extent compared with the same region in the previously
described species. Anteriorly, the sinus expands to form a single, great, bulbous
lobe which is homologous solely with that part of the sinus which in the cetaceans
already described passes ventrally to fill the pterygoid hamulus. Mesially, it is in
relation to the great fossa on the lateral aspect of the conspicuously enlarged hamuli.
Dorsally, it is in relation to the long narrow shelf of the pterygoid bones which
stretches from the pre-orbital region to the tympanic (see p. 40). There are no
traces of a lamina of bone on its exterior face and the latter is quite smooth and
regular in contour, showing none of the minute lobulations which are to be found on
the surface of the sinuses in all the other described species. The significance of this
smoothness of contour is discussed on p. 40. There are no pre-orbital nor post-
orbital lobes of the sinus nor any extension of the latter above the narrow lateral
ridge of the pterygoid bone. The optic infundibulum is formed entirely of bone, its
ventral aspect being bounded by part of the lateral ridge of the pterygoid and its
dorsal aspect by the frontal; it is therefore true to say that none of the cranial
nerves is completely surrounded by an air space, as in some of the other odontocetes.
As previously stated, there is no pre-orbital lobe of the pterygoid and therefore
no anterior sinus. The pre-orbital foramen is bounded only by its associated bones.
The middle sinus
This is similar in shape to that of the other odontocete species. It emerges from
the tympanic bulla above the tympanic annulus and invades the tympano-squamosal
recess. Its two lobes pass respectively posteriorly and anteriorly to the glenoid
fossa.
MYSTICETI
BALAENOPTERA ACUTOROSTRATA
The arrangement of the air sinus system was fully described by Beauregard (1894)
-but for convenience of comparison with that of the Odontoceti his account is repeated
74 HEARING IN CETACEANS
below. He states—‘‘ In order to give an account of the tympanic cavity and its
annexes we made an injection of wax—through the external orifice of the Eustachian
tube. After solidification we sawed through the tympanic bulla horizontally and
took off the whole of the lower wall. The passage of the Eustachian tube—very
nearly rectilinear and directed backwards and outwards passes between the angle
formed by the inferior border of the sphenoid and the digitiform process of the
pterygoid. It intrudes thereafter into the vast pterygoid sinus. This sinus is there-
fore to be considered an enlargement of the posterior extremity of the Eustachian
tube. The communicating orifice of this canal is provided with a valve, formed by
a tongue of membrane hanging from the upper wall and, in the neighbourhood of
the orifice, the dense fibrous tissue which covers the lower surface of the cranium
and closes the sinus ventrally, is thrown into numerous folds and pockets, which we
found filled with injection and are therefore continuous with the Eustachian tube.
The injection filled at the same time the vast pterygoid sinus and the tympanic
cavity proper. These two cavities are in communication by the anterior orifice of
the bulla, or rather by the anterior extremity of the long opening situated between
the two lips of the bulla. The relationship between the pterygoid sinus and the
Eustachian tube on the one hand and the latter with the tympanic cavity shows
that this sinus should be regarded as the homologue of the anterior sinus which we
have described in the dolphins.’”” The present writers find it more convenient to
regard the whole of this structure as the pterygoid sinus since it is entirely delineated
by the pterygoid bones (see p. 8). Beauregard goes on to describe how the injection
passed into three other cavities.
“No.2. A large cavity which corresponds with the whole of the upper and inner
surfaces of the bulla but does not lie underneath it. We refer to it under the name
Peribullary Sinus.
“No, 3. A small diverticulum situated at the posterior extremity of the bulla
in the groove formed by the lower lateral border of the occipital. It is therefore
a Posterior Sinus.”’
No. 4. The fourth sinus described by Beauregard is the conical diverticulum
known as the “ glove finger’’ which he homologized with the middle sinus of the
Odontoceti. The author bases his identification on the fact that the glove finger
protrudes from the tympanic annulus which in the Odontoceti appears to be divided
into two segments, the upper segment forming the boundary of the proximal end
of the middle sinus. It should be pointed out, however, that the glove finger is
covered exteriorly by epidermis whereas the middle sinus of the Odontoceti is
covered externally by periosteal tissue. Fraser & Purves (1945) demonstrated the
similarity between the glove finger and the non-fibrous portion of the tympanic
“membrane ’’ of the Odontoceti, the two structures being homologized with the
pars flaccida of the tympanic membrane of terrestrial mammals. The division of
the tympanic annulus into two segments is peculiar to the Odontoceti and it must
be assumed that the upper segment from which the middle sinus protrudes has been
produced by rupture ofthe dorso-lateral wall of the bulla. The present writers
have been unable to find any structure in the Mysticeti comparable with the middle
sinus and there is no recognizable tympano-squamosal recess (see p. 9).
HEARING IN CETACEANS 75
In this and in the previous chapter, relationship has been demonstrated between
the air sinus system and the contouring of the base of the skull in a number of
cetaceans. The evidence is sufficiently conclusive to enable a reconstruction to be
made of the air sinus systems of species which were not available in the flesh. It
should be pointed out that the indications of the distribution of air sinuses shown
in Pls. 5-47, with the exception of those in which there is the direct evidence of the
plastic injection, have been determined by the distribution of the smoothed areas
on the ventral surface of the skull and the evidence of partial disappearance of the
bones themselves. The limits of the air sacs in all the plates are indicated by a broken
line and the unossified regions by white stippling. The limitations imposed by repre-
senting in two dimensions that which is three dimensional should be borne in mind
when studying the plates.
The evolution of air sinuses in the Cetacea generally is discussed in the following
chapter in which simplified, schematic diagrams are used to illustrate their distri-
bution. If comparison is made between these diagrams and the photographs of the
air spaces it should be remembered that the latter are viewed obliquely, whilst the
former are normal to the lateral and dorso-ventral aspects.
It is the writers’ opinion that however limited or extensive the various components
of the air sinuses may be, they represent a system, which in its early evolutionary
stages was covered by bone, and that, whether or not the osseous content of the
bone remains, the closing fibrous walls of the sacs are periosteal in origin.
The absence of the conventional maxillary, frontal and sphenoidal air sinuses
in cetaceans, and the general distribution of air sacs in this order, appears to give
some justification to Monro’s (1785) homology (see p. 5) but the more likely
explanation seems to be that if the normal mammalian sinuses were ever present
in cetaceans their positions have been occupied by middle ear extension.
EVOLUTION OF THE AIR SACS
Before going on to a discussion of the function of the air sinuses and their impor-
tance in connection with the inter-relationships’ of the Cetacea it is necessary to
consider the possible mode of evolution of the sinuses from the typical mammalian
middle ear. The periotic portion of the tympano-periotic bones of terrestrial mammals
forms a part of the cranial wall and is closely contiguous with adjacent cranial
bones. Further, the tympanic cavity is simple and circumscribed and communicates
directly with the narial cavity through the Eustachian tube. The kangaroo, bat,
tapir, horse and hyrax are notable exceptions to this generalization. In the Cetacea
the tympano-periotic bones are excluded and more or less distant from the cranial
wall, and the tympanic cavity is extended into an elaborate system of sinuses.
The constitution of the air sac system, the dissociation of the tympano-periotic
bones from the skull and the modifications of the skull itself are already present in
the foetus and their genetical origin is obvious. Nevertheless, these modifications
can be interpreted in terms of the mechanical effect of pressure and tension on bone.
The natural condition of rarification of bones is so strikingly similar to the abnormal
conditions found in bone subjected to excessive mechanical stresses, that some princi-
76 HEARING IN CETACEANS
ple such as the so-called ‘‘ Baldwin Effect ’’’ must be invoked to link the natural
to the abnormal. It has been recognized for a long time that of all the tissues com-
prising the body of an animal, with the single exception of blood, bone is the most
plastic, in the sense that it is the most subject to modification under mechanical
stresses. According to Weinmann & Sicher (1947) who quote Wolff's Law of trans-
formation of bone, the effect of increased pressure or tension on bone can be sum-
marized as follows :
“y, Increase of pressure beyond the limits of tolerance leads to destruction of
bone by resorption.
“2. Within the limits of tolerance an increase of the normal forces of pressure or
tension leads to formation of new bone.
‘““Tncreased pressure in such instances acts upon a bony surface which is normally
subjected to pressure and able to withstand it. Such areas are often characterized
by a covering of avascular tissue. Increased traction in an area adapted to traction
will also lead to acquisition of bone. Even slight pressure will lead to resorption of
bone if forces ave applied to an area which is normally neutral, or under tension and
consequently not able to withstand pressure. One characteristic of this adaptation may
be the covering of the bony surface by vascularized periosteum.”
The most violent changes in pressure in the middle ear experienced by a terrestrial
mammal are expressible in terms of small fractions of an atmosphere. In aquatic
mammals a diving depth of even a few feet can bring about a rapid increase of -
pressure and a depth of 30 ft. increases the pressure by one atmosphere. Cetaceans
are known to dive to much greater depths than that represented by one atmosphere,
and it is not surprising therefore that during the acquisition of an aquatic habit a
chain of evolutionary adjustments has occurred to meet the effects of the stresses
imposed.
If the distribution of the muscles as described above is compared with that of the
air sacs, it will be seen that there is a close association of the lobes of the sinus system
with that of the insertion of various important muscles. Thus the peribullary sinus
is associated with the sterno-mastoid, the middle sinus with the masseter, the ptery-
goid sinus with the tensor palati and lateral pterygoid muscles, the post-orbital
lobe with the temporal and orbital muscles, the pre-orbital lobe and the anterior
sinus with the mesial pterygoid.
As previously stated, it is considered that the regions of insertion of these muscles
were originally osseous in nature, as in Platanista. This points to an early situation
where, after the formation of an inter-laminar air space there would be pressure
beyond the normal on the inter-laminar face of bones such as the pterygoid with
resulting resorption of bone on that face. The lateral lamina being thus reduced in
thickness would be inadequate to withstand the normal tension of the muscle,
unless, in accordance with Wolff’s Law, new bone were formed on the external
face. It is easy to see how by such a process of resorption internally and of deposition
externally gradual dilation of the pterygoid bone would take place, which itself
would produce tension parallel with the plane of the lamina. The condition in which
the osseous content of the lamina is completely removed indicates an end point at
which the pressure effect is always in excess of that of tension.
HEARING IN CETACEANS 77
DISSOCIATION OF THE TYMPANO-PERIOTIC BONES
FROM THE SKULL
The dissociation of the tympano-periotic bones from adjacent skull bones and
the development of air sinuses are not of equal extent in all cetaceans. The process
shows a gradation of stages involving the various genera in the Order. Text-fig. 13
gives schematic representations of the variations observed. Ina terrestrial mammal,
the tympano-periotic bones (TB and PE) are fused with the squamosal (sq), and the
mastoid process (MAS) is sutured with the paroccipital process (Text-fig. 13a).
The periotic (PE) forms part of the wall of the cranial cavity but portions of it are
separated from direct contact with thelatter by the superior and inferior petrosal
sinuses. No part of the tympanic cavity separates the periotic from cranial bones
adjacent to it.
In Caperea (Text-fig. 13b) the greater part of the pars mastoidea (MAS) of the
tympano-periotic is not fused but is loosely inserted between the squamosal and
the basioccipital process. There is however a portion of the squamosal immediately
anterior to the pars mastoidea, of a rugose and laminated appearance, very similar
to that of the pars mastoidea itself. With the exception of the condition found in
Kogia this characteristic region of bone is distinguishable to a greater or lesser
extent in all the cetaceans examined. It is situated in the angle formed by the antero-
lateral border of the paroccipital process and postero-lateral margin of the glenoid
fossa. In Platanista, its anterior extent is indicated by a distinct but incomplete
suture, and its posterior limit by what is commonly regarded as the squamo-
paroccipital suture. In other cetaceans the anterior suture is not clearly defined
although the region itself is distinguishable from the adjacent squamosal element.
Since in the Mammalia generally the pars mastoidea intervenes between the zygomatic
process of the squamosal and the paroccipital process, it is justifiable to regard the
area of bone referred to above as a mastoid element.
The periotic of Caperea is in contact with the cranial cavity but is surrounded
by a dorsal extension of the tympanic cavity. Another extension of the tympanic
cavity is accommodated between the bulla and a raised portion of the basioccipital
bone (the basioccipital crest (Boc)). Although no soft parts of Caperea were available
for examination, the skull characteristics of the ear region (see p. 37) together with
what has been observed in other mysticetes (see p. 74) indicate that the extens-
ions of the tympanic cavity referred to above are occupied by the peribullary sinus.
The postero-lateral extension of the cranial cavity (p. 29) can justifiably be
regarded as occupied by the enlarged petrosal sinuses, which have become con-
fluent as a consequence of the partial withdrawal of the periotic from the
cranial wall.
In Balaena (Text-fig. 13c) the portion of the mastoid (mAs) which is fused with
the squamosal (sQ) is very much greater than in Caperea. The base of the cranium
of Balaena is greatly extended laterally, the paroccipital and zygomatic processes
being enormous in comparison with those of Caperea. Correlated with this the
unfused portion of the mastoid is also extended laterally and attenuated. The fused
78 HEARING IN CETACEANS
Fic. 13. Diagrams to show progressive dissociation of tympanoperiotic bones from
adjacent bones of the skull in the Cetacea.
a. Terrestrial mammal. b. Caperea. c. Balaena. d. Balaenoptera. e. Kogia.
f. Physeter. g. Ziphioidea. h. Platanista. 7. Delphinoidea.
Note. The black areas indicate air space.
HEARING IN CETACEANS 79
portion of the mastoid constitutes that which in Caperea is continuous with the
periotic so that the unfused portion appears to be of tympanic association only.
The dissociation of the tympano-periotic from the bones of the cranium is increased
by the further development of the peribullary sinus. The periotic, although not
separated from the cranial cavity by the above sinus, is elongated dorso-ventrayll
and situated at the external end of a long infundibulum (see Caperea above). The
petrosal sinuses appear to be confined within the limits of this infundibulum.
The latter is reduced in diameter by secondary growth of its boundary bones (ss).
In association with the ventral extension of the peribullary sinus the basioccipital
crest (BOC) is more prominent than in the previously described genus.
In Balaenoptera (Text-fig. 13d) the amount of the mastoid (mAs) fused with the
squamosal (SQ) is even more extensive than in Balaena, the unfused portion being
a long, spatulate extension of the tympanic (TB) with a much shorter extension
of the periotic (PE) fused to its dorsal face. The periotic is still more elongated
dorso-ventrally than in Balaena but its dorsal aspect is still a component of the
cranial wall. The peribullary sinus envelops the periotic as far dorsally as the cranial
cavity, and, from the osteological evidence, the vascular supply of the sinus is un-
doubtedly merged with the petrosal sinus (see p. 29). Laterally the peribullary
sinus is insinuated as an extension between the periotic pars mastoidea and the
squamosal. The basioccipital crest is more prominent than in Balaena and its
lateral face is more obviously excavated than in the last named genus.
Turning to the Odontoceti, a similar series of progressive changes can be observed
which, so far as the mastoid is concerned, is parallel to that of the Mysticeti, but in
the development of the peribullary sinus goes much further. Considering the Phys-
seteroidea, Kogia (Text-fig. 13e) resembles Caperea in that the greater part, if not
the whole, of the triangular mastoid (mAs) is not fused to the squamosal (sg). The
apparent attachment of the mastoid exclusively to the tympanic bone is due to the
erosion of the periotic pars mastoidea by the peribullary sinus. The peribullary
sinus not only encircles the periotic but, extending onto its dorsal surface, intervenes
between it and the cranial cavity. The dorsal surface of the periotic presents the
smooth, rounded appearance which is characteristic of the Odontoceti. The peri-
bullary sinus is greatly developed between the tympano-periotic (TB and PE) and
the basioccipital crest (Boc) which is more prominent than in any of the Mysticeti.
The vascular system of the peribullary sinus must be considered as confluent with
the petrosal sinuses (see p. 29).
In Physeter (Text-fig. 13f) a considerable portion of the mastoid (mAs) is fused to
the squamosal. The unfused portion is laminated (laminations not shown in figure).
Only a small portion of the periotic pars mastoidea is unfused. The peribullary sinus,
as in the Odontoceti generally, envelops the periotic, intervening between it and the
cranial cavity. Its vascular system is confluent with that of the petrosal and cavernous
sinuses. These do not lie entirely within the cranial cavity and indeed intrude into
the bulla in the form of the enigmatic cavernous tissue body which contains the
“ degenerate ’’ internal carotid artery (see p. 20).
In the Ziphiidae (Text-fig. 13g) Bevardius, Mesoplodon and Ziphius resemble
Physeter both with regard to the extent of the peribullary sinus, and consequently
80 HEARING IN CETACEANS
with regard to the degree of separation of the tympano-periotic (TB and PE) from
the skull. Only Hyperoodon differs from the remaining ziphioids in the respect
that the unfused portion of the mastoid is very much reduced in its dimensions.
In some respects Platanista (Text-fig. 13) occupies an intermediate position
between the physeterids and the delphinids. Nearly the whole of the mastoid
(MAS) is fused to the squamosal (sQ) although the remains of a squamo-mastoid
suture are clearly discernible. The unfused pars mastoidea of the tympano-periotic
represents only a small portion of the whole mastoid and in its proportions is compar-
able with normal delphinid condition. The part of the peribullary sinus lying above
the periotic is even more restricted than in the ziphioids. The proximity of the
periotic to the squamosal has given rise to the erroneous impression (Hyrtl and
Yamada) that the two elements were fused together. The basioccipital crest (Boc)
is Similar in its general form to that of the ziphioids but its lateral aspect is extensively
pneumatized by extensions of the peribullary sinus. This condition is a precursor
of that common in the delphiniids in which there is such an extension of the
pheumatization with the merging of individual air cavities and the further attrition
of bone that the basioccipital crest is reduced to a thin lamina. The vascular system
of the peribullary sinus is confluent with the petrosal venous sinuses. Above and
anterior to the periotic there is a considerable hiatus in the cranial wall, except in
old specimens in which the hiatus is partially filled by secondary bone. In this respect
Platanista resembles most of the Delphinidae. Stenodelphis and Inia show a condition
of the mastoid resembling that of the delphinids.
Considering the delphinid genera (Text-fig. 137), whilst there is variation in the
degree of development of the peribullary sinus, in general it can be stated that they
show a considerably more advanced evolution of this feature. Nearly the whole of
the mastoid (MAS) is fused to the squamosal (sQ), the unfused tympano-periotic
pars mastoidea being reduced to a small, pointed process frequently separated from
the fixed portion by an appreciable distance.
The ramifications of the peribullary sinus are so extensive that bones adjacent
to it are deeply excavated. The periotic (PE) is separated from the cranial cavity by
a considerable depth of pneumatic sinus.
The basioccipital is generally deeply excavated on its lateral face and thinly
laminar in form, but variations are found between the rather coarse pneumatized
crests of Pseudorca and the extremely thin and sometimes fenestrated crests of
Delphinus.
The blood vascular system of the peribullary sinus is intimately mingled with those
of the petrosal and cavernous sinuses of the cranium. A wide hiatus remains in
the cranium above the periotic until advanced age when secondary bone partially
blocks up the hole.
THE INVASION OF THE PTERYGOID BONE
BY THE MIDDLE EAR CAVITY
With few exceptions in terrestrial mammals, the pterygoid bone (pr) (Text-fig.
14a) in the strict sense consists of a vertical plate of small or moderate size in rela-
tion to the alisphenoid (ALs) with which it is sometimes fused and from which it
Fic. 14.
teridae.
ZOOL. 7, I,
HEARING IN CETACEANS
IM
\
ALS MEP pe
Diagrams of the pterygoid region to show invasion of the pterygoid plate by
the pterygoid sinus.
a. Terrestrial mammal. 6b. Mysticeti. c. Ziphioidea. d. Monodontidae.
f. Platanista. g. Delphinidae.
e. Phys-
6
81
82 HEARING IN CETACEANS
projects ventrally. The pterygoid muscles (MEP) originate on the lateral face of the
pterygoid bone and are inserted on the lower jaw, to which they pass in a slightly
oblique ventral direction. The tensor palati (mrp) muscle originates on the lateral
aspect of the cartilage of the Eustachian tube, passes ventrally over the pterygoid
hamulus whence it spreads out into a delicate aponeurosis which merges with that
of its fellow on the other side. The pharyngeal muscle mass (MPP), including the
levator palati, is inserted into the superior surface of the aponeurosis and together
with the latter forms the soft palate. The tympano-periotic bones (PE) fused with,
and forming part of the cranium, lie dorsal to the pterygoid muscles.
The pterygoid bones (pT) of the Mysticeti (Text-fig. 14b) are not laminar but
exceedingly thickened laterally to such an extent that the alisphenoid (ats) is
obliterated from view in the ventral aspect. The tympano-periotic (TB, PE) has
become displaced ventrally, is not fused with the adjacent cranial bones and has
almost completely lost participation in the formation of the cranial wall. In its
position it has come to lie ventral to the level of the pterygoid muscles (MEP). An
extension of the middle ear cavity invades the pterygoid bone, excavating a rounded
fossa (PTS) in the latter, the cavity of which communicates with the Eustachian
tube (ET).
Correlated with the ventral displacement of the bulla the tensor palati muscle
(MTP) is considerably shortened dorso-ventrally.
The soft palate, although reduced antero-posteriorly as compared with that of
most terrestrial mammals, is relatively much wider than in the latter. The antero-
posterior reduction is due to the posterior extension of the palatine bones, a process
which reaches its maximum in the genus Balaena.
The Ziphiidae (Text-fig. 14c) are characterized by the great enlargement of the
hamular processes of the pterygoids (ptH). The superior portion of the pterygoid
bone is again greatly thickened laterally so as to cover over the ventral aspect of
the alisphenoid (Ars). The extensive excavations of the pterygoid hamulus by the
diverticulum from the Eustachian tube (ET) has not resulted in a symmetrical
splitting of the pterygoid plate (pt). Thus whereas the medial lamina (pr (ML))
persists as a thick, bony wall, the lateral wall (pT (LL)), so far as its osseous content
is concerned, is reduced to a low, ventrally directed ridge at the dorso-lateral margin
of the excavation. The soft, lateral closing membrane of the excavation is the per-
sisting periosteum (P) of the lateral lamina, the greater portion of this lateral wall
of the hamulus having entirely lost its ossification. The great distension of the hamular
process has resulted in displacement and modification of the muscles in its neigh-
bourhood. Thus the external pterygoid muscle (MEP) is greatly flattened dorso-
ventrally and originates above the ventrally directed ridge already referred to.
The tensor palati muscle (mrp), ensheathing the lateral closing membrane of the
air sac, is expanded correspondingly. The pterygoid hamuli are in close apposition
in the median plane so that there is no soft palate. The palatine aponeurosis is
divided by the thickness of the combined hamuli, consequently in the posterior
part of the nasal channel the pharyngeal muscles (mpp) lie within the posterior
nares.
The tympano-periotic bones (TB, PE), as in the Mysticeti, are displaced ventrally
HEARING IN CETACEANS 83
so that they lie below the level of the pterygoid muscle, and the modification in the
form of the periotic is such that it takes no part in the composition of the cranial
wall.
The mode of excavation of the pterygoid in the Delphinapteridae (Text-fig. 14d)
shows a remarkable similarity to that of the Physeteridae (vide infra) in that the
pterygoid hamuli (PTH) remain for the most part unexcavated and of small size.
The osseous portions of the superior and lateral laminae persist to a greater extent
than in the Physeteridae, since there is an osseous portion of the superior lamina
below the orbito-sphenoid uniting the medial lamina with the diminished lateral
lamina. As in the Physeteridae the position of the pterygoid hamulus in relation
to the proximal end of the Eustachian tube is such that the main direction of the
tensor palati muscle (MTP) is more horizontal than vertical.
The interpretation of the condition of the pterygoid in the Physeteridae (Text-fig.
I4e) is based on the evidence obtainable from the skulls of Physeter and Kogia
together with the information contained in Yamada’s paper (1953), no soft parts
being available for examination. It would seem that the excavation of the pterygoid
bones is the reverse of that found in the Ziphiidae. In the latter the pterygoid
hamulus is greatly enlarged and extensively excavated, while the pterygoid plate
is relatively unaffected, whereas in the Physeteridae the hamulus is small, incon-
spicuous, and unexcavated, while the pterygoid plate is extensive in area and
excavated to such a degree that the osseous content of the superior and lateral
laminae of the pterygoid bone is completely absent.
From the condition of excavation of the pterygoid it can be deduced that the
pterygoid muscles (mrp) must be inserted onto the periosteal closing membrane of
the air sac but verification of this must await inspection of the soft parts.
The tensor palati muscle (MTP) ensheathing the air sac must be very nearly hori-
zontal in its main direction, such is the relation of the pterygoid hamulus to the
proximal end of the Eustachian tube. The pterygoid hamuli (PTH) are not quite in
apposition in the middle line, but as in the Ziphiidae the palato-pharyngeal muscles
(mpp) are enclosed within the posterior nares.
Platanista (Text-fig. 14f), so far as the pterygoid bone is concerned, is the least
specialized of the Platanistidae. Indeed its condition is such that it provides (along
with Stenodelphis) the explanation to all the successive changes found in the Cetacea,
and this notwithstanding the great development of the presumably pneumatized
maxillary crests. In Platanista, although both pterygoid plate (pT) and hamulus
(PTH) are excavated, there is little inflation between the laminae, which are connected
by numerous, bony trabeculae. Both the ventral and lateral laminae retain their
Osseous content and only the hamulus shows any degree of fenestration.
The pterygoid hamuli are closely approximated to each other in the middle line,
in this feature resembling what is found in most of the Delphinidae.
No direct inspection of the pterygoid (MEP) and palatal muscles (MPP) was possible,
but it can be inferred from the close approximation of the pterygoid hamuli that the
palato-pharyngeal muscles are enclosed within the posterior nares. Similarly the
tensor palati muscles (MTP) would appear to be more horizontally directed, as in
the Physeteridae and Delphinapteridae. With regard to the pterygoid muscles
84 HEARING IN CETACEANS
it may be noted that their normal place of origin—the lateral aspect of the pterygoid
plate—tretains its osseous condition. This implies that the primary function of the
muscles is as in the normal terrestrial mammal, that of actuating the lower jaw. It
also implies that the articulation of the lower jaw must be similar to that of the
terrestrial mammal. It is interesting to note that Anderson (1879, p. 433) observed
in a specimen of 63 ft long that ‘“‘the jaws are capable of great extension, opening at
their tip ... to 13 inches’’. The size of the zygomatic process of the squamosal
similarly indicates that the masseter muscle is not reduced in size as in the delphi-
nids. The presence of a mandibular articular capsule is conjectural but seems very
likely.
In the Phocaenidae and Delphinidae (Text-fig. 14g) both the plate (pr) and the
hamulus (PTH) of each pterygoid bone are excavated, and inflated to a greater or
lesser extent. The lateral and superior laminae of the pterygoid show a diminution
of their osseous content, which however, is variable from genus to genus. According
to the degree of distension of the pterygoid plate the ventral aspect of the alisphenoid
(ALS) is exposed to a greater or lesser extent. The approximation of the hamuli
to each other in the middle line is also similarly variable, the degree of approximation
depending to a large extent on the state of inflation of the hamuli. The final expres-
sion of this process can be seen in Delphinus delphis in which the greater part of the
pterygoid musculature (MEP, MTP) is attached to the persisting, non-osseous, perio-
steum of the lateral lamina. Due to the expansion of the pterygoid hamuli ina ventral
direction, the tensor palati muscles (MTP) retain more of their vertical orientation,
although they are greatly extended antero-posteriorly. The naso-pharyngeal muscle
mass (MPP) lies within the posterior nares and is separated from the ventral aspect
of the aponeurosis by the pterygoid air spaces.
SYSTEMATIC ARRANGEMENT
The descriptions and figures given in the foregoing section are intended to convey
an impression of the average differences in the middle ear air sac system between
the families of the Cetacea. There is however also intergeneric variation, which is
considered to be significant and which in some families shows a serial gradation of
specialization.
Text-figs. 15-21 show a schematic representation of the splitting of the pterygoid
bone in the Cetacea. The diagrams in the left hand column are of the lateral aspect
of the pterygoid region. The right hand column shows an antero-posterior view of
the same region. In the diagrams the thick black line represents pterygoid bone, the
dotted line (except in Text-fig 150’) indicates those parts of the pterygoid bone
from which the osseous content is absent, leaving periosteal tissue. The peribullary
sinus which is derived from the tympanic cavity is shown in the diagrams but not
discussed.
Text-figs. 22-25 show the dorso-ventral views of the sinus system dissociated
from the skull.
Text-fig. 15a shows schematically the inter-relationship of the alisphenoid (ats),
palatine (PAL), maxilla (MAX), orbito-sphenoid (0s), the pterygoid plate (pr), the
HEARING IN CETACEANS 85
tympanic bulla (TB), optic (No) and adjacent foramina, the foramen ovale (NM)
and the mandibular branch of the 5th nerve, in some terrestrial mammals. Text-fig.
15a’ is an antero-posterior view showing the inter-relationship of the pterygoid
plate, basioccipital (Bo), alisphenoid 5th nerve branch, foramen ovale and squamosal.
MYSTICETI
Text-fig. 156, c shows diagramatically these relationships in Caperea. The tym-
panic cavity and Eustachian tube form a wide diverticulum which invades the
pterygoid plate, and the tympano-periotic is withdrawn from direct contact with
the cranial cavity. The pterygoid has become greatly thickened laterally, enveloping
the mandibular branch of the 5th nerve in a deep fissure, the lips of which are in
contact in a pterygoid to pterygoid suture. The nerve has been partially deflected
simultaneously in a slightly anterior direction, by the forward extension of the
diverticulum i.e. the pterygoid sinus. It should be noted that at this stage there is
no lateral deflection of the 5th nerve branch (Text-fig. 150’).
In Balaena (Text-fig. 15c) the pterygoid sinus (PTS) extends anteriorly beyond the
level of the foramen ovale (NM), and the pterygoid plate (PT) is expanded laterally to
a greater extent than in Caperea. These factors have produced a lateral as well as
forward deflection of the 5th nerve branch (Text-fig. 15c’). That part of the ptery-
goid which would have covered the 5th nerve branch posteriorly has disappeared
owing to the extension of the sinus dorsally. The 5th nerve branch is partially
enclosed within a channel formed dorsally by the alisphenoid (ats) and ventrally by
the superior lamina of the pterygoid plate. A ventrally-directed extension of the
squamosal, the falciform process (FP), lateral to the lateral pterygoid plate deflects
the 5th nerve branch to its original ventral direction. ;
In Caperea the pterygoid hamulus (PTH) remains rather small but in Balaena it
forms a wide, mesially-directed shelf.
In Eschrichtius (Text-fig. 15d) the pterygoid sinus is similar to that of Balaena
in its posterior part whilst anteriorly it projects forward to an extent comparable
with Balaenoptera. The falciform process (FP) is not as prominent as in Balaena.
The mesial lamina of the pterygoid is distended mesially as well as laterally (Text-
fig. 13d’).
Text-fig. 15¢ shows the condition in the Balaenopteridae (see also Pl. 7). The
diverticulum of the Eustachian tube is more elongated and, with reference to the
position of the foramen ovale, has extended anteriorly as compared with its limits
in the Balaenidae. The superior lamina of the pterygoid plate (pr) completely
covers the ventral aspect of the alisphenoid (ats). Again the 5th nerve branch
(NM) is deflected in a lateral direction (Text-fig. 15e’) and is completely enclosed
within a bony tube formed ventrally by the superior lamina of he pterygoid
and dorsally by the alisphenoid. The nerve is directed ventrally by an even greater
development of the falciform process (FP). The falciform process bifurcates antero-
posteriorly round the 5th nerve branch, thus the latter has its exit from the side
of the skull formed by a second bony tube. Text-fig. 15e’ also shows the mesial
dilation of the pterygoid plate which is absent in Balaena, The pterygoid hamulus
86 HEARING IN CETACEANS
NM NM
MAX OS NO ALS pe SQ ats/ats BO
i Bo
TB PTH |
PT
qd a’
M
MAX O& NO ALS
N
sQ 45|
H
NM
SQ Ats|/ ALS BO
FP
PT
PT
ay
NM
sQ ch ALS ag
F
P aes
T
é e’
Fic. 15. Schematic diagrams showing the progressive invasion of the pterygoid bone
by the pterygoid sinus in a (longitudinal section), a’ (antero-posterior transverse section),
terrestrial mammal ; b, b’, Capevea; c, c’ Balaena ; d, d’ Eschrichtius ; e, e’ Balaenoptera.
HEARING IN CETACEANS 87
(PTH) is relatively small and, as in Balaena, unexcavated. Text-fig. 22 a-d shows
the gradual development of the air sacs in the genera referred to above.
ODONTOCETI
ZIPHIOIDEA
Text-fig. 16a shows diagramatically the condition existing in the Ziphioidea.
The distension of the pterygoid bone shows a distinct advance on the condition
found in the Mysticeti. Thus the pterygoid hamulus is so extended anteriorly that
it passes beyond the anterior limit of the alisphenoid (ALS), passes below the orbito-
sphenoid (os) and the optic foramen (NO), compresses the palatine (PAL) antero-
posteriorly and at its anterior limit makes contact with the maxillary (MAX), divid-
ing the palatine into dorsal and ventral components. The superior lamina is fenest-
rated, exposing a small area of palatine. The pterygoid hamulus also extends
posteriorly under the foramen ovale (NM). Its freely projecting, postero-ventral
portion extends ventrally to the level of the basioccipital (Bo).
Above the inflated pterygoid hamulus, in the region of the optic foramen, the un-
divided pterygoid plate persists, and to it the pterygoid muscles are attached (see
p. 82).
The 5th nerve branch (Nm) (Text-fig. 16a’) is directed laterally by the thin superior
lamina of the pterygoid hamulus. Its more distal portions are not enclosed within
a bony tube as in the Mysticeti since the whole of the osseous content of the lateral
lamina is lacking and the falciform process is reduced to a slender spine. The con-
dition of the pterygoid just described is common to all the ziphioids with negligible
variation.
The air sac development is shown in Text-fig. 22e (see also Pls. 8-12).
MONODONTOIDEA
In Monodon the pterygoid hamuli remain unexcavated, inflation being confined
to the pterygoid plate (Text-fig. 16) (and Pls. 13 and 14)). The pterygoid does not
extend so far forward as to bifurcate the palatine but there is some resorption at
the anterior limit of the bone so that, in the prepared skull, the palatine is exposed.
A new feature is a small, anteriorly projecting diverticulum which cavitates the
alisphenoid bone behind and above the foramen ovale. As a result the portion of the
alisphenoid posterior to the foramen ovale is raised in level above the remainder of
the alar process and the tympano-periotic consequently is further removed from the
cranial cavity.
The 5th nerve branch (Text-fig. 16d’), after emergence from the cranium, is not
(for the most part) enclosed within a bony infundibulum because of the loss of the
alisphenoidal part of the superior lamina of the pterygoid plate and because of the
great reduction in size of the falciform process. There is, however, the beginning of
a new infundibulum formed from the alisphenoid.
More anteriorly (Text-fig. 16b’’) considerable parts of the ossified superior and
lateral laminae remain.
88
HEARING IN CETACEANS
paL 9S ji
NM
5/ SB BO
NM
SQ ALS /ais BO
pT AL
¢
e S
Fic. 16. Schematic diagrams showing invasion distention and resorption of the ptery-
goid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section).
Ziphioidea ; 6, b’ and 6” (further rostral than b’) Monodon ; ¢, c’ c” Delphinapterus ;
d, d’ Kogia ; e, e’ Physeter.
HEARING IN CETACEANS 89
The other existing representative of the Monodontoidea, Delphinapterus (Text-fig.
16c and Pl. 15) differs from Monodon mainly in having the pterygoid hamuli slightly
inflated, in this approximating to the condition generally encountered in the
Delphinidae. As in Monodon the alisphenoid is excavated behind the foramen
ovale and in this region is raised in level above that of the rest of the bone. A posterior
extension of the pterygoid periosteum is in contact with this excavation above the
foramen ovale.
The 5th nerve branch (Text-fig. 16c’) shows approximately the same condition
as in Monodon. More anteriorly (Text-fig. 16c’’) there is greater resorption of the
lateral lamina than in Monodon. The hamulus, as shown in this and the previous
figure, is excavated.
The diagram of the dissociated air sacs are shown in Text-fig. 22f and g.
_ PHYSETEROIDEA
In contrast with the Ziphioidea, in the Physeteroidea (Text-figs. 16d and e and
Pl. 16) the splitting of the pterygoid is restricted to the pterygoid plate and does
not involve the hamulus. The degree of anterior extension of the pterygoid plate in
Physeter (Text-fig. 16d) is similar to that effected by the hamular element in the
Ziphiidae except that the palatine bone, although compressed, is not divided
anteriorly. The occipital crest (not shown in the figure) is reduced in size by a
backward projection of the mesial lamina of pterygoid plate, and it is reasonable
to assume that the superior lamina has been similarly extended and that the wide
exposure of the alisphenoid in the cleaned skull is due to the loss of the osseous
content of the superior lamina.
The 5th nerve branch (Text-fig. 16d’) is not enclosed within any bony tube lateral
to its emergence from the alisphenoid since the osseous content of the superior lamina
of the pterygoid is lacking. Similarly the distal portions of the nerve are not sur-
rounded by bone because the lateral lamina is no longer ossified. The falciform
process is reduced to a diminutive plate. The lateral aspect of the mesial plate is
convex which is in contrast to the concavity found in this region in the ziphioids.
Kogia (Text-fig. 16e) is essentially similar to Physeter in the condition of splitting
of the pterygoid, except that in its forward extension the latter divides the palatine
into a dorsal and a ventral component. This condition is comparable with that
found in the Ziphiidae except that in the latter it is the hamular portion of the
bone, which is involved. The 5th nerve branch (Text-fig. 16e’) is not enclosed in any
bony channel after emergence from the alisphenoid and there is no remaining vestige
of the falciform process.
The diagrams of the dissociated air sacs are shown in Text-fig. 22/ and 1.
PLATANISTOIDEA
The members of the family Platanistidae (Text-fig. 17 and Pls. 18-23) show rela-
tively primitive features so far as the ventral region of the pterygoid bone is con-
cerned but they approximate more closely to the conditions found in the delphinids
than to the Physeteridae, Ziphiidae or any of the Mysticeti. The chief characteristic
go
HEARING IN CETACEANS
Sea?
d d’
Fic. 17. Schematic diagrams showing invasion, distention and resorption of the
pterygoid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section),
Platanista ; b, b’, Stenodelphis ; c, c’, Inia; d, d’ Lipotes.
HEARING IN CETACEANS QI
of Platanista (Text-fig. 17a) is that each pterygoid (PT) completely overrides the
palatine and extends onto the posterior end of the maxilla (Max). The pterygoid
hamuli, although small, are completely excavated and to some extent fenestrated.
The mesial (PT (ML)) and lateral (pT (LL)) laminae of the pterygoid plate are connected
by bony trabeculae (Text-fig. 17a’). In addition to the forwardly projecting cavita-
tion of the alisphenoid behind the foramen ovale, there is a posteriorly projecting
diverticulum of the pterygoid bone which comes into contact with the alisphenoidal
cavitation above the foramen ovale. The two diverticula do not merge where they
come together, two very thin bony laminae having been observed which separate
them. The infundibulum of the optic nerve is very greatly reduced.
The internal architecture of the characteristic maxillary crests (Mxc) of Platanista
so resembles that of the interlaminar region of the pterygoid that it is reasonable
to suppose that the cavitation of the pterygoid is continuous with that of the maxil-
lary crests. Bony channels connect the two regions and, in the series of cetacean
skulls examined and described in this paper, there is plenty of evidence of the exten-
sibility of the pterygoid beyond its obvious limits (see for example Text-fig. 19a
of Pseudorca where portions of the pterygoid have penetrated the orbital and pre-
orbital regions). Platanista can be regarded as an extreme example of this process.
Indeed it would not be unreasonable to regard the development of the maxillary
crests as a consequence of a corresponding extension of the pterygoids. A diverticul-
lum of this extension passes obliquely forward on either side of the base of the rostrum
splitting the bone in this region into dorsal and ventral laminae which are connected
mesially, and probably laterally also in the living animal, by bone. In Jmza, as will
be described below, a slender extension of the pterygoid sac projects into the rostrum,
whether this is so in Platanista has yet to be ascertained.
There is no indication in Stenodelphis (Text-fig. 170) of the assumed extension
in Platanista of the pterygoid sinus system onto the dorsal aspect of the skull.
Apart from this, the ramifications of the pterygoid bone on the ventral aspect of
the skull show an advance on Platanista. Each extends forward beyond the limit
of the orbitosphenoid onto the lateral aspect of the frontal. It also invades the orbit
in the region normally occupied by the prominent orbital nerves and muscles. This
condition should be compared with that found in Pseudorca in which the eye and
its muscles are fully functional. The pterygoid hamuli are more pronouncedly exca-
vated and inflated than in Platanista. The posterior diverticulum of the pterygoid
sinus which passes dorsal to the foramen ovale is more dorsally situated in relation
to the latter than in Platanista.
The 5th nerve branch (Text-fig. 176’) issuing from the cranial cavity appears
to be bounded dorsally by the very thin, bony lamina which encloses the small
pterygoid diverticulum passing posteriorly above the foramen ovale. The correspond-
ing ventral boundary of the nerve is not ossified. The lateral lamina of the pterygoid
retains most of its osseous content although it is extensively fenestrated. The
dorsally-directed spread of the pterygoid is accompanied by a corresponding dorsal
deflection of the wing of the alisphenoid.
The distribution of the pterygoid sinus system in Imia has been obtained largely
from radiographic evidence, the bony element of the region being so greatly lacking
92 HEARING IN CETACEANS
(see p. 45). In this species (Text-fig. 17c) the whole of the ventro-lateral aspect
of the frontal is ensheathed by an extension of the sinus system which was presum-
ably enclosed within a corresponding extension of the pterygoid bone, the osseous
element of which has disappeared. In addition to the excavation and extension
of the pterygoid hamulus, there is a slender, elongated extension of the sinus into
the maxillary bone of the rostrum. The exact disposition of the diverticula round
the foramen ovale cannot be ascertained but presumably they are in very close
contact with each other, the 5th nerve on emergence from the cranium being com-
pletely surrounded by a non-ossified boundary. Text-fig. 17c’ shows the remaining,
ossified, mesial lamina of the pterygoid. The extensive loss of osseous content in
the lateral and dorsal laminae is noteworthy. The diverticulum of the pterygoid
sinus above the foramen ovale is much larger than in Stenodelphis and is without
osseous content in its walls.
The distribution of the air sinus system in Lipotes is very similar to that of Ima.
Noteworthy differences are that more of the osseous content of the pterygoid hamulus
persists and that the post-orbital extension is wider and larger. In the absence of
soft parts it is presumed that the anterior extremity of the sinus system invades
the rostrum (Text-fig. 17d, d’).
The diagrams of the dissociated air sacs in the Platanistoidea are shown in
Text-fig. 23a-d. The conjectured maxillary air sac of Platanista is not shown in
Text-figure 23a.
DELPHINOIDEA
Consideration of the splitting of the pterygoid in the Delphinoidea begins with
an examination of the conditions found in the Phocaenidae, because the average
condition in this family is less specialized than in the Delphinidae, particularly with
respect to the portions of the pterygoid on the ventral aspect of the skull. In Phocaena
(Text-fig. 18c), as in Ina, there is an extension of the pterygoid sinus under the post-
orbital process of the frontal (see also Pl. 27), and another pre-orbital extension,
which in Jnia is confluent with the post-orbital because of the reduction in size, in
the latter, of the optic nerve and muscles. In Phocaena the optic nerve and muscles
are fully functional and lie between the two diverticula. An extension of the
pre-orbital diverticulum passes dorso-caudally between the frontal and maxilla ;
the fossa formed by this diverticulum being a characteristic feature in the phocaenid
skull.
Another diverticulum in front of the foramen ovale projects posteriorly and
mesially, producing a cavitation of the alisphenoid in which no osseous trace of the
pterygoid remains. A ventral curving of the posterior margin of the alisphenoid
posteriorly to the diverticulum just referred to, separates the latter from the peri-
bullary sinus. A bony bridge between the hinder margin of the alisphenoid and the
hinder margin of the palatine represents the remaining portion of the lateral lamina
of the pterygoid (Text-fig. 18c’).
The 5th nerve branch, on emergence from the cranial cavity, is surrounded not
by bone, but by the periosteal closing walls of the sinus, except in the vicinity of
the falciform process where the dorsal aspect of the nerve is in contiguity with the
HEARING IN CETACEANS
Fic. 18. Schematic diagrams showing invasion, distention and resorption of the
pterygoid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section),
Steno; b, b’ Sousa; c, c’ Phocaena; d, d’ Neomeris.
94 HEARING IN CETACEANS
ventrally-directed, posterior margin of the alisphenoid. The figure (18c’) shows
the mesial cavitation of the alisphenoid, not the more lateral, ventrally directed
portion.
The pterygoid hamuli are excavated by the sinus but are not greatly inflated.
Anteriorly they do not override the palatines which form an appreciable part of
the palatal area of the skull.
In general, the condition of the pterygoid and its associated sac in Neomeris(Text-
fig. 18d and Pl. 28) are similar to that of Phocaena. The pre-orbital diverticulum is
more prominent, its extension between frontal and maxillary more slender. The
posteriorly projecting diverticulum anterior to the foramen ovale is shorter antero-
posteriorly and occupies a deeper concavity of the wing of the sphenoid. The
anterior lobe of the peribullary sinus extends further anteriorly above the foramen
ovale. The palatines are as in Phocaena. The pterygoid hamuli are only partially
excavated and are uninflated. The small bony bridge (Text-fig. 18d’) of the lateral
lamina of the pterygoid plate remains.
The 5th nerve branch on emergence from the cranial cavity is surrounded dorsally
and posteriorly by the peribullary sinus, ventrally and anteriorly by the pterygoid
diverticulum in the region of the alisphenoid.
The diagrams of the dissociated air sacs of the Phocaenidae are shown in Text-fig.
23g and h.
The sub-family Orcinae, and particularly Psewdorca, provides most useful evidence
about the origin of ramifications of the sinus system. Like Stenodelphis (see above
p- 91), Pseudorca specimens demonstrate how the non-osseous closing membranes
of the pterygoid system are secondary to a phase during which the osseous content
of the ramifying pterygoid bone is still present (see Pls. 29 and 30). Thus there are
individuals in which the pre- and post-orbital diverticula are completely enclosed
in a bony armour. In other specimens again, the bony armour is heavily fenestrated
and frequently represented by a bony cagework. (This last is the condition in the
specimen figured in Pl. 30). At the other end of the scale there are specimens in
which the osseous content of the pre-orbital extensions and the lateral lamina of the
pterygoid is wanting. Text-fig. 19a gives a generalized picture of the Pseudorca
condition and shows the relatively small pre-orbital and post-orbital diverticula.
The posteriorly projecting diverticulum of the pterygoid air sac passes round the
dorsal margin of the foramen ovale (NM) and the implication of the peribullary
sinus (PBS) in the investment of the 5th nerve branch is very small. The bony,
dorsal lamina of the pterygoid is fenestrated to a greater or less extent in different
individuals.
The pterygoid hamulus is excavated and much inflated but only slightly overrides
the palatine (PAL).
The hamulus projects mesially to a greater extent than in previously described
genera (Text-fig. 1ga’) so that the mesial border of the one hamulus closely approxi-
mates to that of the other.
The 5th nerve branch on emergence from the skull is frequently enclosed in a
cagework of small, bony trabeculae which represent the last remnants of a bony
infundibulum.
HEARING IN CETACEANS 95
ALS
Fic. 19. Schematic diagrams showing invasion, distention and resorption of the
pterygoid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section),
Pseudorca ; b, b’ Orcinus ; ¢, c’ Ovcaella; d, d’ Globicephala ; d, d’ Feresa.
96 HEARING IN CETACEANS
The osseous content of the lateral lamina of the pterygoid appears to be wanting,
but external to the pterygoid periosteal closing membrane, is a bony bridge consisting
of a plate formed by a posteriorly directed extension of the palatine and an anteriorly
extending process from the base of the falciform process (see pp. 35-37 supra).
The condition of the sinus system in Orcinus (Text-fig. 19) and PI. 31) is in general
similar to that of Psewdorca but with certain modifications. Thus, the pre-orbital
sac is enlarged in size relative to the post-orbital, both sacs are expanded in a lateral
direction and the anterior sac extends onto the palatal surface of the maxilla (its
anterior limit being difficult to define in the prepared skull). The fossa which gives
access to the maxillary foramen is very much enlarged relative to that of other
dolphins. It is confluent with the bony cavity which houses the pre-orbital sac, but
the significance of their contiguity is not understood.
The peribullary sinus projects anteriorly as far as the anterior margin of the fora-
men ovale.
As in Pseudorca the palatine is not extensively over-ridden by the pterygoid.
The extensive disappearance of the osseous content of the superior and lateral
laminae is indicated in Text-fig. 19h’. The hamuli are extensively excavated and
inflated. They meet in the middle line.
The 5th nerve branch on emergence from the cranial wall is entirely surrounded
by air sac derived from the peribullary and pterygoid sinuses.
In Orcaella (Text-fig. 19¢ and Pl. 32) the pre-orbital cavity is conspicuously wide
and does not become constricted as it passes dorsally behind the maxilla. A diverti-
culum of the pre-orbital extension of the air sac projects forward and overlaps the
ventral surface of the maxilla at the base of the rostrum. In the sphenoidal region
there is no clearly delineated line of demarcation between the posterior limit of the
pterygoid system and the peribullary sinus. Any division that exists between these
systems must be membranous. The pterygoid hamulus overrides the palatine to
such an extent that the latter is divided into two portions, dorsal and lateral
respectively.
The pterygoid hamuli (Text-fig. 19c’) are widely separated, excavated and partially
dilated. There is no trace of an osseous lateral lamina. The 5th nerve branch
is entirely surrounded by air sac. The respective participation of the peribullary
and pterygoid systems in the investment of the nerve cannot be assessed in the
absence of soft parts. The falciform process is considerably reduced and attenuated
in correspondence with the increased development of sinuses.
In the genus Globicephala (Text-fig. 19d, frontispiece, and Pls. 33 and 34) lateral
expansion of the sphenoidal portions of the pterygoid sac has taken place. The
orbital lobes appear to be relatively insignificant. The alisphenoid has been com-
pletely over-ridden by the pterygoid sac and in its lateral aspect presents only the
edge of a thin lamina.
A posteriorly projecting process of the sphenoidal part of the pterygoid sac passes
dorsal to the foramen ovale and superior to the anterior tip of the peribullary sinus.
Anteriorly the pterygoids do not greatly override the palatines so that a fairly wide
band of the latter is exposed on the palate. The palatine bones are themselves
excavated by the forward extension of the hamular cavities.
HEARING IN CETACEANS 97
The osseous content of the dorsal lamina persists (Text-fig. 19d) as a shelf, narrow-
ing from below the orbito-sphenoid to disappearance below the alisphenoid. No
trace remains of a bony, external lamina.
The pterygoid hamuli are completely excavated and widely dilated (Text-fig. 19d’).
They are in contact in the middle line.
On emergence from the cranium, the 5th nerve branch is surrounded proximally
by a bony infundibulum but more distally it is surrounded by extensions of the
peribullary and pterygoid sinuses.
The genus Feresa may be considered conveniently with the Ovcinae because of
its apparent affinity with the latter, although in some respects it bears resemblance
to Grampus griseus also.
The post-orbital and sphenoidal portions of the pterygoid sacs are greatly enlarged
(Text-fig. 19e and Pl. 35). The pre-orbital and post-orbital sacs are apparently in
contact above the optic nerve. Not only has the bony content of the dorsal lamina
of the pterygoid disappeared, but the wide, ventrally exposed alisphenoid is so
reduced in thickness that its lateral aspect, in the temporal fossa, is extremely
narrow. The peribullary sinus passes forward above the foramen ovale. The pre-
orbital sac overlaps onto the palatal aspect of the maxilla to form the anterior sac.
The palatine bones are widely exposed but very deeply excavated by the pterygoid
sacs. This excavation is continued forward so that the posterior aspect of the maxilla
is also involved and both palatine and maxilla are fenestrated on the palatal aspect.
The superior and lateral laminae of the pterygoid (Text-fig. 19e’) have lost their
osseous content. In both of the British Museum specimens and in Yamada’s (1953)
figured specimen, the posterior portions of the pterygoid hamuli are missing. The
heavily fenestrated portions that remain, together with the incompleteness of the
hamuli, are an indication of the extent to which resorption has proceeded in this genus.
The 5th nerve branch, medially to the falciform process, is surrounded by air sac,
‘but proximally an infundibuliform extension of the alisphenoid invests it.
The dissociated air sacs of members of the Orcinae are shown in Text-fig. 24 a-e.
The pre-orbital and post-orbital diverticula of the pterygoid system in Cephalo-
vhynchus heavisidei (Text-fig. 20a and Pl. 36) approximate to each other superiorly
to the optic foramen to a greater extent than was evident in any of the Orcini
with the exception of Fevesa. These lobes have a tendency to spread laterally
rather than vertically, giving them greater width than height, the post-orbital
lobe extending posteriorly as in Phocaena but not to the same degree. The peri-
bullary sinus (PBs) extends anteriorly above the foramen ovale but a well defined
bony ridge of the alisphenoid separates it from the posterior limit of the pterygoid
system. Each palatine bone (PAL), anterior to the pterygoid (pT) is widely exposed
and not overridden by the latter.
The pterygoid hamuli (Text-fig. 20a’) are widely excavated and inflated, they
also approximate to each other in the middle line. The 5th nerve branch (NM) on
emergence from the cranium is completely surrounded by air sinus; posteriorly and
dorsally by the peribullary, anteriorly and ventrally by the pterygoid.
C. commersoni (Text-fig. 20b and 0’) is very closely comparable with C. heavisidet
in the general arrangement of the sinus systems. One or two differences may however
ZOOL, 7, I. 7
98
HEARING IN CETACEANS
Fic. 20. Schematic diagrams showing invasion, distention and resorption of the
pterygoid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section),
Cephalorhynchus heavisidei; b, b’ C. commersoni; c, c’ Lagenorhynchus albirostris ;
d, d’ L. acutus ; e, e’ L. obscurus.
HEARING IN CETACEANS - 99
be noted. The pre- and post-orbital diverticula are in closer approximation to each
other than in C. heavisidei because of the disappearance, on the under surface of the
orbital process of the frontal, of a bony ridge, which in the latter species forms a
barrier between the two diverticula. The pre-orbital diverticulum does not extend
vertically between the frontal and maxilla as in C. commersont.
The air sinus system of Cephalorhynchus dissociated from the skull is shown in
Text-fig. 24 f.
The genus Lagenorhynchus is one about which information regarding the air sacs
has been obtained from plastic casts of L. albirostris (see p. 66), but for comparative
purposes it is necessary to include it in the series of diagrams.
The pre-orbital and post-orbital sacs of this species (Text-fig. 20c and Pl. 38) are
relatively small and of about equal development, although the latter has a small
posterior extension onto the posterior face of the orbital process of the frontal.
They do not meet above the optic nerve. There is nothing in the nature of an
anterior sinus. In the sphenoidal region the sacs do not entirely cover the ventral
aspect of the alisphenoids, which are quite stout, and present a broad lateral surface
in the temporal fossa. The anterior portion of the space normally occupied by the
peribullary sinus is filled with a complex of veins, and by very slender, bony trabe-
culae with air spaces between.
Ventrally and anteriorly the pterygoids override the palatines so that only a thin
strip of the latter are exposed on the palate.
The dorsal lamina (Text-fig. 20c’) lacks any remains of the osseous content, but
the lateral lamina is represented by a bony bridge which may be fenestrated (Pl. 37).
The pterygoid hamuli are very wide, meeting in the middle line. They are fully
excavated although not greatly inflated.
The 5th nerve branch on exit from the cranium lies within a short bony infundi-
bulum formed by the alisphenoid.
Lagenorhynchus acutus (Text-fig. 20d and Pl. 39) differs very little in the distribu-
tion of air spaces from L. albivostris. A bony portion of the ventral lamina of the
pre-orbital extension of the pterygoid persists, in this resembling the condition
found in individual specimens of Pseudorca crassidens. The ventral extent of the
palatine is even more restricted than in L. albirostris. The alisphenoid is more
attenuated, and presents a much thinner surface laterally than in L. albirostris,
indicating a greater lateral extension of the pterygoid sac. There is no apparent
trace of a bony lateral lamina (Text-fig. 20d’). The bony infundibulum associated
with the 5th nerve branch is much larger than in L. albivostvis and almost touches the
falciform process.
In L. obscurus (Text-fig. 20¢e and Pl. 40) the post-orbital lobe of the sinus projects
anteriorly to a greater extent than in either of the two previously mentioned species
and probably unites with the anterior lobe. The bony ridge on the ventral surface
of the orbital process of the frontal is a very narrow crest. The pre-orbital lobe also
shows an anterior extension under the ventral surface of the rostrum.
A small bony fragment of the superior lamina remains under the optic infundi-
bulum. The lateral aspect of the alisphenoid (in the post-temporal fossa) is more
extensive than in L. acutus but less than in L. albivostris.
100 HEARING IN CETACEANS
The osseous lateral lamina of the pterygoid is wanting, as in L. acutus, and the
alisphenoidal infundibulum of the 5th nerve is much shorter than in either of the
previous species (Text-fig. 20e’).
The three species of Lagenorhynchus show a progressive development of a mesial
excavation of the frontal by the post-orbital pterygoid lobe (not shown in figures).
The excavation is present in L. albivostris as an ill-defined shallow depression lateral
to the orbito-sphenoid. It is deeper and better defined in L. acutus and attains
its maximum development in L. obscuvus in which its mesial extremity is dorsal
to the orbito-sphenoid.
In the genus Grampus (Text-figs. 21a and 25 and Pls. 41 and 42) the post-orbital
and pre-orbital lobes are very much expanded laterally, the anterior sac of the
pre-orbital lobe projecting onto the ventral surface of the rostrum.
The post-orbital lobe has a considerable extension posteriorly under the ventral
surface of the frontal. The two lobes are in close apposition above the optic infundi-
bulum and appear in some instances to coalesce. The alisphenoid is completely
covered by the pterygoid sac and its lateral aspect in the post-temporal fossa is
very much reduced. Two posteriorly projecting lobes of the sac in the sphenoidal
region surround the 5th nerve branch exit in addition to the anteriorly projecting
lobe of the peribullary sinus (Text-fig. 21a’).
The palatines (PAL) may or may not be overridden by the pterygoids (PT), in some
specimens each palatine is divided by the forward extension of the pterygoid whilst
in others a continuous band of palatine lies anterior to the pterygoid.
In the orbito-sphenoidal region part of the osseous content of the superior lamina
of the pterygoid remains, but at the level of the foramen ovale no part. The ptery-
goid hamuli are widely excavated and dilated (Text-fig. 21a’).
In Tursiops (Text-fig. 21b and Pl. 43 and 44) the pre-orbital and post-orbital
lobes are merged above the optic infundibulum ; if any separation of the two exists
it must be very thin and membranous. The pre-orbital lobe is extended below the
maxilla as a well-defined anterior sinus. As in Grampus two posteriorly projecting
extensions of the sphenoidal portion of the pterygoid sac surround the exit of the 5th
nerve branch. Laterally in the same region the whole of the alisphenoid is covered
by the sac, the lateral edge of which projects beyond the lateral limit of the bone.
The dorsal lamina in the sphenoidal region (Text-fig. 21b’) has no osseous content
but in the orbito-sphenoidal region a very small remnant persists. The hamuli
are fully excavated but the lateral and mesial laminae are in close proximity.
Stenella (Text-fig. 21c and Pl. 45) closely resembles Tursiops in the general distri-
bution of the air sac system. The pre-orbital and post-orbital lobes have a dorsal
development resulting in the formation of a narrow ridge on the ventral aspect of
the frontal (cf. Lagenorhynchus obscurus, see above. The pterygoid hamuli (Text-
fig. 2c’) are rather more dilated than in Tursiops.
Delphinus in its turn is closely similar to Stenella except that the anterior sac
extends very much further anteriorly below the maxilla (Text-figs. 21d, d’ and Pls.
46 and 47). The pterygoid hamuli are less dilated than those of Stenedla.
The air sinus systems of the Delphininae dissociated from the bones of the skull
are shown in Text-fig. 25 a—f.
rien Ae ce ee
HEARING IN CETACEANS
d /
Fic. 21. Schematic diagrams showing invasion, distention and resorption of the
pterygoid bone by the pterygoid sinus in a (longitudinal section), a’ (transverse section),
Grampus ; b, b’ Tursiops ; c, c’ Stenella; d, d’ Delphinus.
IOI
102 HEARING IN CETACEANS
In Steno (Text-fig. 18a and Pl. 24) the pre-orbital and post-orbital lobes of the
pterygoid sac are well developed and apparently coalesce above the optic infundi-
bulum. As in Delphinus, Stenella and Lagenorhynchus obscurus, there is a conspicuous
dorsal development of the pre-orbital and post-orbital lobes, forming deep cavities
on the ventral surface of the maxilla and frontal bone which are separated by a
smooth, obliquely antero-laterally directed ridge. There is a conspicuous anterior
sinus. More posteriorly the sinus system is not so well developed. Thus a considerable
portion of the alisphenoid (ALS) remains uncovered and the peribullary sinus does
not project very far forward.
A considerable portion of the superior bony lamina of the pterygoid persists
(Text-fig. 18a’) and the 5th nerve branch is invested in a double, bony infundibulum
formed internally of alisphenoid (ALS) and externally of the superior lamina of the
pterygoid. The pterygoid hamuli are fully excavated but not dilated, and they
are in contact in the middle line.
The supra-orbital process of the frontal of Sousa (Text-fig. 186 and Pl. 25) is much
narrower antero-posteriorly than in Steno and correspondingly the excavation of
its ventral surface by the pre-orbital lobe is much smaller. The post-orbital lobe
is rather more developed and extends high up on the posterior face of the frontal (in
the temporal fossa), which is resorbed to the extent that the maxilla is exposed.
The lateral expansion of the pterygoid sac in the alisphenoidal region is only
moderate, so that a fair portion of the alisphenoid is exposed laterally. The peri-
bullary sinus does not extend far forward.
In the specimen examined (No. 1914.1.14.1) avery minute fragment of the osseous
lateral lamina remains in the alisphenoidal region but the dorsal lamina is not
represented osseously.
The mesial lamina of the pterygoid (Text-fig. 185’) has a deep concavity in its
lateral aspect. The hamuli are excavated but not widely dilated and are separated
widely in the middle line.
Text-fig. 23 e and f show the air sac system, dissociated from the skull bones, in
the Stenidae.
The chart shown in Text-fig. 26 shows a co-ordination of increasing specialization
of the sinus system with the orthodox idea of classification of the Cetacea. There are
however certain deviations from the conventional classification which will be dis-
cussed. The chart demonstrates a normal frequency distribution in the degree of
specialization. Thus the majority of forms have a moderately specialized sinus
development while the extremes at both ends are represented by fewer forms.
In terrestrial mammals, generally speaking, the pterygoid plate is a single laminar
bone, and it is noteworthy that amongst the few exceptions to this rule e.g. Myrmeco-
phaga, in which the pterygoid plate is excavated, the latter bone makes contact
with the tympanic bulla.
In the Mysticeti, Caperea and Balaena show approximately the same poorly deve-
loped pterygoid sinus. Eschrichtius and the balaenopterids are slightly more advanced.
The Ziphiidae sa a family show a remarkable uniformity in the development of
the sinus system, a development which, however, is not in the main trend of special-
ization—being almost wholly associated with the pterygoid hamuli.
HEARING IN CETACEANS
ga hh
a b €
Hdd
i
Fic. 22. Diagrams showing progressive distention in the horizontal plane of the air
sac system.
a, Caperea ; b, Balaena; c, Eschrichtius; d, Balaenoptera; e, Ziphius ; £, Monodon ;
g, Delphinapterus ; h, Kogia; i, Physeter.
104 HEARING IN CETACEANS
Fic. 23. Diagrams showing progressive distention in the horizontal plane of the air
sac system.
a, Platanista ; b, Lissodelphis ; c, Inia; d, Lipotes ; e, Steno; f, Sousa; g, Phocaena ;
h, Neomeris.
HEARING IN CETACEANS 105
;
qd 5
cC d
e f
Fic. 24. Diagrams showing progressive distention in the horizontal plane of the air
sac system.
a, Pseudorca; b, Orcinus; c, Orcaella; d, Globicephala; e, Fevresa; f, Cephalo-
rhynchus,
106 HEARING IN CETACEANS
Sg
d e
Fic. 25. Diagrams showing progressive distention in the horizontal plane of the air
sac system.
a, Lagenorhynchus albirostris; b, L. obscurus; c, Grampus; d, Tursiops; e,
Stenella ; {, Delphinus.
HEARING IN CETACEANS 107
In respect of the sinus system, the Monodontidae show a primitiveness which
justifies the position in which they have been placed in the chart. Slijper (1936),
for other reasons, distinguishes the Monodontidae by family ranking, but in respect
of the pterygoid sinus system the removal of the family from the Delphinoidea
and the creation of a separate super-family in which to include Monodon and
Delphinapterus seems justified.
The Physteridae in some respects resemble the Monodontidae, e.g. in the limited
enlargement of the pterygoid hamuli, but in other respects the former are consider-
ably more advanced, there being no trace of superior or lateral laminae.
The Platanistidae, as represented by the four extant genera Platanista, Stenodelphis,
Lipotes and Inia, cover nearly as wide a range of specialization of the sinus system
as encountered in the whole of the rest of the Odontoceti as a sub-order. In this
family Platanista itself is a mosaic of extremely primitive development and of a
specialization encountered nowhere else in the Cetacea. The apparent extension of
pneumatization to the maxillary crests is unique, and indeed, may be associated
with the under-developed state of the sinus system in the pterygoid region.
Slijper’s (1936) opinion about the primitiveness of Sousa and Steno presents
a problem so far as air sinus development is concerned. In this they show a combina-
tion of primitive and highly specialized features. Thus in the sphenoidal region the
development is poor and can be associated with the relatively large size of the temporal
muscles. In'the pre-orbital region there is evidence of the development having reached
a stage comparable with that of Tursiops. In the chart they have accordingly
been placed after the Platanistidae and before any of the remaining Delphinoidea.
The distinctness of the Phocaenidae, recognized in Slijper’s classification, is sup-
ported in the sinus development by the presence, characteristic of this family,
of an extension of the pre-orbital lobe into a vacuity between the maxillary and the
frontal; also in the unusual formation of the sphenoidal part of the sinus. For the
rest they are rather more advanced than some of the Delphinidae, notably Pseudorca.
In the Orcinae, Pseudorca, Orcinus and Orcaella fall into a natural sequence of
specialization. So far as Pseudorca itself is concerned it is found that considerable
individual variation occurs; thus there are some individuals with a more or less
complete bony sheath covering the sinus system, whereas in others all trace of the
lateral portions of this sheath has disappeared. In Orcaella, an incipient extension
of the pre-orbital lobe between the frontal and maxillary is reminiscent of the develop-
ment in this region, just mentioned as occurring in the Phocaenidae. Globicephala
and Feresa show a general similarity to Orcinus, but the development of the pre-
and post-orbital lobes is much greater, and in this respect Feresa is more advanced
than Globicephala.
Skull features other than those related to the sinus system would point to Lisso-
delphis being comparatively unspecialized and to be placed in the neighbourhood
of the Stenidae. The cranium is low, the backward extension of the pre-maxillae
round the nares is limited, so that in this region the maxillae are exposed. The
pre-maxillae are of equal length, those of the more advanced delphinids being further
extended on the right side than on the left. The maxillae in the neighbourhood of
the nares are covered by the mesial margins of the pre-maxillae. On the other hand,
108 HEARING IN CETACEANS
the reduced size of the post-temporal fossa and the teeth, which are hardly distin-
guishable from those of Delphinus, indicate a contrasting specialization.
In the sinus system also there is a mosaic of primitive and specialized features.
Thus there is little lateral expansion of the system in the sphenoidal region and
the paroccipital processes are incompletely excavated. There is no extension of
> post-orbital lobe under the post-orbital process of the frontal. Anteriorly however,
sre is evidence of coalescence of the pre- and post-orbital lobes and a well marked
auterior sinus, which is correlated with almost complete disappearance of the bony
superior lamina of the pterygoid in this region.
A general assessment of the specialization of Lissodelphis borealis with regard to
the sinus system particularly, but considering also other features of the skull, seems
to justify the erection of the sub-family Lissodelphinae, with affinities with the more
specialized genera of the Orcinae on the one hand, and the Cephalorhynchinae
on the other.
In the genus Cephalorhynchus the chief advance in development is in the pre-
and post-orbital lobes which are moderately approximated to each other. In addition,
the post-orbital lobe has a narrow diverticulum which passes dorso-posteriorly
under the post-orbital process of the frontal.
In the remaining genera, included in the Delphininae, there is a gradual augmenta-
tion of the sinus development. Within the genus Lagenorhynchus, L. albirostris
still shows a partial bony lamina while L. obscwrus in the close approximation of
the pre- and post-orbital lobes resembles Stenella. The air sinus development in
Grampus closely resembles that of Tursiops, and in general there appears to be
justification for including it with the Delphininae rather than, as some authors
have done, associating it with the Orcinae. Twursiops, Stenella and Delphinus show
a progressive development of the anterior sinus which reaches its extreme extension
in the last named genus.
The chart thus shows that in the evolutionary development of the sinus system
there is an over-all sub-ordinal trend towards greater specialization, but also within
the lower ranks of the hierarchy similar trends can be distinguished, even to the
specific level in Lagenorhynchus.
FUNCTION
The mode of hearing of whales has for long been a subject of controversy among
cetologists. Apart from those who maintained that cetaceans are unable to hear
water-F..ne sounds, the most generally accepted hypothesis has been that these
animals hear by bone conduction, that is by the perception of vibrations through
the skull directly to the cochlea. It is proposed to show that this method of hearing
is not only undesirable but also that it is impossible in normal circumstances in the
cetaceans.
EXTERNAL AUDITORY MEATUS
In order to substantiate statements which will be made later about the function
of the external and middle portions of the ear, it is necessary to review certain features
of their anatomy.
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HEARING IN CETACEANS 109
Several descriptions exist of the structure and course of the external auditory
meatus in the Cetacea. The absence of an external pinna was noted by some of the
earliest writers ; Rondelet (1554) appears to have been the first to notice the external
aperture of the ear. In the smaller odontocetes it is less than a millimetre in diameter
and can only be detected by careful examination of the region behind the eye.
The aperture in the larger, baleen whales is lenticular in shape, usually concealed
in a groove and measures about 1 cm in its larger diameter.
Fic. 27. Diagram of a dissection of the ear of Globicephala melaena
(cf. Plate 49). Ventral view, left side.
The course of the meatus in Globicephala melaena from the surface of the body
to the external aspect of the tympanic membrane is shown in Text-fig. 27. The tube
(EAM) passes inwards more or less horizontally for about 2-5 cm, then dorsally and
caudally in a sharp bend which occupies another 2:5 cm, rounding again to its
original direction to its termination at the tympanic membrane. The mean axis
of the meatus is at right angles to the long axis of the body.
According to Lillie (1915), in Megaptera novaeangliae, from the external orifice “a
tube about 1/Io in. in diameter traversed the blubber which was about 33 in. thick
in this region. The tube was continued through the underlying tissue for about
2 in. and gradually decreased in diameter until it ended blindly. The meatus was
110 HEARING IN CETACEANS
closed up for about 3 in. of its course It widened out again to a diameter of rather
more than an inch and maintained a more or less uniform size for the remainder of
its passage to the tympanic bulla. The total length of the canal was about 1 ft. 9 in.
in a humpback whale 40 ft. in length. The walls of the wide innermost portion were
invariably pressed together.’’ Lillie pointed out that Burfeld & Hamilton noticed
that in several of the Balaenoptera examined by them the meatus was closed up
for part of its course. This was further confirmed by the present writers during the
GE
Fic. 28. Diagram of a dissection of the ear of a juvenile Balaenoptera acutorostrata
(cf. Plate 50). Ventral view, left side.
dissection of a Fin Whale, Balaenoptera physalus, the closed portion of the meatus
being partially invested in cartilage (see Pl. 51).
Carte & MacAllister (1867) reported that in B. acutorostvata the meatus was open.
In the foetal specimen of B. acutorostrata dissected in this museum (Text-fig. 28)
the meatus (EAM) appeared to be closed about ? in. from the external aperture but a
section through the apparently closed portion (see Purves 1955) shows that a minute
perforation exists.
In a foetal specimen of Megaptera sectioned and kindly lent by Professor D. V.
Davies, St. Thomas’ Hospital Medical School, it was noted that the external open
_ portion was very shallow (PI. 48a), perhaps because of the absence of a thick blubber
Cen ee
HEARING IN CETACEANS Ill
layer. Internal to this opening was a closed portion (PI. 48) followed in its turn by
an open tube, which soon became occluded for a short distance before opening out
again in the innermost portion ending in the tympanic membrane (TM) (Pl. 48c).
In the Sperm Whale, Clarke (1948) describes the external auditory meatus as
commencing as “‘a short blind sac which penetrates from the auditory aperture
for a distance no deeper than the blubber thickness. The sac has somewhat thickened
unpigmented walls. ... Internally these walls are thrown into transverse
folds. ... Dissection reveals that the proximal portion running in the temporal
bone is still intact. Also in two physically immature adults the external meatus
after termination of its cavity was prolonged into a short solid stick representing
the canal after obliteration of its lumen.’’ Yamada (1953) also notes the presence
of a solid cord beneath the blubber layer and could not demonstrate any lumen in
it. In a specimen examined by the present writers, the apparently solid cord con-
tained a number of small, spherical cavities lined by pigmented epidermis separated
by short intervals in which no lumen could be detected.
More or less detailed descriptions of the structure of the meatus have been given
by such writers as Carte & MacAlister (1868), Buchanan (1828), Hanke (1914),
Yamada (1953) and Ryseenbach de Haan (1957). In general it appears that, as
described by Carte & MacAlister, there are three layers forming the wall of the
meatus. Lining the tube is an involution of the cuticle, this is usually pigmented,
and in the specimen of G. melaena dissected (Text-fig. 27) it is of a dense black colour
throughout its length. The cuticle is enveloped by a thick, rigid, fibrous, middle
layer and external to this again a fibro-cellular layer, in which, according to Carte &
MacAlister, a thin stratum of circular constrictor muscle is present.
Elastic fibro-cartilaginous masses are associated with the wall of the meatus in
all those odontocetes which have been examined. In the mysticetes, Hanke (1914)
says that the cartilage is absent but Carte & MacAlister (1868) and Boas (1912)
have described, and the latter has figured, a cartilaginous mass associated with the
meatus of B. acutorostrata. It has also been found in a recently dissected specimen
of Fin Whale (see p. 135 and Pl. 51). It is suggested by the present writers that
Buchanan’s (1828) “‘ globular substance ’’ in Balaena mysticetus may in fact be the
ear cartilage. In the Odontoceti the cartilage is more extensive than in the Mysticeti
(B. acutorostrata). Its position and shape in Phocaena phocoena and Lagenorhynchus
acutus are figured by Boas in his pls. 12 and 25.
The cartilage is also evident in the specimen of G. melaena dissected in this Museum
(Text-fig.27, ac). It occupies much the same position as that figured for Ph. phocoena.
The more reduced condition of the cartilage in B. acutorostrata is indicated in Boas’
figure.
Boenninghaus (1903) compared the ear cartilages in the Odontoceti with those of
seals, and came to the conclusion that the former showed a further stage in the process
of retraction of the pinna to that exhibited in seals, in which the pinna is withdrawn
inside the meatus prior to submergence. Boenninghaus argued that the absence of
external pinna in the cetaceans was correlated with their purely aquatic mode of
life. Boas’ paper on the ear cartilages of mammals (1912) supports this point of
view.
112 HEARING IN CETACEANS
Vestigial outer ear muscles have been described by Boenninghaus (1903) (see
Pl. 1, fig. D), Beauregard (1894) and Hanke (1914), the last discussing their homologies
in detail and producing a comparative table of his own and other workers’ conclusions.
Hanke (p. 303) cites the presence of sweat glands in the meatus of the baleen whales
and suggests, from the absence of sebaceous glands, that the plug in contact with
the “ glove finger ’’ of the tympanum is not a true ear wax but a secretion similar
to this. However it is generally accepted that the glands producing ear wax in
man are modified sweat glands and there appears to be no reason why this should
not apply to the Cetacea also. Carte & MacAlister described “‘ a very distinct series
of ceruminous glands the orifices of whose ducts were visible in the lining membrane’’.
A characteristic feature of the external meatus of the rorquals and the Humpback
is the elongated plug of wax and desquamated epithelium which caps the “ glove-
finger ’’ extension of the tympanic cavity. Typically this is an elongated, roughly
conical mass, brownish in colour, scored longitudinally by numerous shallow grooves
and flattened dorso-ventrally throughout its length. It fills the meatal cavity mesial
to its blind portion. The base of the cone is occupied by a rounded, conical concavity
which fits onto the distal end of the “‘ glove-finger ’’. The homologies of the ‘‘ wax-
plug’ are indicated by Purves (1955).
Buchanan’s (1828) description of the meatus in the Greenland Right Whale
(Balaena mysticetus) indicates that in this species the lumen is continuous throughout
its course. Buchanan’s particular interest was in the ceruminous secretion of the
ear and he describes it as being of a greyish-blue colour and in no great quantity.
The evidence from the Delphinidae is that the lumen of the meatus is continuously
open from the exterior to the tympanic membrane. From this it may be assumed
that the presence of the ear-plug in the rorquals and Humpback is a direct result
of the closure of the meatus along part of its length. The absence of an ear-plug
in the Sperm Whale has yet to be confirmed.
”
TYMPANIC MEMBRANE
Hunter (1787) gives a brief description of the tympanic membranes of Toothed
and Baleen Whales, and Buchanan (1828) describes the membrane of Balaena mysti-
cetus and Monodon monoceros. Of more recent descriptions of this structure in
odontocetes, those of Beauregard (1894) and Boenninghaus (1903) coincide in a
general way with the condition found in the specimen of Globicephala melaena
examined by the present writers (Text-fig. 27, TL and PI. 49).
The general shape of the Narwhal tympanic membrane was described by Buchanan
as comparable with a convolvulus flower in having an oval, concave, exterior surface
and, within the tympanum, a core tapering to a very attenuated attachment on
the malleus. The condition in the recently examined Globicephala melaena is more
in agreement with Boenninghaus’ description of what he found in Phocaena phocoena.
Thus the external aspect of the tympanic membrane is more shallowly concave
than funnel-shaped. Hyrtl’s (1845) description of the tympanic membrane of the
Narwhal disagrees with Buchanan’s. In this species, as in the Bottlenosed Dolphin,
- he describes the membrane as presenting externally not a single, but a double con-
HEARING IN CETACEANS 113
cavity in the form of two pits separated by the rectilinear base or origin of the exten-
sion of the tympanic membrane to the malleus. In the recently examined Glob1-
cephala neither trace of the rectilinear base of Hyrtl, nor of the linear depression
described by Beauregard, could be detected. In G. melaena the internal extension of
the tympanic membrane to the malleus is not centrally placed in relation to the
external concavity, but displaced towards the posterior margin of the tympanic
annulus, so that anterior to the extension there is an incipient depression on the
internal face. This condition corresponds to that in the Common Porpoise described
and figured by Boenninghaus. The internally extending “ fleshy process ’”’ of the
tympanic membrane is flattened, triangular and elongated, its apex being attached
to the malleus (Text-fig. 27, MA). The flattening is obliquely antero-posterior so that
the ventral margin of the process is slightly in advance of the dorsal.
The meatal aspect of the ““‘ membrane ”’ is covered by a densely black epithelium
continuous with that of the external auditory meatus. In the specimen dissected,
the coarse, fibrous structure of the extension to the malleus can easily be seen with
the naked eye (PI. 47). The bundles of fibres spring from a very narrow attachment
on the small tubercle of the malleus, and diverge in straight lines in their course to
the tympanic annulus. On the anterior aspect these fibres extend almost to the same
extent as do those on the posterior aspect. As the fleshy process is not centrally
placed, there is an interval between the outward termination of the fibres and the
anterior margin of the tympanic annulus which is closed by the mucous membrane of
the tympanum internally, and by the epithelium of the external meatus externally.
Boenninghaus found that in Phocaena phocoena the drum membrane had irregular
areas of fibreless tissue, anteriorly between which the fibres continued to bony prongs
on the annulus. In G. melaena the separation of the fibres from the anterior margin
of the annulus is more complete so that a much larger fibreless region is present,
reminiscent of the pars flaccida of the human tympanic membrane.
Boenninghaus saw both radial and circular fibres and made the significant
statement “‘all the radial fibres continued into the spur and the latter owes its
solidarity to their thickness and stiffness. The circular filaments proceed fairly
high up the spur. AU in all the spur is nothing less than the extended centre of the
drum.”
As with the Odontoceti, so with the Mysticeti, the characteristic tympanic membrane
has attracted the attention of such workers as Hunter (1787), Carte & MacAlister
(1868), Beauregard (1894), Hanke (1914), Lillie (1915) and Kernan (in Schulte
Ig16) who concentrated on the rorquals. Home (1812) and Buchanan (1828)
described the tympanic membrane of the Greenland Right Whale.
Lillie employs the similarity of the membrane to a glove finger when describing it.
In his specimen the walls of the sac were 1/Io in. in thickness and consisted chiefly
of white fibres and yellow elastic tissue. There was no evidence of nerve cells, nerve
fibres or muscle fibres in the tissue. ‘‘ From the upper surface of the sac, in the median
line, a ligament about an inch long and 5 mm in diameter projects towards the tym-
panic cavity. The ligament is continued along the sac in the opposite direction as
a ridge. ... The mouth of the sac opens into the tympanic cavity while the
outer portion projects into the external auditory meatus. The ligamentous process
ZOOL. 7, I. 8
114 HEARING IN CETACEANS
passes under the junction of the malleus and incus and becomes attached at its
proximal end to the very much reduced manubrium of the malleus.”’
A re-description of the tympanic membrane in the light of the evidence furnished
by a recently dissected Balaenoptera acutorostrata specimen (Text-fig. 28 and PI. 50),
and a re-examination and further description of Lillie’s specimen of Megaptera
novaeangliae is required. Fundamentally the tympanic membranes in these two
specimens are similar.
From its attachment on the manubrium of the malleus (ma) the ligament (TL)
extends in the direction of the external meatus (EAM) as a broad band which
widens perceptibly as it proceeds outwards. The posterior half of the band is
much stouter than the anterior, and it is the posterior portion which continues into
the glove finger for about one third of the latter’s length. None of the fibres
of the posterior portion of the ligament is attached to the tympanic annulus ; a
deep, tapering concavity penetrates into its fibres from its outer, meatal surface.
The tympanic membrane as a whole is thus composed of two distinct parts, (I) a
fibrous portion with an external concavity and (2) a non-fibrous portion which
projects into the external auditory meatus. The fibrous portion is exactly similar
to, and comparable with, the so-called triangular ligament found in the Odontoceti,
while the glove finger represents a greatly enlarged development of the fibreless
region mentioned above in the descriptions of Globicephala and Phocaena, and repre-
sents a further dissociation of the fibrous portion of the tympanic membrane from
the tympanic annulus.
Beauregard (1894) homologizes the glove finger with one of the accessory air
sacs—the sac moyen. This is referred to on page 10 supra.
The description and figures of Home (1812) and Buchanan (1828) of the tympanic
membrane of the Balaenidae, as exemplified by B. mysticetus, make possible a close
comparison with this region in the Balaenopteridae. Thus the hemispherical exten-
sion into the external meatus can be identified with the glove-finger, and the so-
called valvular process of Buchanan corresponds with the fibrous portion found in
the balaenopterids. From Home’s figure it would appear that the fibrous portion
has a more extensive attachment to the tympanic annulus than exists in the balaen-
opterids; this characteristic, together with the broad triangular shape of the fibrous
portion of the membrane extending to the malleus, is related to the more limited
extension of the glove finger into the external auditory meatus. The general con-
struction of the tympanic membrane in the Balaenidae is intermediate between
that of the Odontoceti and the Balaenopteridee. Incidentally, with reference to
the membrane of B. muysticetus, Knox (1859) corrected the erroneous impression
of Buchanan that it was muscular.
Ridewood’s (1922) description of the skulls of foetal Humpbacks and rorquals
includes accounts of the developmental appearance of the tympanic membrane.
He discusses comprehensively the interpretations of earlier workers, including
particularly those of Hanke, Beauregard & Lillie. His references briefly summarized
are as follows. In a 6-in. foetus of Megaptera the tympanic membrane is still flat
and horizontal in position, forming part of the roof of the inner end of the external
- auditory meatus. He states that the membrane is supported on three sides, anterior,
HEARING IN CETACEANS 115
mesial and posterior, by the tympanic annulus and that its outer edge passes into
a mass of fibrous tissue attached to the lower edge of the squamosal bone. He
draws attention to a pale streak on the area referred to by him as the tympanic
membrane (his fig. 4, p. 223), and states that it marks a tract of fibrous tissue “‘ to
the mesial end of which the extremity of the manubrium mallei is attached, it is
this fibrous tissue that develops later into the long conical ligament of the adult
tympanic membrane’’. Further on in this paper (p. 244) Ridewood states that
“there seems to be no question that the thimble-shaped membrane of the 27-in.
foetus, and presumably the glove-finger membrane of the adult whale, represents
the whole of the tympanic membrane.” This view is not held by Beauregard, Hanke
or the present writers.
Considering first the boundaries of the tympanic membrane as mentioned above,
the sagittal sections of Prof. Davies’ 6-in. Humpback foetus indicate that Ridewood
set too wide a limit to the extent of the membrane. The tympanic membrane
occupies less than a half of the area within the tympanic annulus, in a position
corresponding to the pale streak to which Ridewood refers. The relation of the
tympanic membrane (TM) both to the external meatus (EAM) and to the manu-
brium mallei (MM) are clearly shown in the section (PI. 48c). The external face of
the membrane forms a deeply concave, conical depression on the roof of the external
auditory meatus and is comparable in shape with the tympanic membrane of the
adult odontocete.
Ridewood’s interpretation of the glove-finger of the adult as the whole of the
tympanic membrane is at variance with the present writers’ conclusions. As already
stated the tympanic membrane is represented by the fibrous ligament and the glove
finger and not by the glove finger alone. In this connection it may be pointed out
that, in the 6-in. foetus (Davies’ specimen), while the tympanic membrane is still
horizontal in position, it is already divisible into two parts. Firstly, the portion already
described and shown in Pl. 48c, and, secondly, Pl. 48d shows that the external
meatus continues beyond the limit of the manubrium mallei and is roofed over by
a portion of the tympanic membrane which is flat, and apparently lacking distinct
fibrous structure. It is from this portion that the present writers believe that the
glove finger is developed.
MIDDLE EAR
As in the Mammalia generally, the chain of auditory ossicles is composed of three
elements. Numerous descriptions exist of their form in the Cetacea (Camper, Hyrtl,
Beauregard, Carte & MacAlister, Boenninghaus, Yamada, Reysenbach de Haan).
It is therefore not proposed here to give a detailed description but to refer to those
aspects of their construction which do not appear to have been mentioned previously.
A general impression of their shape and arrangement is shown in Text-figs. 27-29.
The fusion of the processus gracilis of the malleus (pc) with the tympanic bulla
(TB) is frequently considered to be peculiar to cetaceans but, according to Boen-
ninghaus this condition is fairly common in other mammals. He says “‘ it is always
fused (to the tympanic ring) at the Glasserian fissure in the newly born human.
In man however, and in many (other) mammals, the fusion later dissolves and the
116 HEARING IN CETACEANS
connection disappears. In other beasts the connection continues throughout life.
Hyrtl includes monkeys, carnivores and insectivores and, mistakenly, man. I had
the opportunity to examine these connections in the lion and hedgehog and it really
is a bony growth.’’ Boenninghaus goes on to contrast the stoutness of the processus
gracilis of the malleus in whales with its slenderness in other mammals, but it should
Fic. 29. Right tympanic annulus and auditory ossicles of a Humpback Whale,
Megaptera novaeangliae. The dotted line indicates the long axis of the tympanic
ligament.
be pointed out that in the Cetacea generally, while the process is indeed stout in
forms such as the rorquals and Humpback it is of much more slender construction
in the Right Whales. Again, in the odontocetes, while the attachment of the pro-
cess to the tympanic ring is elongated its thickness is very greatly reduced. The
attachment in Phocaena phocoena is so attenuated that, with the exception of
- Boenninghaus, authors have described it as being unfused.
HEARING IN CETACEANS 117
MALLEUS
(a) Anterior process. For the later consideration of the functioning of the malleus,
it is necessary to describe, in some detail, aspects of its structure not previously
emphasized. Starting with the processus gracilis (PG) it will be seen from the figure of
its anterior aspect (Text-fig. 29), that it is closely associated with the sigmoid process
(sp) of the tympanic bulla (TB) which forms a buttress attached to about four fifths
of its lateral border. The mesial border of the process is free from any attachment
throughout its length. Between these two borders, which are thickened, is a roughly
rectangular area of much thinner bone, the borders and the thinner portion forming
what may be described as a channel girder. In posterior view the process forms the
convexity of the girder, and it will be seen from Text-fig. 29 that this surface is
fused to the sigmoid process at a deeply grooved, arcuate junction extending from
the meso-ventral to the dorso-lateral edge of the process. Examination of the junction
in strong light shows that the dorso-lateral part of it is translucent, the bone in the
region being extremely thin, even in the adult rorqual. In general construction the
odontocete processus gracilis is essentially similar to that just described for the
rorqual except that the concavity of the “‘ girder ’’ is not so emphasized.
(b) Manubrium. Unlike the typical, handle-shaped manubrium of most mammals,
including man, that of cetaceans is short, stout and roughly conical (Mysticeti) (Text-
fig. 29) or globular (Odontoceti) in form (Pl. 49). Its mass is comparable with that
of the head of the malleus. At the lateral end of the inferior surface in the Mysticeti,
asmall promontory is identified as the short process (processus brevis). In the Odonto-
ceti a small pointed process, directed towards the head, and situated about midway
along the length of the lower surface of the manubrium, has been identified by
Hyrtl as the short process. In the Mysticeti the attachment of the tympanic membrane
to the malleus extends to the whole length of the posterior face of the manubrium,
whereas in the Odontoceti this attachment is restricted to the short process. On
the proximal edge of the anterior aspect of the manubrium a small tubercle forms
the point of attachment of the tensor tympani muscle (Text-figs. 27 and 28 TT).
(c) Head of the malleus. The massive head of the malleus (Text-fig. 29) is deeply
marked by two large facets making a re-entrant angle on its posterior aspect.
Both these facets have smoothly convex surfaces covered with articular cartilage,
which, with corresponding facets on the incus, form part of a synovial joint. The
radii of the convexities, as well as that of the arcuate junction between the two
facets, lie approximately at right angles to the long axis of the tympanic ligament
(see Text-fig. 34d).
Incus. In general shape the incus (1) is in the form of a short, wide-based cone,
the apex of which is curved upwards to end in the facet which articulates with a
corresponding facet in the stapes (Text-fig. 29). The base of the cone forms the larger
of two facets which articulate with the malleus. The smaller facet is approximately
at right angles to the larger on the ventral aspect of the ossicle. For articulation
with the malleus, both facets are shallowly concave and their line of junction is also
concave. Like the facets of the malleus these also are furnished with articular
cartilage. The short process is a short, conical projection directed anteriorly in line
118 HEARING IN CETACEANS
with the lateral margin of the processus gracilis of the malleus. The facet for
articulation with the stapes is an oval, the long axis of which is parallel to the
larger incudo-malleolar facet.
StapPEs. The stapes (s) is less obviously stirrup-shaped than in most other mam-
mals and although in the rorqual an intercrural foramen exists, this is not so in all
cetaceans. There is no well-defined neck separating the head from the crura and
the foot is oval in shape, with a smooth, flanged edge moulded to fit precisely into
the fenestra ovalis (FEO). Contrary to what has been stated by many authors the
present writers have been unable to find any evidence that the stapes is ankylosed
to the fenestra ovalis. It is believed that the impression of fusion is due to the
perfect fit of the foot of the stapes in the fenestra ovalis.
MUSCLES OF THE MippLe Ear. As Hunter (1787) pointed out, the cetacean
tympanum, like that of other mammals, contains two muscles, the tensor tympani
and the stapedius (Text-figs. 26 and 27, Tr and sm).
In the Odontoceti (Globicephala melaena) (Text-fig. 27) the tensor tympani (TT)
arises from the dorsal wall of the tympanic cavity near that part which transmits
the Eustachian tube. It is attached in a small depression at the tip of the manubrium
mallei. Although it is directed approximately in line with the long axis of the
tympanic ligament (TL) as viewed ventrally, the two attachments are displaced
from each other by about 2 mm when viewed in the lateral aspect. The muscle is
intimately associated with the cavernous body (cc) of the tympanic bulla to the
extent that Beauregard (1894) regarded the muscle as the attachment of the cavernous
body of the malleus.
The stapedial muscle is in the normal position.
The evidence produced by Boenninghaus (1903) and Kolmer (1907), among others
who examined the inner ear of cetaceans, is to the effect that the essential organ
of hearing, i.e. the cochlea, is comparable in general structure with that of terrestrial
mammals. Indeed the essential organ of hearing in certain respects gives indications
of being sensitive to a much wider range of frequencies than that of most mammals.
THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCE
THE HypRODYNAMIC FUNCTION OF THE AIR SACS
It has often been asserted that the function of the auditory ossicles is concerned
with the matching of the incoming air vibrations with those of the fluid vibrations
of the cochlea, and it is on this basis that it has been maintained that there is no
necessity for an ossicular system in the Cetacea. The fact is that the Cetacea have
a functional chain of ossicles and that the stapes is movable in the oval window.
The fenestra rotunda is also functional. This implies that some kind of molar, as
distinct from molecular, disturbance of the cochlear fluid is required to produce
the sensation of hearing. This again points to the maintenance of an air space in
the middle ear. The question of the manner in which this air space persists in spite
of the enormous variations in pressure to which it is subjected is directly related
to one of the functions of the pterygoid sinuses. Amongst other functions, which
~ will be enumerated later, is that concerned with the regulation of pressure on either
HEARING IN CETACEANS 119
side of the “ear drum’’. In the Cetacea (see above p. 113) the pars flaccida is
modified and sometimes greatly enlarged, and the pars tensa drawn out in the form
of a ligament, the tension on which appears to be maintained by the internal pressure
on the pars flaccida and by the operation of the muscle described on p. 135. In
mammals, the pressure in the middle ear cavity is adjusted according to immediate
necessities, by increments of air from the respiratory tract, by way of the Eustachian
tube. In the Cetacea the only opportunities for effecting an adjustment by this
method are when the animal surfaces for breath. It seems likely that the pterygoid
air sinuses form a reservoir for this process of pressure regulation, and that the maxi-
mum depth to which the animal can dive is in relation to the ultimate compressi-
bility of the air sacs and the size of the tympanic cavity.
It has been stated above (p. 30) that the sinuses and tympanic cavity are filled
with a foamed, oil-mucus emulsion so that the compressibility of the air sacs ulti-
mately depends on that of the foam and the rigidity of the surrounding tissues.
The question naturally arises about the persistence of the gas in the foam cavities
and the maintenance of acoustic isolation (see p. 121) under great pressures. Experi-
ments were made on the relation to pressure of gelatinous, albuminous and deter-
gent foams. The foam to be investigated was placed in a pressure-tight, optical cell
and observed by transmitted light through a vertically mounted, low power micro-
scope with micrometer eyepiece. Pressure was applied by pumping B.P. liquid
paraffin into the cell (in direct contact with the foam) and was measured on a
Bourdon gauge. As pressure increased above atmospheric, the gelatinous foam bulk
volume decreased considerably and the foam structure was replaced by a system
of spherical air bubbles dispersed in liquid. These bubbles were a few microns
in diameter and separated by distances of comparable magnitude. The system
was stable at higher pressures, and the bubbles had not disappeared after 20 minutes
at 100 atmospheres. On release of pressure to one atmosphere the foam structure
reappeared. Using egg albumen, the foam structure was again replaced by air
bubbles, dispersed in a continuous liquid phase, which persisted at 100 atmospheres.
The bubbles were of less regular size and shape than in gelatin. Using the detergent,
the foam structure collapsed under pressure and no bubbles were visible at higher
pressures.
From the results of the experiments just described, and assuming that the naturally-
occurring foam behaves in a similar manner to that of gelatinous and albuminous
foams, it may be deduced that, even at the greatest depth to which cetaceans normally
dive, air bubbles would persist and there would be a sound reflecting system surround-
ing the essential organ of hearing. Some of the smaller cetaceans are capable of
undergoing very rapid changes of depth and are also dependent upon a very acute
sense of directional hearing. The rate of change of bulk volume of the foam would
be important because of the variation in pressure involved in such rapid changes
of depth. Acoustic efficiency must ultimately depend on the maintenance of fairly
constant conditions of sound reflection and absorption round the essential organ
of hearing.
The air sacs themselves are so extensive that their contraction would cause
disruption of the adjacent musculature were it not for the intervention of some
120 HEARING IN CETACEANS
space-filling mechanism. It seems that the fibro-venous plexus which surrounds the
sacs is ideally suited for this purpose, because there would be reciprocal filling of the
plexus with reduction in the volume of the sinuses. A conventional venous plexus
might be expected to be turgid at normal atmospheric pressure, but the pterygoid
plexus of the cetacean is strongly adpressed between two sheaths of tough, fibrous
tissue which, as previously stated, has been derived from the periosteum of the
de-ossified pterygoid laminae. It is reasonable to suggest that the venous blood
pressure, which is assumed to be zero at atmospheric pressure, must attain a value
of at least two or three atmospheres before any swelling of the vessels could take
place. There is also evidence to show that there is positive pressure in the pterygoid
sinus under normal surface conditions if the squirting of foam from the newly cut
sinus can be so interpreted. These factors suggest that the pterygoid cavities have
an initial rigidity, and therefore a reserve capacity for withstanding hydrostatic
pressure before appreciable diminution of the air cavity takes place.
If it is accepted that an air space is maintained in the middle ear cavity, it might
be assumed that there would be a safe limit to the depth to which the cetacean
can dive, after which fracture of the bulla would occur. The infrequency with which
fractured bullae have been observed (Fraser & Purves 1953), suggests that there is
a mechanism for overcoming this eventuality. As previously stated, Beauregard
recognized the corpus cavernosus tympanicus as erectile tissue, but Bonninghaus
and also the present authors have been unable to inject this body by manual pressure.
It will be recalled that the lumen of the internal carotid in this body is extremely
narrow and was thought by various anatomists to be degenerate. It is clear,
however, that under the hydrostatic pressures available, the corpus could be erected
by way of the internal carotid, in which eventuality it would occupy the tympanic
cavity sufficiently to prevent fracture.
Unlike the lining of the air sacs, the tympanic cavity proper is lacking in the net-
work of crypts and mucous ducts which are normally present in the lining of the
air sacs, and mucous glands, if present at all, are poorly developed It seems highly
probable that the foam in the sinuses is produced by secretions of the glands in
association with the gaseous content of the air sinuses. In these circumstances, the
air sinuses could be filled with foam leaving a foam-free cavity in the tympanic
bulla. This foam-free cavity would diminish in volume with hydrostatic pressure
and would, in extreme conditions, only occupy the vicinity of the auditory ossicles
and fenestra rotunda. If the air sinus system reaches its limit of compressibility,
there would be a pressure difference between the inside and the outside of the tym-
panic bulla because of the presence of the residual air cavities. It is suggested that
this pressure difference is adjusted by the enlargement of the corpus cavernosum.
The question naturally arises as to how the contained nitrogen in the sinuses
is prevented from passing directly into the blood stream in correlation with the
increased pressure as the animal sounds. The first consideration is that this gas
is not free to circulate in the air sinuses but is imprisoned in bubbles, the walls of
which are composed of a mucus-oil dispersion. Bearing in mind the high solubility
rate of nitrogen in fat, as compared with that in blood, and the very large total
_ surface area of the oil constituent presented to the gas, (for instance 100 cc of oil
HEARING IN CETACEANS 121
reduced to particle size of 1 would present a surface area of 1,200 sq.m.), it is reason-
able to conclude that the nitrogen would be absorbed into the fat before becoming
available for absorption into the blood. Conversely, with diminution of pressure,
nitrogen would be liberated into the sinus system to augment the foam volume.
This liberation of nitrogen would invariably be slower than the rate of decompression
in a rapidly surfacing whale, so that there would be an accumulation of dissolved
nitrogen in the foam. There is evidence that this nitrogen-charged foam is blown
out at expiration (Fraser & Purves 1955).
It would seem that at all times during swimming and diving an equilibrium is
maintained between (a) the hydrostatic pressure, (b) the rigidity of the tissues,
(c) the turgor pressure of the blood vascular system, (d) the viscosity of the foam
and (e) the volume of the gas as determined by the gas laws and by solution of the
contained gas in the oil and mucus. The relative extent to which each factor operates
to produce the equilibrium is beyond the scope of the present paper.
Acoustic FUNCTION OF THE AIR SACS
As previously stated, the air sinus system surrounds the periotic and occupies the
space between that bone and adjacent cranial bones, and the periotic is itself
separated osseously from the adjacent bones of the skull. With these factors operat-
ing it is necessary to discover the most effective sound path to the cochlea. The trans-
mission or reflection of sound energy at the interface between two media depends
upon the ratio of their acoustic resistances, and to some extent upon the frequency
of the vibrations. Since the periotic is virtually surrounded by air space, the con-
ditions are such that the interface can be regarded as being infinite in area as com-
pared with the wave length, therefore the normal conditions of reflection of sound
waves apply. According to Wood (1955) ‘‘ Whenever the radiation resistances (of
two media) are widely different there is almost complete reflection. The difficulty
of transmitting sounds from water e.g. the noise of a ship’s propeller in the sea,
to the air-filled ear-cavity of an observer will be apparent.” In fig. 30, from Wood,
the graph shows the percentage energy of a sound wave reflected from a mass of
bubbles in water. The percentage energy reflected is plotted as a function of the
proportion of air to water. “‘ This curve illustrates the serious reduction of intensity
when a sound wave encounters a mass of air bubbles in the sea. The noise of a
ship’s propeller is seriously reduced by the bubbly water in the wake. In such cases
the incident energy is partially reflected and partially absorbed, the loss increasing
rapidly as the proportion of air to water increases.” The graph refers to a layer of
bubbly water of semi-infinite dimensions, but Rayleigh, according to Wood, has
produced a formula for the reflection of plane waves from a layer of finite thickness :
EV neem (2 R, /\ » 2m (2 BI
pre a) Oo a ls OR) |
where y and i refer to the reflected and incident amplitudes, R, and R, (=p; 4
and p, Cs) are the acoustic resistences of the medium (1) and the layer (2), / is the
thickness, and A the wave-length of the sound in the material of the layer. On
122 HEARING IN CETACEANS
the observed indication that the proportion of liquid to gas in the whale’s ear foam
is somewhere in the region of one to over a thousand, in the following calculation
the proportion r to 10 can be accepted. As calculated from the following formula :
R= Fie ee (t= 2) ps}
xE, + (1 — x) Ey
where E, and E, refer to the elasticity of the two media FE, = 1-2 x 108 and E,
= 2:25 X I0!9; p, and p, the mean densities = o-oorz for air and 1 for water ad
Tp
NS}
BS
3
‘Sy
e
%
=
3
fang
10% 10° 1o* 107 107 10"
Ratio of air to water (by volume)
Fic. 30. Reflection of sound from air-water mixtures (after Wood, 1955).
x and 1—x refer to the proportions of the two constituents. The value for R,
for a I in 10 mixture of water and air is then 348. If this figure is used in the first
formula :
R, = 1-55 x 10° (for standard sea water)
KAS
A = 6-8 cm assuming a frequency of 50 kes.
i = OS; Gan
the calculated result obtained is that 99-73% of the energy is reflected, that is
assuming no loss through absorption. Since all sounds travelling in the direction
of the cochlea by way of the bones of the skull and the soft tissues, with the exception
of the meatus, must encounter the foam filled spaces, it is reasonable to assume that
they must be almost completely reflected or absorbed.
Turning therefore to the meatus, in the Odontoceti it is open to the external
surface of the tympanic ligament (which may be regarded as having the same acoustic
HEARING IN CETACEANS 123
resistance as the column of water filling the meatus) so that the first change of medium
is that at the malleolar end of the ligament. The acoustic resistance of petrous bone
must closely resemble that of ivory for which figures are available (Wood, 1955
p- 590). The velocity c, on a longitudinal bar is 2-2 x 10° and the acoustic resistance
4-1 x 10°. The figure for the torsional velocity is not given but it may be assumed
to be approximately a half the value for the longitudinal velocity. Employing the
given figures for the acoustic resistance of water and ivory in the equation
(Ph (2 — Pe as)’
Ply + Pz le
the result gives a figure of 45° reflection, but if the torsional velocity is used the
figure will be 22°/, approximately. These figures refer to a bar of ivory of circular
cross section, but the malleolar attachment to the tympanic ring is in the form of a
channel girder with roughly half-tubular cross section, so that the rigidity coefficient,
and hence the acoustic resistance, will be rather smaller than the figure quoted for
ivory. Indeed it seems likely that the tympanic ligament transmits nearly all and
reflects almost none of the incident energy. Assuming no slip at the incudo-malleolar
joint, the molar vibrations of the malleus will be transmitted to the incus and thence
to the stapes with very little loss of energy, since the incudal ligament is relatively
minute in length and thickness. In the Mysticeti the inner part of the meatus is
filled by the “ear plug’’ which consists of layers of cholesterol and keratinized
epithelium (Purves 1955). It is an interesting fact that the acoustic resistance of
paraffin wax is given as I-3 x 105 whereas that of sea water of 3:5% salinity is
I-5 x I0° so that at the interface, the wax plug, if considered comparable, would
form no appreciable barrier to sound waves.
It must be appreciated that the foregoing quantitative assessment is in the nature
of an approximation, since all the formulae apply to simple, geometrical forms and
not to a specialized, anatomical system adapted to a particular function. From these
quantitative considerations, so far as sound reflection is concerned, there is no objec-
tion to accepting the meatus as the possible sound path.
EXPERIMENTAL EVIDENCE OF THE SOUND CONDUCTIVITY OF THE MEATUS
In order to test the relative suitability of the meatus from the absorption view
point, a more precise experiment than that referred to in Fraser & Purves 1954,
was carried out. A large portion of the squamo-mastoid region of a Fin Whale
was obtained deep frozen and, when thawed, was dissected to expose the middle
ear, the wax plug and meatus as far laterally as the blind portion. The blind portion
was dissected to expose the cord connecting the inner part of the meatus with the
external aperture. The output of a variable frequency oscillator was connected
to a transducer by a concentric, screened cable. The transducer was in the form of
a probe (see inset, Text-fig. 33), consisting of a steel cone cut transversely near its
base for the insertion of a ceramic disc (barium titanate). A similar probe was
connected to an amplifier and a cathode ray oscilloscope. The output of the oscillator
was monitored by a rectifying voltmeter (see Text-fig. 32). A standard of reference
124 HEARING IN CETACEANS
was obtained by a calibrated deflection on the time base of the oscilloscope equivalent
to 2 cm separation of the probes. The second probe was then moved in a mesial
direction along the cord of the blind portion of the meatus and readings taken at
2 cm intervals (see Pl. 51). The readings consisted of increasing the volume of the
oscillator until the deflection on the oscilloscope reached the reference level. Similar
readings were taken for the inner portion of the meatus, the wax plug, the tympanic
ligament, wax plug to ligament and fibrous tissue parallel with the meatus. The attenu-
ation in decibels is plotted against the distance in centimetres in Text-fig. 31. The
values shown are much greater than the known attenuation of sound in sea-water
(x6 dbs per thousand yards at roo kes) but the probes were set in the tissue and
moved along an axis which was at right angles to direction of propagation of the sound
waves so that the attenuation rate was grossly exaggerated. The attenuation
would be still further exaggerated by the presence of any gas bubbles produced
by decomposition prior to freezing but the latter, if present, were assumed to
have been uniformly distributed in the tissues.
The graphs show a general, comparative picture of the attenuation in the various
tissues involved at three different frequencies. The lowest attenuation rate at
too ke was obtained in the blind section of the meatus immediately internal to
the blubber. (The external, open portion of the meatus was not tested as it was
considered that it would be filled with water under natural conditions.) The figure
for 2 cm of the corium of the lumen of the meatus was slightly below the reference
for 2 cm of the blind section but the attenuation rate of the whole length of the
corium was slightly higher than for the blind section, and was comparable with the
rate of attenuation of wax plug—wax plug— tympanic ligament. The curve for
the fibrous tissue was based on readings taken 4 cm posterior to the lumen of the
meatus. The initial power factor required for 2 cm of this tissue was 12 decibels
above reference and the attenuation considerably higher than that for the lumen
of the meatus. The attenuation for the corium through a distance of 8 cm to the
end of the tympanic ligament was roughly comparable with the figure for an equiva-
lent distance of the blind section. The attenuation of a transmission from the tym-
panic ligament to the thin end of the bulla, the distance being about 3 cm (ie.
I cm above the reference distance) was about 13°5 dbs, or equivalent to ca. 8 cm
of the blind section. The attenuation between the corium of the meatus, adjacent
to the wax plug and the end of the tympanic ligament, a distance of approximately
8 cm, was ca. 16 dbs.
From these qualitative results it would appear that any vibrations transmitted by
the meatus, blind section, lumen or wax plug would be received at the malleolar
end of the ligament at an intensity greater than that of vibrations from the same
source transmitted simultaneously by the surrounding fibrous tissue. Underlying
bone transmissions, conveyed through tissues further away from the meatus, would
suffer reflection at the bulla-tympanic cavity interface. Since the sound transmitted
by the meatal path would be dominant at any level of intensity, the animal must be
subject to an intensity and/or phase difference at the two cochleae, due to the
screening effect of the head and distance apart of the two meatal openings.
The graphs B and C show that the attenuation is rather lower at the lower fre-
OECIEELS
iN
ATTENUATION
HEARING IN CETACEANS 125
+38)
+36)
%
+5,
“2
2
2 fj
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zu
“9
Br
ty OISTANCE IN CM.
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DISTANCE IN CM.
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DISTANCE iN CM.
100 ke.
Fic. 31. Graph showing the attenuation of sound waves of 10-100 Kc in
meatal and adjacent tissues of the ear of a Fin Whale.
126 HEARING IN CETACEANS
quencies, a normal feature in sound vibrations. The reference level was adjusted
to the reduced performance of the crystal at lower frequencies.
Similar tests to those just described were made on the external end of the
external auditory meatus of a Sperm Whale. The results are compared with those
obtained from the inner part of a Fin Whale meatus and are shown in Text-fig. 32.
Fin Whale
Fibrous tissue surrounding
meatus.
Distance |3cms.
Fibrous tissue Surrounding
meatus.
Distance I2 cms.
Corium of meatal Lumen.
Distance IRcms.
Blind section of meatus.
Distance I2cms.
Corium of meatal lumen.
Distance |Ocms.
Attenuation in 2cms. of the
blind portion of the meatus.
ttenuation in Dbs.
40
30
RO
+10
Reference
Sperm Whale
Toms. thickness of blubber.
Skin adjacent to entrance of
meatus ~ blubber adjacent
to blind portion of meatus.
Distance ca.l4 cms.
SRin adjacent to entrance of
meatus — blind portion of
meatus.
Distance |Acms.
Entrance of meatus — blubber
adjacent to blind end.
Distance |Acms.
Entrance of meatus — blind
portion of meatus immediately
below blubber.
Distance |Ocms.
Fic. 32. Comparison of the sound conductivity of the external portions of the ear of
a Sperm Whale with those of the inner portion of the meatus of a Fin Whale.
HEARING IN CETACEANS 127
They indicate that the meatal lumen in both is similar in sound conductivity, and
both are greatly superior to the adjacent blubber and fibrous tissue. It will be seen
that 7 cm thickness of Sperm Whale blubber has a sound attenuation of 45 dbs
above reference.
As previously described, the external surface of the tympanic bulla is encased
in’a closely adherent, fibro-elastic capsule some 10 cm. thick in a large whale. A
slice of this tissue was tested for its sound conductivity. With ro cm. of the tissue
at 100 kc, the attenuation was approximately 8 dbs. above the reference, a figure
some 5 dbs below that for 10 cm. of the blind section and approximately half that
for ro cm of the meatal lumen. This indicates that the acoustic impedance of
the material of the capsule is high relative to that of the meatal tissue, and must
have a highly damping effect on molar vibrations of the tympanic bulla, such
vibrations being a characteristic of the function which some authors have assigned
to this bone. It is submitted that one of the effects of the great weight and
density of the tympano-periotic bones is the avoidance of forced oscillations of
the bones within the frequency band of the animal’s normal auditory range. It is
clear, from the experiment described below, that the fused malleus is capable of
undergoing high frequency oscillations up to 100 kc. It was found experimentally
that these oscillations were transmitted to the thin involucral edge of the bulla, near
the point of attachment of the malleus, but were subject to a power loss double
that for an equivalent extent of meatal tissue. From this it would appear that
vibrations transmitted from meatus to malleus would be greater in intensity than
those transmitted from bulla to malleus. No signal could be obtained experimentally
between malleus and periotic. It was proved experimentally that the malleus can
undergo torsional vibrations independently of the bulla. Any molar, resonant
vibrations of thelatter would only vitiate the efficiency of the signal.
EXPERIMENTAL EVIDENCE OF ACOUSTIC MATCHING
The question arises of the manner in which pressure amplitude is maintained and
displacement amplitude increased. For the investigation of this problem, a thin steel
wire was soldered to the end of one of the transducers, and the other end attached
to the tip of the manubrium of the malleus at the normal point of attachment of
the tympanic ligament, so that it simulated the latter in length and position (Text.
fig. 33). The angle of attachment of the wire could be altered by raising or lowering
the transducer, relative to the position of the manubrium, over a friction-free pulley,
while the tension was kept constant by attaching a small weight to the cable connect-
ing oscillator and transducer. The incus was allowed to rest on the malleus in its
natural position, separated from the latter by a thin film of petroleum jelly. The
stapes was simulated by the stylus of a micro-groove, crystal pick-up, which was
connected to an amplifier and oscilloscope. The frequencies used in this experiment
lay between Io and 100 kc. A considerable difference was noted in the height of the
deflection of the time base in relation to the angle which the wire made with the
long axis of the manubrium mallei. When the wire was pulling at a sharp angle,
approximately 5°, the deflection was about ten times the height attained when
128 HEARING IN CETACEANS
the wire was pulling at right angles to the manubrial axis. The only acceptable
interpretation of this evidence is that the malleus was being thrown into torsional
vibrations, and that the manubrium was behaving like a crank, actuated by the
piston-like movements of the crystal face. When the wire was pulling at right angles
to the manubrium, the relationship between the pressure-displacement amplitudes
of the crystal face and the manubrium would be approximately unity ; whereas,
when the wire was pulling at a sharp angle to the manubrium, the displacement
2no POSITION
MICROGROOVE
PICK UP
Y BARIUMTITANATE
Y ceramic
Y | ee
‘sr POSITION
Y
Z SCREENED
Y CABLE
VA
Z Z EEL
Z A TRANSDUCER
SCREENED CABLE
ac) TS
CATHODE
FOLLOWER
VOLTMETER
AMPLIFIER
WERAIAWAW
SI
OSCILLATOR
Fic. 33. Diagram of apparatus for demonstrating changes in the amplitude of torsional
oscillations of the malleus when actuated by a simulated tympanic ligament vibrating
longitudinally at various frequencies and angles of traction.
CATHODE
FOLLOWER
ratio would be increased. Thus in the middle ear of the cetacean there exists a
mechanism for the increase of displacement amplitude of water-borne sounds.
It might be pointed out that this method of amplification is self-compensating,
since the smaller the displacement amplitude of the sound wave the greater the
relative amplification.
Text-fig. 34a shows the relationships of the tympanic membrane and auditory
ossicles in a terrestrial animal such as man. Assuming the ratio of manubrium of
the malleus to the long process of the incus as 2: 1, then the displacement amplitude
ratio between the tympanic membrane and the stapes is also 2:1. Text-fig. 34)
shows the arrangement in the cetacean. The manubrium is shortened, so that its
- length is approximately that of the long process of the incus ; the tympanic membrane
HEARING IN CETACEANS 129
is closed up into a flat ligament which pulls at a sharp angle to the axis of the manu-
brium. In this case there is an amplification factor dependent upon the length of
the manubrium and the angle of attachment of the ligament (Text-fig. 34c). Assum-
ing this amplification factor to be 30: 1, then the displacement amplitude at the
stapes of a sound wave in water (of which the displacement amplitude for the same
Fic. 34. Schematic representation of the ossicular mechanism.
a. Terrestrial mammal in antero-posterior view.
b. Cetacean 4 5 is .
c. The mode of amplification of lateral displacement of the tympanic ligament by
means of a crank system.
d. The buttressing function of the sigmoid process against lateral movement of the
malleus, and the articulation of the latter with the incus.
intensity and frequency is 1/60 that of the same sound air-borne) would be equal
to that experienced by the terrestrial mammal.
In man, the pressure at the oval window of the inner ear is determined by the
ratio between the area of the ear drum and that of the foot of the stirrup bone, as
well as by the leverage of the auditory ossicles. The ratio is 30:1, the leverage
approximately 2:1 giving a pressure ratio between the stapes and drum of about
60 : 1, which is approximately the same pressure amplitude ratio between a sound
wave of the same intensity and frequency in water and air.
ZOOL, 7, I. 9
130 HEARING IN CETACEANS
In order that the pressure amplitude at the cochlea in the cetacean be the same
as that in terrestrial mammals, some compensation has to be made for the reduction
in pressure due (a), to the 30: r displacement amplification factor described above,
and (6), to the reduction in area of the tympanic membrane resulting from its modi-
fication from the membranous, drum-like structure of terrestrial mammals into the
ligament of the cetacean. It is submitted that the compensation is achieved by
the reduction in the cross-sectional area of the stapes, so that the ligament-stapedial
area relationship remains approximately 30 : I as in terrestrial mammals. Inspection
of dissected specimens indicates that the ratio in the cetacean is of that order (see
Pls. 49, 50 and 53).
For the same intensity and frequency, the pressure amplitude of water-borne
sounds is 60 times greater than in air. Accepting the ligament-stapedial area ratio
as 30:1, and the reduction in pressure due to the leverage at the manubrium as
I : 30, then the pressure of a water-borne sound at the cochlea is also 60 times greater
than a sound of the same intensity and frequency in air. This is the calculated
pressure increase experienced in man. In the experiment described on p. 128 the
minimum angle of attachment of the wire to the manubrium mallei was about
5°. In order to obtain the amplification factor required in the cetacean ear the angle
would require to be approximately 2°. It can be seen from Pls. 49, 50 and 53 that
the angle is of that order.
Since the pressure amplitude of sound presented at the fenestra ovalis of terrestrial
animals is the same as that received at the inner ear of aquatic lower vertebrates,
the evolution of the cochlea would seem to be linked with the increased displacement
amplitude of air-borne sounds.
DISCRIMINATION AND DIRECTIONALITY
Text-fig. 34d shows schematically the attachment of the processus gracilis of the
malleus to the sigmoid process of the bulla and the articulation of the malleus with
the incus. It will be noted that the processus gracilis is of a channel-girder construction ;
its attachment to the sigmoid process is of extremely thin bone. The arrow indicates
the direction of the long axis of the tympanic ligament. Traction or pressure along
the line of this axis would result in rotation of the head of the malleus about the long
axis of the processus gracilis, since lateral movement is prevented by the buttressing
effect of the sigmoid process. The rotation imparts a ‘screw-driver’ movement to
the incus which in turn rotates about its forwardly projecting, short process (not
shown in figure). That is to say, it is exactly the same as in terrestrial mammals.
If, in spite of the buttressing effect of the sigmoid process, the malleus were to undergo
lateral movement, the articular facets of malleus and incus would simply slide over
one another without imparting any movement to the incus. If oscillatory movements
in either of the directions at right angles to the axis of the ligament are assumed,
then positive movement of the incus is possible in the first phase of the first oscillation
only. In the second phase the bones would be partially disarticulated, so that the
movement of the malleus would be expended in taking up the gap between the facets.
It will be recalled that the short process of the incus is attached by a ligament to
HEARING IN CETACEANS 131
the periotic, so that vibrations of the bulla (to which the malleus is attached), resulting
in movements of the malleus in any of the directions other than the rotational one,
would not be transmitted to the incus. This has been proved experimentally by
subjecting a large working model of the auditory ossicles and their attachments to
the types of vibration described above. The unique effectiveness of the rotational
movement of the malleus is one of the fundamental reasons why theories involving
vibrations of the tympanic bulla (e.g. the resonance theories of Lillie & Kellogg
and the seismic theory of Yamada) are not accepted by the present writers, who
believe that the comparable articulation in man and other mammals serves the
same function of preventing resonant vibrations of the bulla and/or adjacent bones
from reaching the cochlea. Transmission to the cochlea of vibrations of the bones of
the skull or the bulla, and of all parts with the exception of the tympanic membrane,
would be accompanied by loss of directionality of hearing.
The conditions of sound transmission in water are such that cetaceans must normal-
ly be subjected to noise intensity levels quite outside the experience of terrestrial
mammals, and yet the construction of the cochlea is such that the ear must be
sensitive to the same threshold levels as those experienced by land mammals. For
example, Fletcher & Wegel according to Wood (1955) have found that at a frequency
of 2000-2500 p.p.s. the human ear can respond to a pressure amplitude of the order
of 10-3 dyne/cm? or 10~® of an atmosphere. He states that in air this corresponds
to a displacement amplitude of 1o~-® cm which is about 1/30 of the diameter of a
molecule of oxygen, or 10~ of the mean free path of the molecules in air at N.T.P.
In view of the high noise intensity in water and the great sensitivity of the cochlea,
it is not surprising that the cetacean meatus is of very small calibre. It is almost
certain that a mechanism exists to protect cetaceans against the harm that excessive
noise can cause.
Most mammals are provided with muscles for closing the meatus, and even in
man the vestiges of these remain and may be stimulated by electrical current
(Beattie 1932). In the Cetacea, although the pinna has disappeared, its cartilages
and muscles are to a greater or lesser degree present beneath the blubber. The
m. occipito-auricularis profundus and the m. zygomatico-auricularis described and
figured by Boenninghaus in Phocaena (Pl. 1, D) seem suitably placed to control the
tension and aperture of the external meatus in the Odontoceti. In the Mysticeti,
Denker (1902) described a number of muscles attached to the blind portion of the
meatus which presumably have the function of increasing or relaxing the tension
of this part of the tube (see also p. 135).
It is concluded that the meatus is the most favourable sound path as in terrestrial
mammals, and, as in the latter, the same conditions for directional hearing obtain,
which are—the degree of separation of the ears, the screening effect of the head and
the association that these have with phase and intensity differences. In terrestrial
mammals such phase and intensity differences can quickly be assessed by the animal,
even when in motion, by adjustments in the orientation of the ears and head. The
Cetacea, lacking external ear pinnae and the degree of freedom of orientation of
the head which a well-defined neck gives, might be expected to have some kind of
compensating facility. Essentially, directionality is obtained by equating the sound
ZOOL. 7, I. 9§
132 HEARING IN CETACEANS
intensity at the two cochleae. It was found experimentally that the sound con-
ductivity of the cetacean meatus could be increased or decreased by varying its
tension. It is suggested that this equation of pressure at the cochlea is achieved
by the traction of the auricular muscles on the meatal tube. The great development
of the pterygoid muscles, despite the reduced lateral mobility of the lower jaw, and
the mode of attachment of these and the tensor palati muscles into the walls of the
air sacs, seem to suggest that they have a second function related to the air sac
system. As already suggested (Fraser & Purves, 1953), the arrangements which
exist in terrestrial mammals for making small, temporary adjustments to the tension
of the tympanic membrane are also present in the Cetacea but, due to the large
adjustments required for the rapid changes of pressure with changes of depth, it
is doubtful if the tensor tympani muscle is as effective in this respect as it is in
terrestrial mammals. It is suggested that this function might well be performed by
the palatal and pterygoid muscles. It is interesting to note that when humans are
subjected to abnormal pressures, whether in diving or in aircraft, adjustment of the
pressure in the middle ear is obtained by swallowing, in which both pterygoid and
palatal muscles are brought into operation. The general arrangement of the air
sac system could also be of value in direction finding.
THEORIES OF CETACEAN HEARING
Dr. Yamada’s contribution to the Anatomy of the Organ of Hearing in Whales
(1953) was received while the present paper was in preparation. Among other
conclusions reached by him are that the external meatus is vestigeal, that the
auditory bones are not acoustically isolated, and that the tympano-periotic bone
is ‘a dynamic unit of seismographic principle ’’.
Yamada’s conclusion that the external meatus is vestigeal is based on the un-
justifiable assumption that it is unable to transmit sound vibrations. He assumes
that the sound waves to be transmitted have the same physical properties as those
received by terrestrial mammals. In all specimens examined by him he has found
a continuous cord of tissue from the external to the internal portion of the meatus,
and it has been proved experimentally by the present writers that this path is an
efficient conductor of longitudinal vibrations. This was also proved for the tympanic
ligament, contrary to Yamada’s conclusions (p. 46). In order to justify the refutation
of the acoustic isolation theory he cites the case of Platanista in which, according
to Hyrtl, the tympano-periotic is fused to adjacent skull bones. As previously
pointed out (p. 43) all the specimens of Platanista gangetica available for examina-
tion in connection with the present paper had tympano-periotic bones which were
not thus fused, in this agreeing with other cetaceans. Yamada also points to the
strong, fibrous connection of the periotic in Balaenoptera physalus which passes
through a canal bordered by the pterygoid and squamosal bones. The feature
referred to in his fig. 18, p. 44 is the foramen ovale and the course he describes for
the ligament to lower jaw is that followed by the mandibular branch of the 5th
nerve. He states that the fibrous connections negative the idea of acoustic isolation,
_but it may be pointed out that the only fibrous connections are those derived from
HEARING IN CETACEANS 133
the periosteum of resorbed bones of the tympano-periotic hiatus. This periosteum
sheathes the periotic and thus is very unfavourably situated for the transmission
of vibrations to the petrous bone. The acoustic resistance of the two substances are
such that on theoretical grounds about 50% of the incident energy would be reflected,
assuming the most favourable conditions of vibrations normal to the surface of the
bone.
With regard to Boenninghaus’ Schalltrichter theory, it has already been stated
by Fraser & Purves (1955) that sound waves could not be transmitted to the funnel
of the bulla by way of the air in the pterygoid sinuses because of the presence of
the albuminous foam in the sinuses. Considering the possibility of transmission
of vibrations from the lateral wall of the sinuses through the mucous membrane of
the tympanic funnel to the tympanic ligament, sound waves emanating from a source
lateral to the body of the animal would have to pass through the thickness of blubber,
muscles, mandible, intra-mandibular fatty tissue, vascular networks and subse-
quently be transmitted in a direction at right angles to that of the original direction.
This would involve shearing stresses on the mucous membrane which are much more
easily damped out than longitudinal ones. When there exists a simple, direct sound
path, from the external meatus to the tympanic membrane, of a homogeneous histolog-
ical structure, and of which the ligament is a prolongation, it is difficult to accept
an explanation which involves an extremely tortuous path with powerful acoustical
barriers.
The adaptation of the sound path normal to terrestrial mammals is, on the face
of it, more acceptable than any de novo method of sound conduction in mammals.
With reference to Yamada’s criticism of Boenninghaus’ Schalltrichter Theory,
while not accepting the latter, it is possible to reply to Yamada’s unanswered question
“How can the vibration of the malleus alone be undamped in spite of its rigid
connection with the bulla?’”’ The functioning of the malleus is stated in Fraser &
Purves (1954) p. 110, where it is also shown that vibrations of the bulla cannot be
transmitted beyond the malleus.
Yamada summarizes his seismographic explanation by stating that the heavy
involucrum (of the tympanic bulla) is the weight of a pendulum, in relation to which
the malleus is motionless, so that vibrations of the involcrum are conveyed to the
essential organ of hearing. Essentially this idea differs little from that of Kellogg
(1938) or from the original explanation of Lillie (1915). The objections to it are that
(a) if the bulla did act like a pendulum and undergo total vibrations, the axis of
rotation would be through the two thin, supporting pedicles mentioned by Kellogg.
It has been shown (Fraser & Purves, 1953) that the articulation between the
malleus and incus is specifically arranged to avoid such vibrations, being transmitted
beyond the junction of the malleus and incus; (0) it is well known that all pendulums
oscillate at a fixed frequency depending on the length of the lever. It is difficult to
understand how a heavy pendulum of the magnitude of the bulla could (with the
limit of power available in a sound transmitted in water) be forced to vibrate at a
frequency of 100,000 cycles per second a frequency to which at least one kind of
cetacean (Schevill & Lawrence, 1953) is known to be sensitive.
In another paper (Schevill & Lawrence, 1953), received while the present work
134 HEARING IN CETACEANS
was in preparation, it was noted that in the authors’ hearing experiments on Tursiops
tvuncatus there was a marked drop in positive response at 120 ke and final lack of
response to frequencies above 130 ke per sec. These authors assumed that the mode
of hearing in their experimental animal was by bone conduction, yet they themselves
mentioned the fact that there is no evidence of an upper frequency limit to bone
conducted sound in man; the highest pitch that is normally audible continues to
be heard even when the subject is exposed to much higher frequencies. They quote
Kunze & Kietz (1849) as having published curves reaching 128 ke for man without
any sign of a break in the upper end of the curve. They consider, in the light of the
bone conduction evidence when man is the subject, that there should be no upper
limit to hearing in cetaceans, but their experimental findings provide sufficient
evidence to suggest that bone conduction is not involved. It has previously been
pointed out that it would be very undesirable to have this mode of hearing from the
point of view of its lack of directionality.
In a recently published, very comprehensive work on hearing in whales, Reysenbach
de Haan (1957) has shown by experimental and quantitative treatment of the
anatomical data that the conclusions reached by the writers (Fraser & Purves, 1955)
are in almost every respect in agreement with his own. He does not however concur
with the hypothesis that the sound is conducted to the middle ear by the external
auditory meatus. His work was received some time after the completion of this
paper, and because of the disagreement referred to above it will be necessary to
supplement the observations on the external meatus already referred to (pp. 108-112
supra) by additional evidence obtained from a gross dissection of the ear of a Fin Whale.
Before proceeding with this account, it is necessary to refer to a disparity between
the present writers’ and Reysenbach de Haan’s interpretation of the Schalltrichter
Theorie of Boenninghaus. It is evident from Reysenbach de Haan’s conclusions that
he regards “ schalltrichter’’ as being synonymous with “tympanic annulus ”’
but this is not so. Quoting from Boenninghaus “‘ the whole processus anterioris
of the tympano-periotic is in the shape of a funnel the anterior diameter of which is
about I cm ... also quite remarkable is the anteriorly concave hearing wall
and the sigmoid process which bounds the funnel from behind’”’. It will be seen
from this that the entrance to the funnel or “ shell’’ as he subsequently calls it
lies at the anterior end and not lateral to the tympanic bulla.
In addition, the tympanic annulus of Delphinus is never as large as I cm in diameter
and the sigmoid process lies anterior to, and is not “‘ behind’’, the annulus. Boen-
ninghaus goes on “the funnel has through the aforesaid turning of the tympanic
bulla been turned forward so that sound waves from the rear do not strike it.
The bony sound funnel is now to be regarded as the functioning substitute of the
pinna and auricular passage of land mammals ’’. Boenninghaus’ sound path is stated
as follows—‘‘ Sound waves from the side and front pass through skin, fat, tongue
and jaw bone musculature—through the anterior opening of the bulla to the anterior
process of the malleus thence through the immovable incus and stapes to the fenestra
ovalis .”’
Pl. 51 shows a dissection of the auditory apparatus of a 60-ft Fin Whale caught
. near Steinshamn, Norway, 1956. It will be noticed that the whole external meatus
HEARING IN CETACEANS 135
is stretched tightly and lies on an approximately straight, horizontal axis from the
middle ear to the external aperture. The feature is not an artifact of preservation
but was found to be the condition in all the freshly killed whales examined at Steins-
hamn. The attenuated, distal, closed end of the meatus passes through a conspicuous
auricular cartilage to which are attached five robust, auricular muscles none of which
is less than 5 cm in diameter. Dorsal to these muscles is an extensive retial mass
of blood vessels which probably indicates that the muscles are functional. The proximal
portion of the meatus, the corium of which contains the ear-plug, lies in a deep
groove between the exoccipital and squamosal bones and in life was surrounded by
loose connective tissue and oil sinuses. Enveloping the whole of this area, and adhering
to the bones, there was in life, a great mass of dense, white, fibrous tissue about
30 cm in thickness and with tough unyielding fibres forming a close reticulum
throughout the entire mass. The meatus was thus enclosed in a tunnel formed
dorsally by bone and ventrally by the white fibrous tissue. In these circumstances
any contraction of the auricular muscles would result in considerable stretching of
the meatal wall and of its closed, distal extremity.
Turning now to the proximal end of the meatus, the same dissection, Pl. 52, shows
that the ear-plug, which fills the lumen of the meatus, is closely applied to the external
surface of the ‘“‘ glove finger ’’. In the dissection the plug has been bisected to show
the ‘“‘ annual rings’’ but in life it would completely envelop the “ glove-finger ’’.
Owing to decomposition, the ear-plug has become detached from the stratum germina-
tivum, but in life it forms the zona cornea of the “‘ glove-finger’’ and meatal epidermis
and is consequently very firmly attached to the latter structures. Pl. 53 shows the
middle ear after removal of part of the bulla and periotic. Originating on the mesial
aspect of the internal face of the bulla anterior to the tympanic annulus, there is
a short, stout muscle the insertion of which merges into the fibrous matrix of the
internal wall of the glove finger opposite the tympanic ligament. Contraction of this
muscle would result in movement of the whole of the “ glove-finger ’’, and of the
ear-plug assembly, as far as the lateral, blind end of the meatus. In this respect
the auricular muscles and the small muscle referred to above would act antagonistic-
ally. Mobility of the external meatus implied in the anatomical arrangement would
be superfluous if the meatus were non-functional.
In terrestrial mammals the special senses, of hearing, scent and sight are all avail-
able for the perception of the animal’s environment. In the Toothed Whales the
olfactory sense is wanting, and in the Baleen Whales, if present at all, it is very
greatly reduced. However efficient the eyes may be, their function must be limited
by conditions of turbidity of the water and by depth. Some River Dolphins may
be totally blind. In all cetaceans the sense of hearing is the most important of the
special senses.
CONCLUSIONS
It is concluded from the examination of specimens, from the evidence of existing
literature and from the results of experiments that:
(1) the configuration of the ventral aspect of the cetacean skull, which is associated
136 HEARING IN CETACEANS
with the development of air spaces, provides a fairly reliable guide to the systematic
arrangement of the Order Cetacea.
(2) The Mysticeti as a whole are more primitive than the Odontoceti.
(3) In the Odontoceti there is a gradation of development and specialization
of the sinus system within the sub-order as a whole, from the relatively primitive
River Dolphins through the estuarine forms to those which are pelagic. There are
distinct series of gradations within the sub-divisions of the hierarchy, intra-generic
as in the species of Lagenorhynchus ; within the sub-family, as in the genera included
in the Delphininae ; within the family, as in sub-families included in the Delphinidae ;
and within the super-family, as in the families represented in the Delphinoidea.
(4) The systematic arrangement of the order in the present paper fits basically
into the framework of Simpson’s (1945) classification, but has been extended in
detail.
(5) A notable exception is in the elevation of the Monodontinae to super-family
rank,
(6) The elaborate sinus system of the Cetacea consists almost entirely of an
extension of the middle ear cavity into the lamina of the pterygoid bone involving
invagination, distension and extension of the latter.
(7) The peribullary sinus is derived from the invasion of the basioccipital crest
and squamosal bone by the tympanic cavity after dissociation of the tympano-
periotic from the adjacent cranial bones.
(8) Hearing is by way of the external auditory meatus as in terrestrial mammals.
(9) Hearing is precisely discriminative and directional, and the ear is sensitive
to a wide range of frequencies.
(10) The qualities of hearing referred to have been achieved by modification of
typically mammalian auditory structures; so far from being non-functional, the
meatus, the tympanic membrane, the auditory ossicles, tympanic bulla, the cochlea,
the tympanic cavity and sinus system are all perfectly adapted for underwater
hearing.
ACKNOWLEDGMENTS
Grateful acknowledgments are made to the following for the use of apparatus
and for technical advice: Professor A. J. E. Cave, Mr. R. W. Fraser, Mr. G. R. M.
Garratt, Mr. M. G. Holloway, Dr. T. C. S. Morrison-Scott, Professor D. M. Newitt,
F.R.S., Dr. H. W. Parker and Mr. C. Urwin. The writers are particularly indebted
to Mr. C. Cropper and his colleagues for their generous and enthusiastic help. They
wish also to acknowledge the great help in the translation of papers given to them
by Commander J. M. Chaplin, R.N. (Rtd.).
HEARING IN CETACEANS 137
KEY
A —Artery. FR —Frontal bone.
AAS —Accessory air sinus. FR(OR) —Orbital process of frontal bone.
AC —aAuricular cartilage. FR(PO) —Post-orbital process of frontal bone.
AcE —External carotid artery. FR(PR) —Pre-orbital process of frontal bone.
ACI —Internal carotid artery. FT —Fatty tissue.
AL —Lachrymal artery. Fvp —Fibro-venous plexus.
ALS —Alisphenoid bone.
ALS(LL)—Lateral lamina of alisphenoid. GL —Glove-finger.
ALT —Anterior ligament. GMu —Mucous gland.
AM —Mandibular artery. Goc —Goblet cell.
AMI —Internal maxillary artery.
AO — Orbital artery. i sre)
oe —Antorbital soa: ILS —Interlaminar space.
ae ape monpeicle: : IMFB —Intra-mandibular fatty body.
AppB —Palato-pharyngeal branch of inter-
nal maxillary artery.
Apt —Pterygoid artery. uM ae Set nate
aptmsB —Arterial branches to internal ptery-
goid muscle. LA —Lachrymal bone.
AS —Anterior sinus. LI —Ligamentum incudis.
AT —Temporal artery (deep). LS —Lymph space.
B —Bone. M —Muscle.
BC —Calcified element of bone. MA —Malleus.
BL —Blubber. MAS —Mastoid process.
BO —Basioccipital bone MD —Mandible.
Boc —Basioccipital crest. MEP —External pterygoid muscle.
BR —Resorbed element of bone. mrs —Striped muscle fibres.
BS —Basisphenoid bone. mip —Internal pterygoid muscle.
MLO —Longitudinalis oesophagi muscle.
c —Cochlea. MLP —Levator palati muscle.
cap —Capillary. MM —Masseter muscle.
cc —Corpus cavernosum. MO —Orbital muscle.
CF —Fat cells. moo —Orbicularis-oris muscle.
cRH —Cranial hiatus. mpp —Palato-pharyngeus muscle.
MPP(E) —Palato-pharyngeus muscle
DMu —Mucous duct. (pars externa).
MPP(I) —Palato-pharyngeus muscle
EAM —External auditory meatus. (pars interna).
ECI —Ciliated epithelium. mpp(s) —Palato-pharyngeus sphincter.
Eco —Columnar epithelium. MS —Middle sinus.
EP —Ear-plug. MSC —Superior constrictor muscle.
ET —Eustachian tube. MSP —Salpingo-pharyngeus muscle.
Exo —Exoccipital bone. MT —Temporal muscle.
MTHP —Thyro-palatinus muscle.
FEO —Fenestra ovalis. MTP —Tensor palati muscle.
FER —Fenestra rotunda. muM —Mucous membrane.
FG —Fat globules. MX —Mazxilla.
FO —Foramen ovale. MAX —Maxilla (figs. 15-21).
FOI —Infundibulum of foramen ovale. mxc —Maxillary crest.
FP —Falciform process. NA —Auditory nerve.
138 HEARING IN CETACEANS
NM —Mandibular branch of trigeminal SB —Secondary bone.
nerve. sc —Semicircular canal.
NO —Optic nerve. SM —Stapedial muscle.
oc —Occipital condyle. so —Supraoccipital bone.
OF —Optic foramen. SP —Sigmoid process.
oI —Optic infundibulum. sQ —Squamosal bone.
os —Orbitosphenoid bone. sgz | —Zygomatic process of squamosal.
ST —Stapes.
P —Periosteum.
PA —Palatine aponeurosis. TA —Tympanic annulus.
PAL —Palatine bone. TB —Tympanic bulla.
PAL(LL)—Lateral lamina of palatine bone. 1B(pa) —Posterior aperture of tympanic
pao —Paroccipital process. iSyrilEy.
Par —Parietal bone. Tc —Tympanic cavity.
pps | —Peribullary sinus. TF —Fibrous tissue.
He —Periotic. ss TL —Tympanic ligament.
a —Processus gracilis. ™ —Tympanic membrane.
pos —Posterior sinus. TP —Tympano-periotic bones.
PP —Posterior pedicle. TsQgR —Tympano-squamosal recess.
prs —Presphenoid bone. na —Tensor tympani muscle.
PS —Periosteal sheet.
PT —Pterygoid bone.
PTF fed fossa. vi EE :
PTH —Pterygoid hamulus. Ae SEE ese eee
pt(1L) —Inferior lamina of pterygoid bone. ve = ee Eat ea) Nae
pT(LL) —Lateral lamina of pterygoid bone. ve ene vem:
pT(ML) —Mesial lamina of pterygoid bone. N ae
pts —Pterygoid sinus. bis ee eee
pts(po)—Post-orbital lobe of pterygoid sinus. ‘rile b= Tonia Senaon ORC TEL
PTS(PR)—Pre-orbital lobe of pterygoid sinus. id 1
pi(sL) —Superior lamina of pterygoid bone. DES/fous! ews)
Ss —Air sinus. ZA —Zygomatic arch.
BIBLIOGRAPHY
ANDERSON, J. 1879. Zoological Results of the two Expeditions to Western Yunnan 1868-75.
First volume. London. Quaritch.
Antuony, R. & Coupin, F. 1930. Recherches anatomiques sur le Vestibule de l’appareil respi-
ratoire (Poche gutturale-Hyoide-Larynx) du Mesoplodon. Mem. Inst. Esp. Oceanogr.
Madrid Mem. 14: 1-40, 2 pls., 22 figs.
Beattigz, R. T. 1932. Hearing in Man and Animals. xi, 227 figs. London.
BEAUREGARD, H. 1894. Recherches sur l'appareil autitif chez les Mammiféres. J. Anat. Paris
1894: 367-413, 3 pls.
Boas, J. E. V. 1912. Ohrknorpel und dusseres Ohy dey Séugetiere. 1-225, 25 pls., 21 figs.
Copenhagen.
Boennincuaus, G. 1902. Der Rachen von Phocaena communis Less. Eine biologische studie.
Zool. Jahrb. 17: 1-92, 1 pl.
— 1903. Das Ohr des Zahnwales, zugleich ein Beitrag zur Theorie der Schalleitung. Ibid.
19: 189-360, 28 fifs., 3 pls.
. Bucuanan, T. 1828. Physiological Illustrations of the Organ of Hearing. London.
HEARING IN CETACEANS 139
CamPER, P. 1777. Verhandeling over de Zitplaats van det Beenig Gehoorting . . . in de
Walvischen. Verh. Holland. Maatsch. 17: Pt. 2, 157-200, 2 Pls.
Carte, E. & MacatistEer, A. 1868. On the Anatomy of Balaenoptera rostrata. Phil. Trans.
158: 210-261, 5 pls.
CrLarKE, R. H. 1948. Hearing in Cetacea. Nature, London, 161: 979-980.
DENKER, A. 1902. Zur Anatomie des Gehdrorgans der Cetacea. Anat. Hefte. 19: 424-448,
2 pls., 6 figs.
FLower, W.H. 1867. Description of the skeleton of Inia geoffrensis and the skull of Pontoporia
blainvilli with remarks on the systematic position of these animals in the Order Cetacea.
Trans. Zool. Soc. 6: 87-116, 4 pls.
1868. On the Osteology of the Cachalot or Sperm Whale Physeter macrocephalus. Ibid.
6: 309-372, 7 pls., 13 figs.
FRASER, F. C. 1956. A new Sarawak Dolphin. Sarawak Mus. Journ. 7: N.S. No. 8, 478-
503, 5 pls., 2 figs.
Fraser, F, C. & Purves, P. E. 1953. Fractured Earbones of Blue Whales. Scott. Nat. 65:
No. 3, 154-156, 1 pl.
1954. Hearing in Cetaceans. Bull. Brit. Mus. (N.H.), 2: No. 5, 103-116, 2 pl.
1955. The ‘Blow’ of Whales. Nature, 176: 1221-1222.
Hanke, H. 1914. Ein Beitrag zur Kenntnis der Anatomie des dusseren und mittleren ohres
der Bartenwale. Jenaische Zs. Natw. 51: (1914), 487-524, 3 pls.
Home, E. 1812. An account of some Pecularities in the Structure of the Organ of Hearing in
Balaena mysticetus of Linnaeus. Phil. Trans. 102: 83-88, 2 pls.
Howe tt, A. B. 1930. Aquatic Mammals : theiy adaptation to Life in the Water. pp. vii: 338.
Springfield, Illinois.
Hunter, J. 1787. Observations on the Structure and Oeconomy of Whales. Phil. Trans. 77 :
371-450, 8 pls.
Hyrtt, J. 1845. Vergleichend-Anatomische untersuchungen tibey das Inneve Gehérorgan des
Menschen und des Sdugethiere viii, 139, 9 pls. Prag.
Jounston, T. B. & WuiILtIs, J. (Editors). 1946. Gray’s Anatomy 29th ed. 1-1,597 figs. London.
Kettoce, R. 1398. Adaptation of Structure to Function in Whales. Publ. Carneg. Instw.,
501 : 649-682.
Kernan, J. D. 1916 [In Schulte H. von W.] Anatomy of a foetus of Balaenoptera borealis.
Mem. Amer. Mus. Nat. Hist. N.s.1: Part IV, 389-502, 15 pls.
Knox, R. 1859. Contributions to the Anatomy and Natural History of the Cetacea. Journ.
Linn. Soc. London [1857], 3: 63-76.
Kormer, W. 1907. Uber das hautige Labyrinth des Delphins. Anat. Anz. 32 : 295-300, 3 figs.
Kunze, W. & Kietz, H. 1949. Ueber Horempfindungen im Ultraschallgebiet bei Knochen-
leitung. Archiv. f. Ohren. Nasen, Kehlkopfheikunde, 155: 683-692.
Litre, D. G. 1910. Observations on the anatomy and general biology of some members of
the larger Cetacea. Proc. Zool. Soc. 1910: 769-792, 1 pl. Io figs.
1915. Cetacea. Brit. Antarctic ‘‘ Terra Nova’’ Expedition 1910. Nat. Hist. Report.
Zool. 1: No. 3; 85-124, 8 pls, 14 figs.
Monro, A. 1785. The Structure and Physiology of Fishes. 1-128. 44 pls. Edinburgh.
Muriez, J. 1873. On the Organization of the Caa’ing Whale, Globicephalus melas. Trans. Zool.
Soc., 8: 235-301, 9 pls.
Purves, P. E. 1955. The Wax Plug in the external auditory meatus of the Mysticeti. Discovery
Reports, 27: 293-302, 5 pls., r fig.
Rapp, W. 1837. Die Cetaceen zoologisch-anatomisch dargestellt. VI, 182, 8 pls. Stuttgart and
Tiibingen.
RipEwoop, W. G. 1922. Observations on the skull in foetal specimens of Whales of the genera
Megapteva and Balaenoptera. Phil. Tvans. ser. B. 211: 209-272, 16 figs.
RONDELET, G. 1554. Libri de Piscibus marinis, in quibus verae Piscium effigies expressae sunt.
Lugduni.
140 HEARING IN CETACEANS
REYSENBACH DE Haan, F. W. 1957. Hearing in Whales. Acta oto-Laryngologica: Supple-
mentum 134, I-I14, 41 figs. Stockholm.
ScHEVILL, W. E. & LAwRENcE, B. 1953a. Auditory Response of a Bottlenosed Porpoise,
Tursiops truncatus, to frequencies above 100 Ke. Journ. Exp. Zool. 124: No. 1, 147-165,
2 figs.
1953). High frequency auditory response of a bottle-nosed porpoise, Tursiops
truncatus (Montagu). Journ Acoust. Soc. America, 25: 1016-1017.
SCHEVILL, W. E. & LAwRENCE, B. 1956. Food-finding by a captive Porpoise (Tursiops trun-
catus). Breviova, No. 52, I-15.
SCHOLANDER, P. F. 1940. Experimental Investigations on the Respiratory Function in Diving
Mammals and Birds. Hval. Skrift. No. 22: 1-131, 88 figs.
Simpson, G. L. 1945. The Principles of Classification and a Classification of Mammals. Bull.
Amer. Mus. Nat. Hist, 85: i-xvi, 1-114.
SLIJPER, E. J. 1936. Die Cetaceen—Vergleichend-Anatomisch und Systematisch. i-xv, 590.
251 figs. Utrecht.
Srannius, A. 1841. Ueber den Verlauf der Arterien bei Delphinus phocaena. Aych. Anat.
Physiol Jg.
—— 1849. Beschreibung der Muskeln des Tiimmlers. /bid.
Tyson, E. 1680. Phocaena, oy the Anatomy of a Porpess. London, 4to.
WEINMANN, J. P. & Sicher, H. 1947. Bone and Bones. Fundamentals of Bone Biology. 1-464,
389 figs. London.
Woop, A. B. 1955. A Text-book of Sound, being an account of the physics of vibration with special
reference to recent theoretical and technical developments. 1-610, 159 figs, tables and plates.
London.
Yamapa, M. 1953. Contribution to the Anatomy of the Organ of Hearing of Whales. Sci. Rep.
Whales Research Inst. (Japan), No. 8: 1-79, 29 figs.
PRESENTED
EXPLANATION OF PLATES
PLATE tr
Phocaena phocoena (from Boenninghaus, 1903, his Plate 12, figs. 3, 4, 5 and 2).
(a) Ventral view of the soft parts of the pterygoid region.
(B) Ventral view of the right side of the pterygoid region 1 cm deep to figure a.
(c) Same view 1 cm deep to figure B.
(p) View of the right side of head after removal of subcutaneous muscle and fat.
The numerals used in the figures are referred to in the text.
Bull. B.M. (N.H.) Zool. 7, = PLATE
pao)
ZOOL. 7, I.
PLATE 2
Sections of the mucous membrane of the pterygoid sinus of Globicephala melaena.
(a) Section cut in a plane parallel with and near to the surface of the mucous membrane
(x 50).
(B) Longitudinal section of the pterygoid sinus lateral wall (x 160).
(c) Enlarged portion of mucous gland shown in figure B ( 600).
PRAT E
Bull. B.M. (N.H.) Zool. 7, 1
PLATE 3
(a) Longitudinal section through the lateral wall of the pterygoid sinus ( 8).
(B) Longitudinal section through the mesial wall of the pterygoid sinus (= 8).
(c) Section cut in a plane parallel with [and deep to that shown in) Plate 2, figure A ( 100).
(p) Section showing contents of lymph spaces (LS) ( 1000).
Bull. B.M. (N.H.) Zool. 7, 1 Pi Ade: 3
PLATE 4
(A) Section at right angles to Plate 3, figure a (x 8).
(B) Section through lateral wall of the pterygoid simus in the region anterior to the tympanic
bulla ( 4).
(c) Transverse section of the intra~-mandibular fatty body ( 8).
(p) Transverse section of fat external to mandible ( 8).
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 4
Bull. B:M. (N.H.) Zool. 7, r PLATE 5
PLATE 5
Caperea marginata (Reg. No, 1876.2.16.1)
Ventral view of postero-lateral region of the skull, left side,
Bull, B.M. (N.H.) Zool. 7, 1 PLATE
A. ed
er
PEATE 16
Caperea marginata (Reg. No. 1876.2.16.1)
Ventral view of postero-lateral region of the skull, right side with tympanic bulla removed.
6
Bull. B.M. (N.H.) Zool. 7, 1 PLATE
mandibular Ii
nerve inf
PLATE 7
Balaenopteva acutorostrata (Reg. No. S.W. 1926/33)
Ventro-lateral view of the pterygoid and adjacent regions of the skull.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 8
PLATE 8
Hyperoodon ampullatus (Reg. No. S.W. 1938/40)
Ventro-lateral aspect of the skull base.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 9
PLATE 9
Berardius arnuxi (Reg. No. 1923.11.16.1)
Ventro-lateral aspect of the skull base.
Bull. B.M, (N.H.) Zool. 7, 1
PLATE to
Ziphius cavirostris (Reg. No. 1920/9)
Ventro-lateral aspect of the skull base.
PASTE,
10
® Bull. BLM. (N.H.) Zool. 7, 1 PLATE 11
RT:
PIA ee aa
Mesoplodon bidens (Reg. No. 5.W.1938/31)
Ventro-lateral aspect of the skull base. |
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 12
eustachian
tube
peribullary s.)7
4 _
TEL YNADIS, 3673
Mesoplodon bidens (Reg. No. S.W. 1949/26)
Skull showing internal cast of air sinuses.
Bull. B.M. (N.H.) Zool. 7, x
PLATE 13
Monodon monoceros (Reg. No. 1949.11.2.1)
Base of skull of adult ventro-lateral aspect.
PLATE
13
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 14
PLATE 14
Monodon monoceros juv. (Reg. No. 1887.9.8.1)
Ventro-lateral aspect of skull base.
ZOOL. 7, I. II
Bull. B.M. (N.H.) Zool. 7, 1
mandibulary
erve int Zaire
RE
PAE 1a5
Delphinapterus leucas (Reg. No. 1933.10.13.1)
Ventro-lateral aspect of skull base.
PLATE
15
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 16
PEATE ]16
Kogia breviceps (Reg. No. 1952.8.23.1)
Ventro-lateral aspect of the skull base.
Bull. B.M, (N.H.) Zool. 7, 1 PA iE 7
Bi pterygoid s
eurtachian)
aren
Na
PICA, 307)
Platanista gangetica, adult (Reg. No. 1843.8.18.5)
Ventro-lateral aspect of the skull base.
Bull. B.M. (N.H.) Zool. 7, 1 LEU IB) iif}
PLATE 18
Platanista gangetica, juv. (Reg. No. 1646A)
Ventral aspect of skull,
Bull. B.M.(N.H.) Zool.
TRE IN ARIE, 006)
Stenodelphis blainvillei (Reg. No. 1925.11.20.1)
Ventro-lateral aspect of skull base.
PLATE
19
Bull. B.M. (N.H.) Zool PLATE 20
orbital
lobe
pterygoid s
peribullary s.
Pie AVE 210
Stenodelphis blainvillei (no history)
Radiograph of head, sinuses injected with iodized oil.
Bull. B.M. (N.H.) Zool. 7, 1 PLATES 2a
posterior 5.
PE AME aee2T |
Inia geoffrensis (Reg. No. 1939.5.13-1)
Ventro-lateral aspect of skull base.
nh
n
Bull. B.M. (N.H.) Zool. 7, 1 PEATE
pterygoid s ———
orbital
lobe
pterygoid s
Sm peribullary s
A
PALEY 22
Inia geoffrensis (Reg. No. 526.12.8.25)
Radiograph of head, sinuses of one side injected with iodized oil.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE
anterior s.
PT(ML
peribullary 5
PLATE 23
Lipotes vexillifer (Reg. No. 22.6
Ventro-lateral aspect of skull base,
22.1)
Bull. B.M. (N.H.) Zool. 7, r PAH 2/4)
tachian
ube
PLATE 24
Steno bredanensis (Reg. No. 1952.8.1.1)
Ventro-lateral aspect of skull base.
Bull. B.M, (N.H.) Zool. 7,§2 PLATES
S|
imandibular
B peribullary »
PEATE 25
Sousa borneensis (Reg. No. 1914.1.14.1)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.H.) Zool. 7, 1
PLATE 26
PLATE 26
Phocaena phocoena (Reg. No. S.W. 1950/15)
Ventro-lateral aspect of skull base.
Bull
B
M
(N.H.) Zool
nerve jaf.
PLATE
Phocaena phocoena (Reg.
Skull showing internal cz
No. S.W.1950/28)
ist of air sinuses.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 28
: a a ML)
; bi jeustachia
PLATE 28
Neomeris phocaenoides (Reg. No. 1903.9.12.3)
Ventro-lateral aspect of skull base.
Bull. B.M
(N.H.) Zool
Pe ASE 8219,
Pseudorca crassidens (Reg. No. S.W.1927,
Ventro-lateral aspect of skull base.
3)
I)
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 30
PLATE 30
Pseudorca crassidens (Reg. No. 1936.6.23.1)
Ventro-lateral aspect of skull base (for comparison with Plate 20).
ZOOL. 7, I.
Bull. B.M. (N.H.)Wool. 7, 1 ( : PLATE 31 |
mandibular »
Anerv
posterior =
PEATE §3r
Orcinus orca (Reg. No. S.W. 1932/13)
Ventro-lateral aspect of skull base.
Bull. B.M.(N.H.) Zool. 7, 1 PLATE
PT(ML)
eustachian
Pi
Peet)
posterior 3,
PALE (32
Orcaella brevivostris (Reg. No. 1883.11. 20.2)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.EH.) Zool. 7, 2 PLATE 33
JEME JNA iE 2G}
Globicephala melaena (Reg. No. S.W.1932/1)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.H.) Zool. 7, 1
pterygoid s
PATE 314
Globicephala melaena (Reg. No. 1950/7)
Skull showing internal cast of air sinuses
PLATE
34
Bull. B.M. (N.H.) Zool. 7, 1
PL ATE? 35
Feresa intermedia (Reg. No, 1874.11.25.1)
Ventro-lateral aspect of skull base,
Bull. B.M. (N.H.) Zool. 7, 1 PEATE
ibutar
nerve inf
x
PLATE 36
Cephalorhynchus heavisidei (Reg. No 1948.7.27.1)
Ventro-lateral aspect of skull base,
Bull. B.M. (N.H.) Zool. 7, t PLATE 37
PEALE 37,
No. S.W.1947/14)
Ventro-lateral aspect of skull base
Lagenorhynchus albirostris (Reg
Bull. B.M. (N.H.) Zool. 7, © PLATE 38
PLATE 38
Lagenorhynchus albirostris (Reg. No. S.W. 1951/9)
Skull showing internal cast of air sinuses.
Bull. B.M. (N.H.) Zool. 7, x
7)
PLATE 39
Rg er a,
PLATE 39
Lagenorhynchus acutus (Reg. No. 1917.9.
Hy)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.H.) Zool. 7, r PLATE 40
y
Vee
- oa
4
mandib
Banorve inf
PLATE 40
Lagenorhynchus obscurus (Reg. No. 1944.11.10.1)
Ventro-lateral aspect of skull base,
Bull. B.M. (N.H.) Zool. 7, x PEAT IE, aan
PEALE 4a
Grampus griseus (Reg. No. S.W.1922/7)
Ventro-lateral aspect of skull base,
Bull. B.M. (N.H.) Zool. 7, x
(Pale ATE 242)
Grampus griseus (Reg. No. S.W.1951/3)
Skull showing internal cast of air sinuses.
PLATE
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 43
PLATE 43
Tursiops truncatus (Reg. No. 1951.11.26. 2)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.H.) Zool. 7, 2 PLATE 44
PLATE 44
Tursiops truncatus (Reg. No. 1951.11.26.1)
Skull showing internal cast of air sinuses.
Bull. BLM. (N.H.) Zool. 7, 1 : PLATE 45
PLATE 45
Stenella euphrosyne (Reg. No. 1938.2.5.1)
Ventro-lateral aspect of skull base.
Bull. B.M. (N.H.) Zool. 7, x PEATE 746
PEATE 46
Delphinus delphis (Reg. No. 1937-11.27.1)
Ventro-lateral aspect of skull base.
ZOOL. 7, I.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 47
IPID AIS, i)
Delphinus delphis (Reg. No. S.W. 1952/2)
Skull showing internal cast of air sinuses
Eee Sti‘ _é( Ore”
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 48
PLATE 48
Longitudinal sections in the region of the ear of a foetal Humpback, Megaptera novaeangliae
(A) Distal end of external auditory meatus ( 40).
(B) Closed portion of external auditory meatus ( 40).
(c) Section through tympanic membrane, manubrium mallei and tympanic cavity ( 40).
(p) Pars flaccida of the tympanic membrane (% 40).
PLATE 49
Dissection of the middle ear of Globicephala melaena (cf. Text-figure 26)
PEATE 50
Dissection of the middle ear of Balaenoptera acutorostrata (cf. Text-figure 27)
Bull. B.M. (N.H.) Zool. 7, r
Bull. B.M. (N.H.) Zool. 7, £
sh
wee
534
yee
PI
IEE ACAD I apr
Dissection of the ear of Balaenoptera physalus
Starting from the right of the figure the following features in succession—open pigmented
part of the external meatus with blubber adjacent ; auricular cartilage with muscles attached ;
the cord-like portion of meatus, the proximal portion of the meatus lying in the squamo-
mastoid groove with part of the corium removed to show the ear plug and glove finger, the
tympanic bulla with mesial half removed to show middle ear cavity and pterygoid sinus.
Acoustic probes are shown in three of the positions used for testing sound attenuation.
PLATE 52
Dissection of the ear of Balaenoptera physalus showing glove finger and ear plug.
The ear plug has been bisected to show laminations, but in life it would completely envelop
the glove finger of which it is the zona cornea. The extension of the middle ear cavity into
the pterygoid sinus shows part of the fibro-venous plexus (bottom left), Acoustic probes are
placed on the malleus and ear plug.
Bull. B.M. (N.H.) Zool. 7, 1 PLATE 51
Bull, B.M. (N.H.) Zool. 7, 1 PEATE 52
PLATE 53
Dissection of the middle ear and cochlea of Balaenoptera physalus
Dissection shows the tympanic ligament (TL) attached to the malleus (MM) which is fused to the
sigmoid process of tympanic bulla. The tensor tympani muscle (TT) passes obliquely down-
wards to the right of the exposed cochlea (c). The incus (1) and stapes (ST) are situated above
the cochlea. The atrophied internal carotid artery (ACI) passes obliquely across the tympanic
cavity to the left of the cochlea. The groove in which the stapedial muscle (SM) lies can be
seen above the cochlea. Note the muscle mass (M) the tendon of which passes through the
tympanic annulus to the internal face of the ‘‘ glove-finger ’’ (Shrapnell’s membrane, GL).
By courtesy of ‘“ ENDEAVOUR”.
53
PLATE
Bull. B.M. (N.H.) Zool. 7, 1
i
4
9
\ PES D HARPAGOPHORIDAE
DE R. L POCOCK
ERVES AU BRITISH MUSEUM
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(MYRIAPODES, DIPLOPODES)
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J. M. DEMANGE
es _ BULLETIN OF
3RITISH MUSEUM (NATURAL HISTORY)
eae ae Vol, ‘7, No.22
~ LONDON : 1960
LES TYPES D’HARPAGOPHORIDAE DE
R. I. POCOCK CONSERVES AU
BRITISH MUSEUM (NATURAL HISTORY)
(MYRIAPODES, DIPLOPODES)
4960
PAR
acSENTED yw DEMANGE
Laboratoire de Zoologie du Muséum National de Paris
Pp. 141-179 ; 87 Text-figures
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 2
LONDON: 1960
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, is
issued in five series, corresponding to the Departments
of the Museum, and an Historical series.
Parts will appear at irregular intervals as they become
veady. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No. 2 of the Zoological series.
© Trustees of the British Museum, 1960
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM
Issued July, 1960 Price Fifteen Shillings
LES TYPES D’HARPAGOPHORIDAE DE
R. L POCOCK CONSERVES AU
BRITISH MUSEUM (NATURAL HISTORY)
(MYRIAPODES, DIPLOPODES)
Par J. M. DEMANGE
AYANT entrepris la révision de la famille des Harpagophoridae nous nous sommes
rapidement apergu qu’une étude particuliére devait étre consacrée aux espéces
décrites par les Auteurs il y a une cinquantaine d’années.
La plupart des descriptions sont en effet succinctes, souvent imprécises et non
illustrées. De plus les figures publiées a 1’époque sont petites et ne montrent qu’une
partie des gonopodes. De ce fait beaucoup de ces espéces ne peuvent étre identi-
fiées et figurent dans une trop longue liste de ‘‘ Species incertae sedis ’’
C’est pour cette raison que nous nous sommes rendu a Londres pour étudier les
types de R. I. Pocock conservés au British Museum.
Le Dr. G. O. Evans, directeur de la section des Arachnides, nous a ouvert large-
ment ses collections et ses laboratoires oti nous avons trouvé de la part de MM. E.
BrownineG, K. H. Hyatt, et D. MACFARLANE une aide précieuse. Nous sommes
heureux de trouver ici l’occasion d’exprimer au Dr. G. O. Evans et a ses collabora-
teurs toute notre reconnaissance et nos remerciements pour leur sympathique et
cordial accueil.
Nous nous proposions d’examiner 32 espéces qui sont les suivantes :
Rhynchoproctus proboscideus Spirostreptus oatesit
Spirostreptus asthenes patric
aterrimus perakensis
baluensis regis
bowringit stenorhynchus
centrurus tavovensis
doriae Thyropygus andersont
dulitianus anurus
everettit aulaconotus
exocoelt evythropleurus
feae pachyurus
gestri vubrocinctus
hoset vubrolimbatus
insculptus webert
jerdant xanthonotus
moseleyt xanthurus
ZOOL. 7, 2 14
144 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Malheureusement 17 seulement ont pu étre examinées auxquelles nous avons
ajouté Spirostreptus vittatus Newp. dont, a notre connaissance, aucune figure précise
n’a été publiée.
Des 15 espéces restantes, 6 n’ont pu étre retrouvées étant conservées, sans doute,
dans un Musée que nous ignorons. II] s’agit de Thyropygus andersoni, perakensis,
Spivostreptus doriae, exocoeti, jerdani, regis; 6 basées sur des 2 ou Q et g juv.:
Thyropygus erythropleurus (2 et g juv.), xanthonotus (2), xanthurus (Q et 3 juv.),
Spirostreptus asthenes (2), insculptus (2), moseleyi (9).
Par contre les 3 espéces suivantes, Thyropygus aulaconotus, pachyurus, rubrolim-
batus n’étaient représentées, comme type dans la collection que par le sexe 9 bien
qu’ayant été décrites sur les deux sexes a l’exception de rubrolimbatus basé sur un
unique ¢ (coquille d’imprimerie probablement puisqu’il n’est fait mention dans la
description d’aucun organe copulateur, ni de caractéres sexuels secondaires). Nous
avouons ne pas bien comprendre ce qui a pu se passer pour les deux premiéres
especes. Nous supposons que la 2 seule a été prise comme “ type’’, le ¢ comme
“cotype’’, celui-ci ayant été envoyé par |’Auteur a l’un de ses collégues. Nous
précisons a ce sujet que H. W. BROLEMANN possédait dans sa collection personnelle,
maintenant conservée au Muséum National d’ Histoire Naturelle de Paris, un certain
nombre de types et “‘ cotypes’’ dont un Spivostreptus feae sur lequel nous revien-
drons.
Quoiqu’il en soit nous ne pouvons actuellement faire état de ces espéces dans notre
systématique.
Ajoutons enfin que seul le “‘ cotype’’’ de Thyropygus anurus a été retrouvé et que
5 bocaux renfermaient des specimens n’étant pas désignés comme type. II s’agit
de Spivostreptus aterrimus, dulitianus, oatesii, tavoiensis et Thyropygus gestri. Nous
considerons les individus comme types et ce pour les raisons que nous exposons au
cours de leur description.
L’étude des types de R. I. Pocock pose naturellement certains problémes de
systématique et de synonymie que nous ne voulons pas résoudre ici nous réservant
d’envisager ces problémes dans un travail plus complet, en cours de rédaction,
constituant les premiers éléments d’une révision de la famille.
DESCRIPTION DES ESPECES EXAMINEES
Les descriptions qui vont suivre concernent plus particuli¢rement les gonopodes
mais nous avons adjoint quelques renseignements morphologiques généraux comme
les sillons collaires, la forme de la cavité stigmatique, les soles etc.
Chaque nom d’espéce est suivi de la station de récolte et d’une série de numéros
correspondant a la référence du British Museum.
Spirostreptus bowringii Pocock, 1892 “ Type’
Journ. Lin, Soc, 24 : 321.
Siam. Bowring. Reg. No. 1960.2.2.1,
3: 59 segments,
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
ALY a
i
Fics. 1-5. Spivostreptus bowringii Poc. Fig. 1. Gonopodes, face antérieure. Fig. 2.
Gonopodes, face postérieure. Fig. 3. Hanche, profil externe. Fig. 4. Télopodite.
Fig. 5. Extrémité du télopodite.
ZOOL. 7, 2 14§
146 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Collum a lobe en angle droit, étroit, 4 bourrelet 4 peu prés régulier. 4 a 5 plis
sur la surface y compris quelques griffures au bord postérieur.
Sternite du dernier segment entiérement libre.
Cavité stigmatique allongée.
Soles sur les deux avant-derniers articles de la 3éme paire a la dernieére.
GONOPODES 4 sternite triangulaire de grande surface, 4 angles arrondis.
Feuillet coxal postérieur (fig. 1) étroit 4 la base puis brusquement élargi par
un épanouissement en palette incliné vers l’intérieur. Bord externe, d’abord droit
en partant de la base, s’inclinant fortement vers l’intérieur et portant, a la partie
supérieure, un grand nombre de petites dents aigués. Lobe interne échancré en
demi-cercle sur son bord dessinant ainsi une large denticulation et un angle
robuste dirigé distalement, 4 bord finement dentelé. Le lobe dentiforme se super-
pose a son homologue en se croisant.
Feuillet coxal antérieur débutant, en avant, par une large piéce dont l’angle
externe est souligné par une forte protubérance arrondie et élevée. Bord latéral du
feuillet, constituant les lévres de l’orifice de la gaine coxale, se retournant vers l’arri€re,
en s€paississant, face postérieure, en un large bourrelet arrondi, recourbé vers la
base de l’organe puis s’amincissant en épaisse lamelle latérale interne qui s’incline
vers l’orifice de la gaine coxale en une sorte de tablier horizontal avant de rencontrer
le feuillet précédent (figs. 2 et 3).
Télopodite (figs. 4 et 5) court et épais. Branche montante €paissie, a sa
sortie de la gaine coxale, par un bourrelet horizontal, en forme de haricot, de l’avant
duquel jaillit une trés longue épine fémorale courbée vers l’arriére dans le méme plan
que l’épaississement et pourvue de plis hélicoidaux a la face inférieure. Télopodite
étranglé aprés l’angle postérieur du bourrelet qui est en quelque sorte la limite du
fémur et recourbé vers la base de l’organe puis brusquement épanoui en lame com-
plexe a partir d’un puissant talon. Aréte interne, dans le sens de la courbure, pro-
jetant une trés longue épine tibiale gréle recourbée en arc de cercle et remontant vers
la grande courbure.
Extrémité distale du membre (fig. 5) élargie en plage arrondie portant, a
son extrémité, l’orifice du canal séminal entouré d’une dizaine d’épines de grosseurs
progressives. Bord lamellaire de cette plage retourné sur lui-méme, sinueux, en
forme de S donnant naissance a une petite plage moyenne située au-dessus de l’épa-
nouissement distal, sous l’épine tibiale et dessinant, avec elle, une large gouttiere par
son mouvement hélicoidal. Axe longitudinal de la face inférieure de la plage distale
principale soulevé en une lamelle hyaline a bords sinueux et plus ou moins rabattue
a laquelle se rattache une deuxiéme formation transversale, plus courte que la pré-
cédente, reliant celle-ci au bord latéral de la gouttieére.
,
Spirostreptus aterrimus Pocock, 1889 “ Type’
Journ. Lin. Soc. 21: 295.
Mergui. Dr. Anderson. Reg. No. 1889.4.24.13.
Aucun type n’était désigné. L’exemplaire examiné étant le seul ¢ de la station
type et le seul disséqué par Pocock nous le considérons comme tel.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Fics. 6-11. Spirostreptus aterrimus Poc. Fig. 6. Gonopode gauche, face antérieure.
Fig. 7. Hanche du gonopode gauche, profil interne. Fig. 8. Hanche droite, profil ex-
terne. Fig. 9. Télopodite. Fig. 10. Télopodite. Fig. 11. Epine fémorale.
147
148 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
6. 67 segments.
Collum 4 lobe en angle obtus. Bourrelet marginal fort. Pas de sillons sur la
surface.
Sternite du dernier segment soudé.
Cavité stigmatique en triangle allongé.
Soles de la 3éme paire de pattes a la derniére sur les deux avant-derniers articles.
Seule la 3éme paire de pattes porte des soles sur |’avant-dernier article.
GONOPODES abimés par |’Auteur. Les deux hanches sont séparées l'une de l’autre
et nous n’ayons pu retrouver le sternite, bien que la trace semble demeurer.
Feuillet coxal postérieur (fig. 6) trés étroit 4 la base et rapidement élargi en
palette vers l’extrémité. Sommet arrondi plus particuliérement a la partie latérale
externe. Portion latérale interne rapidement élevée en angle aigu. Bord latéral
interne du sommet fortement relevé en créte tranchante particuliérement soulignée,
face latérale interne, par un sillon trés profond (fig. 7) se perdant dans le
milieu de la hanche. A cette méme face interne se détache prés du sommet un lobe
épais et arrondi.
Feuillet coxal antérieur élevé et latéralement armé d’une haute et importante
protubérance conique.
Télopodite (figs. 9, Io et 12) trés volumineux, presque aussi volumineux que les
hanches, débouchant au sommet de la gaine coxale.
Dés sa sortie de la gaine coxale la branche montante s’épaissit, devient légerement
globuleuse, se coude en angle droit et s’étale en feuillet recroquevillé en nombreux
plis dans le sens longitudinal et enroulé sur lui-méme en un cercle presque complet.
A partir de la grande courbure, dans la concavité, se différencie un fort épaississement
élevé conduisant la rainure séminale et allant en diminuant de volume jusqu’a
disparaitre prés de l’extrémité. Bord latéral interne replié et épanoui en lobe
subrectangulaire portant une longue et épaisse épine tibiale dont la pointe se dirige
vers l’extrémité du membre, creusée en gouttieére.
On remarque que le bord latéral externe poursuit sa course jusqu’aux épines
distales mais que le bord latéral interne amorce un mouvement hélicoidal tout en
poussant un important processus qui devient globuleux a l’extrémité et dont le
plan est perpendiculaire a l’extrémité du membre portant les épines tout en s’en-
roulant autour de lui. Ilse forme ainsi une gouttiére hélicoidale s’enroulant autour
de l’axe du membre et dont l’un des bords (correspondant au bord latéral interne)
est considérablement aminci en feuillet hyalin.
Grande courbure du télopodite surmontée d’une épine particuliérement développée,
pliée a sa base en angle droit et se dirigeant face latérale interne. Pointe de cette
épine trés aplatie et pliée sur elle-méme (fig. 11).
Thyropygus weberi Pocock, 1894 “‘ Type”’
Max Weber—Zool. Ergeb. III : 382.
Alahang Pandjang. Reg. No. 1896.10.6.76.
6. 67 segments.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 149
Fics. 12-16. Spivostreptus aterrimus Poc. Fig. 12. Télopodite. Thyropygus weberi
Poc. Fig. 13. Gonopodes, face antérieure. Fig. 14. Télopodite de profil. Fig. 15,
Télopodite. Fig. 16. Extrémité distale du télopodite.
150 LES TYPES D’HARPAGOPHORIDAE DE R. 1, POCOCK
Collum a angle antérieur du lobe saillant légérement. Bourrelet marginal normal.
I a 2 rides sur la surface et quelques griffures prés du bord postérieur.
Sternite du dernier segment complétement soudé.
Cavité stigmatique tres allongée latéralement.
Soles sur les deux avant-derniers articles de la 3éme paire de pattes a la derniére.
Seule la 3€me paire de pattes porte une sole sur l’avant-dernier article.
GONOPODES 4 sternite triangulaire avec une large dépression verticale médiane.
Sillons de la surface profonds.
Feuillet coxal postérieur (fig. 13) étroit 4 la base s’évasant brusquement en
palette triangulaire large. Bordinterne droit. Bord externe largement prolongé par
un processus tres développé latéralement. Sommet en pointe aigue. Surface anté-
rieure finement et profondément striée particuliérement dans les angles.
Feuillet coxal antérieur muni d’une gorge délimitant un bourrelet conique.
Télopodite (figs. 14 et 15) large et spiralé 4 base pourvue, a sa sortie du
fourreau coxal, d’une grosse épine fémorale longue et épaisse, 4 pointe avec talon
proximal, cannelée face inférieure. Epine recourbée en demi-cercle vers |’intérieur.
Le membre est complétement recourbé vers le bas a partir de l’épine fémorale,
tout en s’élargissant et s’amincissant en plage pour se terminer en une mince feuille
dont le bord latéral s’enroule pour former une large gouttiére tout en se recourbant
a nouveau en fer 4 cheval. Extrémité distale du bord de ce feuillet se continuant
sous l’extrémité du membre, passant sur la face opposée de cette extrémité pour se
souder a elle. Examinée de face (fig. 15) cette portion complexe a la forme
générale d’une gouttiére, constituée par le bord lamellaire hyalin, dans laquelle se
couche l’extrémité proprement dite du télopodite qui est elle-méme lamellaire a
l’exception du bord épaissi qui conduit la rainure séminale et de son embouchure
entourée des épines classiques (fig. 16).
Portion moyenne du télopodite (fig. 14), sous la grande courbure, fortement
différenciée en lame épaisse, subrectangulaire face postérieure, 4 angle antérieur
arrondi, fortement saillant vers l’arriére et denticulé. Portion inférieure concave
enroulée en cornet. Sur la face opposée est plantée une large et longue épine tibiale
en angle droit, de méme direction que le membre.
Le télopodite présente de nombreuses sinuosités et mouvements de torsion qui lui
donnent un aspect tourmenté.
Thyropygus rubrocinctus Pocock, 1894 “‘ Type”
Max Weber—Zool. Ergeb. III : 382.
Paningaham. Reg. No. 1896.10.6.75.
g. 66 segments.
Collum avec un large bourrelet marginal. Pas de sillons sur la surface.
Sternite du segment terminal entiérement soudé. Valves (fig. 22).
Soles sur les deux avant-derniers articles de la 3¢me paire de pattes a la derniere
(les 2 derniéres paires de pattes sont absentes). 3éme paire de pattes avec sole seule-
_ment sur l’avant-dernier article.
Pores répugnatoires débutant sur le 6¢me segment.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
A
An
a
MN
Ww
Fics. 17-22. Thyropygus vubrocinctus Poc. Fig. 17. Gonopodes, face antérieure. Fig.
18. Gonopodes, face postérieure. Fig. 19. Hanche gauche, profil externe. Fig. 20.
Télopodite. Fig. 21. Télopodite. Fig. 22. Extrémité postérieure du corps. a. épais-
sissement du télopodite, b. épine tibiale, 7. lobe du télopodite.
152 LES TYPES D/ HARPAGOPHORIDAE DE RR. ft; (POCOCK
GONOPODES 4 sternite complétement soudé a la base des feuillets coxaux et por-
tant des traces de division sous forme d’un sillon vertical profond. Le sternite n’est
indiqué en quelque sorte que par un relief un peu plus accusé et une couleur diffé-
rente. Cette région proximale est finement striée longitudinalement.
Feuillet coxal postérieur (fig. 17) étroit jusque prés de la moitié puis brusque-
ment épanoui latéralement en une large palette triangulaire. Les angles latéraux
externes sont particuliérement développés et allongés. Sommet sinueux et arrondi.
La partie supérieure du feuillet est entiérement épaissie face postérieure et forme
une sorte de plateforme en cuvette (fig. 18) qui se raccorde d’une part a l’angle
externe de la palette et d’autre part au feuillet suivant. Orifice de la gaine coxale
(figs. 18 et 19) arrondi, a lévres fortement saillantes en arriére et latéralement
tout en se redressant vers le haut. Cet orifice, juste suffisant pour laisser passer le
télopodite, est en quelque sorte constitué par les feuillets coxaux enroulés en cornet
et c'est l’angle externe du feuillet postérieur qui fait largement saillie.
Feuillet coxal antérieur (fig. 18), face antérieure, volumineux et large, presque
aussi haut que le précédent et creusé au sommet d’une profonde rigole déterminant
une saillie conique latérale.
Télopodite trés complexe et volumineux (figs. 20 et 21). Dés sa sortie de la
gaine coxale, ot il est a peine libre, il se recourbe en angle droit s’épaississant con-
sidérablement tout en poussant, vers le haut, une trés importante épine recourbée
en crochet vers l'intérieur. A la moitié environ de sa longueur, face antérieure, une
pointe secondaire aigue se développe vers le bas. A partir de la grande courbure le
membre s’amincit en feuillet, demeurant encore relativement épais, dont les bords se
recourbent en gouttiére tout en s’enroulant en spirale. On remarque, face inférieure,
un petit talon (a) arrondi, peu important auquel fait suite, cdté latéral externe, une
excroissance lobiforme (e) creusée en cuillére, de forme triangulaire, 4 sommet aigu.
Le bord opposé a la pointe, dans l’axe du corps, reste épais et sinueux et porte a la
portion inférieure une longue et robuste épine coudée en angle droit (6) dont la
pointe se dirige vers l’extrémité du membre. Extrémité distale du télopodite en
feuillet aminci, enroulé en gouttiére. Le bord latéral, celui conduisant la rainure
séminale, continue son mouvement helicoidal et passe sur le bord opposé latéral interne
auquel il vient se souder. En examinant de face l’extrémité du membre on re-
marque ainsi un feuillet mince en gouttiére dans lequel repose et avec lequel il se
soude, le bord épais conduisant Ja rainure séminale.
Spirostreptus everettii Pocock, 1892 “‘ Type”’
Journ. Linn. Soc. 24 : 324.
N.W. Bornéo. R. Everett. Reg. No. 1888-122.
3. 66 segments.
Collum en angle droit avec un large bourrelet. Pas de sillons sur la surface.
Sternite du dernier segment entiérement libre.
Cavité stigmatique allongée.
Soles sur les deux avant-derniers articles de la 4éme paire de pattes a la derniére
- (les 5 dernieres paires de pattes sont absentes).
Pores répugnatoires débutant au 6€me segment.
LES TYPES D’HARPAGOPHORIDAE DE R. I, POCOCK 153
Fics. 23-27.
ZOOL. 7, 2.
Spirostreptus everettii Poc.
Fig. 23. Gonopodes droit, face antérieure.
Fig. 24. Sommet des gonopodes, face postérieure. Fig. 25. Télopodite. Fig. 26. Télo-
podite. Fig. 27. Extrémité du télopodite. a et b arétes, e. épine tibiale.
14§§
154 LES TYPES D’'HARPAGOPHORIDAE DE R. I. POCOCK
GONOPODES 4 sternite triangulaire profondément sillonné, avec une dépression prés
du bord postérieur.
Les organes génitaux sont légérement abimés, la hanche droite est cassée.
Feuillet coxal postérieur trés étroit (fig. 23) 4 la base puis rapidement épanoui
en une large palette 4 sommet arrondi, armé d’une pointe aigue recourbée en crochet
vers l’intérieur lui donnant une forme de téte d’oiseau. Aréte interne, sous le
crochet, verticale, considérablement amincie, translucide, lobiforme au sommet.
Surface du feuillet creusée d’une profonde dépression oblique délimitant la base de la
palette.
Feuillet coxal antérieur subrectangulaire, épais 4 la base, avec, dans le milieu, une
faible dépression. Face postérieure (fig. 24), au niveau de la soudure avec le
feuillet précédent, il est profondément échancré et orné coté latéral externe d’une
protubérance conique 4 pointe aigue.
Télopodite (figs. 25 et 26) simple, progressivement courbé a sa sortie de la
gaine coxale, 4 extrémité considérablement épanouie en palette arrondie, légérement
recourbée. Face inférieure de cette palette en cuillére, face postérieure fortement
bombée (fig. 26) de ce fait et surmontée d’une longue aréte de chitine trans-
lucide (a). Le fond de la dépression présente une longue créte longitudinale (0)
(figs. 25 et 26). De la base de la palette issue de ]’étranglement, limitant cette
palette du reste du télopodite, une longue et large épine 4 pointe trés aigue (@).
Face inférieure, 4 la base de l’épanouissement en cuillére, on remarque un important
processus globuleux terminé par une pointe aigué fortement colorée (figs. 26 et
27). Ce processus est une véritable ampoule dont l’extrémité distale est munie
d’une ouverture semi-circulaire 4 bords déchiquetés.
Spirostreptus hosei Pocock, 1892 “ Type”’
Journ. Linn. Soc. 24 : 323.
Bornéo. Reg. No. 1889.8.5.11.
6. 70 segments.
Lobe du collum avec angle antérieur obtus et angle postérieur saillant en arriere.
Pas de sillons sur la surface.
Sternite du dernier segment complétement soudé.
Cavité stigmatique allongée.
Soles sur les deux avant-derniers articles de la 4¢me paire de pattes a la dernieére.
GONOPODES 4a sternite en triangle de grande surface, 4 angles arrondis. Des stries
longitudinales.
Feuillet coxal postérieur (fig. 28) trés étroit a la base puis rapidement élargi
vers le haut. Sommet en large palette subarrondie, en feuillet mince, soulignée a
la base, prés de l’aréte interne, par une profonde échancrure. Cd6té interne tres
large pres de la palette distale qui se soude dans son milieu.
Feuillet coxal antérieur considérablement développé, pas trés étalé latéralement et
bas. Une profonde dépression sur ce sommet délimitant un petit bourrelet latéral.
Face postérieure (fig. 29) le feuillet est trés élevé atteignant les ? de la longueur
du feuillet précédent. Sommet pointu, en tronc de cone. i
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 155
Fics. 28-33. Spirostreptus hosei Poc. Fig. 28. Gonopodes, face antérieure. Fig. 29.
Gonopodes, face postérieure. Fig. 30. Télopodites. Spirostreptus baluensis Poc.
Fig. 31. Gonopodes, face antérieure. Fig. 32. Hanche, profil externe. Fig. 33. Télo-
podite. c. lamelle du télopodite, d. denticulation distale.
156 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Télopodite (figs. 29 et 30) court et large, progressivement recourbé a sa
sortie de la gaine coxale. Une petite épine fémorale en crochet sur la courbure.
Extrémité distale largement étalée en palette semi-ronde dont la pointe, légére-
ment allongée, se recourbe sur elle-méme et porte les épines classiques. Coté latéral
du membre, a sa sortie de la gaine coxale, élargi en lame qui se replie sur la face
postérieure du membre et adopte une forme en serpe. Chaque angle porte une
épine d’importance différente. L’épine latérale externe robuste, courte et épaisse,
lépine latérale interne, au contraire, gréle, trés allongée et sa pointe dirigée vers le
sommet des hanches. Face inférieure on remarque une longue créte hyaline (c),
épaisse, longitudinale et légérement oblique, sous l’épanouissement distal.
Spirostreptus baluensis Pocock, 1892 “‘ Type”’
Journ. Linn. Soc. 24: 326.
Mt. Kina Balu, Bornéo. Whitehead. Reg. No. 1960.2.2.2.
6. 67 segments.
Collum a lobes en angle droit tres arrondi. Bourrelet marginal étroit. Quelques
courtes griffures prés du bord postérieur.
Sternite du dernier segment soudé.
Cavité stigmatique triangulaire, allongée.
Les gonopodes sont en mauvais état et les deux hanches droite et gauche ont été
légérement écrasées 4 la base et séparées l’une de l’autre. I] nous a donc été im-
possible de donner une figure exacte de l’orifice de la gaine coxale et de la forme des
gonopodes face postérieure. Néanmoins la figure telle que nous la publions est
suffisante pour reconnaitre l’espéce.
GONOPODES 4 sternite triangulaire tres étroit et allongé avec un sillon longitudinal
médian.
Feuillet coxal postérieur (fig. 31) a bords latéraux a4 peu pres paralléles, a
peine sinueux ; long et étroit, 4 sommet en pointe aigue recourbée en crochet vers
lintérieur. Les deux pointes se font face. Surface a peu prés lisse sans dépression
particuliére. Face latérale interne creusée d’une profonde rigole triangulaire
(fig. 32) servant de logement a la branche montante, trés épaisse et sinueuse du télo-
podite.
Feuillet coxal antérieur peu développé en largeur et en hauteur. Latéralement
la portion supérieure est creusée d’une gorge profonde. Face postérieure le bord
supérieur est épaissi en un bourrelet limitant l’orifice de la gaine coxale. Nous
n’avons remarqué aucune protubérance conique particuliére.
Télopodite (fig. 33) court et trapu, 4 extrémité largement étalée en palette
subcirculaire, pliée vers l’arriére et enroulée sur elle-méme. Extrémité distale de
cette palette armée d’une large denticulation (d) se dressant perpendiculairement et
située a proximité de l’orifice de la rainure séminale. Au niveau d’un rétrécissement
marquant le début de la palette distale, on remarque une robuste épine aigué. Face
inférieure, sous l’épine, fortement épaissie le long du bord.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
(
Mp y
OQ,
Yili
Fics. 34-38. Spivostreptus dulitianus Poc. Fig. 34. Gonopodes, face antérieure. Fig.
35. Extrémité distale des gonopodes, profil interne. Fig. 36. Télopodite. Fig. 37.
Télopodite, profil. Fig. 38. Extrémité du corps. 4. lobe du télopodite.
oH)
158 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Membre réguliérement arqué, épais 4 la base et brusquement gibbeux au niveau
de l’épanouissement distal. Cette gibbosité porte deux robustes épines distales
recourbées vers l’extérieur latéralement et une microscopique denticulation a la
partie latérale interne au méme niveau que l’épine proximale de la palette. Une
épine fémorale épaisse et courte.
Spirostreptus dulitianus Pocock, 1892 “‘ Type”’
Journ. Linn. Soc. 24 : 325.
Mt. Dulit. C. Hose. Reg. No. 1892.5.29.4.
Aucune mention particuliére ne désignait ce Myriapode comme type mais nous le
considérons comme tel car un seul exemplaire de cette espéce a été capturé et par
conséquent il ne peut s’agir que du Type.
3g. 68 segments.
Collum a lobe en angle droit, 4 bourrelet marginal étroit. Pas de stries sur la
surface.
Sternite du dernier segment entieérement soudé. Valves (fig. 38.)
Cavité stigmatique en triangle allongé.
Pas de soles sur les pattes ambulatoires.
GONOPODES 4a sternite triangulaire petit.
Feuillet coxal postérieur (fig. 34) étroit et élancé, progressivement aminci en
pointe et 4 sommet recourbé vers l’intérieure, en faucille. Sommet mince, lamel-
laire, 4 bord interne tranchant. Face postérieure épaisse dans la concavité de la
courbure et relevée en lamelle épaisse placée transversalement par rapport au plan
du feuillet (fig. 35).
Feuillet coxal antérieur large et peu élevé, muni d’une large gouttiére arrondie,
profonde, déterminant deux saillies bossues, latérale et interne, tout contre le feuillet.
Ce bourrelet interne constitue le bord latéral externe de l’orifice de la gaine coxale et
face postérieure se détache en tronc de céne.
Télopodite (figs. 36 et 37) sortant latéralement, court et complexe. Forme
générale ramassée 4 extrémité épanouie en lamelle discoidale. EExaminée de profil
cette lamelle est recourbée sur elle-méme (fig. 37), enroulée, tandis que ses bords
latéraux se replient légérement vers le dessous. A la naissance de |’épanouissement
un long processus vaguement rectangulaire dirigé vers l’intérieur (a, figs. 36 et 37).
Télopodite avec une robuste épine fémorale crochue. Le long de son parcourt on
remarque un fort épaississement longitudinal, comme chez heteruvus, auquel fait
suite une large piéce libre armée de 4 épines robustes (fig. 36). Cette piece et
la lamelle latérale interne (a) rejoignent presque l’extrémité du télopodite pour
former une sorte d’anneau.
Thyropygus anurus Pocock, 1896 “ Cotype ’”
Ann. Mus. Civ. St. Nat. Genova, 16 : 349.
- Kaibii hills. Reg. No. 1895.11.10.59.
Malgré nos recherches nous n’avons pu retrouver le type de cette espéce.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 159
=
< ~ Ss \
(Ce—~ —* sine )
{om
A we IN ae > ay
Figs, 39-43. Spirostreptus anurus Poc,
Gonopodes, face postérieure.
Fig. 39. Gonopodes, face antérieure. Fig. 4o.
télopodite. Fig. 43. Collum.
Fig. 41. Télopodite. Fig. 42. Extrémité distale du
ZO Gd: épines du télopodite, 7. lamelle.
160 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
3. 70 segments.
Collum a lobe développé vers le bas. Bourrelet marginal volumineux et large
(fig. 43).
Sternite du dernier segment libre.
Cavité stigmatique triangulaire.
Soles sur les deux avant-derniers articles de la 3éme paire de pattes a la derniére.
GoNOPODEs 4 sternite triangulaire 4 angles arrondis. Surface lisse.
Feuillet coxal postérieur (fig. 39) trés étroit 4 la base et progressivement étalé
en palette vers l’extrémité. Bord interne trés fortement échancré au sommet pro-
duisant, a la base de l’échancrure, une petite dent mousse. A l’opposé de cette dent
une longue épine mince recourbée vers le bas continuant le bord supérieur du feuillet.
Surface fortement déprimée en cuillére et plus ou moins striée-striolée.
Feuillet coxal antérieur (fig. 40) trés volumineux, peu développé en largeur,
mais surtout en hauteur. Prés de l’extrémité on constate un brusque rétrécissement
correspondant au passage du feuillet face postérieure. Bord supérieur, oblique vers
l’extérieur, trés mince et découpé en deux dents larges et a pointe arrondie.
Télopodite (figs. 40 et 41) volumineux et complexe. Dés sa sortie de la
gaine coxale le membre pousse une gibbosité trés volumineuse, s’étale en feuillet
épais et se replie sur lui-méme tout en se courbant en angle aigu. Gibbosité de la
grande courbure en forme de croissant dont la pointe antérieure pousse une volumi-
neuse €pine bifide développée horizontalement et dans le sens circulaire coté interne-
cété externe et dont l’une des pointes (a) est au moins trois fois moins longue que
l'autre (6). Pointe postérieure saillant en une large épine denticulaire (c) dont la
racine est noyée dans le repli du membre. Sommet du processus avec une 4éme
épine (d) robuste, légérement recourbée vers |’intérieur.
A partir de la pliure le membre s’étale (fig. 41) en un épais et large lobe
latéral arrondi, dont le bord conduit la rainure séminale. Aprés un étranglement du
bord et un léger mouvement helicoidal l’extrémité se recourbe en crochet et se creuse
en un profond bonnet. Extrémité distale (fig. 42) épaissie et portant en son
centre un petit appendice séminal recourbé en angle droit planté de 20 a 25 épines
translucides. Sur le bord externe, 4 cété du rameau séminal, une longue lamelle (/)
chitineuse horizontale pointue issue du bord et de méme longueur que le rameau.
Spirostreptus oatesii Pocock, 1893 “‘ Type’
Ann. Mus. Civ. St. Nat. Genova, 13 (33) : 404.
Double Island. Reg. No. 1892.5.4.113.120.
6. ? segments.
Collum avec lobes en angle droit et un large bourrelet. 4 4 5 gros plis sur la
surface venant buter contre le bord marginal.
Sternite du dernier segment libre.
Cavité stigmatique triangulaire.
. Soles sur les deux avant-derniers articles de la 3éme paire de pattes a la derniére.
Pores répugnatoires débutant au 6¢me segment.
LES TYPES D'HARPAGOPHORIDAE DE R. I. POCOCK 161
Fics. 44-48. Spivostreptus oatesii Poc. Fig. 44. Gonopodes, face antérieure. Fig. 45.
Gonopodes, face postérieure. Figs. 46, 47, 48. Télopodite. a. épine fémorale, 6, d, if
€pines tibiales, i. gibbosité du télopodite.
162 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Nous avons trouvé un bocal contenant plusieurs individus ¢ et 2 mais un seul a
été disséqué parl’Auteur. Les gonopodes, encore attachés au segment, se trouvaient
dans un tube de verre. Manifestement c’est cette piece qui a été décrite par R. I.
Pocock et nous la prenons comme type.
Il nous a été impossible de reconstituer le corps de l’animal les fragments de
plusieurs exemplaires étant mélangés.
GoONOPODES 4 sternite triangulaire.
Feuillet coxal postérieur (fig. 44) de forme a peu pres identique a celui de
tavoiensis mais la portion proximale est plus étroite et le sommet de la palette légére-
ment acuminée. Face postérieure, la lamelle limitant la face interne de l’orifice de
la gaine coxale est beaucoup plus étroite. On remarque de plus que le bord interne
de la fusion des deux feuillets coxaux est plus lobiforme que chez favoiensis et se
recourbe nettement vers l’orifice de la gaine coxale.
Feuillet coxal antérieur (fig. 45) de forme 4 peu prés identique également a
celle de tavoiensis mais beaucoup plus volumineux. Face antérieure, on reconnait
une portion inférieure nettement délimitée par une profonde dépression de la surface
du feuillet. Cette portion inférieure est elle-méme fortement échancrée et posséde,
tout contre la base du feuillet précédent, une forte excroissance lancéolée. Portion
supérieure s’élevant considérablement et brusquement tout en se courbant vers
l’arriére développant une énorme excroissance dirigée latéralement horizontalement.
Extrémité globuleuse de cette excroissance légérement en crochet. Bord antérieur
du feuillet fortement sinueux face postérieure. Face latérale interne, l’extrémité de
ce bourrelet en balcon est limitée par une profonde échancrure en V.
Télopodite proche de celui de tavoiensis mais beaucoup plus simple. Grande
courbure, en angle aigu, portant une minuscule épine fémorale (a, figs. 46-47
et 48). A partir de cette grande courbure le membre se différencie et développe un
robuste tronc, gibbeux par endroit. Face inférieure, au niveau de la cassure, une
gibbosité (7) importante, allongée et dirigée obliquement vers le bas, fortement
étranglée 4 sa base pour abriter une longue épine (f). Cette épine est issue du bord
latéral interne du feuillet distal, elle rencontre, face inférieure, une seconde épine
beaucoup plus longue (d) et toutes deux s’insérent au niveau de la grande courbure.
Milieu du feuillet distal armé d’une troisiéme épine (0) plus courte, recourbée en
crochet et disposée face latérale externe. Extrémité distale du télopodite étalée
largement en un feuillet mince dont le lobe latéral interne est arrondi et épaissi. Lobe
latéral externe conduisant la rainure séminale qui débouche dans une sorte de cuvette
profonde densément colorée et dont le bord est un cercle presque parfait. A coté
de cet orifice une petite lamelle hyaline. Les deux lobes du feuillet distal se re-
courbent vers le bas formant une large gouttiére rectiligne (fig. 48). Dans le
fond de cette gouttiére, au sommet d’un soulévement chitineux, une haute créte
hyaline (z) 4 bord trés découpé. Cette aréte se développe dans le sens longitudinal
et atteint presque la gibbosité de la base de la grande courbure.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
prem
\
iy,
Ie , Ze,
WY
Fics. 49-54. Spirostreptus tavoiensis Poc. Fig. 49. Gonopodes, face antérieure. Fig.
50. Gonopodes, face postérieure. Figs. 51, 52, 53, 54. Télopodite. a. talon de l’extré-
mité du télopodite, b. feuillet séminal, c. feuillet distal avec épine, d, e, f, g, 7. épines
fémorales, h. aréte lamellaire, 7. gibbosité du télopodite.
163
164 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Spirostreptus tavoiensis Pocock, 1893 “‘ Type’
Ann. Mus. Civ. St. Nat. Genova, 13 (33) : 405.
Reef Island. (Tavoy.) Reg. No. 1892.3.4.102.112.
6. ? segments.
Collum comme oafesii mais 4 angle antérieur un peu plus aigu.
Sternite du dernier segment entiérement libre.
Cavité stigmatique triangulaire.
Soles sur les deux avant-derniers articles de la 4éme paire de pattes a la derniére.
Pores répugnatoires débutant au 6¢me segment.
Nous avons trouvé un seul bocal contenant plusieurs individus J et 2? mais aucun
“type ’’ n’est désigné. Parmi les nombreux troncons contenus dans ce bocal, nous
avons découvert un tube de verre qui renfermait 3 segments dont le segment gono-
podial. Manifestement ces segments avaient été écartés pour examiner les gono-
podes. Nous pensons ne pas faire une grande erreur en annongant qu'il s’agit des
organes génitaux examinés par l’Auteur et par conséquent ceux du type. C’était
d’ailleurs le seul exemplaire disséqué. Le fait que ces organes n’étaient pas détachés
des segments n’est pas particulier car la systématique de l’époque n’exigeait pas un
examen approfondi, le seul dessin des feuillets coxaux postérieurs suffisait. De plus
R. I. Pocock n’a pas figuré les gonopodes dans son travail mais la description cor-
respond dans tous ses détails.
Les segments génitaux étant seuls isolés, le reste du corps mélangé aux autres
individus, nous n’avons pu vérifier le nombre des segments.
GONOPODES 4 sternite triangulaire.
Feuillet coxal postérieur étroit (fig. 49) 4 la base puis progressivement élargi
en une vaste palette simple, arrondie au sommet. Surface fortement déprimée dans
la moitié antérieure et profondément striée. Stries irréguliéres. Face postérieure,
Vorifice de la gaine coxale est limitée, cété interne, par une lamelle hyaline élevée
(, (fig. 50). Cet orifice est d’ailleurs placé trés bas latéralement. Bord interne
du balcon échancré (e, fig. 55).
Feuillet coxal antérieur (figs. 49 et 50) volumineux et bien développé latérale-
ment, découpé en deux portions, antérieure et postérieure, par une profonde rigole
faisant tout le tour de la piéce 4 mi-hauteur. Premiére partie basse, développée
latéralement. Seconde partie s’élevant progressivement tout en s’élargissant et
prenant la forme d’un entonnoir trés évasé. Bord €paissi et arrondi délimitant
lorifice de la gaine coxale, face postérieure, par un large balcon saillant et droit.
Télopodite volumineux, court et trés complexe. La hampe montante ne se re-
courbe pas immédiatement mais s’éléve jusqu’a l’extrémité de la lamelle du feuillet
coxal postérieur (/) puis se courbe brusquement en angle aigu tout en devenant
gibbeux. A ce niveau (figs. 51, 52, 53 et 54) et face latérale externe, jaillissent
deux épines g et 7 dont la premiére, la plus longue, s’éléve verticalement tandis que
la seconde s’applique étroitement contre le membre. A partir de la grande courbure
le membre se replie latéralement tout en s’amincissant et developpe deux processus
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 165
Fics. 55-59. Spirostreptus tavoiensis Poc. Fig. 55. Hanche gauche des gonopodes, pro-
fil externe. Spirostreptus patricii Poc. Fig. 56. Gonopode droit, profil externe.
Fig. 57. Gonopode droit, face postérieure. Fig. 58. Extrémité du télopodite. Fig.
59. Extrémité postérieure du télopodite. a. lamelle supérieure, b. lamelle inférieure.
166 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
lamellaires (0 et c), dont l’un conduit la rainure séminale, qui se font face comme les
machoires d’une paire de tenailles et se développent horizontalement. Lamelle
supérieure (c) poussant un lobe latéral externe et se terminant par une longue épine
gréle. A sa base, un peu au-dessous, face latérale interne se place un processus por-
tant trois épines dont l'une, la supérieure, est longue et se dichotomise en deux
pointes, une trés longue (d) et une petite (e) placée non loin de la racine. La direction
de cette pointe bifide est celle du membre. La troisiéme épine (f), par contre, pousse
sa pointe vers le bas et prend naissance sur le tronc du processus. Cette épine (f)
est couchée et en partie dissimulée entre une grosse gibbosité de la lamelle inférieure
(7) et le talon de celle-ci. Lamelle inférieure épaisse cété latéral interne (coté rainure
séminale) mais trés amincie et translucide, lobiforme, cété latéral externe. La
partie proximale de cette lamelle est toutefois considérablement €paissie et pousse
un large processus gibbeux, récurrent (a). Face latérale interne, entre les deux la-
melles, une petite créte hyaline plantée verticalement (/).
,
Spirostreptus patricii Pocock, 1892 “ Type’
Journ. Linn. Soc. 24 : 323.
Batavia. Kirkpatrick. Reg. No. 1891.4.30.8.
g. ?segments. Corps brisé en plusieurs trongons et écrasé.
Collum a angle antérieur un peu saillant. Bourrelet marginal épais dans l’angle.
3-4 plis et griffures légeres.
Sternite du dernier segment libre.
Cavité stigmatique allongée.
Soles sur les deux avant-derniers articles de la ? paire de pattes (pattes antérieures
absentes) a la derniére.
x
GONOPODES ramassés a sternite en triangle isocéle 4 pointe arrondie. Surface
irréguliérement sillonnée.
Feuillet coxal postérieur 4 bord interne vertical. Bord externe légérement
épanoui latéralement en palette amincie au sommet qui dessine une large plage
arrondie en cuillére recourbée vers l’arriére. Face postérieure le lobe distal est
muni, dans sa concavité, d’une lamelle verticale le partageant en deux parties.
Feuillet coxal antérieur (figs. 56 et 57) en une large piéce creusée, face anté-
rieure, d’une profonde gorge se continuant vers l’arriére. Face postérieure, feuillet
large, étranglé 4 la base par la gorge venant de la face antérieure et au-dessus de
laquelle la piéce est gibbeuse et se termine en lobe cylindrique coiffé d’une raquette
globuleuse, trés volumineuse fortement rabattue vers le feuillet postérieur et incliné
vers la face externe (fig. 56).
Télopodite (figs. 56 et 57) épanoui en lame épaisse allongée, subrectangulaire,
dés sa sortie de la gaine coxale et munie d’une saillie en pointe émoussée. Cette
lame est rabattue, transversalement, sur le feuillet coxal antérieur entre la gibbosité
_ externe et la lamelle en raquette. Prés de l’orifice de la gaine une épine fémorale
sinueuse gréle et courte dissimulée derriére la raquette du feuillet. Au-dela de la
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 167
Fics. 60-65. Spirostreptus centrurus Poc. Type. Fig. 60. Télopodite.
Extrémité distale du télopodite. Fig. 63. Lobe collaire.
Fig. 64. Gonopodes, face antérieure.
Figs. 61, 62.
Exemplaire de M. P. Remy.
Fig. 65. Hanche droite, face postérieure.
168 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
grande courbure le membre s’épanouit en plage subrectangulaire portant a son
origine une épine tibiale mince et allongée. Extémité distale (figs. 58 et 59)
large, découpée en deux lobes. Lobe supérieur subrectangulaire, cannelé transver-
salement portant 6 a 8 épines. Lobe inférieur en lamelle hyaline enroulée sur elle-
méme en gouttiére et saillant du reste du télopodite. Le feuillet le plus externe se
continue en aréte perpendiculaire sur la surface supérieure de la plage (a). Face
inférieure on remarque une deuxiéme lamelle (6), homologue, prenant naissance sur
la surface inférieure prés du bord interne et aboutissant sur la surface inférieure du
feuillet le plus interne de la gouttiére distale, face latérale. Bord du feuillet souligné
d’une bande de couleur brun-rouge foncé.
Spirostreptus centrurus Pocock, 1982 “ Type”
Journ. Bombay Nat. Hist. Soc. 7: 162.
Ceylan. Holdsworth. Reg. No. 1960.2.2.3.
Nous avons trouvé un exemplaire sec de cette espéce, disséqué et ne portant
aucune mention “‘type’’. Pour nous il s’agit réellement du type.
Les organes génitaux disséqués et secs ont été brisés notamment les hanches dont
le sommet a complétement disparu.
Nous avons fait subir a ]’animal un traitement au phosphate trisodique afin de le
ramollir et donnons ci-dessous la description des organes tels que nous les avons
trouvés. Les télopodites étaient intacts et nous les représentons ici.
Nous compleéterons la description et figurerons les hanches des gonopodes 4 l'aide
d’un exemplaire de méme espéce que M. le Pr. P. Remy vient de capturer lors de sa
mission aux Indes. Nous le prions de trouver ici ]’expression de toute notre recon-
naissance pour nous avoir permis de faire une étude complete de cette espéce fort mal
connue.
6. 66 segments.
Collum a angle antérieur du lobe fortement saillant. Bourrelet marginal large,
souligné, au niveau de l’angle antérieur, par une trés profonde dépression (Text-fig.
63).
Sternite du segment postérieur libre.
Cavité stigmatique triangulaire.
Soles sur les deux avant-derniers articles de la 3¢me paire de pattes a la derniere.
Pores répugnatoires débutant au 6¢me segment.
GONOPODES.
Feuillet coxal postérieur incomplet.
Feuillet coxal antérieur large et développé latéralement avec une profonde gorge
supérieure déterminant un cone latéral élevé, volumineux. Face postérieure le
feuillet est simple, élevé, 4 sommet taillé en pointe.
Télopodite (figs. 60, 61 et 62) gréle courbé en angle aigu des sa sortie de la
gaine coxale. Au niveau de la grande courbure une longue et €épaisse épine fémorale
droite, dirigée vers le haut. Des la grande courbure le membre se développe en un
large feuillet enroulé en gouttiére. I] est remarquable de noter que les deux bords
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 169
Fics. 66-71. Rhynchoproctus proboscideus Poc. Fig. 66. Gonopodes, face antérieure.
Fig. 67. Gonopodes, face postérieure. Fig. 68. Extrémité du gonopode droit. Fig. 69.
Télopodite. Fig. 70. Extrémité distale du télopodite. Fig. 71. Extrémité postérieure
du corps. a. denticulation de la gaine coxale, b. pointe du tablier, c, d, e. épines du
télopodite, /. lamelle du télopodite.
170 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
latéraux de ce feuillet prennent naissance a la partie supérieure du membre
(fig. 61). Les deux bords divergent dés leur origine et s’enroulent l’un autour de
lautre. Bord latéral externe s’allongeant pour donner naissance 4 un rameau sémi-
nal a bords minces, lamellaires. Bord latéral interne poussant une excroissance
lobiforme concave vers l’intérieur, en cuillére se soudant a la partie inférieure de la
gouttiére qui s’allonge vers l’avant tout en se redressant légérement vers le haut et
portant, latéralement, une gibbosité en amande.
Male récolté par M. le Pry. P. REMY
Ceylan. Jardin de Nuwara Eliya, 2.100 m. altitude. vuiI.59.
70 segments.
Sternite des gonopodes triangulaire, trés étroit 4 la pointe et élevé. Surface
irréguliére.
Feuillet coxal postérieur (fig. 64) étroit, élancé, progressivement élargi en
palette étroite, 4 surface réguliérement stri¢ée. Sommet arrondi. Face postérieure
(fig. 65) a bord latéral externe brusquement recourbé. Surface postérieure du
sommet creusée d’une profonde gouttiére longitudinale dans laquelle se loge la grande
courbure du télopodite surmontée d’une €paisse et longue épine fémorale. La gout-
tiére est entiérement occupée par cet appareil.
Feuillet coxal antérieur (fig. 65) bien développé latéralement saillant a
Vextrémité externe en un cOne large et arrondi. Bord interne, le long du feuillet
précédent, profondément cannelé. Sommet élevé, trés rétréci, muni face postérieure
d’une profonde échancrure déterminant une pointe mousse latérale. Sous 1’échan-
crure une dépression longitudinale en gouttiére.
Rhynchoproctus proboscideus Pocock, 1894 “ Type”’
Max Weber—Zool. Ergeb. I11 : 386.
Luwu (Celebes). M. Weber. Reg. No. 1896.10.6.80.
6. 69 segments.
Collum a lobe en angle droit.
Sternite du dernier segment libre. Segment terminal (Text-fig. 71).
Soles sur l’avant-dernier article de la 3¢me paire de pattes a la derniere.
Cavité stigmatique triangulaire.
GONOPODES Sans sternite.
Feuillet coxal postérieur (fig. 66) trés allongé, étroit, a bords subparalleles,
légérement étranglé prés de l’extrémité. Sommet élargi et courbé vers l’intérieur en
capuchon dirigé vers l’arriére. Surface finement striée dans le sens longitudinal
surtout dans les 2 proximaux. Une profonde rainure sublatérale externe détermi-
nant un épais et large bourrelet longitudinal. Une faible dépression longitudinale
dans le milieu. Sommet ridé. Face latérale externe avec fortes cannelures, prés du
sommet, se continuant face postérieure ot le feuillet dessine un large lobe subtrian-
gulaire rabattu sur l’ouverture de la gaine coxale. Seul le bord latéral externe se
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 17I
développe ainsi en large feuillet. Le bord interne se limite a la face antérieure sans
expansion d’aucune sorte. Face postérieure le sommet est en profond capuchon.
Feuillet coxal antérieur (fig. 67) considérablement moins volumineux et
étroit en forme de fer de lance. Sommet pointu. Postérieurement le bord latéral
externe dessine d’abord une longue protubérance aigueé (a, fig. 68) puis s’échancre
et se développe en hauteur tout en amorcant un léger mouvement de torsion. L’ex-
trémité de ce processus dominant la premiére pointe externe (a) s’étale en une sorte
de balcon disposé horizontalement et enroulé en gouttiére. La portion latérale
externe se développe en une large pointe placée dans la concavité du feuillet posté-
rieur (6) tandis que la portion latérale interne dessine une seconde pointe plus courte.
Télopodite (figs. 69 et 70) long et mince débouchant au dehors entre le pro-
cessus supérieur en balcon et la pointe proximale externe (a). Immédiatement 4
sa sortie le membre se recourbe en angle aigu et porte une longue épine fémorale
entiérement dissimulée en arriére du balcon supérieur. La grande courbure se heurte
également a ce processus.
Extrémité du membre épanouie en un large feuillet de forme légérement hélicoidale
conduisant la rainure séminale le long du bord externe qui se développe exclusive-
ment latéralement. Portion distale de ce feuillet amincie et recourbée en crochet.
Son bord postérieur porte une dizaine d’épines translucides dont les premiéres sont
plus ou moins rassemblées en rameaux. Une (c) récurrente de dimension moyenne
a la base de l’épanouissement distal et deux autres beaucoup plus longues au bord
opposé a cet €panouissement ; une courbe externe (d) un peu en retrait et une trés
longue (e) inerme. L’épine interne (e) est de beaucoup la plus longue, se recourbe en
crochet et la racine se trouve en fait au méme niveau que le bord de la palette distale.
Face inférieure de cette longue épine parcourue dans le sens longitudinal par une petite
lamelle hyaline se heurtant A un petit lobe (2) lamellaire, translucide, planté trans-
versalement par rapport 4 elle.
Spirostreptus vittatus Newport
Détermination de R. I. Pocock. Penang (2.500 pt), S. Flower. Reg. No.
1896.6.20.51.
On ne connait pas de figures des gonopodes de cette espéce, a part celles publiées
par Cari et Pocock. Celles-ci sont par trop imprécises et c’est pour cette raison
que nous publions la description et les dessins des organes génitaux de cet exemplaire.
3g. 80 segments.
Collum a lobe en angle droit légérement saillant. Bourrelet marginal large, beau-
coup plus large au niveau de l’angle. 2 rides environ prés du bord postérieur.
Sternite du dernier segment libre.
Cavité stigmatique triangulaire.
Soles de la 3éme paire de pattes A la derniére sur les deux avant-derniers articles.
Seule la 3éme paire de pattes posséde des soles uniquement sur l’avant-dernier
article.
GONOPODES sans trace de sternite.
172 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Feuillet coxal postérieur large (fig. 72) et haut 4 bords latéraux subparalléles.
Vers le sommet le bord entier s’échancre légérement tandis que le bord distal se
recourbe en crochet vers l’intérieur. Celui-ci est profondément échancré. Face
postérieure le feuillet est en gouttiére dans la moitié distale environ, l’orifice de
cette gouttiére, face latérale interne, faisant vis 4 vis 4 son homologue. Bord latéral
du feuillet, face postérieure (fig. 73) considérablement épanoui en un lobe épais
se repliant vers le bord interne déterminant ainsi une profonde gouttiére s’ouvrant
face interne. Fond de cette gouttiére, vers le sommet de la hanche, soulevée par
une longue aréte se développant progressivement et saillant au dela du bord du
feuillet. Cette aréte produit ainsi 4 l’extrémité de la hanche deux larges encoches
séparées par une longue pointe médiane.
Feuillet antérieur (fig. 73) étroit peu développé latéralement. Face posté-
rieure il se continue par une large denticulation externe et un petit processus en
forme de massue situé contre le bord de l’orifice de la gaine coxale. A ce niveau se
développe, prés du bord latéral interne, un complexe appareil reposant sur un étroit
pédoncule et s’épanouissant en balcon horizontal. Bord postérieur de ce processus
globuleux, épais mais s’amincissant rapidement en feuillet transparent subrectangu-
laire dont le c6té externe et l’angle postérieur s’allongent en pointe ; cette derniére
se glissant sous le bord latéral lobiforme du feuillet coxal précédent. On remarque
une profonde échancrure en V coté latéral interne.
Télopodite (fig. 74) gréle et allongé. Branche montante atteignant le pro-
cessus coxal en balcon avant de se recourber en angle aigu. Grande courbure sur-
montée d’une longue et épaisse épine fémorale qui se dissimule entre le feuillet coxal
postérieur creusé d’une rigole et le processus en balcon. Au dela de la grande cour-
bure le membre s’élargit progressivement, se recourbe en demi-cercle et développe un
large feuillet vaguement triangulaire dont la surface inférieure, prés du bord interne,
porte de nombreuses cannelures élevées. Le long de ce méme bord interne, on ren-
contre une large épine récurrente et une petite denticulation. Extrémité distale
externe (fig. 75) prolongée par un délicat processus acuminé, rabattu vers le
bord opposé. 3 a 4 pines translucides autour de l’orifice de la rainure séminale.
Bord latéral externe, le plus épais, 4 surface inférieure soulevée et armée d’un robuste
processus en forme de faucille s’opposant au processus séminal.
Spirostreptus feae Pocock, 1893 “‘ Type”’
Ann. Mus. Civ. St. Nat. Genova, 13 (33) : 402.
Rangoon. Oates. Reg. No. 1892.5.4.77.78.
Nous avons trouvé dans le bocal marqué “‘type’’ deux individus complets 3 et 2
et un tube de verre contenant des gonopodes isolés qui manifestement sont ceux du
type décrit par Pocock. Ils correspondent exactement a la description publiée.
Ce sont ces organes que nous décrivons et figurons comme type. Les caractéres
de morphologie externe ont été tirés des deux exemplaires g et 9 non disséqués.
Nous devons faire état au sujet de cette espéce d’un grave probleme. En effet,
mous possédons au Muséum National de Paris 3 individus étiquettés feae de la main
de Pocock et portant la mention ‘‘ exemplaire type’’ Palon Birmanie 1885-89.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 173
Fics. 72-75. Spirostreptus vittatus Newp. Fig. 72. Gonopodes, face antérieure. Fig.
73- Gonopodes, face postérieure. Fig. 74. Télopodite. Fig. 75. Extrémité du télopo-
dite.
174 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Viaggio L. FEAE. Ces exemplaires (1 g, 2 9) ont été offerts par l’Auteur a H. W.
BROLEMANN mais il s’avére qu’ils appartiennent a une espéce totalement différente
de celle de Londres (proche de Thyroglutus astutus Att.). Notons que la description
publiée correspond aux exemplaires du British Museum tandis que les gonopodes et
plusieurs caractéres de morphologie externe, notamment le nombre de paires de
pattes et le sternite du segment terminal montrent que les individus du Muséum de
Paris n’ont pas été examinés par l’Auteur bien que les classant feae.
6. 72 segments.
2. 73 segments.
Collum a lobe saillant chez le ¢ (fig. 80) en angle droit chez la 9 (Text-fig. 81).
Sternite du dernier segment pedifére soudé.
Soles sur les deux avant-derniers articles de la 3éme paire de pattes a Ja derniere.
GONOPODES sans sternite.
Feuillet coxal postérieur (fig. 76) large et élancé, étroit 4 la base et épanoui
distalement en palette arrondie a l’extrémité. Les deux hanches sont légérement
tordues vers l’intérieur dos a dos. Surface peu sculptée.
Feuillet coxal antérieur de faible volume, triangulaire face antérieure et médiocre-
ment développé latéralement. Face postérieure le feuillet s’éléve trés rapide ment
vers la bord interne et s’épanouit a son extrémité en un large lobe (figs. 77 et
78) subrectangulaire 4 bords irréguliers rabattus horizontalement vers l’arriére et
recourbé obliquement vers la base des gonopodes. Bord latéral de la lamelle large-
ment et profondément échancré en rond. Prés du bord postérieur, c’est-a-dire celui
faisant face 4 l’observateur, surface profondément déprimée en entonnoir, le bord
lui-méme orné d’une grande Jamelle hyaline verticale dominant la dépression. Cette
dépression est compensée, face inférieure, par une forte boursouflure conique.
Télopodite (figs. 77 et 79) tres simple et gréle a branche montante atteignant
la lamelle du feuillet coxal qui forme toit et se recourbant brusquement en angle
aigu. Epine fémorale de la courbure grande et épaisse, se développant verti-
calement, logée, ainsi que la branche montante, dans une gorge en gouttiére
verticale et dépassant le processus coxal en toit.
Reste du membre long et gréle armé a4 mi-parcours d’une longue et robuste a
dont la pointe se dirige vers le bas.
Extrémité distale du télopodite étalée en une plage hyaline dont le bord est armé
d’une douzaine de pointes transparentes.
Les gonopodes de l’individu 3 a 72 segments présentant une légére différence Jess
la forme de Ja lamelle coxale nous les figurons ici (fig. 82).
Spirostreptus gestri Pocock, 1893 ‘“‘ Type”’
Ann. Mus. Civ. St. Nat. Genova, 13 (33) : 402.
Plapoo. Mt. Mooleyit. Fea. Reg. No. 1895.11.10.54.
Le bocal contenant cette espéce portait l’étiquette Thyropygus gestri Poc., nous
pensons que |’Auteur a changé cette espéce de genre sans en publier les raisons.
“L’étiquette originale était bien Thyropygus. D’autre part, la mention “ type”’
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 175
Fics. 76-82. Spivostreptus feae Poc. Fig. 76. Gonopodes, face antérieure. Fig. 77.
Gonopodes, face postérieure. Fig. 78. Hanche gauche, profil externe. Fig. 79.
Extrémité du télopodite. Fig. 80. Téte et collum du g. Fig. 81. Collum de la 9.
Fig. 82. Extrémité des hanches des gonopodes du second exemplaire.
176 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
n’était pas indiquée mais le seul individu 3 présent et disséqué ainsi que la station
correspondant a la publication nous le font désigner comme tel.
3. 65 segments.
Collum a lobe en angle droit avec un gros bourrelet marginal surtout élargi dans
langle antérieur.
Sternite du segment terminal libre.
Cavité stigmatique triangulaire.
Soles sur les deux avant-derniers articles de la 3éme paire de pattes a la derniére.
Pores répugnatoires débutant au 6¢me segment.
GONOPODES 4 sternite trapezoidal, lisse.
Feuillet coxal postérieur (Text-fig. 83) trés étranglé a la base puis progressivement
élargi et épanoui en lamelle au sommet. Cette lamelle est de forme semi-circulaire,
déprimée en son centre sur les deux faces (Text-fig. 85) et rabattue verticalement de
facgon a se disposer perpendiculairement a l’axe de la hanche. La partie circulaire
est dirigée vers l’avant, la portion droite continuant le bord interne de la hanche qui
est sinueux demeurant ainsi dans le plan général de l’organe et produisant un léger
ressaut distal duquel est issue une petite lamelle perpendiculaire située antérieure-
ment. Le bord aminci du processus est lamellaire et irrégulicrement dentelé. Face
postérieure (fig. 84) et correspondant a la pliure longitudinale du lobe distal, on
remarque un tronc €pais, plus ou moins bossu, s’évasant vers le bas.
Feuillet coxal antérieur (fig. 84) élevé et creusé latéralement d’une dépression
classique faisant le tour de l’organe. Face postérieure, avant et au niveau de sa
jonction avec le feuillet précédent, le bord est épanoui en un large lobe latéral.
Télopodite court et relativement simple. Branche montante épaisse et brusque-
ment rabattue en angle aigu des sa sortie de la gaine coxale. A partir de la grande
courbure le membre s’épanouit en large et épaisse lamelle semi-lunaire dont |’extré-
mité étranglée pousse un long processus tout en s’amincissant et en se recourbant en
angle droit. Ce processus (fig. 84 et 87) dont les bords sont lamellaires et
transparents porte, le long de son bord, une série de pointes fragiles et translucides au
nombre de 22 a 23 et présente au bord latéral interne, au niveau de la courbure en
angle droit, une denticulation hyaline. Dans le milieu de l'appareil, face inférieure,
(fig. 87) on remarque, étroitement accolée a sa surface, une petite lame a bord
distal nettement dentelé et conduisant la rainure séminale. Nous sommes donc en
présence d’un télopodite bifide dont, des deux branches, l’une conduit la rainure,
autre porte les épines.
Au niveau de la grande courbure, latéralement et un peu au-dessous de 1’épaissis-
sement lobiforme, une trés robuste et large épine dont la pointe se dirige vers l’extré-
mité du membre (fig. 86).
Spirostreptus stenorhynchus Pocock
Nous avons examiné deux ¢ et deux 2 mais n’avons pas trouvé de type désigné.
_ Nous ne sommes pas certain que l’un des ¢ soit le type bien qu’un seul ait été dis-
séqué.
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 177
Fics. 83-87. Spirostreptus gestri Poc. Fig. 83. Gonopodes, face antérieure. Fig. 84.
Gonopodes, face postérieure. Fig. 85. Sommet du gonopode gauche de profil. Fig.
86. Epine fémorale. Fig. 87. Extrémité distale du télopodite.
178 LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK
Pour cette espéce la description et les dessins ont moins d’importance que pour les
autres espéces étudiées car depuis Cart elle est bien connue et figurée.
Les segments, pour ces individus, sont au nombre de:
he Seb
©: 61,33 ?
Thyropygus erythropleurus Pocock, 1894 “ Type ”’
Max Weber—Zool. Ergeb. III : 384.
Manindjau, Sumatra. Weber. Reg. No. 1896.10.6.78.
Cette espéce a une importance trés grande car elle a été désignée comme type du
genre par Pocock.
Malheureusement le matériel ayant servi a |’Auteur n’est constitué que par 2 2
et un jeune 3.
Nous n’avons retrouvé comme type qu’une @ qui est bien caractéristique avec ses
points jaune-rouge prés des pores répugnatoires et son corps annelé de marron-
rouge et blanc-jaune sale. Les pattes sont également trés distinctement annelées
de méme couleur.
En l’absence de ¢ adulte et dans l’état actuel de nos connaissances des 2 nous ne
pouvons que suivre les Auteurs qui ont désigné l’espéce javanicus, la plus ancienne
décrite et la plus commune, pour la remplacer.
SUMMARY
The object of this paper is to redescribe and figure R. I. Pocock’s species of Harpa-
gophoridae represented in the Collections of the British Museum (Natural History).
Although Pocock described thirty-two species, I have been able to deal in detail
with only seventeen of them. The remainder are either not represented in the
Collections or are represented only by females, or by females and young males.
BIBLIOGRAPHIE
ATTEMS, C. 1914. Die indo-australischen Myriopoden. Ayrch. Natur., Abt A, H. 4.
Cart, J. 1917. Spirostreptides nouveaux ou peu connus du Muséum de Genéve. Rev. Suisse
Zool. 25, No 12.
Pocock, R. I. 1889. Report on the Myriopoda of the Mergui Archipelago, collected for the
Trustees of the Indian Museum, Calcutta by Dr. John Anderson. Journ. Linn. Soc. 21.
1892. Report upon two collections of Myriopoda sent from Ceylon by Mr. E. E. Green,
and from various parts of Southern India by Mr. Edgar Thurston of the Government Central
Museum Madras. Journ. Bombay Nat. Hist. Soc. VII.
— 1892. Supplementary Notes on the Arachnida and Myriopoda of the Mergui Archipelago:
with Descriptions of some New Species from Siam and Malausia. Journ. Lin. Soc. 24.
—— 1893. Viaggio di Leonardo Fea in Birmania e Regioni Vicine. LV. On the Myriopoda of
Burma. Pt. 3. Report upon the Iulidae, Chordeumidae and Plyzonidae collected by Sig.
L, Fea and Mr, E, W. Oates. Ann, Mus, Civ. St, Nat., Genova, 13 (33).
LES TYPES D’HARPAGOPHORIDAE DE R. I. POCOCK 179
Pocock, R. I. 1893. Report upon the Myriopoda of the ‘‘Challenger’’ Expedition with Remarks
upon the Fauna of Bermuda. Ann. Mag. N. H., ser. 6, XI.
—— 1893. Upon the Identity of some of the Types of Diplopoda contained in the Collection
of the British Museum, together with Descriptions of some New Species of Exotic Iulidae.
Ibid. XI.
1894. Chilopoda, Symphyla and Diplopoda from the Malay Archipelago in Max Weber—
Zool. Evgeb. III.
1896. Viaggio di Leonardo Fea in Birmania e regioni vicine. LXX. Supplementary
Note upon the Iuloidea, containing descriptions of three New Species. Ann. Mus. Civ. St.
Nat. Genova, 2@me ser., 16. y
<h
\
Ty
a
B
ARTHOLOME
¥
GASTROPOD FAMILY
~VERMETIDAE
SS
= 2 MAR 1961
PRESENTED
A. MYRA KEEN
BULLETIN OF
ITISH MUSEUM (NATURAL HISTORY)
Vol. 7 No. 3
LONDON : 1961
4
A PROPOSED RECLASSIFICATION OF
THE GASTROPOD FAMILY VERMETIDAE
= 2 MAR 1961
PRESENTED
BY
A. MYRA KEEN
Stanford University, California, U.S.A.
Pp. 181-213; Plates 54-55; 33 Text-figures
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No 3.
LONDON: 1961
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, 1s
issued in five series corresponding to the Departments
of the Museum, and an Historical Series.
Parts will appear at irregular intervals as they become
ready. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No.3 of the Zoological
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© Trustees of the British Museum, 1961
PRINTED BY ORDER OF THE TRUSTEES OF
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“Issued February 1961 Price Fifteen Shillings
A PROPOSED RECLASSIFICATION OF
THE GASTROPOD FAMILY VERMETIDAE
By A. MYRA KEEN
CONTENTS
Page
A. INTRODUCTION < : : 5 2 : ‘ - : a ately
B. NoMENCLATURAL UNITS IN THE VERMETIDAE . a ‘ oO
C. REVISED CLASSIFICATION OF THE VERMETIDAE 6 5 : . 192
D. Notes oN TYPE AND OTHER SPECIMENS . : ; a 4 Zeee200)
E. CuHeck List oF West AMERICAN SPECIES ‘ z 4 9 - 208
F. EvoLuTIoN OF THE VERMETIDAE . : 4 ; 5 : . 209
G. ACKNOWLEDGMENTS . ‘ ‘. is i ; 2200
H. REFERENCES CITED : 5 é dj é - 5 6 2 LO
I. INDEX 4 s 5 0 “ 3 + o 2) 203)
ABSTRACT
Because of their widespread occurrence in the intertidal zones of warm-temperate to tropical
seas and their peculiar adaptations, the Vermetidae could become useful to the marine ecologist
if they were readily identifiable in the field. The present paper is an attempt to show what
characteristics are most constant and useful in recognition, to review the nomenclatural history
of the group, and to indicate something as to the geographic distribution of species. In the
revised classification, five genera, with five additional subgenera, are recognized. Brief lists of
the species that may be assignable to each are given, although these must remain tentative
until detailed studies are made by students who have access to properly collected material.
In this paper, Tvipsycha is proposed as a new genus ; Siphonium lituella Morch is selected as
the type species of Dendropoma Morch, Serpulorbis polyphvagma Sassi as that of Thylacodes
Morch, and Bivonia contorta Carpenter as that of Thylacodus Mérch and of Thylaeodus Morch ;
and lectotypes are selected for Vermetus adansonii Daudin, V. afey Gmelin, Bivonia contorta
Carpenter, B. c. var. indentata Carpenter, Petaloconchus macrophyvagma Carpenter, Siphonium
(Dendropoma) leucozonias Mérch, and Siphonium (D.) lituella Morch.
A. INTRODUCTION
THE Vermetidae (worm gastropods) probably hold a record among molluscs for the
degree of confusion they have promoted, both in collections and in the literature ;
for they have been misconstrued at every level from subspecies to phylum. An
attempt is made here to point out objective criteria for separation of groups within
the family. A complete monograph of the species, however, must wait until field
observations have confirmed or disproved laboratory analyses of seeming
differences.
Although in many parts of the world—especially in the tropics—the vermetids
are abundant intertidal organisms, they have never been popular with collectors.
Properly recognized, they could become, on account of their peculiarities in habit
and distribution, useful indicators for the ecologist in the description of intertidal
zones. Most of the few papers on the family deal with anatomy and physiology of
the animals or with local faunas. We still lean upon the systematic reviews by two
ZOOL. 7, 3 15
184 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
authors whose works were published a century ago : Carpenter (18570), for a mono-
graph of the genus Petaloconchus, and Mérch for, first, a tentative classification of
the family (1859-60a) and then (apparently after a survey of the extensive Hugh
Cuming Collection) a review of the species (1861-626). His second arrangement
differs at many points from the first one. Conceptual tools for the study of variation
had not been worked out in Morch’s time. Small wonder, then, that in trying to
cope with some of the most variable of gastropods he finally resorted to a naming
system so complex and confused that Carpenter (1864 : 558, footnote) later dis-
missed it asa “‘ posture of binomial nomenclature’. Indeed, one now concedes
that, useful as Mérch’s work may be in a general way, we must, under modern rules,
reject many of the new names he proposed, for all those below specific rank are
polynomial and inconsistent. Citation by Tryon (1886) and reprinting by Clessin
(1901-04) were not in a form that would validate any of them.
Both Mérch and Carpenter relied upon the adult shells alone for their classifications.
Perhaps neither had an adequate microscope, for they both missed some conspicuous
features in the nuclear whorls, and Mérch saw structures in certain opercula that
later research has failed to confirm.
The first step in a fresh study of the family is to define its limits and to exclude
what does not properly belong. Tubicolous annelid worms are frequently confused
with vermetids. Some of these worms do build irregularly coiled tubes, but on
close inspection one sees that the tubes are lustreless and of two-layered construction,
either beginning with a non-coiled initial chamber or open at the posterior end. The
genera Burtinella, Discovermetulus, Lemintina, Serpula, Spirorbis, Tubulostium and
Vermilia may be rejected without hesitation, for their type species are now generally
recognized as annelids. Although from time to time authors have listed Caporbis,
Segmentella, Serpulus, Stoa, and Spiroglyphus as gastropods, these groups also should
probably be classed as annelids. At the family level, the Vermetidae have been
traditionally associated with Vermicularia, a group that Morton (1953) has shown
to be related rather to Turritellidae, for the juvenile shell is coiled in much the same
general plane as the later whorls. Stephopoma and Siliquaria, also with turritelloid
apices, belong near Vermicularia.
Remaining in Vermetidae, then, are those forms, solitary or colonial, in which the
juvenile snail, upon emergence from the capsular membrane and the protection of
the parent’s tube, attaches itself to a favourable substrate and begins coiling its
adult shell around an axis at a go° angle to that of the larval shell. Several named
genera may be recognized, combining differences in anatomical and shell structures,
manner of coiling, and habits. The present paper will attempt to subdivide the
restricted family Vermetidae in terms of the hard parts and general external aspects,
while a paper by Dr. Morton, to be published later, will discuss differences in anatomy
and feeding patterns.
The Vermetid Shell
An isolated section of a vermetid tube is nearly useless for specific or even generic
determination, but texture and structure may indicate its placement within the
‘family. The shell is three-layered, with an inner layer that is glossy and porcel-
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 185
lanous, mostly white or tinged with some shade of brown. The middle layer is less
distinctive but thicker than the other two, and the outer layer carries whatever
sculpture is present, its colour ranging from white through buff or pink to brownish
black. Sculpture may be either longitudinal or transverse. The irregular coiling
of the shell makes the use of such terms as “‘ spiral’ and “axial” ambiguous. Full
expression of sculpture may be inhibited by such factors as crowding, rate of growth,
and unfavourable environment, which adds to the problems of recognition. Several
writers have commented on the frequent sealing off of the early whorls, especially
if the shell has been broken. The posterior part of the mantle is capable of secreting
a convex septum that closes off either an unneeded or a broken portion of the tube,
and in some specimens this sealing may be repeated at close intervals. In one genus
(Petaloconchus) one or more spiral laminae or shelves may encircle the columella
throughout the medial whorls.
The Operculum
The operculum is a spirally-wound plate of chitin. At its most complex develop-
ment it is thickened at the centre, with a button-like scar on the inner surface,
the spiral so tightly appressed as to seem nearly flat. An intermediate or simple
form of operculum shows only a few turns, the whole structure reduced in size to
half or less of the diameter of the aperture, with spirals that stand up as coiled
laminae on a saucer-shaped base. One group of the vermetids (Serpulorbis) has
dispensed with the operculum entirely. Correlations of opercular patterns with
feeding habits will be discussed by Dr. Morton.
The Nuclear Whorls
Few gastropods are adapted to a sessile existence. Perhaps this accounts for
the vermetids having developed a special means for the newly-emerged young to
cement their shells to the substrate without becoming imprisoned in the process.
The larval shell is comprised of two to four normal-appearing whorls except that the
aperture is either twisted forward or provided with a sinuous or almost clawlike
outer margin. So shaped, the shell can lie firmly against the substrate while the
animal continues both feeding and the formation of the next volutions of the shell,
which encircle the juvenile shell on an axis of coiling go° different from that of the
initial whorls. This is reminiscent of the submerged nucleus in Architectonicidae,
to which group the Vermetidae may be related.
Nuclear whorls may be found in three ways : (a) By scanning the underside of a
colony or an individual coil broken loose from the substrate ; (b) by inspecting the
outer surfaces of adult tubes—especially crevices near the apertures—for newly-
emerged young that creep down the outside of the parent’s tube and attach in the
first protected niche they encounter : (c) by extracting the soft parts from adult tubes
(especially from those that have been quickly dried after collection or preserved in
neutral alcohol) for the young or larval shells that may still be sheltered in the mantle
cavities of the adults. With practice one soon learns to recognize the newly-
attached young, which may be detected even with a small hand-lens. At first glance
they look like a plump little wheel of an automobile, with a shiny central cap.
18 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Under higher magnification, differences become apparent, as one compares the
young of groups here called genera for size, number of nepionic whorls, colour, and
relative shape.
Habits of Growth
It is impossible to arrive at any generalizations as to growth patterns that will
apply to every contorted mass of vermetids that one finds. Nor is it even possible
to identify every such mass, a fact that accounts in part for the unpopularity of the
family with collectors. However, there are some features for which one should
watch. Are the tubes entrenched in the substrate or slotted into each other where
one overrides another? Is coiling rather regularly planorboid during the earlier
part of the adult whorls? Are the whorls uniformly small and coiled like a “* Turri-
tella squeezed sideways’’? Are there fairly regular scars of broken tube ends,
where a vertical feeding tube has been abandoned and replaced by one taking off
at a different angle? It is this sort of pattern that may give a clue as to generic
placement, but confirmation should be sought in the other characteristics. One
group, Petaloconchus, has an internal structure that is a sure clue—spiral laminae
of complex form that project into the tube from the columellar wall. The function
of these structures is yet open to investigation. Another problem that remains for
future solution is the relationship between form of shell and the degree of crowding
in colonies. Is solitary versus colonial development a specific character? Or do
isolated individuals producing young inevitably form a tight-knit colony? No one
has yet performed the observational experiments that would give the answer, or at
least no published record has come to our attention.
Some of the early authors, especially Morch and Carpenter, thought that many
vermetids were sinistrally coiled, but this seems to be a matter of faulty observation,
for no sinistral specimens have been seen during the course of the present study,
which has involved scrutiny of hundreds of specimens over a period of some ten years.
Probably the go° change of angle, which they failed to note, may have led to this
impression. Also, they, like other authors, may have mistaken specimens of
Spivorbis, an annelid worm that coils either way, as vermetids.
B. NOMENCLATURAL UNITS IN VERMETIDAE
The generic and subgeneric names that have been, with some plausibility, applied
to members of the family Vermetidae are arranged here in alphabetical order (except
for the type genus, Vermetus, which is considered first), with references, statement of
type species, and discussion of any nomenclatural problems involved. Names
available within the family are in bold face type.
Vermetus Daudin, 1800 : 34.
Type species (absolute tautonymy) : V. adansonii Daudin, 1800 [based on “ Le
Vermet ”’ of Adanson, 1757].
The status of this name is somewhat equivocal and will remain so unless it is
_ placed on the Official List of Generic Names by the International Commission on
Zoological Nomenclature. Some authors have tried to avoid the difficulties implicit
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 187
in Daudin’s proposal by crediting the name to Cuvier, 1800, but his usage is as an
absolute nomen nudum, without description or mention of any species. Daudin
cited six species that had been described by Adanson, but he gave no formal biblio-
graphic reference to Adanson’s publication. On this ground one could justifiably
disregard Vermetus Daudin and credit the name to the next author who fulfilled the
requirements of publication. A substantial barrier stands in the way of this, how-
ever, for Daudin at the same time described, in an acceptable manner, four new
species that he assigned to Vermetus. Although he cited the group as belonging in
Gastropoda, every one of his four new species, as the illustrations show, are tubicolous
annelids. Therefore, if Verymetus as a name cannot be tied to one of the cited
Adanson species (all but one of which are molluscan), the name must be transferred
to the Annelida, where it would either fall as a synonym or jeopardize some later-
established name. In the interests of stability, it seems wisest to be a little lenient,
by interpreting Daudin’s obvious intention as having been fulfilled. Following is
an exact transcription of Daudin’s proposal :
“Genre Vermet. Vermetus. Adanson
Vermicularia. Lamarck.
“Caractére générique. Coquille tubulée, tortillée en spirale irréguliére,
ordinairement adhérente, et garnie d’une ouverture orbiculaire et operculée.
“Ce genre déja formé par Adanson dans son histoire des coquilles du
Sénégal, et confondu par les autres naturalistes et par Bruguiére méme avec
les Serpules, est formé par un gastéropode voisin de celui des planorbes par
ses deux tentacules en languette, munis d’un oeil a leur base extérieure ;
mais il en différe essentiellement par sa bouche prolongée en une trompe
cylindrique garnie de plusieurs rangées de dents crochues, et de plus par un
opercule rond trés-mince qu’il peut retirer avec lui dans |’intérieur de son
tube. II reste toujours dans la méme place, parce que le tube qu’il habite
est attaché sur les rochers et sur des coquilles.
“ Adanson a décrit les six espéces suivantes.
1. Vermet d’Adanson. Vermetus Adansonii.
Serpula lumbricalis Linn.
2. Vermet musier. Vermetus arenarius.
Serpula arenaria Linn.
3. Vermet Datin. Vermetus afer.
Serpula afra Gm.
4. Vermet Dofan. Vermetus Goreensis.
Serpula Goreensis Gm.
5. Vermet Lispe. Vermetus glomeratus.
Serpula glomerata Linn.
6. Vermet Jélin. Vermetus intestinalis
Serpula intestinalis Gm.”
Examining the work by Adanson that Daudin obviously meant—the Histoire
naturelle de Sénégal, Coquillages (which, being published in 1757, does not itself qualify
as a source of generic names)—one finds on page 160 the description of ‘‘ Le Vermet ”,
188 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
This is the only form so termed by Adanson, although his other five species were
described in close association with it and evidently were considered to belong in the
same group. I believe that one may interpret Daudin’s statement, ‘‘ Vermet
d‘Adanson. Vermetus adansoni’”’ as fixing the type of Vermetus by absolute
tautonymy under the current definition of that term in the International Code.
The first subsequent designation of the type of Vermetus is by Gray (1847), who
selected Serpula luwmbricalis Linné. This would make Vermetus an objective
synonym of Vermicularia Lamarck, 1799. [One may remark that Daudin’s citation
of Lamarck’s species as a synonym perpetuated a common confusion of early authors. ]
Acceptance of absolute tautonymy as the mode of type fixation for Vermetws seems to
be the only possibility for retaining the name in its accustomed sense.
Aletes Carpenter, 1857a: 226 [not Aletes Carpenter, 1857c: 301].
Type species (monotypy) : A. sqwamigerus Carpenter, 1857.
Carpenter included the name Aletes, as a new subgenus of Szphonium, in two
manuscripts on which he was working. By the fortunes of publication, the one
that carried only a partial diagnosis appeared first, and the only species cited by
name therein was of a form described as new that he himself later recognized
(Carpenter, 1864 : 654) not to be congeneric with the species he had used as basis for
his subgeneric description, Vermetus centiqguadrus Valenciennes. The latter is, in
fact, the only species discussed by Carpenter that fits his diagnosis, ‘‘ Operculo
parvum concavo, multispirvali, fere ut in Turritella formato’, and it was selected as
type of Aletes by Clessin in 1902. My earlier attempt (Keen, 1958: 297), to pre-
serve Carpenter’s intended usage by using the signature dates of what seemed to be
an earlier private edition issued by Carpenter, now seems ill-advised in view of
evidence published by Iredale (1916: 36) that I had not considered sufficiently. As
Iredale demonstrated, Carpenter’s edition was instead a later re-issue of the British
Museum official publication. These signature dates must therefore be regarded
as dates of printing rather than dates of release to the public.
The species A. squanugerus is non-operculate, and the shell is so similar in form
to that of the type of Serpulorbis that we can hardly maintain Aletes as a morpho-
logically distinct group with it as type. The only way the generic name could be
salvaged for use in the West American fauna would be to petition the International
Commission on Zoological Nomenclature that Aletes be made a nomen conservandum,
with A. centiquadrus as type. One might argue that Carpenter’s mis-allocation of
his new species to Aletes, which he himself later rejected, might constitute a form of
misidentification, and one could thus ask to have Aleftes preserved. However, one
would be on rather insecure ground in trying to prove that this is the accustomed
sense in which the generic name has been used, for a census of the literature would
be most apt to show that the combination “ Aletes squamigerus ”’ has appeared more
frequently than the combination “ A. centiguadrus’’. Also, such action is a matter
that would require several years of time. At present, it seems better to let Aletes
lapse into synonymy and to place Vermetus centiquadrus in Vermetus, s. 1., until
‘material is available for a careful study of soft parts and nuclear whorls, neither of
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 189
which have been described. The one operculum illustrated here (figs. 2-3) is
distinctive, and if additional material proves similar, a separate generic category for
this species would surely seem justified.
3
Fic. 1. Vermetus centiquadrus. Stanford Univ. specimen, West Mexico. x }.
Fic. 2. Same, operculum, full view. x9.
Fic. 3. Section of operculum to show laminae. 9.
Anguinella Conrad, 1845-46 in 1838-61: 77. [Not Anguinella Van Beneden, 1845.]
Type species (monotypy) : Serpula virginica Conrad.
Bivonia Gray, 1847: 156. [Not Bivonia Cocco, 1832.]
Type species (original designation) : Vermetus glomeratus Bivona-Bernardi, 1832.
Cladopoda Gray, 1850 : 83.
Type species (subsequent designation, Tryon, 1886): C. grandis Gray, 1850
[based on ‘‘ Vermetus arenarius ’’ of Quoy & Gaimard, not Linné].
Cryptobia Deshayes, 1863:65. [Not Cryptobia Leidy, 1846. Probably not a
mollusc. ]
Dendropoma Morch, 1861 : 153.
Type species (here designated) : Szphonium (D.) lituella Morch, 1861.
Dofania Mérch, 1860a : 34.
Type species (subsequent designation, Bucquoy, Dautzenberg & Dollfus, 1884) :
Le Dofan Adanson = Serpula goreensis Gmelin, 1791.
Adanson’s type specimen of Le Dofan seems no longer to be discoverable, accord-
ing to Fischer-Piette (1942 : 264). As the type figure does not permit of specific
determination, the generic name is at present unusable.
Elliptovermetus Cossmann & Peyrot, 1922 : 69.
Type species (original designation): Vermetus breigneti Cossmann & Peyrot ;
Aquitanian (Upper Oligocene) of France.
Hatina Gray, 1847 : 156.
Type species (monotypy): ‘“‘Verm. inoperculatus”’ [apparently an error for
Vermetus inopertus Riippel & Leuckart, 1830-31].
ZOOL. 7, 3- 15§
190 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
This is probably a synonym of Serpulorbis, but uncertainty as to the name of the
type species suggests that it be classed as a genus dubium.
Macrophragma Carpenter, 18570 : 308.
Type species (absolute tautonymy) : Petaloconchus macrophragma Carpenter, 1857.
The name was only tentatively proposed by Carpenter but was accepted by
Morch in 1861, so that it is available for use.
Magilina Vélain, 1877 : 105.
Type species (monotypy) : M. serpuliformis Vélain.
Novastoa Finlay, 1927 : 386.
Type species (original designation) : Siphonium lamellosum Hutton, 1873.
Petaloconchus Lea, 1843 : 233.
Type species (monotypy) : P. sculpturatus Lea ; Miocene of Virginia.
Polyphragma Vaillant, 1871: 189. [Not Polyphragma Quatrefages, 1866. ]
Type species (monotypy) : Vermetus varians Orbigny, 1841.
Scolissedium “Rein.” Verany, 1846:15. Evidently an erroneous spelling of
Scolixedion, q. v.
Scolixedion Renier, 1807, of authors. Invalidated by the International Commission
(I.C.Z.N., 1957), and placed on the “‘ Official Index of Rejected Generic Names ”’
(I.C.Z.N., 1958).
Serpuloides Gray, 1850: 83. [Not Serpuloides Murchison, 1839.]
Type species not selected.
Serpulorbis Sassi, 1827 [also recorded as Sasso] : 482.
Type species (monotypy) : S. polyphragma Sassi = Serpula arenaria Linné, 1758.
The generic name has been misspelled as Serpulopsis by some authors.
Siphonium Gray, 1847, of authors [not Siphonium Link, 1807] = Vermicularia.
Siphonium “ Browne ”’ of Mérch, 1859 : 348, 353 [mot of Link, 1807] = Dendropoma.
Spiroglyphus Daudin, 1800 : 39.
Type species (subsequent designation, Mérch, 1861) : S. annulatus Daudin.
Daudin described the shells of two species, without being sure whether they were
worms or molluscs. He cited the type locality of S. annulatus as the Indian Ocean,
on Fissurellas and Patellas. His principal distinction for the genus was that it
corrodes a channel for itself. His type figure is of an irregularly coiled shell on what
looks to be a Caribbean Diodora, which has led some authors to reinterpret the type
locality. There are some tube-dwelling worms that resemble his figure, although
‘they may not truly corrode a channel as one group of vermetid gastropods do.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 191
Dr. Olga Hartman, specialist on Annelida, to whom a photograph of Daudin’s figure
was submitted, could not positively identify the form either as an annelid or as not
an annelid. I feel the same hesitation about saying definitely whether or not the
figure represents a vermetid gastropod. Hence, we would need some objective
basis other than the figure before we could accept the name Spiroglyphus as valid in
Vermetidae. Rediscovery of Daudin’s type specimen might solve the problem,
but inquiries in France have brought no clues. Dr. E. Fischer-Piette, in fact,
reported that he would not even know where to start a search. Another possibility
would be the selection of a neotype, a course acceptable under the International
Rules and one which I had planned to adopt, but I have found no specimen in the
collections available (including that storehouse of malacological treasures, the British
Museum of Natural History) that would satisfy the necessary requirements. The
name Spiroglyphus has been widely used in the Gastropoda—true—but it has also
been used by some palaeontologists, probably incorrectly, for the annelid group of
Tubulostium Stoliczka, 1868, or Rotularia Defrance, 1827. For the present, there-
fore, it seems advisable to set it aside as a genus dubium until such time as it can be
given unequivocal status with a type species based on a recognizable specimen,
either by rediscovery of Daudin’s material or by finding an acceptable neotype—
both possibilities now seeming rather unlikely.
Tetranemia March, 1859 : 353.
Type species (monotypy) : Serpulus (T.) dentiferus (Lamarck) of Quoy & Gaimard
(not of Lamarck) = Thylacodes (T.) longifilis Morch, 1862.
Thylacodes Agassiz, 1846 : 370, 381. Nomen nudum.
Thylacodes Morch, 1862 : 64 (ex Guettard, 1774, non-binomial).
Type species (here designated) : Serpulorbis polyphragma Sassi, 1827 = Serpula
arenaria Linné, 1758.
Thylacodus Mérch, 18600 : 77 (July).
Type species (here designated): Vermetus contortus (Carpenter) = Bivonia
contorta Carpenter, 1857.
Other species included by Moérch: V.subcancellatus Bivona-Bernardi, V. conicus
Dillwyn, and V. contortus var. indentatus Carpenter.
Thylaeodus Morch, 1860a : 48 (January).
Type species (here designated): Vermetus contortus (Carpenter) = Bivonia
contorta Carpenter, 1857.
Morch proposed the name in a postscript to his first paper, as follows: ‘‘ Enfin,
je proposerai le nom de Thylaeodus pour les Vermets sans plis.”’ As it stands,
this seems too vague to be a valid proposal, but careful reading of the paper, especially
page 39, shows that he would include these species in the category of vermetids
without folds: V. contortus and its variety, V. albidus Carpenter ; V. subcancellatus
Bivona-Bernardi; and V.carinatus Quoy & Gaimard. Onemay suspect that the spell-
192 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
ing “‘Thylaeodus”’ wasa printer’s error, for in the subsequent paper, where more formal
treatment was given, the spelling was consistently ‘‘ Tiylacodus’’. However, under
the International Rules, the original spelling must be accepted unless evidence in
the paper itself demonstrates an error. Mdérch having given no clue as to derivation,
we must adopt Thylaeodus as the valid spelling. Ina way this is advantageous, for
thus we avoid the confusion of Thylacodus with Thylacodes, names used by Morch
in different senses.
Veristoa Iredale, 1937 : 254.
Type species (original designation) : V. howensis Iredale.
Vernuculus Moérch, 1859: 348 (ex Lister). [Not Vermuiculus DaCosta, 1776 nor
Linck, 1783.]
As of Mérch, this is a synonym of Vermicularia. The name is a pre-Linnean term,
used non-binomially by later authors for a mélange of forms. The earliest such use
is by DaCosta for three unnamed species, one of which is a Serpulorbis. It would
seem to serve no useful purpose and should be placed on the Official Index of Rejected
Generic Names.
Vermitoma Kuroda, 1928 : 40.
Type species (monotypy) : V. luchuwana Kuroda (ex Hirase MS.). [Description
in Japanese. ]
C. REVISED CLASSIFICATION OF THE VERMETIDAE
Generic synonymies, as now understood, are given below, with notes on shell
morphology and lists of the species that, with some confidence, one may assign to
each group. Citations are, in the main, only to author and date but full references
for many species are given in Section D.
Family VERMETIDAE Gray, 1828
Sessile gastropods with shells more or less firmly attached throughout life to rock
or to other shells; coiling irregular to disjunct (lax) ; axis of coiling of nuclear
whorls at a right angle to that of later whorls ; operculum chitinous, spiral, with a
tendency toward external laminae.
Genus VERMETUS Daudin, 1800
? Dofania Morch, 1860.
Mainly solitary or in small clusters, coiling usually irregular; columellar wall
smooth, without laminae; nuclear whorls two, globose to elongate ; operculum
thin, spiral, one-half or less the diameter of the aperture.
Subgenus VERMETUS, s. 1.
Into this category must be grouped all the otherwise unassignable species—those
‘described on the basis of incomplete shells, those of unknown provenance, and those
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 193
not yet studied in adequate detail. The major part of some 250 named forms,
fossil and living, fall herein.
Subgenus VERMETUS, s. s.
(Text-figs. 4-7)
Coiling irregular but shell mostly well attached: without feeding-tube scars ;
colour, brown; operculum small, less than half the diameter of the aperture, con-
sisting of a concave disc with a spiral lamina of one to two turns (Text-figs. 6-7) ;
nepionic shell of two subglobular whorls (Text-fig. 5).
Until recent years (Fischer-Piette, 1942), the type material of V. adansonii was
lost to science. In the meantime, authors had misdetermined the species and
confused it with a Petaloconchus (M. acrophragma) from other parts of West Africa.
That the type species of Vermetus does not show any internal spiral laminae is
4. Vermetus adansonii, lectotype, after Fischer. 0°75.
5. Nuclear whorls of V. adansonii, topotype. x 30.
Fic. 6. Same, operculum full view. X35.
7. Oblique view of operculum as seen on dried animal. x 35.
confirmed both by the original material (Fischer-Piette, 1942, pl. 9, figs. 3-5) and
by topotype specimens.
Assignable species :
V. (V.) adansonii Daudin, 1800 [type species]. West Africa, especially Sénégal.
V. (V.) afer (Gmelin, 1791). West Africa, especially Sénégal.
V. (V.) triqueter (Bivona-Bernardi, 1832). Mediterranean.
Subgenus THYLAEODUS Mirch, 1860a (January)
(Text-figs. 8-11)
Bwwonia of authors, not of Gray, 1847 ; Thylacodus Morch, 1860b (July).
Buff to brown shells of moderate or small diameter, with strongly cancellate to
beaded sculpture ; feeding-tube scars (abandoned remnants of former vertical tubes)
present on most specimens ; operculum one-half to three-fourths the diameter of
the aperture, with a spiral lamina of chitin that rises free from the disc.
These shells have been grouped by many authors, following Carpenter, in the genus
Bivonia, but this is untenable on two counts: the name is preoccupied and the type
species differs in several significant features. Though resembling Petaloconchus
externally, this group consistently lacks the internal spiral laminae and thus is
closer to Vermetus, s. s,
194 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Assignable species :
V. (T.) contortus (Carpenter, 1857) [type species]. Tropical West America.
. (T.) indentatus (Carpenter, 1857). Tropical West America.
V. (T.) ?quoyt (H. & A. Adams, 1854). Indo-Pacific.
. (Z.) semisurrectus Bivona-Bernardi, 1832. Mediterranean.
Fic. 8. V. (Thylaeodus) contortus, showing operculum in place in a broken aperture.
Topolobampo, West Mexico. x 12.
Fic. 9. V. (T.) contoytus, apex of nuclear whorls, as seen from attached side, showing also
the first subsequent whorl. 12.
Fic. 10. V. (T.) indentatus, operculum, full view. Guaymas, West Mexico. 17.
Fic. 11. Same specimen, side view of operculum. X17.
Genus SERPULORBIS Sassi, 1827
Lemintina of authors (not of Risso, 1826); Anguinella Conrad, 1846, preoccupied; Hatina
Gray, 1847; Serpuloides Gray, 1850, preoccupied; Alefes Carpenter, 1857a; Tetranemia
Morch, 1859; Thylacodes Morch, 1862b.
Shells among the largest of the family, the coiling of roughly concentric loops,
especially in the early whorls, the later coiling in colonial forms being densely con-
torted, lax, or hardly apparent. Scars of broken feeding tubes apparent on most
specimens. Colour of shells ranging from dark brown to pure white. Nuclear whorls
lighter in colour than the rest of the shell, of two to four whorls, globose-conic rather
than cylindrical. Operculum wanting.
Subgenus SERPULORBIS, s. s.
(Text-figs. 12-14)
Colonial forms, in the main, with tubes that are concentrically looped in the
young to weakly contorted in the adult; sculpture of spiral lines variously inter-
sected to form nodes or scales.
Assignable species :
(S.) arenaria (Linné, 1758). Mediterranean. (Synonyms: S. polyphragma
Sassi, 1827 [type species] ; Vermetus gigas Bivona-Bernardi, 1832.)
(S.) decussatus (Gmelin) [Serpula]. Caribbean.
(S.) eruciformis (Morch, 1862) [Thylacodes]. West Mexico.
(S.) masier (Deshayes, 1843) [Vermetus]. West Africa.
(S.) medusae (Pilsbry, 1891) [Thylacodes]. Japan.
WD
Dunn
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 195
S. (S.) novaehollandiae (Chenu, 1843, ex Rousseau MS) [Vermetus]. ?Australia.
S. (S.) sipho (Lamarck, 1818) [Serpula]. Indo-Pacific.
S. (S.) squamigerus (Carpenter, 1857) [Aletes]. California.
S. (S.) validus Kuroda & Habe, 1952. Japan.
This group seems to have appeared earliest in time of the vermetids, as early at
least as Eocene time: for example—among others—S. morchi and S. cancellatus
Deshayes, 1861, from the lower and middle Eocene of Europe, and S. chavani
Harris & Palmer, 1946, from the upper Eocene of south-eastern United States.
Some Upper Cretaceous forms have a pattern of coiling that seems Serpulorbis-like—
as in S. lamellosus (Stoliczka, 1868), from India—although the preservation is not
complete enough to provide indisputable evidence that these are gastropods and not
tubicolous annelids.
Fic. 12. Serpulorbis arenarius (Linné), after Monterosato. Mediterranean. xt.
Fic. 13. S. arenarius, nuclear whorls. Sicily (Stanford Univ. collection). 22.
Bic. 14. S. polyphragma, shell, after Priolo. x}.
Fic. 15. S. (Cladopoda) grandis, shell, after Quoy & Gaimard, somewhat modified from
specimens. Indo-Pacific. x4.
Subgenus CLADOPODA Gray, 1850
(Text-fig. 15)
Coiling planorboid throughout life (rarely lax) ; shells mostly solitary rather than
colonial, large in diameter, with the entire coil in contact with the substrate ; colour
of shell ivory white to blackish brown ; sculpture of longitudinal threads that are
but weakly intersected by transverse sculpture.
Assignable species :
S. (C.) colubrinus (Réding, 1798) [Serpula]. Indo-Pacific area. (Synonym: JV.
ater Chenu, 1844.)
S. (C.) grandis (Gray, 1850) [type species : as Cladopoda]. Indo-Pacific.
S. (C.) imbricatus (Dunker, 1860) [Vermetus]. Japan.
S. (C.) margaritaceus (Chenu, 1844, ex Rousseau MS.) [Vermetus]. Probably West
Mexico. (Synonym: V. margaritarwm Valenciennes, 1846.)
196 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Genus TRIPS YCHA, new genus
(Text-figs. 16-20)
Type species : Vermetus tripsycha Pilsbry & Lowe, 1932. West Mexico.
White shells of moderate size, with the early whorls firmly attached and coiling
as in Serpulorbis ; medial and later whorls mostly unattached and coiling in hollow
cone form, somewhat as in Petaloconchus, s.s.; last whorl lax and uncoiled. Oper-
culum slightly concave, with an appressed spiral lamina of several volutions. Nu-
Fic. 16. Tvipsycha tripsycha, holotype, after Pilsbry & Lowe; Guyamas, Mexico. * }.
Fic. 17. T.tripsycha, operculum, fulland side views. Stanford Univ. collection. Guaymas.
Fic. 18. Same, nuclear whorls, side view ; from brood capsule. 15.
Fic. 19. Same specimen as Fig. 18, apertural view. X15.
Fic. 20. Nuclear whorls, after attachment to substrate. Stanford Univ. collection,
Guaymas. X17.
clear whorls unusually large, with several turns, rather more elongate than in most
vermetids except some Petaloconchus (Macrophragma). Mainly solitary shells, but
when crowded they may form a radiating cluster of tubes, due to the tendency of
each individual to grow away from any nearby competitor.
The name of the subgenus is that of the type species, as this seems to be a very
suitable noun coined by Pilsbry & Lowe from the Greek words tri and psyche and
evidently intended to convey the meaning, “‘ of three minds ’’, in reference to the three
modes of coiling during the life of the individual.
Assignable species :
T. tripsycha (Pilsbry & Lowe, 1932). West Mexico.
Genus PETALOCONCHUS Lea, 1843
Petaloconcha, unjustified emendation by Cossman, 1912.
Coils forming a hollow cylinder, at least in the young ; medial whorls with a more
or less complex internal structure of spiral laminae projecting from the columellar
wall.
Subgenus PETALOCONCHUS, s. s.
(Text-fig. 21)
Last whorl lax or unwound, earlier whorls forming a symmetrical hollow cone.
Nuclear whorls and operculum unknown. Sculpture, when present, evenly cancel-
late.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 197
The type species was described from the Miocene of the eastern United States.
A few closely related species have since been described, all in the Middle Tertiary
of the Caribbean area. The subgenus in the strict sense is not recorded elsewhere.
Assignable species :
P. (P.) sculpturatus Lea, 1843. Miocene, Virginia [type species : holotype refigured,
Gardner, 1947, pl. 55, fig. 21]. (Synonym: P. domingensis Sowerby, 1849.)
Fic. 21. Petaloconchus sculpturatus. Specimen, Stanford Univ. collection, from the
Miocene of Trinidad, with internal laminae showing in the broken section of one coil.
xt.
Fic. 22. P. (Macrophragma) macrophragma, sketch of lectotype, to illustrate coiling.
Mazatlan, Mexico. x2. B.M. (N.H.) Reg. No. 57.6.4.1500,
Fic. 23. P. (M.) macrophragma. Operculum. Stanford Univ. collection. x 13.
Fic. 24. Same, nuclear whorls. West Mexico. xX 12°5.
Fic. 25. Detail of columellar laminae. Stanford Univ. collection, Oaxaca, Mexico.
x6.
Subgenus MACROPHRAGMA Carpenter, 1857
(Text-figs. 22~25)
Polyphvagma Vaillant, 1871 [not Quatrefages, 1866] ; Petaloconchus, s. s. of authors.
Coiling regular, especially in the early whorls, described by Carpenter as “like
a Turritella squeezed sideways ”’. Sculpture cancellate, but with the longitudinal
ribs tending to be predominant and sub-carinate.
Nuclear whorls two to four, ivory white to waxy yellow, conic to cylindrical.
Adult shell medium to dark brown in colour. Operculum concave, with an upstand-
ing spiral lamella of one or two volutions, diameter less than that of the aperture,
resembling that of Vermetus (Thylaeodus) in form.
The shells are either solitary or colonial and are mostly smaller in size than in
other vermetid groups except Vermetus (Thylaeodus), which they closely resemble
except for more regular coiling and the internal spiral lamellae. Scars of broken
feeding tubes are common and may recur at regular intervals along the coil.
Assignable species :
P. (M.) cereus Carpenter, 1857. Philippines.
P. (M.) cochlidiwm Carpenter, 1857. Australia.
P. (M.) complicatus Dall, 1908. Panama Bay.
198 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
(M.) flavescens Carpenter, 1857. ‘‘ Sicily’ (evidently in error). Probably from
West Mexico.
(M.) floridanus Olsson & Harbison, 1953. Florida, Pliocene to Recent.
(M.) glomeratus (Linné, 1758) [Serpula]. Mediterranean. (Synonym: Vermetus
subcancellatus Bivona-Bernardi, 1832.)
(M.) innumerabilis Pilsbry & Olsson, 1935. Tropical West America.
(M.) interlivatus Stearns, 1893. Cape Verde, West Africa.
(M.) macrophragma Carpenter, 1857 [type species]. West Mexico.
(M.) mcgintyi (Olsson & Harbison, 1953) [Lemintina?]. Florida, Pliocene to
Recent.
P. (M.) montereyensis Dall, 1919. California.
P. (M.) nerinaeoides Carpenter, 1857. Australia.
P. (M.) renisectus Carpenter, 1857. Indo-Pacific.
P. (M.) tokyoensis Pilsbry, 1895. Japan.
P. (M.) varians (Orbigny, 1841) [Vermetus]. Caribbean.
USER Ue ae
Genus DENDROPOMA March, 1861
Spivoglyphus of authors, probably not of Daudin, 1800; Stoa of authors, not of De Serres, 1846
(annelid) ; Bivonia Gray, 1847 [not Cocco, 1832] ; Siphonium Morch, 1859 [not Link, 1807] ;
Magilina Vélain, 1877 (?) ; Vermitoma Kuroda, 1928; Veristoa Iredale, 1937.
Solitary to colonial forms, corroding a trench in the substrate, in which the lower
part of each volution is embedded ; coiling planorboid in early whorls, becoming
looser in later whorls, with a tendency toward right-angled turns. Colour of adult
mostly white, variously stained with dark brown, especially within. Sculpture of
lamellar growth-striae that may or may not be intersected by longitudinal lines,
sinuous and rising toward a crest near the outer edge of the whorl in most species.
Nuclear whorls two, dark brown in colour, inflated, smooth to malleated or axially
ribbed, the apertural lip pointed or claw-like in some species. Operculum well
developed, as large in diameter as the aperture, its inside surface having a distinct
central attachment-scar that is somewhat button-like, its outside composed of
chitinous plates in a spiral arrangement, either compactly welded to form a smooth
surface or variously agglutinated with foreign materials.
Subgenus DENDROPOMAA, s. s.
(Text-figs. 26-29)
Mainly solitary forms, minute to large, burrowing in other shells or in coral,
rarely attached to rock. Operculum concave in large forms, flattened in smaller
ones, buff-brown to mahogany red in colour. Sculpture varying from weak trans-
verse threads to heavy longitudinal rows of scales.
The largest specimen of D. maximum seen (at the British Museum [Nat. Hist.]),
had attained a length of over 18 inches. This is very exceptional. A diameter of
22 mm. is not uncommon in the larger forms, however. D. maximum is the form
cited by Yonge and others from the Great Barrier Reef under the incorrect identifica-
‘ tion of Vermetus novae-hollandiae, the latter being a Serpulorbis,
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 199
Fic. 26. Dendropoma lituella, sketch of lectotype, to illustrate manner of coiling.
California. 3. B.M. (N.H.) Reg. No. 195917.
Fic. 27. D. lituella, nuclear whorls. Stanford Univ. collection, southern California.
X25.
Fic. 28. Same, operculum, full view of a specimen with the membranous laminar surface
exceptionally well preserved. Io.
Fic. 29. Side view of same specimen.
Assignable species :
. (D.) andamanicum (Prashad & Rao, 1933) [Vermetus]. Indian Ocean.
. (D.) corrodens (Orbigny, 1842) [Vermetus]. Caribbean.
(D.) leucozonias (Mérch, 1861) [Siphonium]. West Africa.
(D.) lituella (Mérch, 1861) [type species : as Siphonium]. California.
. (D.) luchuanum (Kuroda, 1928) [Vermitomal]. Japan.
(D.) marchadi Keen & Morton, 1960. West Africa.
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. (D.) planorbis (Dunker, 1860) [Vermetus]. Japan.
D.) rastrum (Méorch, 1861) [Vermiculus]. California.
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Subgenus NOVASTOA Finlay, 1927
(Text-figs. 30-33)
Colonial forms, usually encrusting rocks in honeycomb-like sheets. Nuclear
whorls as in Dendropoma, s. s., later whorls in tight, angulate coils spiralling upward
from substrate. Operculum bright reddish brown, flattened to convex, the inner
central mamilla conspicuous, the inner margin polished, the outer surface scaly.
or,
Fic. 30. D. (Novastoa) lamellosum. Detail of part of a colony. Stanford Univ.
collection, from New Zealand. x1- 5-
Fic. 31. Nuclear whorls, redrawn, from Morton, 1951. X25.
Fic. 32. Operculum, inner surface, showing the polished rim. After Morton. x Wo
Fic. 33. Same, side view, showing the large mamilla. x 7.
200 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
This group may be only situs forms, not a true genetic unit, for specimens in the
dense clumps may be, to the eye, indistinguishable from solitary specimens as to
operculum, nuclear whorls, and sculpture. Yet, when one compares such clumps
from various geographic areas with the type species of Novastoa, one finds such a
similarity of appearance as to suggest the usefulness of a subgeneric group name.
Assignable species :
D. (N.) corallinaceum (Tomlin, 1939) [Vermetus]. South Africa.
D. (N.) ghanaense Keen & Morton, 1960. West Africa.
D. (N.) irregulare (Orbigny, 1842) [Vermetus]. Caribbean.
D. (N.) lamellosum (Hutton, 1873) [type species : as Siphonium]. New Zealand.
D. (N.) petraeum (Monterosato, 1884) [Bivonia]. Mediterranean. (Synonym :
Vermetus glomeratus Bivona-Bernardi, 1832 [not Linné, 1758].)
D. (N.) tholia Keen & Morton, 1960. East Africa.
Subgenus ELLIPTOVERMETUS Cossmann & Peyrot, 1922
The tube of the type species is ovate in cross-section, deeply immersed in a coral
and showing lamellar growth-striae fluted by longitudinal ribs. Known only in
beds of Aquitanian age (U. Oligocene) of France.
Assignable species :
D. (E.) breigneti (Cossman & Peyrot, 1922) [type species: as Vermetus]. French
Aquitanian.
D. NOTES ON TYPE AND OTHER SPECIMENS
Vermetus adansonii Daudin, 1800
(Text-figs. 4-7)
V. adansonii Daudin, 1800 : 35.
Topotype material supplied by M. I. Marche-Marchad, of the Station de Biologie
Marine de l'Institut Francais d’Afrique Noire, provides at long last a firm basis for
reappraisal of this type species. Concerning the locality M. Marche-Marchad says,
(letter dated 20th December, 1954) : ‘“‘ Les exemplaires que je vous ai envoyés sont
probablement des topotypes au sens le plus étroit du terme. En effet l’Ile aux
Serpents = I’Ile de la Madeleine d’Adanson. C’est un petit ilot rocheux, tres battu,
situé 4 environ 2 milles 4 ]’ouest du Cap Vert. Les ‘bassins ou |’eau de la mer est
tranquille’ et ‘creusés naturellement dans le roc’ (Adanson) n’abondent pas; il
n'y y en qu’un, c’est le ‘lagon’ d’ot proviennent nos Vermets. Ce lagon n’a pas
plus de 200 m. de periphérie et si ces mollusques ne viennent pas du rocher méme ou
Adanson les a observés—ce qui est probable—ils n’en sont certainement pas trés
éloignés! ”’
Fischer-Piette (1942) has figured Adanson’s actual type material, rediscovered
during the early part of World War II. The coiling of the shell is loose and rather
irregular, and the medial whorls do not exhibit within any sign of the spiral laminae
attributed to the species by Mérch. The present topotype specimens supply needed
' details as to the nuclear whorls (Text-fig. 5) and the operculum (Text-figs. 6-7).
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 201
A lectotype for Vermetus adansonii Daudin is here selected, the specimen of fig. 4,
illustrated by Fischer-Piette on his pl. 9, fig. 3. It is in the collection of the Muséum
National d’Histoire naturelle de Paris.
One concludes that the “crust ’’ from Gaboon, equatorial Africa, identified by
Mérch (1861 : 337) as Vermetus adansonii—which formed the concept of the species
for many later authors—was not a true Vermetus. The latter seem to be rather more
solitary forms than Mérch’s description implies. His may have been the Petalo-
conchus interliratus Stearns, 1893 (a species based only on a type locality [Porte
Grande, St. Vincent, Cape Verde, West Africa] and a vague description [‘‘ an elevated,
threadlike ridge following the coiling spirally ’’]). Stearns’ syntype material, cited
by number (U.S. Nat. Mus. No. 125,378), is a tight colony of Petaloconchus (Macro-
phragma) with internal laminae well developed.
Vermetus (Vermetus) afer (Gmelin, 1791)
Serpula afer Gmelin, 1791 : 3745.
Fischer (1942 : 264) in refiguring Adanson’s “‘ Le Datin ” suggested that it may be
composite. Topotype specimens, however, taken by M. Marche-Marchad with the
V. adansonu, match Fischer-Piette’s figures well and seem to constitute a good
species differing from V. adansonit by having rather regular planorboid coiling. This
seems also to be more solitary. As a lectotype the specimen figured by Fischer-
Piette on pl. 9, fig. 6 is here selected. It is in the Muséum National d’Histoire
naturelle de Paris. The operculum of the topotype specimens is like that of V.
adansoniv.
Vermetus (Thylaeodus) contortus (Carpenter, 1857)
(PL. 55, fig. 3)
Bivonia contorta Carpenter, 1857€ : 305.
Lectotype (here selected): B.M.(N.H.) Reg.No. 57.6.4.1490. Mazatlan,
Mexico.
Carpenter’s best specimen was broken and his others considered to be young, which
has led to misinterpretation of the adult form by later authors, including myself
(Keen, 1958 : 208, fig. 200—a figure actually of an enigmatic Serpulorbis). However,
Tryon (1886, pl. 49, fig. 27) seems to have figured it correctly. New material from
near Mazatlan, collected by Mr. James McLean in December, 1959, affords op-
portunity to study a growth series taken alive. The adults are small (diameter of
aperture about 2 to 3 mm.), the coiling somewhat less regular than that of the super-
ficially similar Petaloconchus (Macrophragma) macrophragma. The colour is a warm
wax-brown, and the sculpture is of longitudinal threads evenly beaded at the inter-
sections of cross-threads, the whorls rounded in section, rarely rendered angulate by
the lirae. Internal spiral laminae are completely lacking. A mature coil may be
only 15-20 mm. in length. The two nuclear whorls are conic, moderately inflated,
and pinkish brown in colour. The operculum has a spiral lamina that stands up
from the cup ; the diameter is about half the diameter of the aperture.
202 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
This species is here selected as type of Thylaeodus. Previous allocation to Bivonia
is untenable on two counts, as shown above (p. 193). The assignment to Petalo-
conchus—suggested by workers who discount the importance of the internal laminae
in classification—although plausible as to form of operculum and nuclear whorls,
would seem to broaden the limits of that group unduly. With a new insight as to the
morphology of Vermetus, we can now suggest that this and a few related species
could well form a subgenus under Vermetus.
Vermetus (Thylaeodus) indentatus (Carpenter, 1857)
(Plate 55, fig. 4)
Bivonia contorta, var. indentata Carpenter, 1857¢ : 307.
Lectotype (here selected): B.M.(N.H.) Reg. No. 57.6.4.1494. Mazatlan,
Mexico.
In the lectotype, the longitudinal sculpture is heavier and less evenly beaded than
in V. (T.) contortus. Coiling seems also to be less regular. The lectotype is dark
brown in colour. A variant form, which may prove to be a separate species, is
pinkish buff, with evenly cancellate sculpture. This species ranges more widely in
the Gulf of California than does V. contortus.
Serpulorbis (Serpulorbis) arenarius (Linné, 1758)
(Text-figs. 12-13)
Serpula avenaria Linné, 1758: 787. “‘ Habitat in Indiis.”’
Serpulorbis polyphvagma Sassi, 1827: 484. Mediterranean.
Vermetus gigas Bivona-Bernardi, 1832: 5, pl. 2, figs. 1-2. Mediterranean.
Linné’s species is now generally considered to be the common large Mediterranean
vermetid, better known under the name of S. gigas. S. polyphragma Sassi, type of
Serpulorbis (see Text-fig. 14), seems to be only a smooth or unsculptured variant of
the species. S. arenarius may form dense colonies of contorted tubes. Coiling of
the young shellis planorboid. A report by Dr. Ottavio Priolo (19562) gives evidence
on the rapidity of growth: the hull of a boat sunk ina Sicilian harbour during World
War II, raised in 1956, was covered with large masses of these shells. Specimens
of these, sent to Stanford University, measure 13 mm. in diameter at the aperture
and would be several inches long if the tubes were not contorted.
Serpulorbis (Serpulorbis) constrictor (Morch, 1862)
Bivonia constrictoy Morch, 1862b: 63. Australia.
? Holotype: B.M. (N.H.) Reg. No. 195919.
Hedley (1913: 294, pl. 18, fig. 71) figured this species with the statement, “ In
the British Museum is a single specimen, perhaps the type, but not so labelled
” Tredale (1937: 254) considered that it is the type, which seems plausible.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 203
Serpulorbis (Serpulorbis) eruciformis (Moérch, 1862)
(Pl. 54, fig. 3)
Thylacodes erucifoymis M6érch, 1862b: 70. “‘ California.”
Holotype: B.M. (N.H.) Reg. No. 195915, on a Crucibulum. Probable type
locality, the Gulf of California.
The type specimen consists of three whorls, with a beaded sculpture pattern. It
measures about 30 by 35 mm. in total size.
Serpulorbis (Serpulorbis) squamigerus (Carpenter, 1857)
(Plate 55, fig. 5)
Aletes squamigerus Carpenter, 1857a: 226. Santa Barbara, California.
Syntype cluster: B.M. (N.H.) Reg. No. 55.3.14.57 (Nuttall Coll.) [teste S. P.
Dance, 1959].
Carpenter himself in 1864 referred this to Serpulorbis, evidently realizing that it
is not congeneric with V. centiquadrus. The sculpture varies from extreme scaliness
to weak wrinkles, depending upon such factors as rapidity of growth, degree of
crowding, etc. The geographic range is from Monterey, California, to southern
Baja California. A similar and hitherto unrecognized species of Dendropoma, D.
vastrum (see p. 207), occurs in the same area, distinguishable by the presence of an
operculum and by a corroding habit. The two are doubtless confused in most
collections.
Serpulorbis (?Cladopoda) oryzata (Morch, 1862)
(Pl. 54, fig. 1)
Thylacodes ? oryzata Morch, 1862b: 78. ‘‘ China.”
Holotype: B.M. (N.H.) Reg. No. 195912. Probably West Mexico.
Morch correctly surmised that this shell in the Cuming collection had not come
from China but from West Central America. It is a solitary form, with a few closely
coiled whorls at first, and then coiling becomes not merely lax but obsolete, for the
tube may stretch out in a weak curve for a distance of several inches. The white
surface is rendered pebbly by intersecting striae, the longitudinal sculpture tending
to twist spirally around the tube. A specimen in the Stanford University collection
Measures 250 mm. in total length, 15 mm. in diameter at the aperture. The geo-
graphic range seems to be between Guaymas and Acapulco, West Mexico. No
living material was available for this study ; hence, the allocation of the species is
highly tentative, especially as the shell has some points of resemblance both to
S. eruciformis and to Tripsycha tripsycha.
204 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Petaloconchus (Macrophragma) cereus Carpenter, 1857
P. ceveus Carpenter, 1857) : 316, fig. 7. Philippines.
Holotype: B.M. (N.H.) Reg. No. 195920.
As Mérch commented, the type specimen is acid-etched and reveals a golden-
yellow underlayer. The shell is regularly coiled and solitary, about 50 mm. in
length. Some of the other British Museum specimens identified by Morch show fine
cancellate sculpture and appressed whorls.
Petaloconchus (Macrophragma) cochlidium Carpenter, 1857
P. cochlidium Carpenter, 18570 : 314, fig. 2. Australia.
Syntypes : B.M. (N.H.) Reg. No. 195921.
The syntype lot consists of a cluster of tightly coiled shells not unlike P. flavescens
in appearance but dark brown in colour, with heavy lamellae, the upper double-
keeled. Maximum diameter of the clump, 60 mm. ; length of one coiled individual,
20 mm.; diameter of one tube, I-2 mm.
Petaloconchus (Macrophragma) flavescens Carpenter, 1857
(Pl. 54, fig. 4)
P. flavescens Carpenter, 1857) : 314, fig. 3. ‘‘ Sicily.”
Syntype cluster: B.M. (N.H.) Reg. No. 195918.
As early as 1892 Monterosato pointed out that no such species is known in the
Mediterranean, and it is not cited in the recent review of Sicilian vermetids by
Priolo (1956). However, anyone who has examined vermetids from the Guaymas-
Mazatlan area of Mexico can recognize in this cluster a familiar form. The type lot
having come from the Cuming collection makes its actual West American origin the
more probable. Locally, the form is one of the commonest West Mexican vermetids.
The Turritella-like tubes radiate outward in profusion, forming characteristically-
shaped masses. The similar but much more loosely coiled P. (M.) innumerabils
Pilsbry & Olsson, 1935 (type locality, Tumbez, Pert) occurs also in the Guaymas-
Mazatlan region, and only controlled laboratory studies will show whether the two
are variants of a single species. The shells of P. flavescens vary in colour from terra-
cotta to dark brown. Individual tubes are about 50 mm. in length, with a diameter
at the aperture of 2 mm.
Petaloconchus (Macrophragma) lilacinus (Mérch, 1862)
Vermetus lilacinus Morch, 1862a: 352. Zanzibar.
The type cluster of this form was from the Dunker collection, and may be in the
Humboldt Museum, Berlin. Specimens of the “var. alpha” of Mo6rch, from
Madagascar, are in the B.M. (N.H.) coll., Reg. No. 195922. They should probably
best be considered hypotypes rather than syntypes. The shells are bright pinkish
“lavender, with weak laminae reduced to mere lirae in some tubes.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 205
Petaloconchus (Macrophragma) macrophragma Carpenter, 1857
(Pl. 55, fig. 2)
P. macrophragma Carpenter, 1857¢ : 309. Mazatlan, Mexico.
Lectotype (here selected) : B.M. (N.H.) Reg. No. 57.6.4.1500.
The specimen is attached toa Muricanthus. It is small, tightly coiled, dark brown,
strongly sculptured, and with an internal lamina.
In a recent discussion of Carpenter’s material by Palmer (1958 : 172), a printer’s
error in assembling type has introduced ambiguity, which the reader of Palmer’s
paper can resolve by transferring the last six lines of the text under P. macrophragma
to precede the last paragraph of the page. (Also, the generic heading “‘ Aletes ”’
and the following seven lines should precede the discussion of A. squamigerus on
page 173.)
Petaloconchus (Macrophragma) nerinaeoides Carpenter, 1857
P. nerinaeoides Carpenter, 18576 : 316, fig. 6. Australia.
Syntypes : B.M. (N.H.) Reg. No. 195923.
The syntype lot is a cluster that shows a few laminae. Carpenter’s illustration
seems somewhat exaggerated as to their strength.
Petaloconchus (Macrophragma) octosectus Carpenter, 1857
P. octosectus Carpenter, 18570 : 317, fig. 8. South Africa ?
Holotype : B.M. (N.H.) Reg. No. 195924.
Length of the 5 volutions is about 30mm. The coiling is not distinctive, and the
locality remains open to doubt.
Petaloconchus ( Macrophragma) renisectus Carpenter, 1857
P. venisectus Carpenter, 18570 : 315, fig. 5. Oceano Indica ?
Type material was not detected at the B.M. (N.H.) upon search in 1958. The
variety P. r. woodwardi Carpenter (18576 : 316), from an unknown locality, is
represented by a compact cluster showing some laminae (B.M. (N.H.) Reg. No.
19595). Morch (1862a : 348) described it as “ forma 1’.
Petaloconchus (Macrophragma) varians (Orbigny, 1841)
Vermetus varians Orbigny, in 1834-46 : 456, pl. 54, figs. 7-10. Rio de Janeiro.
Syntype cluster : B.M. (N.H.) Reg. No. 54.12.4.533.
Orbigny’s figures (reprinted by Tryon, 1886, pl. 47, figs. 22-23) are good. The
syntype cluster measures about 56 mm. high by 55 mm. across. Two opercula are
glued on a separate slide. They are thin and chitinous but too crushed to show
whether they had the characteristic upstanding spiral lamellae. The tubes have
Macrophragma coiling, though internal laminae are not evident. They resemble the
Floridan P. (M.) nigricans (Dall) but are larger in diameter,
206 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Dendropoma (Dendropoma) corrodens (Orbigny, 1842)
Vermetus corrodens Orbigny, 1841-42 : 235. Orbigny, 1845-53 ?: 129, pl. 18, figs. 1-3.
Syntypes: B.M. (N.H.) Reg. No. 54.10.4.159. Cuba.
Several specimens constitute the type colony, burrowing on the spire of an Astraea
tuber. Most of the specimens are white ; a few are brown. The operculum, on a
separate mount, shows the internal mamilla or button. Diameter of a typical coil,
6-5 mm.
Dendropoma (Dendropoma) dacostae (Mérch, 1860)
Spiroglyphus dacostae Mérch, 1860a: 46. East Indies.
Holotype: B.M. (N.H.) Reg. No. 195925. Figured by DaCosta (1771, pl. 11,
fig. 15) ; figure reprinted by Tryon (1886, pl. 55, fig. 9).
The specimen is attached to what looks like a block of marble but is probably part
of a large shell, perhaps a Cassis, that has been cut to leave only the immediate base
of the vermetid. Although the apical whorls are missing, their spiral trench shows
that this is a close relative of D. maximum. At the large end the tube is only lightly
attached. It is brown within. Some spiral and longitudinal sculpture may be
made out, and the junction of the shell with the substrate is scalloped.
Dendropoma (Dendropoma) leucozonias (Morch, 1861)
Siphonium (D.) leucozonias Morch, 1861: 155. West Africa.
Lectotype (here selected) : B.M. (N.H.) Reg. No. 195926.
Solitary shells, with planorboid coiling, these are brown on the upper surface,
white on the outer side of the whorl beyond the weak crest. Operculum red,
conical, mamillate within. Diameter of a coil about 6-5 mm.
Dendropoma (Dendropoma) lituella (Moérch, 1861)
(Pl. 55; fig. x)
Siphonium (D.) lituella Morch, 1861 : 154. California.
? S. (D.) megamastum Morch, 1861 : 153, pl. 25, figs. 12-13. California.
Lectotype (here selected) : B.M. (N.H.) Reg. No. 195917, on Hahotis fulgens.
The syntype colony of D. litwella consists of a number of separated individuals
burrowing and well entrenched in the cortical layer of the Haliotis. The brown
juvenile shell has 1} volutions. On the largest adult there is a slight crest. This
shell measures 6 mm. in maximum length of coil. The operculum is in a separate
vial ; it is flat, with a frayed edge.
Morch gave no indication as to the collection from which his type specimens of
S. megamastum came, but they are evidently not among the British Museum holdings,
for no specimens bearing Mérch’s labels were found there upon search in 1958. The
form was described as shallowly burrowing in a Haliotis. Mérch thought that he
saw bristles on the outside of the operculum, as in Stephopoma (hence, the choice of
‘the name Dendropoma, meaning “branched lid”). Long and diligent modern
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 207
search having failed to bring such an operculum to light, it seems plausible to con-
clude that his supposed bristles were hydroid stalks or other agglutinated material
on the scaly outer surface. Some specimens in the Stanford University collection
have an operculum with tufts of sponge spicules that faintly resemble Mérch’s
sketches. Until his type specimens become available, it will be unwise to dis-
tinguish D. megamastum however much one would like to use the name for one of the
two or more Californian vermetids that are clearly distinct from D. lituella.
Dendropoma (Dendropoma) platypus (Mérch, 1861)
Siphonium (Stoa) platypus Morch, 1861 : 157.
Holotype: B.M. (N.H.) Reg. No. 195927. Hawaiian Islands, on a Chama.
The operculum, in place, is concave in form, as in D. maximum, which the shell
resembles save that it is attached to another shell instead of being entrenched in
coral. Moérch considered the operculum to be flatter than that of some others, but
it now appears to be distinctly concave.
Dendropoma (Dendropoma) rastrum (Moérch, 1861)
(Pl. 54, fig. 2)
Vermiculus vastrum Morch, 1861: 180. No locality cited for shell.
Holotype: B.M. (N.H.) Reg. No. 195916.
The type material for this species is composite, consisting of a coarsely scaly,
loosely coiling shell, without locality, and an operculum that Mérch assumed to have
come from it. Other material that he had in hand, from Puntarenas, Costa Rica,
probably influenced him in placing the species in Vermiculus (now Vermicularia).
The operculum is not a vermetid operculum and probably is from a tropical West
American Vermicularia (family Turritellidae). The shell itself, however, matches
well a large form from California hitherto confused with “‘ Aletes’’ squamigerus
by Californian workers. It became evident that species representing two genera
were masquerading under one name when, a few years ago, in the Stanford University
collection, a Dendropoma operculum was observed in one tube of a cluster labelled
“A.” squamigerus. Careful study of the entire contorted colony showed that the
initial whorls were entrenched and Dendropoma-like in form and that the later whorls
were a little corroded where one tube crossed another. Only a practised eye could
distinguish the second species, so similar was the sculpture to that of Serpulorbis
squamigerus. Morch’s holotype of “‘ V.’’ vastrum corresponds perfectly with this
otherwise nameless Californian form, and the recommendation is here made that it be
regarded as probably Californian in origin, even though we lack the nuclear whorls
and an authentic operculum to confirm unequivocally its position. None of the
specimens available at Stanford University or in other collections studied have
precise locality data, unfortunately, but the geographic range seems to be from
central California southward to the northern part of Lower California. Specimens
have been found attached in large clusters to soft rock as well as to such shells as
Haliotis. Fully developed, the white tubes are heavy, as much as 10-12 mm. in
diameter, and strongly sculptured with longitudinal rows of scales,
208 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
E. CHECK LIST OF WEST AMERICAN VERMETIDAE
It is to be hoped that with the aid of the clues given by this paper, other workers
will undertake studies of the vermetids in areas of abundance. The present study
was not begun with the intention of stressing any special geographic provinces, but
as it progressed, one area became conspicuous for the occurrence of an unusual num-
ber of species and genera (with seven out of the presently-recognized ten generic
units). A species list for this area—the west coast of North and Central America—
seems appropriate, and it may serve as a start toward a more thorough review, which
is now planned. The names of the species—most of which have already been
mentioned—are arranged alphabetically, with original generic allocation, author,
and date of proposal. Allocation in terms of the present classification is attempted
(necessarily provisional for several forms) ; lastly, there are brief notes on the
species not discussed elsewhere in this paper. [Generic names are abbreviated to
initial letters, as follows: D., Dendropoma; P., Petaloconchus; S., Serpulorbis ;
V., Vermetus.|
albida, Bivonia, Carpenter, 1857. Nuclear whorls only, probably indeterminate.
Holotype in B.M. (N.H.).
angulatus, Vermetus, Chenu, 1844, ex Rousseau MS. ?SERPULORBIS. No type
locality stated ; possibly not West American.
centiquadrus, Vermetus, Valenciennes, 1846. VERMETUS, s.l., probably West
Mexico.
compacta, Bivonia, Carpenter, 1864. V. (THYLAEODUS) (?). Type locality,
Vancouver Island area.
complicatus, Petaloconchus, Dall, 1g08. P. (MACROPHRAGMA).
contorta, Bivonia, Carpenter, 1857. V.(THYLAEODUS).
effusus, Vermetus, Chenu, 1844, ex Valenciennes MS. ?SERPULORBIS. No
type locality stated ; possibly not West American.
eruciformis, Thylacodes, Mérch, 1862. S. (SERPULORBIS).
flavescens, Petaloconchus, Carpenter, 1857. P. (MACROPHRAGMA).
imbricatus, Aletes? centiquadrus, Carpenter, 1857. Type specimen, B.M. (N.H.),
probably indeterminate ; juvenile.
indentata, Bivonia? contorta, Carpenter, 1857. V.(THYLAEODUS).
innumerabilis, Petaloconchus, Pilsbry & Olsson, 1935. P. (MACROPHRAGMA).
lituella, Siphonium, Morch, 1861. D. (DENDROPOMA).
macrophragma, Petaloconchus, Carpenter, 1857. P. (MACROPHRAGMA).
margaritaceus, Vermetus, Chenu, 1844, ex Rousseau MS. S. (CLADOPODA).
margaritarum, Vermetus, Valenciennes, 1846. = S. MARGARITACEUS.
megamastum, Siphonium, Mérch, 1861. = D. LITUELLA.
montereyensis, Petaloconchus, Dall, 1919. P. (MACROPHRAGMA). California,
from Monterey southward.
oryzata, Thylacodes?. Mérch, 1862. S.(CLADOPODA) (?).
panamensis, Vermetus, Chenu, 1844, ex Rousseau MS. S. (SERPULOKBIS).
peronii, Vermetus, Chenu, 1844, ex Rousseau MS. S. (SERPULORBIS). No
type locality stated; . possibly not West American. Not V. peronii of
Valenciennes, 1846, which is probably V. centiquadrus,
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 209
rastrum, Vermiculus, Morch, 1861. D. (DENDROPOM A).
squamigerus, Aletes, Carpenter, 1857. S. (SERPULORBIS). California and
southward to southern Baja California.
sutilis, Bivonia, Moérch, 1862. ?>SERPULORBIS. Holotype in B.M. (N.H.).
tripsycha, Vermetus, Pilsbry & Lowe, 1932. TRIPSYCHA.
tulipa, Vermetus, Chenu, 1843, ex Rousseau MS. S. (SERPULORBIS) (2). No
type locality stated ; possibly not West American.
F. EVOLUTION OF THE VERMETIDAE
The earliest fossil that may possibly qualify as a vermetid is of Upper Cretaceous
age. However, the preservation is not good enough to permit its unqualified
acceptance as a gastropod. Some of the Lower Eocene fossils, from the Cuisian of
France, are unquestionably vermetid, for they show clearly the scars of broken
feeding tubes characteristic of several vermetid groups. The coiling of these shells
suggests that of the genus Serpulorbis. Several similar species occurred in Europe
during Middle and Upper Eocene time, and there were a few—perhaps only two—
on the Gulf Coast of the United States. The genus continued to be represented
throughout the Tertiary in Europe. By early Miocene time, Petaloconchus, with its
internal spiral lamellae, had appeared in Europe as well as in the Caribbean area.
Dendropoma is not so easily recognized in the fossil state, but Elliptovermetus, which
seems to be an extinct subgenus of it, appeared in the Upper Oligocene of France.
We cannot trace directly the evolutionary history of nuclear whorls and opercula,
as these are difficult or impossible to obtain fossilized, but some hint as to their
pattern of development may be gained by a study of the range of form of these
structures in modern vermetids, as shown in the various figures given here. The
nuclear whorls of some Macrophragma species and some Serpulorbis are almost
indistinguishable. This may represent the primitive form, away from which most of
the groups have moved in different directions and to diffierent degrees, Dendropoma
seeming to have diverged farthest. The same is true also for opercula. Hence,
we may conclude that the evidence of the fossil record is at least not inharmonious
with that derived from the study of living forms.
G. ACKNOWLEDGMENTS
During the more than twelve years since Professor T. A. Stephenson’s first
request for an identification set me to studying the Vermetidae, I have had much
fruitful exchange of letters and ideas with Professor John E. Morton, whose paper
will flesh out the bare bones of the present taxonomic treatment.
I wish to express to the officials of the British Museum (Natural History) my
gratitude for the privilege of studying type material under their care and for permis-
sion to publish the photographs of several hitherto unfigured forms. These excellent
pictures were made in the Photographic Section of the Museum. Mr. Peter Dance
and Mr. Ian Galbraith, of the Mollusca Section, were especially helpful in making
my stay worthwhile, and I appreciated their many thoughtful courtesies.
My debt to M. Igor Marche-Marchad has been mentioned above, for having
210 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
provided topotypes—taken alive—of (among others) the type species of Vermetus,
from West Africa. Iam indebted also to Mr. James H. McLean, student at Stanford
University, for some topotypes from West Mexico. Grateful acknowledgment, too,
should go to the many colleagues who have sent vermetid specimens for my study,
such background material having been invaluable in a review of the whole family.
Line drawings used as Text-figures in this paper were prepared by Mr. Perfecto
Mary, technician in the Department of Geology, Stanford University.
Two funds at Stanford University defrayed the costs of my trip to London in
1958, one supplied by an anonymous donor, the other from the Shell Oil Company’s
Grant for Scientific Research. Thus, I was privileged to handle the actual material
studied a century ago by Carpenter and by Morch, two authors of important
systematic works on Vermetidae. More recently, an advantage came to me that
neither of them had—first-hand study of these molluscs in an area where they are
abundant. Through the kind auspices of the Belvedere Scientific Fund of San
Francisco, California, I had a few days of observation and collecting at La Paz,
Baja California, which afforded fresh insights into vermetid relationships and made
a fitting climax to my several previous years of museum study.
For all this aid, so generously given, my thanks. One may hope that as a
result, the Vermetidae will regain the esteem of malacologists and will not again be
accorded a century of disregard.
H. REFERENCES CITED
Apanson, M. 1757. Histoive naturelle du Sénégal. Coquillages. [viii] + 275 pp., 19 pls.,
imap. Paris.
Acassiz, J. L. R. 1846. Nomenclatoris zoologici index wniversalis. ... vill + 393 Ppp.
Soloduri.
Bivona-BERNARDI, A. 1832. (Apr.). Continuazione dell’ articolo sui vermeti. ... Effem.
Sci. Lett. Sicilia, 2 (1) : 3-8.
Bucoguoy, E., DautzENBERG, P. & Dotxrus, G. 1884 (Feb.). Les mollusques marins du
Roussillon, 1 (6) : 223-257. Paris.
CARPENTER, P. P. 1857a (Jan. 26). Monograph of the shells collected by T. Nuttall Esq. on
the Californian coast, in the years 1834-35. Proc. zool. Soc. Lond. pt. 24 for 1856 : 209-229.
1857 (Mar. 10). First steps towards a monograph of the Recent species of Petaloconchus,
a genus of Vermetidae. Proc. zool. Soc. Lond. pt. 24 for 1856 : 313-317, 8 figs.
1857c¢ (after June). Catalogue of the collection of Mazatlan shells, in the British Museum :
collected by Frederick Reigen. i-iv + ix—xvi + 552 pp. London.
—— 1857d (after June). Catalogue of the Reigen collection of Mazatlan Mollusca, im the
British Museum. xvi + 552 pp. Warrington [private re-issue of 1857c, differing only in
title page and preface ; published later fide Iredale, 1916 : 36).
—— 1864 (Aug. 1). Supplementary report on the present status of our knowledge with regard
to the Mollusca of the west coast of north America. Rep. Brit. Ass. for 1863 : 517-686.
Ciessin, S. 1901-04, 1912. Die Familie Vermetidae. Systematisches Conchylien Cabinet von
Martini und Chemnitz, 2nd ed, Kiister & Kobelt, 6 (6) : 1-124, 15 pls. Nurnberg [see J.
Bibl. nat. Hist. 1 (4) : 89-99, 1937].
Conrap, T. A, 1838-61. Fossils of the Tertiary formations of the United States. ... [Fosstls
of the Medial Tertiary. ...]. xvi+ 136 pp., 49 pls. Philadelphia [see intr. to 1893
re-issue, or Bull. phil. Soc. Wash. 12 : 215-239, 1895].
Cossman, M. & Peyrot, A. 1922 (June 25). Conchologie néogénique de 1’Aquitaine [cont.].
Act. Soc. linn. Bordeaux, 73 (1) : 5-321, 7 pls.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 211
(Costa, E. M. Da] 1771. Conchology, or natural history of shells. ... ii + 26 pp., 12 pls.
London [see Proc. malac. Soc. Lond. 11 : 307-309, 1915].
Daupin, F.M. 1800. Recueil de mémoires et de notes sur les espéces inédites ou peu connues de
mollusques, de vers et de zoophytes. ... 50pp.,4pls. Paris.
DesHayes, G.P. 1863. Catalogue des mollusques de l’ile de la Réunion (Bourbon). Maillard,
Notes sur Vile de la Réunion (Bourbon), 2 (E). 144 pp. Paris.
Fintay, H. J. 1927 (Mar. 10). A further commentary on New Zealand molluscan systematics.
Trans. Proc. N.Z, Inst. 57: 320-457 [not Dec. 23, 1926, as stated on reprints ; see Opin.
int. Comm. zool. Nom. 16 : 402-403, 1957].
FIscHER-PIETTE, E. 1942. Les Mollusques d’Adanson. J. Conchyliol. 85 (2-4) : 101-366.
GaRDNER, J. 1947. The molluscan fauna of the Alum Bluff group of Florida. Part VIII.
Prof. Pap. U.S. geol. Surv. (142-H) : 493-656.
GMELIN, J. F. 1791. Systema naturae. ... 13thed.1 (6): 3021-3910. Lipsiae.
Gray, J. E. 1847 (Nov.). A list of the genera of Recent Mollusca, their synonyma and types.
Proc. zool. Soc. Lond. pt. 15 for 1847 : 129-219.
Gray, M.E. 1850. Figures of molluscous animals. ... 4:iv +219 pp. London.
HEDLEY, C. 1913 (Nov. 5). Studies on Australian Mollusca. Part XI. Pyroc. Linn. Soc.
N.S.W. 38 (2) : 258-339, 4 pl.
I.C.Z.N. 1957 (Jan 8). Opinion 436. Addition to the “ Official index of rejected and invalid
names in zoology’ of certain names attributed to Renier (S. A.) as from 1804 and 1807
respectively (Opinion supplementary to Opinion 427). Opin. int. Comm. zool. Nom.
15 (1) : 1-24.
—— 1958 (June 10). Official index of vejected and invalid generic names in zoology. First
instalment : names I-1169. xiv + 132 pp. London (ed. Hemming).
TREDALE, T. 1916 (Mar. 20). On some new and old molluscan generic names. Proc. malac.
Soc. Lond. 12 (1) : 27-37.
1937 (Mar. 12). Middleton and Elizabeth Reefs, South Pacific Ocean. Mollusca.
Aust. Zool. 8 (4) : 232-261, 3 pls.
Keen, A.M. 1958. Sea shells of tropical west America ; marine mollusks from Lower California
to Colombia. x + 624 pp. [+ 3 issued separately], many pls. Stanford.
—— & Morton, J. E. 1960. (April). Some new African species of Dendropoma (Vermetidae :
Mesogastropoda). Proc. malac. Soc. Lond. 34 (1) : 36-51, 5 figs., 3 pls.
Kuropa, T. 1928 (June 8). Catalogue of the shell-bearing Mollusca of Amami-Oshima (Oshima,
sumi). 126 pp. Kagoshima.
Lea, H. C. 1843. Descriptions of some new fossil shells, from the Tertiary of Petersburg,
Virginia. Tvans. Amer. phil. Soc. (1) 9 (1) : 229-274, 4 pls.
Linnf, C. von. 1758. Systema naturae. ... t0thed.1. 824 pp. Holmia.
MonteErosato, T. A. pi. 1892 (Aug. 25). Monografia dei Vermeti del Mediterraneo. Bull.
Soc. malac. Ital. 17 (1-3) : 7-48, 7 pls.
Morcu, O. A. L. 1859 (June). Etudes sur la famille des vermets. /. Conchyliol. 7 (4):
342-360.
— 1860a (Jan.). Etudes sur la famille des vermets [cont.]. Ibid. 8 (1) : 27-48.
1860) (July). Beitrage zur Molluskenfauna Central-America’s. Malakozool. Bl. 7 (1) :
66-106.
1861 (Sept.). Review of the Vermetidae (Part I). Proc. zool. Soc. Lond. for 1861:
145-181.
—— 1862a (Apr.). Review of the Vermetidae (Part II). Ibid. for 1861 : 326-365.
18626 (June). Review of the Vermetidae (Part III). Ibid. for 1862 : 54-83.
Morton, J. E. 1953 (Sept. 2). Vermiculavia and the turritellids. Pvoc. malac. Soc. Lond.
30 (3) : 80-86, 3 figs.
Orsicny, A.D.p’, 1834-46. Mollusques. Voyage dans l’ Amérique méridionale. ... 1826-
33. 5 (3). 758 pp., 82 pls. Paris [see Ann. Mag. nat. Hist. (10) 13 : 130-334].
212 RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE
Orpicny, A. D. bp’, 1841-42. Mollusques 1. Sagra, Histoive physique politique et naturelle de
Vile de Cuba (2). 264 pp., 28 pls. Paris [see Arch. Naturgesch 1842 (2) : 376; 1843 (2) : 116].
— 1845-53? Mboluscos. Sagra, Historia fisica politica, y natural de la isla de Cuba (2) 5.
376 pp., 28 pls. Paris.
Patmer, K. vaN W. 1958 (Dec. 8). Type specimens of marine mollusca described by P. P.
Carpenter from the west coast (San Diego to British Columbia). Mem. geol. Soc. Amer.
(76). villi + 376 pp., 35 pls.
PRIOLO, O. 1956a. Molluschi del porto di Catania. Aft. Soc. tosc. Sci. nat. (B) 63 : 9-13.
1956b (Dec. 20). Nuova revisione delle conchiglie marine de Sicilia. Memoria VIII, IX.
Atti Accad. gioenia (6) 10 : 55-97, 219-254, 1 pl.
Sassi, A. fas Sasso]. 1827 (Sept.). Saggio geologico sopra il Bacino terziario di Albenga.
G, ligust. Sci. Lett. Art. Genova 1 (5) : 467-484.
Tryon, G. W. 1886 (July 28). Family Vermetidae. Manual of conchology ; structural and
systematic. [1] 8 (31) : 163-191. Philadelphia.
VAILLANT, L. 1871. Recherche sur la synonymie des especes placées par de Lamarck dans
les genres Vermet, Serpule, Vermilie. Nouv. Avch. Mus. Hist. nat., Paris (1) 7: 181-201.
VéLaiIn, C. 1877. Expédition frangaise aux iles Saint-Paul et Amsterdam. Zoologie.
Description des mollusques. Arch. Zool. exp. gén. 6 : 96-144, 4 pls.
VERANY, J. B. 1846. Catalogo degli animali invertebrati marini del golfo di Genova e Nizza.
30 pp., 3 pls. Genova.
RECLASSIFICATION OF THE GASTROPOD FAMILY VERMETIDAE 213
adansonii, 183, 186, 187-188,
193, 200-201
afer, 183, 187, 193, 201
albida, 191, 208
Aletes, 188-189, 194, 205
andamanicum, 199
Anguinella, 189, 194
angulatus, 208
annulatus, 190
arenarius, 187, 189, 190, I9gI,
194-195, 202
ater, 195
Bivonia, 189, 193, 198, 202
breigneti, 189, 209
Burtinella, 184
cancellatus, 195
Caporbis, 184
cavinatus, 191
centiquadrus, 188-189, 203, 208
cereus, 197, 204
chavani, 195
Cladopoda, 189, 195, 203, 208
cochlidium, 197, 204
colubrinus, 195
compacta, 208
complicatus, 197, 208
conicus, 191
constrictor, 202
contorta, 183, 191, 194, 201-202,
208
covallinaceum, 200
corrodens, 199, 206
Cryptobia, 189
dacostae, 206
decussatus, 194
Dendropoma, 183, 189, 190,
198-200, 203, 206-207, 208—
209
dentiferus, 191
Discovermetulus, 184
Dofania, 189, 192
domingensis, 197
effusus, 208
Elliptovermetus, 189, 200, 209
eruciformis, 194, 203, 208
flavescens, 198, 204, 208
florvidanus, 198
ghanaense, 200
gigas, 194, 202
glomeratus, 187, 189, 198, 200
goreensis, 187, 189
grandis, 189, 195
Hatina, 189, 194
howensis, 192
ZOOL. 7, 3.
» MAR 1964
I. INDEX
imbricatus, 195, 208
indentatus, 183, 191, 194, 202
innumerabilis, 198, 204, 208
inoperculatus, 189
tnopertus, 189
interlivatus, 198, 201
intestinalis, 187
trvegulare, 200
lamellosum, 190, 199-200
lamellosus, 194
Lemintina, 184, 194
leucozonias, 183, 199, 206
lilacinus, 204
lituella, 183, 189, 199, 206-207,
208
longifilis, 191
luchuanum, 192, 199
lumbricalis, 187-188
Macrophragma, 190, 193, 196,
197-198, 201, 204-205, 208,
209
macrophragma, 183, 190, 197,
198, 201, 205, 208
Magilina, 190, 198
marchadi, 199
margaritaceus, 195, 208
margaritavrum, 195, 208
masier, 194
maximum, 198, 199, 206
megintyi, 198
medusae, 194
megamastum, 206-207, 208
montereyensis, 198, 208
morchi, 195
nebulosum, 199
nerinaeoides, 198, 205
Nigvyicans, 205
novaehollandiae, 195, 198
Novastoa, 190, 199-200
octosectus, 205
oryzata, 203, 208
panamensis, 208
peronii, 208
Petaloconcha, 196
Petaloconchus, 184, 185, 186, 190,
193, 196-198, 201, 204-205,
208, 209
petraeum, 200
planorbis, 199
platypus, 207
Polyphragma, 190, 197
polyphragma, 183, 190, 191,
194-195, 202
quoyt, 194
vastyum, 199, 203, 207, 209
renisectus, 198, 205
Rotularia, 191
Scolissedium, 190
Scolixedion, 190
sculpturatus, 190, 197
Segmentella, 184
semisurrectus, 194
Serpula, 184
serpuliformis, 190
Serpuloides, 190, 194
Serpulopsis, 190
Serpulorbis, 184, 188, 190-191,
192, 194-195, 196, 198, 201,
202-203, 208-209
Serpulus, 184
Siliquaria, 184
stpho, 195
Siphonium, 188, 190, 198
Spiroglyphus, 184, 190-191, 198
Spirorbis, 184, 186
squamigerus, 188, 195, 203, 205,
207, 209
Stephopoma, 184, 206
Stoa, 184, 198
subcancellatus, 191, 198
sutilis, 209
Tetranemia, 191, 194
tholia, 200
Thylacodes, 183, 191, 192, 194
Thylacodus, 183, 191, 192, 193
Thylaeodus, 183, 191-192, 193-
194, 197, 201-202, 208
tokyoensis, 198
Tripsycha, 183, 196, 203, 209
tripsycha, 196, 203, 209
triqueter, 193
Tubulostium, 184, 191
tulipa, 209
validus, 195
vavians, 190, 198, 205
Veristoa, 192, 198
Vermetus, 186-188, 192-194, 197,
200-202, 208, 210
Vermicularia, 184, 188, 190, 192,
207
Vermiculus, 192, 207
Vermilia, 184
Vermitoma, 192, 198
virginica, 189
woodwardi, 205
16
PLATE 54
Fic. 1. Serpulorbis oryzata (Mérch). Holotype. British Museum (Nat. Hist.) Reg. No.
195912. o*7. Diameter of aperture, 15 mm.
Fic. 2. Dendyvopoma rvastrum (Mérch). Holotype. B.M. (N.H.) Reg. No. 195916. X1°3.
Diameter of aperture, 9 mm.
Fic. 3. Serpulorbis eruciformis (Mérch). Holotype. B.M. (N.H.) Reg. No. 195915. X13.
Diameter of aperture, 7 mm.
Fic. 4. Petaloconchus (Macrophragma) flavescens Carpenter. Syntypes. B.M. (N.H.) Reg.
No. 195918. X2°6. Diameter of aperture, I°5 mm.
PLATE 55
Fic. 1. Dendropoma lituella (Mérch). Lectotype (upper specimen), on Haliotis, the photo-
graph retouched to block out a number of extraneous tubicolous annelids of the genus Spirvorbis.
B.M. (N.H.) Reg. No. 195917. 4. Diameter of aperture, 1°5 mm.
Fic. 2. Petaloconchus (Macrophragma) macrophragma Carpenter. Lectotype (central speci-
men). B.M. (N.H.) Reg. No. 57.6.4.1500. 3. Diameter of aperture, 1 mm.
Fic. 3. Vermetus (Thylaeodus) contortus (Carpenter). Lectotype. B.M. (N.H.) Reg. No.
57-6.4.1490. 3. Diameter of aperture, approximately 3 mm.
Fic. 4. Vermetus (Thylaeodus) indentatus (Carpenter). Lectotype. B.M. (N.H.) Reg. No.
57.6.4.1494. 3. Diameter of aperture, 1°5 mm.
Fic. 5. Serpulorbis squamigerus (Carpenter). Syntypes. B.M. (N.H.) Reg. No. 55.3-14.57-
x1. Diameter of aperture, 9 mm.
Bull. B.M. (N.H.) Zool. 7, 3
55
PLATE
M. (N.H.) Zool. 7, 3
Bull. B
PRINTED IN GREAT BRITAIN BY
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BARTHOLOMEW PRESS, DORKING
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ais
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—
A REVISION OF THE GENUS
DINOTOPTERUS BLGR.
(PISCES, CLARIIDAE)
= § WITH NOTES ON THE
COMPARATIVE ANATOMY OF
_ THE SUPRABRANCHIAL ORGANS
IN THE CLARIIDAE
qo FED 188 RR
_-ppEsENTe? + eee
iad P. H. GREENWOOD &°8"<c0
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BULLETIN OF
BRITISH MUSEUM (NATURAL HISTORY)
( GY 7 Vol. 7 No. 4
LONDON : 1961
A REVISION OF THE GENUS
DINOTOPTERUS BLGR. (PISCES, CLARIIDAE)
WITH NOTES ON THE COMPARATIVE
ANATOMY OF THE SUPRABRANCHIAL
ORGANS IN THE CLARIIDAE
get
BY ¥ nt
P. H. GREENWOOD
Department of Zoology, British Museum (Natural History)
Pp. 215-241 ; 1 Text-figure
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 4
LONDON: 1961
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(NATURAL HISTORY), mstituted in 1949, 1s
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PRE ESE NTED
A REVISION OF THE GENUS
DINOTOPTERUS BLGR. (PISCES, CLARIIDAE)
WITH NOTES ON THE COMPARATIVE
ANATOMY OF THE SUPRABRANCHIAL
ORGANS IN THE CLARIIDAE
By P. H. GREENWOOD
CONTENTS
Page
INTRODUCTION . 4 5 E - . a RG
THE GENERA Dinotopterus AND Bathyclarias F < c 5 é a Zusfe
THE Genus Dinotopterus : c c 7 c + 219
THE LAKE TANGANYIKA SPECIES, D. ainrhveinee 5 7 c ‘ ZO
THE SPECIES OF Dinotopterus OCCURRING IN LAKE NYASA : =) 3220
Dinotopterus nyasensis (Worthington) - 6 c < o WL
D. jacksoni sp. nov. : 5 5 2 : - 5 - 222
D. loweae (Jackson) 3 ; ; 3 : ‘ 5 PB}
D. ilesi (Jackson) . : é : : c : é a Ve
D. longibarbis (Worthington) A é : e 0° é BaF
D. votundifrons (Jackson) 2 c 0 - c 5 i + 220
D. foveolatus (Jackson) : : ; 5 c - : 7220
D. euryodon (Jackson) . fi ¢ A 5 c é 0 cB)
D. filicibarbis (Jackson) ¢ 7 : - 3 3 ez20)
D. worthingtoni (Jackson) : ¢ 5 : ti : - 2277)
D. gigas (Jackson) : : 6 : . ‘ 5 GC e227
D. atribranchus sp. nov. . é : : “ cl : a wes)
KEY TO THE SPECIES OF Dinotopterus 2 ‘ ezZ0)
THE SUPRABRANCHIAL RESPIRATORY ORGANS 1 IN THE ) CLARIDAE : . 231
THE SUPRABRANCHIAL ORGAN IN Dinotopterus 4 232
SUPRABRANCHIAL REGRESSION IN OTHER CLARIIDAE AND A CoMPARISON WITH
Dinotopterus . ; : : c : : 4 : 2 + 239
CoNCLUSION 5 : : e : : : : 5 - 240
ACKNOWLEDGMENTS. : a a . : 0 0 . 241
REFERENCES 2 ° ; : : 5 c 5 o é + 241
INTRODUCTION
TuE genus Bathyclarias was created by Jackson (1959) to accommodate ten endemic
species of predominantly deep-water Clariidae from Lake Nyasa. Anatomical work
which I have carried out on Jackson’s material, and on other specimens, leads me
to conclude that Bathyclarias does not differ substantially from the genus Dino-
topterus (Boulenger, 1906). At present, Dinotopterus is a monotypic genus confined
ZOOL. 7, 4. 17§
218 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
to Lake Tanganyika; a second species, D. jallae G. & T., 1917 from Southern
Rhodesia should be referred to the genus Clarias (R. A. Jubb, personal communication).
THE GENERA DINOTOPTERUS AND BATHYCLARIAS
No comprehensive definition of Dinotopterus has been published. Combining
published descriptions and observations on specimens of D. cunningtoni, the genus
can be distinguished from other clariids by the following characters : sides of head
incompletely enclosed by bone, there being an appreciable gap between the supra-
orbital, dermosphenotic and sphenotic bones ; eyes laterally placed, forming part
of the head outline when the fish is viewed from above ; no arborescent organs
present in the suprabranchial chamber (this character was first observed by Poll
[1953]; other accounts of the genus [David, 1935 ; Marlier 1938; Bertin & Aram-
bourg, 1958] imply that the arborescent organs are well developed) ; a small adipose
dorsal fin present.
The last character calls for some comment. In all but the smaller specimens of
D. cunningtoni, the fin is poorly developed ; it is little more than a slightly thickened
and humped upper margin to the caudal peduncle. However, contrary to Boulenger’s
opinion, the fin is supported by the elongated neural spines of the posterior caudal
vertebrae. These spines are c. 1-3-1:5 times longer than those of the preceding
vertebrae. Thus, although superficially the adipose dorsal fin of adult D. cunningtoni
is not a striking character, its presence is clearly manifest in the underlying bony
structure.
The most outstanding morphological characters of Bathyclarias are the laterally
placed eyes and the greatly reduced or even non-existent arborescent organs ;
that is to say, characters which distinguish Bathyclarias from Clarias but not from
Dinotopterus. Only two characters given by Jackson (op. cit.) seem to separate
Bathyclarias and Dinotopterus, namely “sides of head enclosed in bony shields ”
and“... no adipose fin present.” The former is not correct ; the arrangement of the
lateral roofing bones in all species of Bathyclarias conforms to the Dinotopterus
pattern, with a large space separating the supraorbital, dermosphenotic and sphenotic
bones. The thickened cephalic skin gives a superficial appearance of continuity
but when the skin is removed, the true relationship of the bones is revealed.
The question of presence or absence of an adipose dorsal fin is more equivocal.
Species referred to Bathyclarias show considerable variation in the posterior extension
of the dorsal fin ; in some, it is narrowly separated from the caudal whilst in others
there is a longer gap. In none is the distance separating the two fins as great as it
is in Dinotopterus cunningtont. I have examined all the available material of Bathy-
clarias and conclude that in some (those with the greatest dorsal-caudal interspace)
a weakly developed adipose fin is visible externally. In these fishes the upper caudal
peduncle margin is thickened and, in a few, its outline is slightly humped. In none
is the adipose fin as obvious as in Dinotopterus cunningtoni of the same size. However,
the osteological picture is more convincing. I have examined radiographs of two
Bathyclarias representing species with long and short dorsal-caudal interspaces.
In both species the most posterior caudal vertebrae have elongate neural spines
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 219
which are clearly longer than those of the preceding vertebrae underlying the
rayed dorsal. Comparison between the more posterior caudal vertebrae of Dinotop-
terus cunningtoni and the two Bathyclarias species shows that the latter have relatively
shorter neural spines (c. 1:3 x longer than the preceding spines; cf. 1:3-1-5 x in
D. cunningtont). Despite these differences, I consider that the state of caudal peduncle
development represented in the two Bathyclarias species serves to bridge the gap
between the presence and absence of an adipose fin.
An identical situation exists within the genus Clarias (see David op. cit.). Here,
three species of the subgenus Heterobranchoides, Clarias mellandi Blgr., C. ngamensis
Casteln., and C. pentissgrayi (Fowler), all exhibit traces of an adipose fin. Again,
the fin is poorly differentiated externally but is supported by elongate neural spines.
The osteology of the skull in these fishes is typically that of a heterobranchoid
Clarias, as is the condition of the hypertrophied suprabranchial arborescent organ
(C. ngamensis and C. mellandi from personal observations, C. pentissgrayi from
Fowler's [1931] description which does not include the suprabranchial organs).
Certainly the “ adipose ” fin in C. mellandi and C. ngamensis is comparable, externally,
with the dorsal thickening of the peduncle found in many Bathyclarias species.
Furthermore, the condition of the supporting neural spines in C. mellandi (the only
species examined for this character) is comparable with that found in the Bathyclarias
species mentioned above.
Thus it seems that the presence or absence of a small adipose dorsal fin can no
longer be considered sufficiently trenchant to warrant its use as the sole criterion for
separating Dinotopterus and Bathyclarias.
One other point may be touched upon here. That is, the condition of the supra-
branchial organ in the two “ genera”’. In Dinotopterus cunningtont the arborescent
organs, so characteristic of the genus Clarias, are not developed, even in the largest
specimens. In Bathyclarias the various species provide examples of development
covering the entire range, from complete absence through simple stumps and sparsely
branched “trees” to arborescent organs closely approaching the Clarias type in
size and complexity. This wide range of variation in suprabranchial structure is
described and discussed on p. 231—240.
If all these characters are considered, there seem to be no anatomical grounds for
Tecognizing two genera and I propose to treat Bathyclarias Jackson, 1959 as a
synonym of Dinotopterus Blgr., 1906, a redescription of which is given below.
THE GENUS DINOTOPTERUS BOULENGER, 1906
Dinotopterus Blgr. 1906, Trans. zool. Soc. Lond. 17: 550; Idem. Cat. Afr. Fish., 1911, 2: 276;
David, 1935, Rev. Zool. Bot. Afr. 28, 95 (misspelt Dinopterus). Clarias, part (C. nyasensis
and C. longibaybis) Worthington, 1933, Proc. zool. Soc. Lond., 285. Bathyclavias Jackson,
1959, Proc. zool. Soc. Lond. 132 : 109-138.
TyPE sPEciES. Dinotopterus cunningtoni Blgr., 1906.
Clariid fishes with the lateral roofing bones of the skull not forming a continuous
casque because the supraorbital, sphenotic and dermosphenotic are separated by a
220 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
distinct space. Eyes lateral, forming part of the head outline when viewed from
above. Dorsal and caudal fins separated by a distinct space which, at least super-
ficially, shows all stages of intergradation between a weakly-developed adipose fin
and the complete absence of such a fin ; whether the fin is clearly developed or not,
the more posterior caudal vertebrae have relatively elongated neural spines.
Suprabranchial chamber always present, as are the “ gill-fans’’ forming its
lateral and ventral walls; suprabranchial arborescent organs variously developed,
from completely absent to moderately large and much branched.
DIsTRIBUTION. Lakes Tanganyika and Nyasa: essentially a lacustrine genus,
rarely occurring in streams and rivers.
THE LAKE TANGANYIKA SPECIES,
DINOTOPTERUS CUNNINGTONI BLGR., 1906
This species was recently redescribed by Poll (1953) ; in this description he remarks
that the suprabranchial cavity is without arborescent organs. In general, this
statement is correct but requires some amplification. None of the specimens I have
examined possesses large or many-branched trees of the Clavias type, but a small
stump or knob may be present on the fourth gill-arch of both large and small fishes.
In some small specimens this structure is relatively large and bifid, occupying a
fair volume of the cavity ; in others, it is reduced to a slight swelling. No external
indication of a knob is apparent in fishes with a head length of less than 0-7 cm.
(at which size the “ gill-fans”’ are still incompletely developed). In four specimens
with head lengths of 1-4—3-5 cm. a well-developed knob is present on the epibranchial
of the fourth arch. The next largest specimen available (standard length 17-5 cm.;
head 4-7 cm.) has completely developed “ gill-fans ”’ but no trace of an arborescent
organ.
Of particular interest is an apparently ontogenetic change in the histology of the
suprabranchial epithelium (see p. 235 for a full explanation of the terms used). In
young D. cunningtoni (smallest fish examined, 11-8 cm. S.L.) the gill tissue in this
epithelium is arranged in the “ Clarias”’ pattern of regular but sinuous lines or
lamellae. Such is also the condition in fishes up to 17-5 cm. S.L. But, in the next
larger specimen (46-5 cm.S.L.) and in all larger fishes, the lamellae are arranged in the
“ coralline,’’ pattern of small circular patches of gill-cells. Unfortunately, I have not
found any specimen in an intermediate condition, although in two of the smaller
fishes (12-5 and 17:5 cm.S.L.), a few lamellae are in the form of elongate ovals. These
could be interpreted as having arisen from the union of two neighbouring lamellae
in a “‘ Clarias ’’-type pattern. Subsequent development may involve the fractioning,
by union at several points, of these ovals.
The only other Dinotopterus species (D. worthingtoni) for which a wide size range is
available, does not show any difference in lamellar pattern between large and small
fishes. Because the adult size of D. worthingtoni is considerably less than that attained
by D. cunningtoni, ontogenetic changes might take place at a size smaller than any
represented in the collection,
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 2
iS)
H
THE SPECIES OF DINOTOPTERUS OCCURRING IN LAKE NYASA
Jackson (1955 and 1959) gave the first detailed account of the remarkable species-
flock of Clariidae in Lake Nyasa. In his later paper, he drew attention to several
taxonomic points which still required further study. On the basis of Jackson’s
original material, supplemented by other specimens collected by J. F. R. O., the
Survey party of 1939 and Dr. Rosemary Lowe-McConnell, I have been able to
investigate these points and also expand the descriptions of certain species.
My primary interest in the Nyasa Dinotopterus lay in their peculiar suprabranchial
organs (see p. 232) ; when more material became available it was clear that the con-
dition of these structures was more variable, both inter- and intraspecifically, than
I had led Mr. Jackson to believe (see Jackson, 1959, p. 112). Furthermore, the
suprabranchial organ showed itself to be a character of some taxonomic importance.
A brief description of the suprabranchial region is now given for each species and
should be read in conjunction with Tables I and II, and with the detailed account
on pp. 231-240. Certain new descriptive terms are defined in that section.
Dinotopterus nyasensis (Worthington), 1933
Clarias nyasensis Worthington, 1933, Proc. zool. Soc. Lond., 308, fig. 9.
Bathyclarias nyasensis (part), Jackson, 1959, Proc. zool. Soc. Lond. 132: 113.
Lectotype. B.M. (N.H.) Reg. No. 1932.11.15. 584.
The so-called ‘“ smooth-headed”’ form of this species (Jackson, 1959) is now
recognized as a distinct species (see p. 222). Within D. nyasensis as defined here there
is considerable variation in the roughness of the skull. Three small specimens,
(27, 33 and 39 cm. S.L.) have the roofing bones almost completely smooth except
for a few scattered tubercles on the occipital and frontal regions of the skull. In
larger fishes the skull is entirely rugose, but in the largest specimen examined the
tugosity is like that of the three smallest fishes. Such cyclical ontogenetic changes
in skull ornamentation seem common amongst the larger Clariidae (personal observa-
tions).
As the additional material does not otherwise differ from the descriptions given
by Worthington (1933) and Jackson (1953) a full redescription of the species is not
warranted.
SUPRABRANCHIAL ORGAN. The suprabranchial cavity is large; its length is
about 33% of the head in fishes 49-62 cm. standard length (see also Table II).
The arborescent organs, on the other hand, are poorly developed. In a fish of head
length 20 cm. the tree on gill-arch II is polyfid and about 12 mm. high, that on arch
IV about 16 mm. high and more extensively branched. In a smaller individual
(H.L. 8-3 cm.) no tree is developed on the second arch and that of the fourth arch
is a low, bifid stump. Such variability is not entirely size-correlated ; for example,
a specimen of 21 cm. head length has trees substantially less developed than another
individual of 18 cm. H.L. In this fish, the trees are almost as well developed as in
a specimen of 23 cm. head length.
The epithelium lining the suprabranchial cavity is highly vascular and the gill-
like tissue is distributed in the “ Saccobranchus ” pattern (see p. 235).
ZOOL. 7, 4. 17§§
222 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
Dinotopterus jacksoni sp. nov.
Bathyclarvias nyasensis (part), Jackson, 1959, Proc. Zool. Soc. Lond. 132 : 113 (the smooth-headed
forms only).
Bathyclarias loweae (part). Idem, ibid., 114, fig. 1B.
Hototyre. A fish 61 cm. standard length, from Nkata Bay; B.M. (N.H.) Reg
No. 1960.2.29.26.
DESCRIPTION. Based on the holotype, two entire specimens 46 and 68 cm. S.L.,
and one head 23-3 cm. long.
Length of head contained 3-1-3-8 times in standard length, the dorsal surface
smooth or relatively smooth; when present, the rugose areas are most apparent
on the posterior and antero-lateral regions of the skull. In large specimens the
squamosal region (i.e. the sphenotic and pterotic bones) is slightly domed; the
intervening occipital region is flat. Frontal and occipital fontanelles barely visible
beneath the thick cephalic skin ; the frontal fontanelle very narrow, the occipital
fontanelle almost circular. Head broad, its width contained 4-4—4-9 times in standard
length and 1-4-1-6 times in head length. Eye lateral, its diameter 15-8-18-8 in
head length and g:8—10°5 in the interorbital width, which is contained 1-6—1:9 times
in head length and is about equal to the width of the mouth. Dorsal outline of the
snout rounded ; snout length contained 3-7—4-4 in the head.
Barbels smooth, the base of the maxillary pair somewhat fleshy. Length of nasal
barbel 1-9-4:5 in head; maxillary barbel 1-3-1-7, outer mandibular 1-3-2°8, inner
mandibular 2-2-5:3 in head. Barbel length shows negative allometry with head
length.
Premaxillary and vomerine teeth fine and pointed ; length of half the premaxillary
band 4:7-5:2 in head length, that of half the vomerine band 5-0-5:9 ; vomerine
band interrupted in the mid-line, its width equal to or slightly less than that of the
premaxillary band.
Gill rakers long (almost equal to the longest gill filaments) and numerous, 172-230
on the first gill-arch, the number showing positive correlation with standard length.
In preserved material the gill filaments are colourless.
Dorsal fin with 64 rays, the distance between its origin and the supraoccipital
contained 3-8—4-6 times in head length. Anal with 44 rays. Both fins are clearly
distinct from the caudal. Pectoral fins short and covered with thick skin, the anterior
face of the spine weakly denticulate or smooth; greatest length of the pectoral
contained 2-2~2:8 in head length. Caudal peduncle as long as deep to 1-4 times
deeper than long. Adipose dorsal weakly developed.
Vertebrae (excluding the fused anterior mass) in the single specimen radiographed
(the Type), 54.
I have great pleasure in naming this species after Mr. P. B. N. Jackson, who first
recognized that certain specimens he referred to Bathyclarias nyasensis might repre-
sent a new species.
SUPRABRANCHIAL ORGANS. The suprabranchial chamber is moderately large
(its length c. 32% of head; see Table II for volumes) and the gill-fans are well
developed. The arborescent organs are greatly reduced. In the three largest speci-
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 223
mens there is no macroscopic indication of an anterior tree and the posterior one is
represented by a simple, short phallic outgrowth. There is no posterior tree in the
smallest specimen (S.L. 46 cm.) but there is a small stump occupying the usual
site of the anterior tree.
Gill tissue in the suprabranchial epithelium is arranged in the “ Saccobranchus ”’
pattern. A striking feature in the histology of this epithelium is an abundance of
large mucous cells widely distributed amongst the gill tissue and the undifferentiated
epithelial cells.
Discussion. From Jackson’s arrangement of the Nyasa species now referred
to Dinotopterus, D. jacksonz is closely related to D. nyasensis and D. loweae. Indeed,
specimens of D. jacksoni were previously included in both these species, although
Jackson did stress the possibility that smooth-headed specimens of Bathyclarias
nyasensis might represent a distinct species. At first sight the virtually smooth
head of D. jacksoni seems a distinctive character, but as Jackson noted, this condi-
tion intergrades with that occurring in large D. nyasensis. Also, the skull of the smal-
lest D. jacksont specimen is as rough as that of a comparably sized D. nyasensis.
From the examination of numerous Clarias mossambicus skulls and the skulls of
most Dinotopterus species, it seems that the degree of rugosity is chiefly dependent
on the size of the individual. The smooth-headed D. gigas may prove exceptional
to this generalization (see also p. 221).
The principal difference between D. myasensis and D. jackson lies in the greatly
reduced suprabranchial structure of the latter. Although the arborescent organs
of D. nyasensis are reduced, in no adult specimen is the reduction so marked as in
D. jacksont.
Two other, less pronounced, differences are the shorter pectoral fins of D. jacksoni
and the tendency in this species for the squamosal region of the skull to become
domed.
Even though D. jacksont, D. loweae and D. nyasensis are closely related on “‘ key ”’
characters, I do not think that this reflects the phyletic relationship of the species ;
more material is required, however, before this problem can be investigated.
Dinotopterus loweae (Jackson), 1959
Bathyclarias loweae (part) Jackson, 1959, Proc. zool. Soc. Lond. 132: 114, fig. 1A.
One of the two specimens from which the original description was made is now refer-
red to D. jacksont. The redescription is based on the holotype (82 cm. S.L.), two
other fishes 71 and 72 cm. S.L. and two heads 17-0 and 17:6 cm. long. A juvenile
specimen 19°5 cm. S.L. is tentatively determined as D. loweae, but is not included
in the description.
Hototyre. B.M. (N.H.) Reg. No. 1960.2.29.3 from Nkata Bay.
Description. Length of head contained 3-1-3-7 times in standard length, its
dorsal surface moderately rugose on the posterior half, smooth anteriorly. Head
width contained 4-9-5-3 times in standard length and 1-4-1-7 times in head length.
Eye diameter 14-2-18-0 in head length and 6-9-10-3 in interorbital width (showing
224 A REVISION OF THE GENUS TINOTOPTERUS BLGR.
negative allometry with head length). Interorbital width 1-8-2-1 in head length,
snout length 3:5-4:4; distance between anterior nostrils 3:5~-4:2 times. Barbels
smooth; length of nasal barbel 3:0-4:3 in head, maxillary barbel 1-3-1-7, outer
mandibulars I-g-2-2, inner mandibulars 2-7-3-7 in head.
Premaxillary and vomerine teeth fine and pointed, length of half premaxillary
band contained 4:5-5:7 times in head length, that of half vomerine band 4-5-6-5
times ; vomerine band interrupted in the mid-line, its width equal to or slightly
greater than that of the premaxillary band.
Gill rakers numerous and fine, from 180 (in fishes of 15-6 cm. H.L.) to 260 (H.L.
23:2 cm.) ; length 0-7—1-0 of the length of the longest gill filament (see also Jackson,
1959, P- 113).
Dorsal fin with c. 63-65 rays, the distance from its origin to the occiput contained
3°7-4°9 times in head length. Anal fin with 49-54 rays. Caudal peduncle 1-1-1-5
times as deep as long.
The strongly humped body of the holotype is less marked in other specimens and
may thus be correlated with size or may be due to post-mortem muscular contraction.
SUPRABRANCHIAL ORGAN. The suprabranchial cavity is large (see Table II)
and the arborescent organs well developed and much branched in all the specimens
examined. In the smallest fish (a specimen 19:5 cm. S.L. and only tentatively
placed in this species) the future anterior tree appears as a low swelling on the second
gill-arch whilst the posterior tree is four-branched and is 3 mm. high.
Gill tissue in the suprabranchial epithelium is arranged in the “ Clarias ”’ pattern
(see p. 235).
Dinotopterus ilesi (Jackson), 1959
Bathyclarias ilest Jackson, 1959, Proc. zool. Soc. Lond. 132 : 116, fig. 2.
HoLotyPEe. A male 66 cm. S.L. from Nkata Bay, B.M. (N.H.) Reg. No. 1960.
2.29.8.
This description is based on the holo- and paratypes (66 and 59 cm. S.L. respec-
tively) and one other specimen, 69 cm. 5S.L.
Length of head 3-2-3-3 in standard length, the dorsal surface rugose in the smaller
specimens, smoother in the largest fish. Head width 4-7-5-1 in standard length
and 1-4-1:6 in head length. Eye diameter 16-0—19-6 in head length and 10-:0—-10°5
in interorbital width, which is contained 1-7—-1-9 times in the head. Snout length
3°9-4:1 ; distance between anterior nostrils 3-7-3-9 in head.
Barbels smooth, base of the maxillary barbel somewhat swollen. Length of nasal
barbel 4:1-5-7, maxillary barbel 1-8-2-1, outer mandibular 3-7—4-8, inner mandibular
2:4—-3'1 in head length.
Premaxillary and vomerine teeth fine and pointed, length of half premaxillary
band about 5 in head. Vomerine band interrupted in the mid-line and slightly
narrower than the premaxillary band, its half length contained 4:5-5:0 times in
the head.
Gill rakers c. 0-8 length of longest gill filament ; 170-184 on the first arch. Filaments
‘dark, purplish-black (cf. D. atribranchus, D. filicibarbis and D. worthingtont).
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 225
Dorsal fin with 65-67 rays, rather narrowly separated from the caudal ; distance
between its origin and the occipital process contained 3-8—4-5 times in the head length.
Anal fin with 50-52 rays. Caudal peduncle 1-1-1-6 times as deep as long.
The ‘“‘ black removable mucus over the body ” which Jackson notes, is not easily
discernible in preserved material.
SUPRABRANCHIAL ORGAN. The suprabranchial cavity is large (see Table II),
the arborescent organs present and much branched. There is considerable individual
variation in the size of the trees ; those of the type (66 cm. S.L.) are much smaller
than the trees in the paratype (59 cm. S.L.).
Gill tissue in the lining epithelium is arranged in the “ Saccobranchus”’ pattern
(see p. 235).
Dinotopterus longibarbis (Worthington), 1933
Clarias longibarbis Worthington, 1933, Proc. zool. Soc. Lond. 309 ; fig. 10.
Bathyclarias longibarbis, Jackson, 1959, Proc. zool. Soc. Lond. 132: 117.
Hototype. A male 75 cm. S.L. B.M. (N.H.) Reg. No. 1932.11.15. 592.
DESCRIPTION. Based on the holotype and two other specimens, 44:5 and 40:5 cm.
SL.
Length of head 3-4-3-7 in standard length, dorsal surface rugose, especially over
the posterior two-thirds. Width of head contained I-4-1-5 in head length. Eye
diameter 14:0-14-7 in head length, 7-4—8-8 in interorbital width which is contained
I-6-1'9 in head. Snout 3-5-3-6 in head length; distance between anterior nostrils
3:6 times.
Barbels long and smooth, length of nasal barbel contained 1-1-1-6 times in head,
maxillary and outer mandibular barbels respectively 1-2-1-3 and I-I-1-2 times as
long as the head; inner mandibular barbels 1-2—-1-6 in head. It is interesting to
note that the negative allometry of barbel length with standard length usual in
other species is not at all marked, despite the size discrepancy between the type and
the two smaller specimens.
Premaxillary and vomerine teeth fine and pointed, half length of either band
contained about 5 times in head length. Vomerine band narrowed medially but
continuous in two specimens, interrupted in the third, its width slightly less than
that of the premaxillary band.
Gill rakers relatively short, about 0-5-0-6 of the length of the longest gill filaments ;
there are, on the first gill arch, 145 rakers in the type (75 cm. S.L.) ; go and 83 rakers
in the two smaller fishes (S.L’s. 44-5 and 40-5 cm. respectively).
Dorsal fin with c. 65 rays, distance from its origin to the occiput contained 5 times
in the head. Anal fin with c. 56 rays. Caudal peduncle 1-4 times as deep as long.
SUPRABRANCHIAL ORGAN (see also Table II). A good ontogenetic series is provided
by this material. The type specimen has large, polyfid arborescent organs on both
the second and fourth arches. In the fish 44-5 cm. S.L., the anterior tree is merely a
stub, whilst the posterior tree is small, with seven branches. A similar developmental
state is seen in the 40-5 cm. fish, except that the anterior tree is even less developed.
Gill tissue in the suprabranchial epithelium is distributed in the “‘ Clarias”’
pattern,
iS)
iS)
fo)
A REVISION OF THE GENUS DINOTOPTERUS BLGR.
Dinotopterus rotundifrons (Jackson), 1959
Bathyclarias votundifrons Jackson, 1959, Proc. zool. Soc. Lond. 132: 118. fig. 3.
Hototype. B.M. (N.H.) Reg. No. 1960.2.29.11, from Nkata Bay.
As there are no additional specimens, reference is made to the original description.
SUPRABRANCHIAL ORGAN. The cavity is relatively small (see Table II) and the
arborescent organs are greatly reduced. There is no macroscopic indication of an
anterior tree and the posterior tree is represented by a single, phallic projection about
5 mm. high (i.e. in a specimen of 14:5 cm. head length).
Gill tissue in the suprabranchial epithelium is arranged in a “‘ coralline’”’ pattern
(see p. 236).
Dinotopterus foveolatus (Jackson), 1955
Clarias foveolatus Jackson, 1955, Proc. zool. Soc. Lond. 125: 681, text-fig.
Bathyclarias foveolatus, Idem, 1959, Ibid. 132 : 118.
The only information additional to that given by Jackson (op. cit.) concerns the
structure of the suprabranchial organs.
Jackson was misled by the well-developed “ gill fans’
breathing organs present, as is usual in this family se
The suprabranchial chamber of D. foveolatus is considerably reduced, its length
being only about 20% of the head. There is a corresponding decrease in depth so
that the chamber is noticeably shallow (see Table II). No appreciable reduction is
apparent in the “ gill-fans”’. The tree associated with the fourth gill arch is reduced
to a small “ T-shaped outgrowth and there is no macroscopic indication of an
anterior tree.
In preserved material the suprabranchial epithelium is jet-black except for the small
patches of white gill tissue, distributed in the “ coralline ”’ pattern (see p. 236).
?
into stating “ Accessory
Dinotopterus euryodon (Jackson), 1959
Bathyclarias euryodon Jackson, 1959, Proc. zool. Soc. Lond. 132 : 120, fig. 4.
Ho.otyre. B.M. (N.H.) Reg. No. 1960.2.29.13.
No further specimens have been obtained for study purposes.
SUPRABRANCHIAL ORGAN. In the single specimen (S.L. c. 104 cm.) I have been
able to dissect, the cavity is not appreciably reduced (length c. 28% of head ; volume
107 cc.) but there are no indications of arborescent organs. The gill-fans, on the other
hand, are fully developed.
Because the specimen is poorly preserved it was difficult to get a clear histological
picture of the suprabranchial epithelium. However, the gill tissue is apparently
distributed according to the ‘‘ Saccobranchus ’’ pattern (see p. 235).
Dinotopterus filicibarbis (Jackson), 1959
Bathyclarias filicibarbis Jackson, 1959, Proc. zool. Soc. Lond. 132 : 120, fig. 5.
Hototyre. B.M. (N.H.) Reg. No. 1955.6.14.1 from Nkata Bay.
No further specimens have been collected, but the original description must
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 227
be emended. In the holotype, at least after preservation, the gill filaments are
greyish-black (cf. D. ilesi and D. foveolatus).
SUPRABRANCHIAL ORGAN. The cavity is long (c. 34% of the head) but shallow so
that its volume, in the holotype, is 32 c.c. No arborescent organs are visible.
Gill tissue in the suprabranchial epithelium is arranged in the “ coralline ” pattern
(see p. 236); the undifferentiated tissue is jet-black. Identical tissue occurs in
D. foveolatus.
Dinotopterus worthingtoni (Jackson), 1959
Bathyclarias worthingtont Jackson, 1959, Proc. zool. Soc. Lond. 132 : 123, fig. 6.
HototyPe. B.M. (N.H.) Reg. No. 1960.2.29.18 from Nkata Bay.
No additional study material of this species has been deposited in the Museum.
When re-examining the original specimens I found that the gill filaments of the
two paratypes (25:4 and 27-5 cm. total length) are greyish-black, except at their
extreme distal tips. Neither the small individuals (7-5 and 8-0 cm. S.L.) nor the
large holotype (68-2 cm. T.L.) have dark filaments. It seems unlikely that such
pronounced darkening of the filaments can be attributed to preservation or to any
post mortem changes, such as a branchial haemorrhage. If both these explanations
are discounted, there remains the suggestion that darkening of the gills can occur
as an individual variation. The character might therefore be of reduced taxonomic
importance. The gills of D. ilesi, D. foveolatus and D. atribranchus are black in
preserved specimens, but as these species are known from very few specimens it is
impossible to determine the intraspecific constancy of the character.
SUPRABRANCHIAL ORGAN. The cavity is somewhat reduced (see Table II).
Ontogenetic changes in the development of the arborescent organs are clearly seen
in these specimens. The trees are greatly reduced at all sizes; no anterior tree is
developed, even in the largest fish (the holotype, 68-2 cm. T.L ), and in this fish the
posterior tree is represented by a small knob about 3-5 mm. length. In a smaller
specimen (23 cm. S.L.) the posterior tree is a weakly trifid knob, proportionately
larger than that of the holotype. The smallest fish examined (6-6 cm. S.L.) shows
a very early stage in suprabranchial ontogeny, at wae no trees are visible and even
the “ gill-fans ”’ are incomplete.
Gill tissue within the suprabranchial epithelium is distributed in the “ Sacco-
branchus’’ pattern ; no ontogenetic changes in pattern were detected (cf. D. cun-
ningtoni, where such changes are found).
Dinotopterus gigas (Jackson), 1959
Bathyclarias gigas Jackson, 1959, Proc. zool. Soc. Lond. 132 : 125, fig. 7.
Hototyre. A head and skin B.M. (N.H.) Reg. No. 1960.2.29.35.
Originally based on a single giant specimen 135 cm. S.L., the description must now
be modified to include four smaller specimens (one head 28 cm. long and three entire
fishes 47-0, 61-0 and 64:5 cm. S.L.).
Length of head contained 2-6-3-6 times in standard length, the dorsal surface
228 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
smooth and covered with thick skin; head width 3-9-5-0 in standard length and
I-3-1'4 in head length. Eye diameter 13-7—19°3 in head (showing negative allometry
with head length) and 7-2-14:0 in interorbital width (again, negatively allometric).
Interorbital width 1-3-1-9 in head, length of snout 3:3-4:3.
Barbels smooth, their length negatively allometric with head length ; nasal barbel
2-7-6:0 in head, maxillary 1I-I-2:3, outer mandibular 1-9-3-1, inner mandibular
2:5-4'2.
Premaxillary and vomerine teeth slender and pointed, half length of either band
contained about 5 times in head length. Vomerine band continuous or interrupted
medially, its width equal to or slightly greater than that of the premaxillary band.
Gill rakers short, 0-5-0-65 of the length of the longest gill filaments ; 100-149
on the first gill arch, the number positively correlated with standard length.
Dorsal fin with c. 69 rays, anal with c. 56. Caudal peduncle as long as deep or,
deeper than long.
SUPRABRANCHIAL ORGAN. The suprabranchial cavity is relatively reduced,
particularly in large fishes (see Table II).
In the holotype (S.L. 135 cm.) both arborescent organs are of approximately
equal size (an unusual feature but one possibly correlated with the great size of this
fish) relatively large and extensively branched. These organs are of disparate sizes
(the posterior tree larger) in a head 28 cm. long—estimated to be from a fish c.
go cm. S.L.—and although small in relation to the volume of the cavity are much
branched. The same condition is found in a fish 61 cm. S.L. but in a larger specimen
(64:5 cm. S.L.) the arborescent organs are reduced to a small, bifid outgrowth on the
second arch and a slightly larger, trifid structure on the fourth arch. In the smallest
specimen examined (47 cm. S.L.) the anterior tree is represented by a small knob
and the posterior tree by a large, sparsely branched outgrowth.
The gill tissue in the suprabranchial epithelium is arranged in the “ Clarias”’
pattern (see p. 235).
Dinotopterus atribranchus sp. nov.
Hototyre. A male, probably adult, 39 cm.S.L. B.M. (N.H.) Reg. No. 1960.2.29.
7p
DEscRIPTION. Based on the unique holotype. Length of head 3-5 in standard
length, the dorsal surface relatively flattened ; roofing bones rugose, the tubercles
arranged in definite patterns. Frontal fontanelle long and narrow, its length 3-7 in
head. Width of head 5-2 in standard length and 1-5 in head length. Eye diameter
contained 11:2 in head length and 4-8 in interorbital width, which is contained
2:3 times in head length. Length of snout 4-9 in head, distance between anterior
nostrils 5-6 times.
Barbels smooth ; length of nasal barbel contained 2-7 times in head length, maxil-
lary 1-4, outer mandibular 2-0 and inner mandibular 3-3 times.
Premaxillary and vomerine teeth fine and pointed, the width of the vomerine
band about three-fifths that of the premaxillary.
Gill rakers very short, about 0-3 of the length of the longest gill filament ; 85 on
the first gill arch, Gill filaments dark greyish-black,
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 229
Dorsal fin with c. 60 rays, anal with c. 45. Caudal peduncle slightly deeper than
long, adipose dorsal very weakly developed.
Vertebrae (excluding the anterior fused mass) 54.
SUPRABRANCHIAL ORGAN. The suprabrancial cavity is reduced,, the anterior
tree a small stump and the posterior tree a short, six-branched outgrowth. The
“ gill-fans ” are well developed.
Gill tissue in the suprabranchial epithelium is arranged in the “ Saccobranchus ”’
pattern (see p. 235).
Discussion. Because this specimen is relatively small it is most likely that the
low number of gill rakers is not definitive. On the other hand, the very short rakers
may be looked upon as a character unaffected by growth. From Jackson’s (1959)
analysis of gill raker proportions in D. nyasensis and D. worthingtoni, and mine of
D. cunningtoni (below) it is clear that very little change occurs in the relative length
of the rakers, even over a wide size range. The gill rakers in D. atribranchus are
remarkably short even for a species within the group having reduced rakers.
If the possession of black gill filaments is a good specific character (but see p. 227)
then D. airibranchus is readily distinguished from all other species in the short-
takered group.
The condition of the suprabranchial organs in D. atribranchus, even though these
probably have not completed their development, distinguishes the species from
D. rotundifrons, D. worthingtont and D. euryodon.
From D. gigas, Dinotopterus atribranchus is readily distinguished by its rugose
skull (at least in the size ranges represented), shorter and narrower snout, and its
wider interorbital region.
KEY TO THE SPECIES OF DINOTOPTERUS
This key has been built around that produced by Jackson (1959). Like most
keys it is unsatisfactory especially since the known range of variation for many
of the characters used blurs several of the dichotomies. Two particular points should
be noted with care. One is the second dichotomy, based on the number of gill rakers
and their relative lengths. I have examined a wide size-range of Dinotopterus
cunningtoni and find that although the proportional measurement is constant at
allsizes, the number of rakers shows a fourteen-fold increase in large fishes (see below).
Similar results were obtained by Jackson (op. cit.) for D. nyasensis and D. worthing-
tont.
Gill raker counts and proportional measurements for D. cunningtoni :
Head length Length of longest raker
(cm.) Length of longest filament | Number of rakers
O-7 ; 0°5 : 12
I*4 0-7 20
I°7 0-7 20
Ae, OS 55
I3°I 0°5 t47,
16°5 Oz Ff)
19°3 0-7 200
26:0 o-7 172
230 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
From these figures it is clear that the relative length of the rakers is the more
reliable “ key character’; in larger fishes it is reinforced by the number of rakers.
The second unsatisfactory major dichotomy is the seventh, which is based on the
relative length of the maxillary barbels. This measurement is known to show
negative allometry with head length, so that small specimens of the species-group
alternative to D. longibarbis will tend to show the D. longibarbis character.
References to the suprabranchial organs and the nature of the suprabranchial
epithelium (“ Clarias ’’-like or “ Saccobranchus ’’-like) are discussed fully on pp.
232-7.
I have not used Jackson’s character of “ black, tarry removable mucus on body ”
to separate D. ilesi from D. nyasensis because with preserved material this character
is difficult to apply and may be misleading.
1. Adipose dorsal fin poorly developed or apparently absent . . : 2
Adipose fin clearly discernible é ¢ ° D. cunningtoni
2. Gill rakers on first arch 0-3-0°6 length of filaments, rarely more than 145 (at least in
fishes 7-75 cm. S.L.) . 3 3
Gill rakers 0-7—1-0 length of filaments, more e than 150 (usually 170-260) i in specimens
> 46cm. S.L., fewer in smaller fishes . : . : c 5 c 7 10
3. Barbels rounded, smooth and simple : 4
Barbels flattened and broad, the maxillary and outer mandibular: pair with rounded
lappets distally . : : : 5 : 5 é . D. filicibarbis
4. Body smooth, not mired : : cb 5 . : a A 5
Body rough and pitted . : ¢ é " - c 5 D. foveolatus
5. Gills and suprabranchial cavity black ° ° c 6 ¢ . _D. atribranchus
Gills and suprabranchial cavity not black. c 2 6
6. Vomerine tooth-band less than 1} times as broad. as the premaxillary band ;
teeth fine, discrete and pointed
Vomerine tooth-band more than 14 times broader than the premaxillary band, teeth
coarse and blunt : P : D. euryodon
7. Maxillary barbel not reaching beyond the tip of the pectoral fin . c : : 8
Maxillary barbel reaching well beyond extremity of pectoral fin . é D. longibarbis
8. Snout length contained less than 4:6 times in head length ; dorsal outline of snout
slightly curved ; head not noticeably chubby re : é 9
Snout at least 5 in head, rounded. Head chubby 4 5 D. rotundifrons
g. Base of maxillary barbel markedly conical, swollen and fleshy. Suprabranchial trees
greatly reduced ; only a small stump with 4 or fewer branches on the fourth gill
arch, at least = fishes > 20 cm. S.L., absent in fishes, < 7 cm. S.L.
D. worthingtoni
Base of maxillary barbel not markedly enlarged. Arborescent suprabranchial
organs on second and fourth gill arches, at least in fishes > 45 cm. S.L., much
branched in large fishes, sparsely branched in specimens 45-60cem.S.L. . D. gigas
10. Body relatively slender ; Leet barbel Ss least in fishes 27-69 cm. S.L.)
contained 1+8-2:2 in head . 6 Y c - 5 II
Body stout ; maxillary barbel 1-2—1-7 in head c 0 0 12
Tie Gill filaments and epithelium of suprabranchial cavity purplish- black ~ : D. ilest
Gill filaments and epithelium of suprabranchial cavity colourless in preserved
specimens . : D. nyasensis
12. Suprabranchial arborescent organs ‘merely a simple stub on the 4th gill arch ;
suprabranchial epithelium of the ‘‘ Saccobranchus”’ type. Dorsal surface of
head with few rugosities . : ; : . ’ : 3 . D. jacksoni
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 231
Suprabranchial arborescent organs moderately well developed on 2nd and 4th arches,
much branched in specimens 50-80 cm. S.L. (but reduced to a small four-branched
tree on the fourth arch in a fish 20 cm. S.L.) ; suprabranchial epithelium of the
“Clarias ”’ type . : . 3 é o J : : : . D. loweae
THE SUPRABRANCHIAL RESPIRATORY ORGANS
IN THE CLARIIDAE
Several descriptions of the suprabranchial organs have been published since the
original but remarkably complete account of their anatomy given by E. Geoffroy
St. Hilaire in 1802. This author’s preliminary notes (published by Lacepéde, 1836)
describing the appearance of the organs and their probable respiratory function,
still provide one of the most succinct accounts available.
Of the more recent papers, that of Rauther (1910), giving a detailed histological
account, and that of Marlier (1938), providing a more general description, are the
most comprehensive.
Variation in the suprabranchial region of the Clariidae is considerable (see below
and also David, op. cit.: Poll, 1942 ; Greenwood, 1956 and 1959) but in the majority
of species the following brief description 1 is applicable.
Above the gill chamber there is a spacious cavity, enlarged posteriorly where it
extends ventrally to about the level of the pharyngeal floor. The lateral floor and
walls of the cavity are formed by certain modified and membraneously united,
fan-like gill filaments on the upper part of each gill arch (hereafter referred to as
the “ gill-fans”’). The entire chamber, excluding the fans, is lined with highly
vascularized epithelium irrigated by afferent and efferent blood vessess from each
gill arch. As might be expected, the “ gill-fans ’’ have the histological structure of
gill filaments. A similar histology is shown by the epithelium lining the cavity
(Rauther, op. cit. and personal observations).
Thus, as Carter (1957) emphasized with regard to the arborescent organs in
Clarias (see below), the respiratory epithelium is not merely a direct modification of
an unmodified internal surface. It is, in fact, a modification and extension of the
normal branchial tissues. What at first sight appears to be the differentiation of
typical gill tissue within unmodified epithelium during the ontogeny of the supra-
branchial cavity (see below, p. 235), can be interpreted in a different way. The
spatial relationships of the tissue to the gills is extremely intimate as is clearly seen
in the embryo. This tissue could, therefore be considered as primarily branchial ;
if this is so, the relatively late appearance of gill cells could be interpreted as the
delayed manifestation of its competence to develop into branchial tissue.
Contained within the cavity and occupying up to four-fifths of its volume are
two much-branched arborescent structures (the “ trees”) developed from the
epibranchials of the second and fourth gill arches. The epithelium covering the
cartilaginous skeleton of each tree has the histological structure of gill tissue. It is
supplied with afferent and efferent blood vessels from the corresponding gill arch.
In every Clarias species investigated the size and complexity of the arborescent
organs are positively correlated with the size of the individual and, of course, with
its ontogenetic stage. I have studied the complete ontogeny of the suprabranchial
232 A REVISION OF THE GENUS TINOTOPTERUS BLGR.
organs in Clarias mossambicus and the following notes summarize my observations.
For comparative purposes it should be noted that the modal adult size-range of
C. mossambicus in Lake Victoria is 50-90 cm.
The arborescent organs develop late in post-larval ontogeny (Greenwood, 1956) ;
a single knob associated with the fourth arch appears in fishes of c. 3 cm. length.
The anterior tree (second arch) develops somewhat later. When the fish is about
5 cm. long, the posterior tree is trifid; branching then continues until the much-
branched definitive condition is attained when the fish is about 30 cm. long. Develop-
ment of the anterior tree follows a similar pattern but always lags behind that of
the posterior one; ultimately it is about two-thirds the size of the latter. When
fully developed, the two trees occupy 70-80% of the suprabranchial cavity.
Differentiation of gill tissue within the suprabranchial epithelium occurs before
the appearance of the trees; suprabranchial lamellae first appear when the fish
is about 1 cm. long.
The “ gill-fans”’ are the last suprabranchial structures to develop and usually
complete their differentiation from the gill filaments only after the macroscopic
appearance of the posterior tree. Obvious morphological changes are, however,
apparent in those filaments destined to form the “ fans’’ at about the time of the
first appearance of lamellae in the lining epithelium. Until the “fans” are fully
developed, the suprabranchial cavity has wide openings into the branchial and
pharyngeal cavities. The cavity must, therefore, be filled with water and in early
post-larval fishes probably acts as an aquatic gill. Hora (1935) has shown that the
lung-like air-sacs of Amphipnous can be utilized in this way.
Suprabranchial respiratory organs are not well developed in all Clariidae and in
some genera may be entirely absent. With one exception (the genus Dinotopterus),
clariids with greatly reduced organs are small. Various stages in suprabranchial
reduction are manifest by these genera and also in some of the smaller Clarias
species (those belonging to David’s subgenera Clarias (Clarias) and C. (Allabenchelys)).
THE SUPRABRANCHIAL ORGAN IN DINOTOPTERUS
Perhaps the most outstanding anatomical feature of the Lake Nyasa Dinotopterus
species is the wide interspecific variation in the suprabranchial organ. Differences
are most evident in the morphology of the arborescent organs but also appear in
the histology of the suprabranchial lining epithelium. No other clariid genus shows
such variation ; I have examined seventeen Clarias species and found that, within
any one of the three subgeneric groups, the degree of suprabranchial organization
and development is remarkably constant. Dinotopterus stands in sharp contrast.
Here one finds within a single species-flock some species in which both trees are
present and fully developed, others with small, sparsely branched trees and finally,
a large group of species in which no anterior tree is developed and the posterior
tree is greatly reduced or even absent (see Table I). When polyfid arborescent organs
are present, as in large D. ilesi and D. gigas, the trees are relatively reduced and
occupy a smaller volume of the cavity than do the trees of adult Clarias mossambicus
and other members of the C. (Heterobranchoides) subgroup. Such trees in Dinotop-
233
DINOTOPTERUS BLGR.
A REVISION OF THE GENUS
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234 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
terus bear the same relationship to those of C. (Heterobranchoides) species as do the
reduced arborescent organs found in the subgroup Clarias (Allabenchelys), (see
David, op. cit.).
Interspecific variation in the volume of the suprabranchial cavity is moderately
high, but only four species have an obviously shallow chamber (see Table II). In
all Dinotopterus species the “ gill-fans ”’ are fully developed.
Interspecific variability is not confined to gross structures but also occurs in the
histology of the epithelium lining the cavity. Indeed, apparently novel arrangements
of certain tissues are found in some Dinotopterus species, although it should be
remembered that this aspect of the suprabranchial organ has not been studied at
all intensively.
Fic. 1. Fragments of suprabranchial lining epithelium seen in surface view, showing the three
types of lamellar organization. A. ‘‘ Clarias ’’-type ; B. ‘‘ Saccobranchus ’’-type ; C. “‘ coralline ’’-
type. Magnification c. 50x.
Reference should be made to Rauther (1910) for a full and well-illustrated account
of the histology of the suprabranchials in the Clariidae. As this author demonstrated,
the epithelium lining the suprabranchial cavity of Clarias and the air chamber of
Saccobranchus (= Heteropneustes) is differentiated into branchial and non-branchial
tissue. The branchial tissue, which is arranged along the numerous blood-vessels,
has the histological structure of normal gill-lamellae, save for the absence of gill
rays. In the Clarias which I have examined (C. mellandi, C. mossambicus, C. carson,
C. pachynema, C. salae, C. jaensis, C. hilgendorfi and C. dumerili) the suprabranchial
lamellae are arranged in a basically linear but gently sinuous fashion (see Text-fig. 1A).
This distribution of suprabranchial lamellae I have named the “ Clarias”’ type or
pattern. A second pattern is that found in the air-sac of Heteropneustes (see Rauther,
op. cit., fig. 22). Here, the linear arrangement is obscured by the extreme sinuosity
of the lamellae. A very similar pattern occurs in the suprabranchial epithelium of
several Dinotopterus species (see Text-fig. 1B, and Table I) ; it differs slightly from
the Heleropneustes type inasmuch as the lamellae are shorter and more irregularly
arranged. This type of tissue occurring in Dinotopterus I have called the “ Sacco-
‘branchus ”’ type.
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 235
Yet a third pattern is found in Dinotopterus. In this type (the “ coralline ”), many
lamellae have, as it were, contracted and formed small, circular or ovoid patches of
gill tissue interspersed amongst the less numerous patches of elongate lamellae.
In contrast to the ‘‘ Saccobranchus ” type, there is much less inter-lamellar tissue
in the “coralline”’ type of epithelium (see Text-fig. 1C). A further peculiarity in
two of the five species with “coralline”’ epithelium is the heavy concentration of
melanin deposited in the inter-lamellar tissue. As a result, the suprabranchial
chamber is black except for the patches of gill tissue. Some melanin is found between
the lamellae in other species but in none does it reach sufficient density to colour
the epithelium.
Taking the “ Clarias”’ pattern as basic, a comparison of the three types of supra-
branchial epithelium suggests that the others could have evolved by a process of
folding and fragmentation of the originally linear lamellae. Evidence from D. cun-
ningtoni (see p. 220) seems to support this idea, at least for ontogeny.
Correlating the type of suprabranchial epithelium with the type of arborescent
organ present, shows that (i) The “ Clarias”’ type only occurs in species in which
both trees are present and well- or moderately well-developed. (ii) Species without
trees or with mere stumps on the fourth arch have either the “‘ Saccobranchus ”
or “ coralline ” types of epithelium. (iii) The “ Saccobranchus”’ pattern also occurs
in species with well- or poorly-developed trees (see Table I). No adaptive value for
any particular type of epithelium is immediately suggested by this analysis. That
question is unlikely to be answered until we know more about the physiological
significance of the suprabranchial organ in these essentially deep-water species.
When compared with the definitive condition in Clarzas, the suprabranchial
region in Dinotopterus shows a wide range of developmental types. The question
then arises: are these stages representative of a regressional or a developmental
phase ? This question is not readily answered but must be considered.
Evidence from comparative anatomy and ontogeny is somewhat equivocal but,
I believe, suggestive of regression from the Clarias and Heterobranchus condition.
Dinotopterus is most closely related to Clarias and, more distantly, to Heterobranchus.
In both these genera the suprabranchial organ is complete and well-developed, at
least in adult and near-adult fishes. Species of both genera are virtually restricted
to shallow waters of lakes, rivers and certain types of swamp. By inference from
experiments made on several Clarias species (see below), the species are dependent
on the suprabranchial structures as aerial respiratory organs; purely aquatic
respiration is insufficient to fulfill their respiratory requirements. Species of Dino-
topterus on the other hand, are characteristic of deep-water habitats although some
have a wide vertical range, which includes the pelagic as well as benthic zones
(Jackson, 1959). For fishes living at depths of 40-70 metres, dependence on aerial
respiration would be a severe handicap. Indeed it would probably prevent the
invasion of these depths. Since the original fish-fauna of Africa would be essentially
one of rivers and swamps, it seems that the trend in Dinotopterus is one leading away
from an adaptation to such habitats and towards a bathypelagic and benthic
existence. Deep-water habitats can be looked upon as relatively ‘“‘ youthful ”’
because the East and Central African lakes are geologically young features, certainly
236 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
post-dating the primary distribution of freshwater fishes over the continent.
A second indirect approach to this problem is afforded by the vertical distribution
of the Nyasa species. No general correlation exists between the type of supra-
branchial organ and the depths at which the species occur. Thus, and rather unex-
pectedly when compared with Clarias, at least one pelagic and one partly pelagic
Dinotopterus species is without arborescent organs; in contrast, one deep-water
species (D. gigas) has well-developed trees. Furthermore, developed trees are found
in three species whose range extends from the pelagic zone down to a depth of 50
metres. These data strongly suggest that the species involved have broken away
from the obligatory aerial respiration which restricts the vertical distribution of
Clarias and Heterobranchus to shallow water. Once this physiological step has been
taken, the stage is set for the regression of organs primarily concerned with air-
breathing. It is interesting to note that three species found at the greatest depths.
and which have not been recorded from the pelagic region (D. foveolatus, D. filici-
barbis and D. rotundifrons), are all without arborescent organs and the volume of the
suprabranchial cavity is greatly reduced.
The means whereby this breakaway from obligatory air-breathing was achieved,
is discussed below.
PROBABLE METHODS OF RESPIRATORY COMPENSATION
IN DEN OTOP TER US,
Many experiments on several Clarias species (Boake, 1865; Das, 1927; and
personal observations) all indicate that the suprabranchial organs are essential
for life in this genus, the nearest living relative of Dinotopterus. Even in well-
aerated water Clarias are apparently incapable of sustaining themselves by purely
aquatic respiration. Hora (1935) is the only worker to claim that Clanias is not
asphyxiated if it is kept in well-aerated water. Unfortunately, none of the authors
investigating this phenomenon has cited the actual oxygen tensions of the water
in which the fishes were kept. Personal field observations on Clarias mossambicus
in Lake Victoria strongly suggest that even in the well-oxygenated waters of the
Lake (O, concentrations 6-7 p.p.m.; 85-100% saturation) larger individuals (c. 50-
80 cm. long) are forced to utilize their aerial respiratory organs. From this, I
can only conclude that if purely aquatic respiration is possible, then the water would
have to be oxygenated to an extent not generally encountered in the usual habitats
of the species.
No Dinotopterus species has such well-developed suprabranchial arborescent organs
as are found in C. mossambicus nor is there any indication that the oxygen concentra-
tions occurring in Lake Nyasa are much greater than 7 p.p.m. (Beauchamp, 1953).
Furthermore the depths at which most species occur is such that it seems impossible
for the species to utilize the organs for surface air-breathing.
Some compensatory device is clearly involved and, as would be expected, this
involves an increase in the surface area of the gills. The gills in all Dinotopterus
species are considerably larger than those of equivalent sized Clarias (see Table II).
The increase in area has been achieved both by elongation of the filaments and an
increase in the number of filaments per arch. In large specimens there are about
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 237
50-70% more filaments on the first arch than in a comparably sized Clarias. As
far as I could determine, the number of lamellae per millimetre of filament is approxi-
mately the same in large fishes of both genera.
The data given in Table II are admittedly crude but nevertheless clearly show
intergeneric differences in gill size as well as interspecific differences within Dino-
topterus. As a basis for size comparison I have chosen head length, principally because
most of the larger Clavias material is of heads only. The character “ gill area”’
was measured by tracing the outline of the filamentous part of the first gill arch
(excluding the “‘ gill-fans ’’) onto squared paper divided into millimetre units. The
results, therefore, by no means reflect the true surface area of the gill, but are merely
a convenient way of indicating the size differences in this gill. It is obvious that
with these crude measurements the figures obtained cannot be compared with the
exact measurements given by Gray (1945) or Saxena (1958) for the gill areas of
various marine and freshwater fishes.
The volume of the suprabranchial cavity was measured by filling the chamber with
fine lead-shot ; in those species (particularly Clarias) with expansive arborescent
organs, the organs-were removed before determining the volume.
Data in Table II show not only the remarkably larger gills of Dinotopterus but
also several points in connection with the volume of the suprabranchial cavity,
its correlation with gill area and its.relationship to head size in the different species.
With so few specimens it is difficult to generalize on intraspecific variation in the
volume of the cavity, which may be greater than appears from these figures. In
the Clarias species studied, the suprabranchial cavity is large and becomes relatively
larger with the growth of the individual. This allometric relationship is also shown
by all species of Dinotopterus. In two species (D. ilesi and D. loweae) the volume of
the cavity is equivalent to that of Clarias mossambicus and C. lazera, at least in
fishes with a head length of 14-20 cm.; but in larger D. loweae (H.L. 23-26 cm.)
the cavity is relatively smaller. Only one species, D. longibarbis (represented by a
single specimen), has a suprabranchial cavity relatively larger than that of Clarzas.
All other Dinotopterus species have the cavity smaller than in Clavias and in some
(D. foveolatus, D. rotundifrons and D. cunningtoni) very considerably smaller both
in relation to Clarias and to other Dinotopterus species.
With one exception, in all the Dinotopterus species compared there is a weak
inverse correlation between “ gill area’’ and cavity volume; even species within
the group having the most reduced cavities show this relationship.
The functional significance of the suprabranchial cavity in Dinotopterus has not
been investigated. That the cavity is highly vascular and predominantly branchial
in its histology, strongly suggests that it serves some respiratory function. Jackson
(1959) reports sighting several species feeding at the surface. In these species and
under such circumstances, the suprabranchial organ may still function as a means
of aerial respiration. But the vertical range of the same species also extends to
the deep water and there are those species which apparently never leave the depths.
Under such circumstances, the suprabranchial epithelium may serve as an aquatic
respiratory surface. Hora (op. cit.) has shown that, if emptied of air, the aerial
respiratory organs of Ophiocephalus, Anabas and Amphipnous can serve as gills.
238 A REVISION OF THE GENUS DINOTOPTERUS BLGR.
It is, of course, essential that the cavities be largely emptied of air and I can see
no reason to believe that this could not happen in Dinotopterus, especially when the
fish is subjected to pressure. The valve system formed by the “ gill-fans” is not
particularly muscular and water under pressure should easily flood the suprabranchial
chamber. The shape of the cavity and the arrangement of the valves are such that
little or no air could remain trapped in it.
The four species with the proportionately smallest suprabranchial cavities
(D. filicibarbis, D. rotundifrons, D. foveolatus and D. cunningtoni) all have supra-
branchial epithelium of the “ coralline ’’ type. The significance of the relationship
has still to be determined. The only other species with “ coralline’’ epithelium is
D. euryodon but here the cavity is relatively large. Altogether there is little correla-
tion between tissue-type and cavity size, except the negative one that “ Clarias ’’-
type epithelium is not found in species with a reduced chamber and tends to be
associated with large arborescent organs. ‘‘ Saccobranchus ’’-type tissue, on the
other hand, occurs in both large and small chambered species but is commonest in
the group of species which have reduced arborescent organs or are without these
structures.
«e
SUPRABRANCHIAL REGRESSION IN OTHER CLARIIDAE
AND A COMPARISON WITH DINOTOPTERUS
The regressional series represented in descending order of suprabranchial organiza-
tion by the genera and subgenera Heterobranchus, Clarias (Heterobranchoides),
C. (Clarias), C. (Allabenchelys), Chanallabes, Clariallabes, Gymnallabes and Tangani-
kallabes (the organ is absent in G. thioni and T. mortiawxi) is well known and need
not be elaborated upon here (David, op. cit.; Marlier, op. cit.; Poll, 1942b; Green-
wood, 1956). Three points, however, should be noted; first, the series shows an
overall decrease in maximum size ; second, the body becomes increasingly anguilli-
form and third, the trend also involves the regression of certain roofing bones in
the skull. Indeed, this series has been interpreted as an example of evolution through
neoteny (Poll, 19426 ; Greenwood, 1956).
Another unrelated example of suprabranchial regression is provided by the genus
Xenoclarias, at present known from two deep-water species in Lake Victoria (Green-
wood, 1958). In this genus, there is no suprabranchial cavity, no arborescent organs
and the “‘ gill-fans’’ do not develop. Instead, the upper filaments of each gill arch
retain their filamentous nature. Unlike the more regressed members of the Clarias >
Tanganikallabes line, Xenoclarias does not show any neotenic characters. Apart
from its peculiar branchial arrangements it is a typical member of the subgenus
Clarias (Clarias), although its adult size is small (15-16 cm. S.L.).
As David (op. cit.) first pointed out, the small size of fishes with regressed supra-
branchials would enhance the possibility of cutaneous respiration and thus provide
some compensation for the loss of the aerial respiratory organs. In Xenoclarzas,
besides increased surface area relative to volume there is an increase in gill surface
because the “ gill-fans ’’ are suppressed.
The species of Dinotopterus provide yet another line of suprabranchial regression
which differs in certain respects from the other two, An outstanding difference is
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 239
the large adult size of all Dinotopterus species, amongst which are to be found some
of the largest Clariidae. Clearly, increased cutaneous respiration is not a compensat-
ing respiratory mechanism in these fishes ; increased gill area, however, seems to be
the factor involved (see p. 237 and Table II).
The state of the suprabranchial organ in a few of the less regressive Dinotopterus
(group 1 in Table I) is comparable with that of certain Clarias (Allabenchelys) dumertli;
other species of this subgenus, the most regressive of the Clarias, have arborescent
organs relatively larger and more complex than Dinotopterus. I have found regressed
arborescent organs in only one population of Cl. (A.) dumerili, that occurring in
the Cuvo River, Mount Maco, Angola. Other populations of this species have arbores-
cent organs typical of the subgenus, of which the following species were dissected :
C. carson, C. submarginatus, C. philipst, C. longior, C. poensis, Allabenchelys longi-
cauda and All. brevior). Likewise, the relative development of the suprabranchial
_organ in Chanallabes species is greater than in Dinotopterus. In certain respects,
namely the absence of arborescent-organs and a decrease in the volume of the cavity,
the suprabranchials of Clariallabes petricola and Dolichallabes microphthalmus
compare with the majority of Dinotopterus species ; in Cl. petricola, however, the
“ gill-fans ”’ are less developed. The only clariid species which seem to show regres-
sion in the suprabranchials even greater than that of Dinotopterus are Gymnallabes
thiont and Tanganthkallabes mortiauxi (see Poll, 1942a ; 1953).
CONCLUSION
Regression of the suprabranchial respiratory organs has been achieved in many
species of Clariidae. The manner of their decline and the provision of compensatory
means of respiration show considerable variation, but all seem to involve hetero-
chronic growth either affecting the organs alone or the entire skull. Species with
reduced suprabranchials are found in a great variety of habitats including swamps,
fast flowing rivers and the deep waters of lakes. Those species with elongate bodies
have even invaded such habitats as the interstices of rocks and coarse gravel on
river beds. As a group the “ regressive ”’ clariids have probably proved more success-
ful (as measured by variety of habitat) than those species and genera which have
retained a fully-developed suprabranchial organ and the concomitant obligatory
air-breathing habit. Geographically, however, their distribution is limited to the
approximate area of 5° N. to 15° S. as compared with the almost pan-African and
Asiatic distribution of the fully air-breathing species (see David, op. cit.).
This study has not thrown much more light on the evolution of air-breathing
organs in the Clariidae. However, from what has been said it is clear that I support
Beadle’s (1932) views on the environmental conditions favouring the origin and
development of such structures. Beadle supposed that aerial respiration was of
considerable adaptive value to fishes living in near-stagnant and poorly oxygenated
closed swamps. That is, swamps not connected with open water as are most present-
day African swamps. He further supposed that closed swamps probably preceded
the formation of the open type. The geological history of most African lakes certainly
supports this interpretation of geomorphological events. Thus, invasion of open-
240 A REVISION OF THE GENUS TINOTOPTERUS BLGR.
water habitats would perforce take place at a later date and after the fishes had
evolved an accessory aerial respiratory mechanism.
When reviewing Beadle’s ideas, David (op. cit.) doubted this sequence of events,
particularly since there is the implication in Beadle’s paper that in open lake condi-
tions, the suprabranchial respiratory organs would be redundant. As David com-
ments, the highly developed accessory respiratory organs of Heterobranchus and
Clarias hardly have the appearance of “ Reliktorgane’’. But, from what we know
of the respiratory requirements of Clarias this is literally what these structures are,
organs developed in a different environment but now forming an integral part of
the animal’s physiology no matter what environment it may occupy. This inter-
pretation of the suprabranchial organs in Clarias and Heterobranchus seems to
answer David's objection and to link the ideas of both this author and Beadle.
A truly regressive accessory respiratory organ is only seen, so I believe, in those
Clariidae which have developed some compensatory respiratory mechanism (such
as increased cutaneous respiration through decreased body-size, or enlargement of
the gill area). With regard to these organs, the Clarlidae as a whole may be an
example of cyclic evolution. That is to say there has been the primary evolution
of an aerial respiratory organ to meet the challenge of a severely deoxygenated
environment and then, in certain branches, the loss of these structures when a
new set of moderately well-oxygenated habitats were themselves evolved and were
available for exploitation.
ACKNOWLEDGMENTS
It gives me great pleasure to thank Mr. P. B. N. Jackson for his co-operation in
this study. To Dr. Ethelwynn Trewavas go my thanks for her critical reading of the
manuscript, and to Mr. A. C. Wheeler I am indebted for the radiographs of two
species.
REFERENCES
Brave, L. C. 1932. Scientific results of the Cambridge expedition to the East African
lakes, 1930-1-3. Observations on the bionomics of some East African swamps. J. Linn.
Soc. (Zool.) 38 : 135-155.
BEAucHAMP, R.S. A. 1953. Hydrological data from Lake Nyasa. J. Ecol. 41 : 226-239.
BeErtIN, L. & ARAMBOURG, C. 1958. In Traité de Zoologie, Agnathes et Poissons, 13, fasc. 3.
Boake, B. 1865. On the air breathing fish of Ceylon. J. Ceylon Br. Asiat. Soc. 4 : 226-239.
BouLencer, G. A. 1906. Fourth contribution to the ichthyology of lake Tanganyika. Tyvans.
zool. Soc. Lond. 17: pt. 6, 537-576.
Carter, G.S. 1957. Air breathing: in The physiology of fishes (M. E. Brown ed.) 1 : 65-79.
New York.
Das, B. K. 1927. The bionomics of certain air-breathing fishes of India, together with an
account of the development of their air-breathing organs. Philos. Tvans. B, 216 : 183-219.
Davin, L. 1935. Die Entwicklung der Clariiden und ihre Verbreitung. Rev. Zool. Bot. Afr.
28 : 77-147.
Fow er, H. W. 10931. The fresh water fishes obtained by the Gray African expedition in 1929.
Proc. Acad. nat. Sci. Philad. 82 (1930) : 27-83.
Grorrroy St. HirarrE, E. 1802. Notes sur les brachies du Si/urus anguillaris. Bull. Philom.
3: 105.
A REVISION OF THE GENUS DINOTOPTERUS BLGR. 241
Gray, I. E. 1954. Comparative study of the gill area of marine fishes. Biol. Bull., Wood’s Hole,
107, (2) : 219-225.
GREENWoop, P. H. 1956. A new species of Clariallabes (Pisces, Clariidae), from the Nile.
Proc. zool. Soc. Lond. 127 : 555-564.
(z958). A new genus and species of cat-fish (Pisces, Clariidae) from the deeper waters of
Lake Victoria. Ann. Mag. nat. Hist. (13) 1: 321-325.
Hora, S. L. 1935. Physiology, bionomics and evolution of the air-breathing fishes of India,
Trans. Nat. Inst. Sci. India, 1 : 1-16.
Jackson, P. B. N. 1955. A new fish of the genus Clavias Gronov. from Lake Nyasa, with notes
on the distribution of the Clariidae and other cat-fishes in the lake. Proc. zool. Soc. Lond.
125 : 681-684.
(1959). A revision of the clariid cat-fishes of Nyasaland with a description of a new genus
and seven new species. Ibid. 132 : 109-128.
Martier, G. 1938. Considérations sur les organes accessoire servant a la respiration aerienne
chex les Téléostéens. Ann. Soc. zool. Belg. 69 : 163-185.
Pott, M. 1942a. Description d’un genre nouveau de Clariidae originaire du Congo Belge.
Rev. Zool. Bot. Afr. 36 : 94-100.
1942b. Notes sur l’osteologie de Dolichallabes microphthalmus Poll et remarques sur
lévolution des Clariidae. Ann. Soc. zool. Belg. 73 : 222-235.
1953. Poissons non Cichlidae Explor. Hydrobiologique du lac Tanganika (1946-1947), 3,
fasc, 5a, 1-251. Brussels.
RavuTHER, M. 1910. Die akzessorischen Atmungsorgane der Knockenfische. Ergebn. Zool.
2: 517-585.
Saxena, D. B. 1958. Extent of the gill surface in the teleosts Heteropneustes fossilis Bloch and
Clarias batvachus Linn. Proc. nat. Acad. Sci. India, 28 : 258-263.
PRINTED IN GREAT BRITAIN BY
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BARTHOLOMEW PRESS, DORKING
LONDON: 1961
THE TAXONOMY AND IDENTIFICATION
OF PIPITS (genus Anthus)
Pp. 243-289 ; Plates 56-61 ; 1 Map
12 APR 1961
PRESENTED
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY | Vol. 7 No. 5
LONDON: 1961
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, is
issued in five series corresponding to the Departments
of the Museum, and an Historical Series.
Parts will appear at irregular intervals as they become
ready. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No. 5 of the Zoological series.
© Trustees of the British Museum, 1961
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM
Issued March, 1961 Price Twenty-one Shillings
THE TAXONOMY AND IDENTIFICATION
OF PIPITS (genus Anthus)
By B. P. HALL
CONTENTS
Page
INTRODUCTION . 246
THE DIAGNOSTIC UsEFuLNess AND 5) Ib toner anens OF Guess GaneneraG 247
Colour and pattern, and the effects of moult and wear . 5 3 a BAG
Size : ¢ : : c c 5 : . 248
Conformation of the hind claw . : . : : . 3 . 249
Tail pattern. a é c c 5 ¢ : 6 2 A9)
Wing formula 0 0 0 6 5 6 3 é e250
JUVENILE PLUMAGE . 5 0 5 AGH
SUBSPECIFIC VARIATION, Dueiarrion AND Tatami Oneti : 251
Group A. PaLArarcTic, ASIAN, AFRICAN AND AUSTRALASIAN Species
WHICH PRESENT DIFFICULTY IN IDENTIFICATION . 6 : 258
1. A. novaeseelandiae—Richard’s Pipit : : 5 ° : 8253
2. A. godlewskii—Blyth’s Pipit : si 4 ; , z = 258
3. A. campestyis—Tawny Pipit c 2 c . 259
4. A. similis—Long-billed or Indian Rock Pipit : 261
5. A. vaalensis, A. leucophrys and A. pallidiventris—the Plain- backed
Pipits (with Map) . 5 6 5 7 3 . 202
6. A. pratensis—Meadow Pipit ° 2 : c : . - 266
7. A. trivialis—Tree Pipit 4 c 6 c : : : ez O7,
8. A. hodgsoni—Indian Tree Pipit . 0 ; : - R . 268
9. A. roseatus—Hodgson’s Pipit 3 : . c é : ZOO
Io. A. cervinus—Red-throated Pipit . : : F z ‘ 5 297K
11. A. gustavi—Pechora Pipit . 3 6 4 . a a ea7ft
12. A. spinoletta—Rock and Water Pipits : : 5 : e272
MEASUREMENTS OF SPECIES IN Group A (Tables 2-9) . bi = 275)
Group B. Distinctive Asian, AFRICAN AND AUSTRALASIAN SPECIES a TK
Asia. (A. nilghivensis, A. syluanus) . a Zaye)
Africa. (A. berthelotii, A. lineiventris, A. brachyurus, A. cafe, A. soko-
kensis, A. melindae, A. chloris, A. crenatus) ; 3 6 - 279
Australasia. (A. gutturalis) 5 3 a ezo2
Group C. AMERICAN AND SOUTH ATLANTIC SPECIES. (A. spragueti, A. fur-
catus, A. lutescens, A. chacoensis, A. correndera, A. antarcticus, A. nat-
tevert, A. hellmayri, A. bogotensis) . 0 : c 9 ¢ 5 233}
ACKNOWLEDGMENTS. : 3 ; . 2 : 0 0 . 286
SUMMARY . : : é : : c > : = | shy)
BIBLIOGRAPHY AND REFERENCES 5 5 287
ApPENDIX—Amendments proposed in this paper to the systematic list of
pipits in the Check-List of Birds of the World, 9, 1960 3 : ZoS
Plates
DorsSAL AND VENTRAL VIEWS OF SPECIES IN GRouP A - 56-59
DRAWINGS OF SECOND OUTERMOST RECTRICES, WING TIPS AND Hinp CLaws
OF SPECIES IN GRouP A si : : 7 A 5 . 60-61
ZOOL. 7, 5. 18
246 THE TAXONOMY AND IDENTIFICATION OF PIPITS
INTRODUCTION
Tue difficulties of distinguishing the different species of pipit, both in the hand and
in the field, are well known. While the standard handbooks for different countries
deal with identification of the various forms in their own areas, little attempt has been
made to define the characters and relationships throughout the world. Unfortunately
lack of adequate field experience of pipits precludes me from discussing this aspect,
but the collection of over 2,000 skins in the British Museum, supplemented by loans
of critical specimens from elsewhere, has enabled me to study all species in the hand,
with particular emphasis on those Old World species: that present most difficulty in
recognition. From that study this paper has been compiled in order to help others
to identify pipits and to understand better the relationship between the different
species.
The first part deals with an analysis of the diagnostic usefulness and limitations
of five important characters—colour and pattern (with particular reference to changes
caused by moult and wear), size, conformation of the hind claw, tail pattern, and
wing formula. These characters have been selected for specific identification, though
this does not imply that there are no others. In identifying the majority of pipits
all five should be used in conjunction, and the evidence of the eye in respect of
colour and pattern should be backed by measurements and comparison of tails,
wings and claws. Since no one character is wholly diagnostic, and all are lable to
occasional misinterpretation, no “‘ Key to Species’’ has been made, for doubt and
error would always be liable to intrude in its use. Furthermore, it is inevitable
in any key that more stress is laid on the characters first used to subdivide a group
than on subsequent characters, which gives them an exaggerated importance. I
find it impossible also to subdivide the genus on a systematic basis without over-
stressing the importance of one or other character, and propose instead to divide it
into three groups which may facilitate identification.
Group A includes fourteen species of Old World and Australasian pipits all of which
have a typical pipit-like appearance and a wide range, and therefore present most
problems in identification. The measurements of all species in this group are
listed together in Table 2-9 for easy comparison and all are illustrated by photo-
graphs and by sketches of their tail patterns, wing tips and hind claws. Any
typical Old World pipit should be compared with these plates and then checked with
the text and the tables of measurement.
Group B comprises two Asian, eight African and one Australasian species which,
through some distinctive feature in colour, pattern or size, are unlike the typical
pipits of Group A. Most of them have a restricted distribution and offer few prob-
lems of identification to anyone with the appropriate regional handbook. They are
not illustrated but their characters are outlined under the same formula as is used in
Group A for easy comparison, with a final summary of their distinctive features.
Group C comprises ten exclusively American or South Atlantic species. Lack of
extensive material has prevented these being studied as fully as the Old World
pipits, but they also have their characters outlined as in Group B
While this study is chiefly concerned with specific characters, subspecific variation
cannot wholly be ignored and therefore some of the difficulties of subspecific
THE TAXONOMY AND IDENTIFICATION OF PIPITS 247
definition and recognition have been discussed. Under each species geographical
variation is outlined but the ranges and characters of individual races are defined
only when they are relevant to the discussion, or in the few cases in which I disagree
with currently accepted views.
Since this paper was completed Volume 9 of the Check-List of Birds of the World
has been published. This contains the systematic list of the family Motacillidae
with full references to all subspecies and to many names considered synonyms. It
seems therefore superfluous to list these again here, but I have listed in the Appendix
all amendments proposed in this paper to that systematic list.
THE DIAGNOSTIC USEFULNESS AND LIMITATIONS
OF CERTAIN CHARACTERS
Colour and Pattern, and the Effects of Moult and Wear
In appearance the majority of pipits vary only in the basic shade of brown above,
the whiteness or buffiness below, and in the degree of streaking above and below.
Furthermore, since pipits have a soft plumage, noticeably softer for instance than
that of larks, and many spend much of their time on the ground or in grass, there is
considerable seasonal wear as a result of which some differences of colour and pattern
become lost. To off-set this wear and abrasion many species have a partial or a
complete spring moult which may, or may not, be into a distinctive breeding dress.
The completeness of this moult may vary within populations of the same species as
Mayaud (1952) has shown in his study of the European Rock Pipits; in these the
apparent differences between the spring plumages of the Scandinavian and British
populations are due to the former having a more complete moult.
It is not generally appreciated that some other species have a haphazard partial
moult during the winter months, of body feathers, rectrices, innermost secondaries,
wing coverts and, occasionally, primaries. This moult has been observed in
Richard’s Pipit, A. novaeseelandiae, the Tawny Pipit, A. campestris, and Blyth’s
Pipit, A. godlewskii ; it has been studied chiefly in the migrant Asiatic races of
Richard’s Pipit (A. ». richardi subspp.) for in these races the breeding season is
limited to a few weeks in mid-summer and it is therefore possible to limit the date
of post-breeding moult within a short period. Moreover there are abundant winter
specimens of this pipit available. An analysis of the moults in two hundred and
sixty-eight specimens collected from October to May shows that moult in the prim-
aries is more prevalent in birds which reach furthest south, the examples examined,
being from Ceylon (5 specimens), Andaman Islands (2), Madras (x), Siam (3), Laos (1),
and Bengal (1 on migration, 24th April). This suggests that the moult has a
functional usefulness in replacing worn feathers prior to a long journey and may be
developing in the course of evolution as an efficient character increasing the survival
chances. Where there is moult in the primaries it is symmetrical in both wings,
complete and in sequence, but otherwise there seems no regular sequence to the
winter moult: in different specimens central rectrices have been found coming in
before, after, and concurrently with other rectrices : moult may be found in body,
Wings and tail alone, or in all three together, or in any two alone.
248 THE TAXONOMY AND IDENTIFICATION OF PIPITS
Post-breeding moult in A. 7. vichardi subspp. takes place in July and August, or
early September at the latest: I have found no indication that it is other than a
normal complete moult. The following table (Table I) shows the percentage of
specimens examined in which moult in different parts of the body is taking place in the
winter ; it suggests that, in some birds, some feathers may be moulted three times a
year, and there are three peak moulting seasons, in July, December and March—
April.
These figures are based only on specimens in which actual feathers in sheath
have been found. As these feathers are frequently lost in skinning the number of
specimens in moult at the time of collecting is probably higher than indicated.
TABLE 1.—Haphazard Winter Moult in A. n. richardi subspp. (% to nearest whole)
Month
= aS =)
Oct. Nov. Dec. Jan. Feb. Mar. Apl May
Number of specimens : 2 , 23 33 39 44 39 31 290 30
Moult of body, wing-coverts or secon- | | |
daries 21% | 57% | 66% | 36% 35% | 87%| 80% | 53%
Moult of central rectrices : ‘ T7 iol D2%| 284 7a LSye: |) 451i lidar | —
Moult of other rectrices . 5 A 8% Bal) LOY oy The | 29. %4|\ 207% | LO%s
Moult of primaries . i ~ A 10% | -- 6% BDH 2% | 16%| 14% | —
Total showing moult in some part, or | | | |
parts 35% | 57% | 72% | 38% | 41% | 87% | 80% | 53%
It will be appreciated therefore from the examples of the Rock Pipit and Richard’s
Pipit how important an understanding of moult can be in making comparisons of
colour and pattern in pipits, and only birds collected in the same month and in the
same condition of plumage should be used. In all species of Group A I have
indicated where possible what moults are to be expected but in many species of
Groups B and C too few specimens are available on which to generalize, and too
little is known of the breeding seasons.
In describing the plumages it is difficult to express some of the differences in colour
and pattern. For the basic colour of the upper parts I have used the term “ tawny
brown’ to indicated a light, sandy shade such as is characteristic of the Tawny
Pipit, A. campestris ; “light brown’ for a less sandy tone ; “ olive-brown eed ORR:
greener brown ; and “ dark brown”’ or “ chocolate ’’ for the darker tones ; but these
terms, must, inevitably, cover a wide range of individual variation.
In defining the amount of pattern on the breast I have used the terms “ streaking "’
and “spotting ’’ to differentiate between the species which have true streaks and
those which, like A. novaeseelandiae, have the streaks reduced to small triangular
marks.
The term ‘ scalloping ’”’ has been used for the effect caused by white or light edges
to the mantle feathers, which is found in some young birds.
Size and Measurements
The uniformity in size among pipit species enhances the value of small differences
THE TAXONOMY AND IDENTIFICATION OF PIPITS 249
in proportions, and the usefulness of detailed measurements is readily apparent in
the various tables that have been compiled: this usefulness, unfortunately, is
limited to a large extent by human inconsistency in measuring, particularly in the
dried skin. This does not apply to wing measurements of small birds like pipits in
which little or no variation will be found between the figures arrived at by two
careful measurers on the same series. I believe, however, that the range of wing
measurements for any form based on a series of skins, will always be found to be
a trifle smaller than the range based on live birds handled in ringing, due to some
shrinkage of the wing in drying. Tails, in the dried skin, present a greater difficulty
and an experiment carried out with four experienced measurers, on tails between
60 and 80 mm., showed a degree of variation up to 5 mm., due wholly to the degree
of pressure exerted in fitting the tip of the dividers into the angle where the central
rectrices join. On a re-trial each measurer was found to obtain consistent results in
his or her technique. This individual variability obviously detracts from the value of
published tail measurements but they have been included since specimens measured
by the same hand are useful comparatively and the variation is limited. However
it should be borne in mind when consulting the table that I am among those who
give shorter measurements than some others. There is a further difficulty with the
wings and tails of pipits for, due to wear, the feathers are rarely wholly perfect
especially among birds that are on their breeding grounds. Since it is only these
birds that are useful in studying geographical variations they must be used but
some judgment is needed to determine which are too worn for inclusion in measure-
ment tables.
Bill measurements made with different quality dividers may show a difference of
0-5 mm. : all quoted in this paper have been taken from the base of the skull using
a fine-pointed pair. Tarsus measurements are dependent on the make-up of the
skins but the degree of possible error is limited.
These difficulties are stressed here since it is important that the ‘“ Tables of
Measurements ’’ shall be used with discretion and understanding for identification.
Conformation of the Hind Claw
The length and shape of the hind claw is one of the most reliable aids to specific
identification but the limitations must also be understood. Firstly there is in all
species some individual variation in length and curvature, which is indicated in the
text by the measurements for each form and in the species figured. To this is added
some geographical variation, particularly among the ground species, due possibly to
populations living on harder or softer ground. In all species odd specimens may
also be found occasionally with stubby claws, due to some deformity or accident,
and these have not been included in the measurements : similarly occasional speci-
mens may be found with exceptionally long claws in which the tapered tip, which is
very fine and delicate, has not worn down as much as usual.
Tail Pattern
The pattern of white in the tail is another aid to identification within the limits
250 THE TAXONOMY AND IDENTIFICATION OF PIPITS
imposed by individual variation. In nearly all species the greater part of the outer-
most pair of rectrices is white, and specific differences are not obvious, I have there-
fore concentrated entirely on the pattern in the second outermost pair. In all species
this pattern will be found to vary individually but always within strict limits, which
have been illustrated. While it is never possible on tail pattern alone to say to
which species a pipit belongs, it is usually possible to name a number to which it does
not belong.
There is some variability in the clearness of the tail pattern, some species having it
always pure white, in others it is always dusky white or buff, in others, such as
A. spinoletta, it varies racially. Too much reliance should not be placed on this
colour variation in single specimens since it is frequently difficult to distinguish a
pure white pattern that has become dirty through soil-staining, from one that was
dusky white originally. Also in old plumage the pure white loses some of its purity,
while dusky white tends to bleach.
Wing Formula
The wagtails and pipits have a distinctive wing noteworthy for the length of the
inner secondaries which, in fresh plumage, often equal the longest primaries. They
are among the group of passerines that have nine primaries, but the outermost
primary is so small as to escape notice. For this reason it has become customary in
many text books to ignore this feather and to refer to the outermost fully-developed
primary as the first. To avoid confusion I have followed this custom.
Variation in the wing formula and in the number of emarginated primaries in
the pipits has been cited as a useful aid to specific identification. While recognizing
fully this usefulness I do not believe that too much stress should be laid on this
character as a guide to relationship, since Savile (1957) has shown that the wing is
one of the avian features most readily adapted in the course of evolution to special
requirements, and it is therefore as likely to illustrate convergence as relationship.
This adaptability is borne out well in the pipits and, at the same time, they illustrate
that more pointed wings are the most efficient for long migrations ; even within a species
slight variation in shape can usually be correlated with the distance that birds of
different races migrate. For example the two pipits with the most pointed wings
are the Pechora Pipit, A. gustavi, and the European race of the Tree Pipit, A. ¢. trzvi-
alis ; in both these forms the wing tip is composed only of the first three primaries
with the fourth at least 4mm. shorter. They are, respectively, the only Palaearctic
migrants to reach as far south as the Moluccas and South Africa. On the other hand
the Himalayan race of the Tree Pipit. A. t. haringtoni, which does not move further
than the north Indian plains, has a blunter wing with the fourth primary less than
3, mm. shorter than the third.
In more than half the other species the first four primaries form the wing tip with
the fourth not more than 2 mm. shorter than the third. These species include all
the other migrant Palaearctic forms and some of the resident forms of Africa, Asia,
the Americas and Australasia. The remaining species are blunt-winged with the
first five primaries forming the wing tip. None of these is a true migrant though
some forms may move locally.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 251
Emargination is found on the second and third, and sometimes on the fourth and
fifth primaries. It is invariably correlated to the length of the feather so that in
the pointed wings, in which the fourth primary is short, only the second and third
are emarginated, whereas in the blunt wings, in which the first five primaries are
nearly equal, the second to fifth are all emarginated.
In describing the wing formula I have used the term “‘sub-equal’’ of a group of
primaries that are nearly equal in length but in which the relative lengths vary
slightly in different individuals.
JUVENILE PLUMAGE
Two distinct types of juvenile plumage are found among the pipits. In many
species the juvenile feathers of the upper parts are edged with white, giving a
scalloped effect. A few of these feathers are often retained for some months,
especially in the wing coverts, so that first winter birds can usually be recognized.
In the other species there is no light edging to the feathers and the juveniles are very
similar to the adults: in most of these species there is no way of distinguishing
between first winter birds and adults.
In Group A a brief description of the juvenile plumage of all species is given as an
aid to identification, but, through lack of young birds of many species, it has not
been described in Groups B and C.
SUBSPECIFIC VARIATION, DEFINITION AND INDENTIFICATION
There is possibly more controversy on the number of recognizable subspecies in
Anthus than in any other genus of comparable size. There are several reasons for
this but perhaps the greatest is the difficulty of obtaining birds in fresh plumage
actually on their breeding grounds. The only certain residents of any area are
birds actually breeding, and these, as has already been noted, are highly unsatis-
factory for either colour comparison or measurement, because of the wear in the
plumage, so that, while varieties may be seen to exist in non-breeding birds, their
ranges are hard to define. Outside the breeding season much remains to be learnt
of pipit movements: some forms are true migrants, others are subject to small
altitudinal local movements, others move locally in association with the rains :
there is thus no certainty that any freshly moulted bird is still on its breeding
ground.
Another difficulty in the determination of pipit subspecies is that of micro-popula-
tions, or ecological variations. Pipits, through their cryptic coloration, are particu-
larly susceptible to variation under different ecological conditions. Thus
micropopulations are found in limited areas recognizable from their immediate
neighbours but not necessarily from populations living in approximately the same
conditions some distance away. Examples of this can be found in the dark popu-
lations of A. novaeseelandiae found on mountains in central Africa and Asia, and very
bleached populations associated with the limestone pans such as the Etosha and
Makarikari Pans of southern Africa. On a larger scale all desert populations are,
as would be expected, paler than those from wetter areas.
252 THE TAXONOMY AND IDENTIFICATION OF PIPITS
In deciding which of these varieties can be accepted as subspecies one is con-
fronted by the unsatisfactory character of a subspecies as a taxonomic unit. If
its definition is to be accepted as “‘ geographically defined aggregates of local
populations which differ taxonomically from other such divisions of a species ’’
(Mayr et al., 1953 : 30) one is forced to be illogical with these varieties. Thus the
bleached populations of the pans and the dark populations of the mountains have
no range that can be geographically defined and cannot therefore be recognized as
subspecies. On the other hand, from the topography of the country, the pale desert
birds of southern Africa have a range in the west and centre which can be defined and
they can therefore be recognized as a subspecies, A. n. bocage, though logically their
status in respect to the species as a whole is no different from the bleached or dark
varieties. However these difficulties and seeming illogicalities are not confined to
pipits and are relatively unimportant as long as they are understood.
A third difficulty in determining subspecies is the vexed question of how many to
recognize inacline. Clinal variation is found throughout most of the Palaearctic and
Asian species and in deciding which subspecies to recognize I have been influenced
largely by the usefulness, or otherwise, of retaining a name. For instance if a popu-
lation, intermediate in size, contains a high percentage of specimens which, on
measurement, can be identified as belonging to it alone, it seems useful to give it a
name, for then a proportion of wintering birds will also be identifiable and their
movements can be plotted.
This point introduces the question of subspecfic identification of wintering birds.
The majority of regional handbooks which define the characters of subspecies do
so in such a confident and assured manner that the student is led to believe that all
individual birds can be named. This is certainly not true : it is especially misleading
in studying the Palaearctic species in which birds from breeding populations as far
apart as Russia and Japan may be found together in winter on the north Indian
plains alongside the resident forms. Some individuals can, through some diagnostic
character of size or pattern, be identified subspecifically with certainty and ascribed
to a particular breeding population : these specimens are of great value in plotting
migration routes and local movements. However, in my opinion, any attempt to
name others individually which have not wholly diagnostic characters results in
the building up in collections of alleged subspecies which bear little relation to the
breeding populations of the same name. More can be learnt by studying series of
wintering birds from a given area and comparing their characters and ranges of
measurement with series of breeding birds. In this way it can be deduced, for
example, that the majority of Rock Pipits wintering on the east and southern
coasts of Britain belong to the Scandinavian race, A. spinoletta littoralis, rather than
to the British race, A. s. petrosus, although few individuals can be named. Similarly
it can be shown that the Tawny Pipits, A. campestris, that winter in eastern India
are drawn from a different breeding population from those wintering in Africa.
This paper is not, however, concerned with detailed definition of the characters
and ranges of subspecies except in so far as they affect specific identification, or in
cases where I have additions or corrections to make to accepted views. For the
‘Palaearctic species I have used Vaurie (1954 and 1959) as a basis, and for African
THE TAXONOMY AND IDENTIFICATION OF PIPITS 253
species the list prepared by White for the Check-List of Birds of the World, vol. 9.
Both these authors have answered patiently all my questions and I have been
fortunate in being able to work with White on the African pipits ; any revisions
to his list, as sent to press, have been discussed with him.
Subspecific variation has not been studied in the Australasian and American
species.
GROUP A. PALAEARCTIC, ASIAN, AFRICAN AND AUSTRALASIAN
SPECIES WHICH PRESENT DIFFICULTY IN IDENTIFICATION
All the species in this group have a wide range and many are highly migratory :
they have few distinctive characters common to all plumages and are therefore the
most likely to present difficulties in identification. It seems important to under-
stand these difficulties fully rather than to minimize them. For this reason I have
tried to illustrate in the discussion and in the plates the amount of variation found
in all characters, rather than to illustrate only a typical pattern, claw, wing or tail,
which might indicate a distinctiveness not found in all individuals.
The characters aré described under each species, or each geographical group
within a species, but the measurements have been grouped in eight tables (Tables
2-9, Pp. 275-278) for easy comparison. Inthe sections on identification of each species
notes have been made on how it can best be distinguished from all others likely to
occur in the same area.
In the widespread Richard’s Pipit, A. novaeseelandiae, it is convenient to discuss
variation and identification under four geographical groups, but no other species
has been divided.
1. Anthus novaeseelandiae—Richard’s Pipit
Specific characters—Variable in size. Above, tawny to dark brown, clearly
streaked on head and mantle: below, pale buff or white, the breast spotted with
well-defined spots, but these are sparse and confined mostly to the upper breast
except in Australasia. The hind claw medium or long, comparatively weak and
often rather straight. The first three primaries longest and sub-equal with the
fourth slightly shorter except, occasionally, in Australasia: the fifth primary about
7-10 mm. shorter than the fourth: the second, third and fourth emarginated and
the fifth slightly emarginated in Australasia. The tail pattern white, the pattern
on the inner web of the second outermost rectrix usually in the form of a narrow
white streak up more than half the shaft, only slightly wider at the tip; this is
sometimes reduced to a short streak against the shaft, near, or at, the tip ; occasion-
ally, in Africa only, reduced to a mere speck at the tip.
The juvenile has scalloped plumage, with rather darker and heavier spotting
on the breast than the adult.
AUSTRALASIAN, MELANESIAN AND PHILIPPINE RACES OF RICHARD’S PIPIT
Characters and variation.—There is still some difference of opinion as to whether or
not the African and Asiatic races should be considered conspecific with the Austra-
lasian races of Richard’s Pipit. Australasian races are generally whiter and more
254 THE TAXONOMY AND IDENTIFICATION OF PIPITS
streaked below, and have blunter wings. These are very slight differences but
might be sufficient to justify recognizing two species were it not that the Australasian
races are linked to the Asiatic races through the small white-bellied albidus of Flores
and Lombok, the slightly buffier medius of Timor and the Moluccas, and the lightly
streaked /ugubris of the Philippines. The slightly blunter wing of the Australasian
birds seems likely to indicate that they are more sedentary, rather than to have
specific significance. Many subspecies have been separated in the Australian area
on slight differences of colour and pattern, and in the New Zealand area island races,
aucklandicus, steindachneri and chathamensis are recognized from Auckland, Antipodes
and Chatham Islands. The New Guinea exiguus is a dark montane form.
It has also been suggested that the resident races of southern Asia should be
included with the Australasian races in A. novaeseelandiae, and the Palaearctic and
African races separated as A. richardi. The presence of populations in Annam and
south China, s7mensis, which are intermediate between the two groups, shows that
this also would be an artificial and arbitrary division which does not seem justified.
Identification. With the exception of the very distinctive and un-pipit-like
A. gutturalis of New Guinea, A. novaeseelandiae is the only pipit resident in the
Australasian area. The Pechora Pipit, A. gustavi, winters in Indonesia but can be
distinguished by its more pointed wing, richer colour above with heavier streaking
extending on to the tail coverts, and some white streaks in the mantle. It also has
broader white edges to the wing coverts, more streaks on the breast and flanks
and the tail pattern dusky rather than white.
Occasional stragglers of other migrant species may be found as far south as New
Guinea, but the only ones likely to be confused with the resident birds are those of
other races of A. novaeseelandiae. In particular a straggler of the Philippine race,
lugubris, or malayensis of south-east Asia, might be confused with medius of the
Moluccas. It should be noted that medius has a shorter and more curved hind claw
than either, is whiter below than malayensis and has heavier streaking on the breast
than lugubris. However, lugubris and malayensis are not normally migratory and
are less likely to be found outside their territory than the migrant races of north
Asia. All of these are larger and have buffier underparts than any of the resident
Australasian or Melanesian forms.
THE NON-MIGRATORY ASIATIC RACES OF RICHARD’S PIPIT
Characters and variation. The non-migratory pipits breeding in India, Burma,
Siam and Indo-China southwards to Ceylon, Sumatra and possibly Borneo, are
distinguished from the migratory Palaearctic races by smaller size. There 1s
considerable variability in colour among small breeding populations throughout the
area: in particular Col. W. W. Phillips has drawn my attention to the relative
darkness of birds from the highlands of Ceylon in comparison with those from the
coastal districts. These dark birds can, however, be matched with some from highland
districts in Malaya, and it is not therefore practical to subdivide this group on any
but broad lines. Three intergrading races are all that I can define—wazte?, from
north-west India is generally greyer and less heavily streaked both above and below :
malayensis from south of lat. 14°S.in both India and south-east Asia is the most
THE TAXONOMY AND IDENTIFICATION OF PIPITS 255
rufous and heavily streaked : vuwfulus links the two, ranging north to Upper Burma,
Yunnan and Tonkin in the east, and is intermediate in colour, intergrading with
both malayensis and wattet.
There is also indication of a slightly larger breeding population in Annam which
is worthy of note only because it may be a step in the cline between the smaller
southern and the larger northern races.
In all this group there is haphazard partial moult throughout the non-breeding
season.
Identification—subspecific. Table 3 shows how the resident southern races can
usually be distinguished on size alone from the migrant races. In India and Burma
the only overlap in size is between males of the resident races and females of the
migrant races. In Indo-China and Thailand a small proportion of winter visitors of
the Chinese race, sinensis, cannot be distinguished from the resident vwfulus or from
the Annam population.
Identification—specific. In the east there is no other pipit with which birds of
this group are likely to be confused, but in north-west India A. . waited and the
smaller race of the Tawny Pipit, A. campestris kastschenkot, are very similar. They
can be distinguished by some minor differences in the relative lengths of the tarsus
and wing, and in the structure of the hind claw, billand wing. These will be discussed
more fully under A. campestris.
Similarly a small female of the migrant A. godlewskii could be confused with large
males of both resident races of Richard’s Pipit but has slight differences in size and
tail pattern which will be discussed under that species.
Among other pipits which may occur in winter in northern India, only some
autumn birds of A. cervinus, which have not acquired the red throat, are at all similar
in colour, pattern and size to the resident Richard’s Pipits: these Red-throated
Pipits can be distinguished by the streaking on the breast being darker, more clearly
defined and extending further down the breast. They are also darker, less tawny,
brown with a streaked rump and slight differences in tail pattern and wing formula.
THE MIGRATORY PALAEARCTIC RACES OF RICHARD’S PIPIT
Characters and variation. The large races of Richard’s Pipit breed across Asia
from western Siberia and migrate chiefly to southern Asia, but stragglers have
occurred in many countries from Britain and Lake Chad to Borneo and New Guinea.
Breeding birds have been divided into several races on combinations of colour and
size, but variation is still imperfectly understood owing to lack of adequate breeding
series throughout Siberia and central Asia. A large, rather dark race, A. n. richardi,
breeds in western Siberia; a smaller, paler race, A. n. dauricus, in Transbaikal ;
a large race, centralasiae, from Tian Shan eastwards is said also to be pale, though
this is not apparent in the few specimens studied ; a small, dark, semi-migratory
Trace, sinensis, breeds in South China, and a darker race, wssuviensis, in east Siberia
and north China is intermediate in size between sinensis and richardi (ussuriensis is
considered a synonym of sinensis by Vaurie but a fairly extensive series of breeding
birds from south China indicates that there is little overlap in measurements between
birds of the two populations)
256 THE TAXONOMY AND IDENTIFICATION OF PIPITS
In Table 3 measurements quoted by Vaurie and other workers that are outside the
dimensional limits of specimens measured personally, are included in brackets, since
my own are obtained from very short series of breeding birds.
It has already been noted in the discussion on moult that all the migrant races of
Richard’s Pipit are particularly subject to haphazard winter moult. This enhances
the difficulties of using colour and pattern in the identification of wintering birds,
since no two specimens are ever in truly comparable plumage. Since dimensions
are only diagnostic in a very small proportion of birds of the four Siberian races
I consider it is best to refer to all wintering birds of these races collectively as
A. n. vrichardi subspp.
Identification. Distinction between the Palaearctic and resident races has been
shown to be chiefly in size and is illustrated in Table 3.
Specifically A. n. vichardi subspp. cannot be distinguished in the colour and
pattern of the plumage from A. godlewskiz, but are a richer colour and usually more
heavily marked above and below than A. campestris. Detailed difference will be
discussed under those two species.
The other large pipits of Asia are not likely to be confused with Richard’s Pipit.
A. nilghiviensis of the Nilgiri Hills is not unlike in colour but is short-winged with
streaking on the lower breast and flanks. A. sylvanus of the Himalayas is also
short-winged with very fine streaking below, and A. similis is a comparatively
unpatterned species both above and below. All have blunter wings and other
differences in tail pattern and in the conformation of the hind claw.
Migrants to Europe and Africa of A. m. vichardi subspp. are also unlikely to be
confused with any endemic African or European species but it seems very possible
that a straggler to north-east Africa would be overlooked among the resident races
of Richard’s Pipit, A. n. cimnamomeus. Dimensions are the most reliable guide in
distinguishing between them, czmmamomeus having a usually shorter tail and tarsus,
but, in addition, the African birds are usually less heavily patterned above due to
the feathers having darker edges contrasting less with the dark centres.
AFRICAN RACES OF RICHARD’S PIPIT
Characters and variation. Richard’s Pipit is found through south, east and
central Africa westwards to the Cameroons, though it is inexplicably absent from
any of the countries of the Middle East except as an occasional migrant. Taxo-
nomically the varying African populations form a most unsatisfactory group though,
at the same time, their inconsistencies give rise to fascinating speculation on their
relationships and origins. Too little is known of some of the most interesting forms
to go far with this at present and it is outside the scope of this paper except in so far
as it is necessary to recognize that in central and southern Africa there are three
isolated atypical forms, lwenarum, editus and hoeschi which seem more closely
linked to each other than to surrounding races. This suggests that there has been
a double invasion of the territory and that the atypical birds represent an older
population. The two isolated western races, cameroonensis and lynesi, have also
some atypical characters and it is convenient to discuss all these atypical forms
separately from the other races.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 257
Typical races of A. movaeseelandiae are found in the eastern half of the country
from Abyssinia southwards, and in the whole south and south-west. They have
the same general colour and pattern as Asiatic forms but with the patterning not
quite so distinct on the mantle. They are intermediate in size between the resident
and migratory Asiatic races but with a shorter tarsus in relation to the wing: the
hind claw never reaches the exaggerated lengths of some Asiatic birds and is commonly
about 12 or 13 mm. long: the tail pattern on the second outermost rectrix is
commonly the typical elongated streak up the shaft but in occasional specimens of
central Africa it is reduced to a little more than a white tip. These specimens will
be discussed with the atypical races. There are also examples, notably among darker,
montane varieties, in which the pure white in the tail is replaced by dusky white.
The protracted breeding season of African pipits makes it difficult to study the
sequence of moult, but it is apparent that in most populations there are two peak
periods in the year, probably corresponding to the normal complete post-breeding
moult and the partial pre-nuptial moult. However, the preponderance of specimens
collected in other months in which there are feathers in sheath, or some recently
moulted feathers, suggests that African as well as Asiatic birds are subject to
haphazard off-season moult.
White (1957) has shown that it is impractical to recognize more than three races
among the typical populations. These correspond to the three resident races of
Asia. The tropical cinnamomeus is the most heavily streaked and corresponds to
malayensis : the sub-tropical bocagei of the dry south-west is the palest, greyest, and
least heavily streaked and corresponds to waite: of the Punjab: rzufuloides of the
wetter south-east, north about to the Zambezi, is intermediate and corresponds to
vufulus. As in Asia there are recognizable micro-populations in different ecological
conditions : very dark birds are associated with the mountains of the eastern Congo,
Tanganyika and Nyasaland; rather more richly coloured birds with areas of red
soil (though in many cases the rich appearance is largely due to soil-staining) :
within the paler race there are exceptionally bleached populations associated with
limestone pans such as the Etosha and Makarikari Pans. Though names have
been given to many of these varieties their discontinuous distribution precludes
them being recognized as true subspecies.
The three southern atypical forms, dwenarum, editus and hoeschi, which I have
suggested belong to an older population, have also a discontinuous distribution within
the range of the typical forms. All three are large and rather dark, unique in having
the pattern of the second outermost rectrix reduced to a tiny spot: the pattern on
the outermost is dusky rather than pure white. The race Jwenarum from north-
western Rhodesia is also uncharacteristic of A. novaeseelandiae in having the dark
centres of the mantle feathers and the spots on the breast ill-defined, giving a less
streaky effect. The Basutoland editus has exceptionally dark centres to the mantle
feathers. The South West African hoeschi is known only from two specimens, of
which the type only has been examined. It is similar in size and in colour above to
lwenarum, below the spotting on the breast is closer to bocagei: the tail pattern is
reduced to a spot on one second outermost rectrix and a tiny faint streak on the
other.
258 THE TAXONOMY AND IDENTIFICATION OF PIPITS
It has already been noted that the abnormal reduction in the tail pattern is found
occasionally in specimens of cinnamomeus near the range of lwenavum, and so is the
dusky white of the tail pattern.
The two atypical western races, cameroonensis and lynest, are both dark with
heavy streaking on the breast : cameroonensis of Mt. Cameroon is paler below and
rather greyer above than /ynesz, which has rich buff underparts. Apparently lynesi
occupies other montane areas in the Cameroons, migrating as far as Darfur in May
and June.. These two races differ from others in having consistently shorter hind
claws, never over Ir mm., and in having the tail pattern dusky (cameroonensis) or
buff (lynes), but of the typical elongated pattern. ;
Identification. In general colour and pattern the African forms of A. novaesee-
landiae and A. similis are very alike, simulis being only slightly less distinctly
streaked. Chapin (1937) has pointed out that they can be distinguished by the
fifth primary, which is emarginated in szmlis but not in novaeseelandiae. This is
not, however, always easy to determine in worn or damaged specimens and a further
check is provided by the relative lengths of the inner primaries, particularly the
difference between the fourth and fifth which in novaeseelandiae is about 7-9 mm.
so that the wing tip appears to be formed of the first four primaries ; in similis the
difference is less than 4 mm. so that the first five form the wing tip. The majority
of specimens of A. novaeseelandiae can also be distinguished by the elongated tail
pattern and the long hind claw, but the wing is an additional and surer check where
atypical forms of novaeseelandiae occur, especially in central Africa, for here A. similis
has also an atypical form, A. s. schoutedeni, with a tail pattern similar to that of
A. novaeseelandiae. :
Very worn specimens of Richard’s Pipit, which have lost the pattern on the
mantle, might also be confused with the plain backed species, A. leucophrys and
A. vaalensis, which have the same wing formula. In all but atypical A. novaesee-
landiae the whiteness and extent of the tail pattern should be diagnostic, and in
most cases the measurements as well, since A, novaeseelandiae is usually smaller
with a shorter tail than sympatric Plain-backed Pipits.
The migrant, A. tvivialis, has a shorter bill, more extensive streaking on the breast,
a different wing formula and hind claw.
2. Anthus godlewskii—Blyth’s Pipit
Specific characters. Large. Above, tawny brown, clearly streaked on head and
mantle: below, pale buff, the breast spotted with well-defined spots, but these are
sparse and confined mostly to the upper breast. The hind claw of medium length
and comparatively weak. The first three primaries longest and sub-equal with the
fourth slightly shorter : the fifth about Io mm. shorter than the fourth : the second,
third and fourth emarginated. The tail pattern white with the pattern on the second
outermost rectrix a triangle, broad at the tip and tapering to a point close to the
shaft not more than 30 mm from the tip and usually about 15 mm.: occasionally
reduced further but always retaining a triangular shape rather than appearing as a
streak along the shaft.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 259
Blyth’s Pipit has a haphazard winter moult and a partial spring moult, similar
to Richard's Pipit, in the body feathers, innermost secondaries, wing coverts and
central rectrices, but no specimens have been examined in which primaries or other
rectrices have been in winter moult.
The juvenile has scalloped plumage and below the spotting is slightly denser and
darker but less well-defined than in the adult.
Range. Breeds in central Asia from Transbaikal and eastern Manchuria to Tibet
and Assam, migrating to India, Ceylon, Andaman Islands, Burma and Yunnan.
It has once been found at Lake Chad (White, 1957 : 33).
Geographical variation. None recognized.
Identification. The identification of Blyth’s Pipit was discussed fully (Hall,
1957) : it was found that individual specimens are quite indistinguishable in colour
and pattern from A. novaeseelandiae richardi subspp., except for the tail pattern.
The triangular shape, as distinct from the elongated shaft streak, is diagnostic in
the majority of specimens but in the extreme variations when the triangle is most
elongated or greatly reduced it is not so easy to recognize.
In series it is just apparent that the spots on the breast of Blyth’s Pipit are rather
more sharply defined and triangular.
A. godlewskit can, however, be best distinguished from all Asiatic races of Richard’s
Pipit by the relative length of wing and tarsus, though the difference is fine. In the
length of the wing and tail A. godlewskii is similar to the migratory races, A. novae-
seelandiae richardi subspp., but has a tarsus 24-28 mm. against 28-33 mm. It has
a longer wing and tail than the resident races but a similar tarsus. There is a small
overlap in overall dimensions with A. . sinensis which can be resolved by taking
the wing/tarsus ratio into account as this in A. godlewskii is 3:2-3°8, against 2-9-3:I
in sinensis.
Added to the differences in dimensions and tail patterns it will be found that the
length of the hind claw in many migrant specimens of Richard’s Pipit is wholly
diagnostic, since in A. godlewskii it is rarely over 14 mm.* and in the rare extreme
cases the weak tapering tip is curved sharply, while in A. n. richardi subspp. the
claw is rarely under 15 mm. with a straighter tip. In series the legs of A. godlewskii
in the dried skin appear paler than those of A. novaeseelandiae.
There are therefore several fine distinctions on which these two species can be
distinguished but it is advisable to take all into consideration.
A. godlewskii is generally more heavily streaked above and below than A. campes-
iris, but confusion might arise in comparing worn skins with young campestris which
are more heavily streaked than the adults. Table 5 shows that A. godlewskit has
usually a shorter bill than A. c. campestris and a longer wing than the eastern race
A. c. kastschenkoi. In addition A. campestris has a similar elongated tail pattern to
A. novaeseelandiae, and a slightly stouter, more curved hind claw.
3. Anthus campestris—Tawny Pipit
Specific characters. Large. Above, light or tawny brown, indistinctly streaked
* Hall (1957 : 730) recorded in error the maximum length as 17 mm. This should be 15 mm.
ZOOL, 7, 5. 19
260 THE TAXONOMY AND IDENTIFICATION OF PIPITS
on the head and mantle in adults : below, pale buff, with little or no spotting on the
breast in adults: the young bird quite distinctly streaked above and on the breast.
The hind claw short to medium, curved and moderately strong. The first three
primaries longest and sub-equal with the fourth slightly shorter: the fifth about
ro mm. shorter than the fourth: the second, third and fourth emarginated. The
tail pattern white with the pattern on the second outermost rectrix usually in the
form of a long narrow streak up the shaft, only slightly wider at the tip: this is
sometimes reduced to a short streak near the tip.
The Tawny Pipit has a haphazard winter moult of some body feathers, wing
coverts, innermost secondaries and central rectrices, and a partial spring moult into
similar plumage.
The juvenile has scalloped plumage and distinct dark spotting on the upper breast.
Range. Breeds in the Palaearctic region westwards from the Yenisei to Britain
(one record) and south to northern India, Palestine and the Atlas Mts. Winters
also in southern India, Arabia and Africa north of the equator.
Geographical variation. There is considerable local variation in colour from
sandy to greyish among the Tawny Pipits, with a higher proportion of greyer birds
in the east, and some conspicuously pale birds breeding in parts of the Middle East,
but these variations seem to be ecological and discontinuous rather than geographical
and no races are here recognized on colour alone. There is, however, a significant
decrease in size eastwards and I recognize A. c. kastschenkoi as a smaller race breeding
between the Ob and Yenisei rivers, and wintering in India. Measurements of all
Indian wintering birds show that both A. c. campestris and A. c. kastschenkot winter
in the west of the country, and many specimens are indeterminate, but that kast-
schenkoi alone winters in the east, in United Provinces and Bihar. In series
kastschenkoi is rather greyer than campestris. The smaller, greyer Indian birds
were formerly known as A. c. griseus, described from Tian Shan, but it has since
been found (Hall, 1957) that Tian Shan birds are not smaller than European birds,
so that griseus is considered a synonym of campestris.
Identification. The plainer back and plain breast of the majority of the specimens
of the Tawny Pipit serve to distinguish it from all other pipits in the area except
for some races of A. similis: these, however, can always be recognized by their
blunter wings, dusky and reduced tail pattern and usually by longer tails.
First winter birds and some adults of A. campestris which have retained some
spotting on the breast are not, however, easily distinguishable from some Richard's
Pipits, which have a similar wing formula and tail pattern. In particular some
specimens of the small A. c. kastschenkoi are easily confused with the paler, lightly
streaked A. 1. waitei in north-west India. The best guides to identification are the
relatively short tarsus and long wing of A. campestris and its shorter and more curved
hind claw and finer bill. In the dried skin the bill and legs of A. campestris are usually
paler than those of A. novaeseelandiae.
The same principles of identification apply to juveniles as to adults but the fact
that measurements are useless makes it difficult to identify all juveniles of A. campes-
tris, A. novaeseelandiae and A. godlewskii with certainty.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 261
4. Anthus similis—Long-billed or Indian Rock Pipit
Specific characters. Large with a long tail, except in central and west Africa.
Above, variable in colour from light to dark brown, with the streaking on the head
and mantle sometimes very indistinct, sometimes heavy, but never sharply defined
except in first winter birds: below, light to rich buff, with the streaking on the
breast variable, sometimes very indistinct and sparse, sometimes dark and extending
to the lower breast, but never very sharply defined. The hind claw short, curved
and strong. The first four primaries longest and sub-equal with the fifth never more
than 8 mm. shorter than the fourth and usually under 5 mm. shorter, so that the
first five primaries from the wing tip: the second to fifth primaries emarginated.
The tail pattern dusky white or buff and the pattern on the inner web of the second
outermost rectrix limited to a small triangle near the tip except in one atypical form
in central Africa, schoutedent.
A. similis has no apparent winter or spring moult, and the plumage does not seem
to wear as quickly as that of other species that have been discussed.
The juvenile has scalloped plumage and has well-defined spotting, rather than
streaking, on the breast.
Range. Breeds in suitable territory in most of Africa south of the Sahara,
Sokotra, Arabia, and from Palestine to India with an isolated population in central
Burma. Not truly migratory but subject to local movement, particularly in the
sub-tropical forms which come down from the hills in winter.
Geographical variation. About twenty races are recognized varying for the most
part in small degrees of colour, patterning and size. There are broadly two groups,
one of the almost unstreaked races found in the sub-tropics and the other of the
more heavily patterned tropical races.
The plain-backed Asiatic races include the large, sandy jerdoni of north-eastern
India, the greyer decaptus of north-western India westwards to Iraq, and the small
grey captus of Palestine. The large dark races, travancoriensis and similis of southern
India, and the smaller yamethini of central Burma, are more heavily patterned :
in tvavancoriensis the triangular pattern on the second outermost rectrix is con-
sistently of the more extensive varieties (illustrated as 1 and 2 on Plate 60) which are
found only rarely in other Asiatic forms. Both arabicus and the long billed sokotrae
are small and heavily patterned. In Africa north of the equator mivescens, jebel-
marrvae and asbenaicus are less heavily patterned than the races of eastern and central
Africa, hararensis, hallae, nyassae, dewittei and schoutedent, and the dark bannermani
and josensis of West Africa. South of the Zambezi the races leucocraspedon and
nicholsoni are again less heavily patterned.
None of these races show any noteworthy characters except for jebelmarrae and
asbenaicus of Darfur and the Sahara, and schoutedeni of the southern Congo and
Angola. In jebelmarrae and asbenaicus the tail pattern is heavily reduced, so that it
is absent or a mere tip, on the second outermost rectrix and confined to a small
triangular pattern on the outermost : in schoutedeni the tail pattern on the second
outermost rectrix is often elongated in a streak up the shaft and nearly as extensive
as in novazseelandiae. Furthermore schoutedeni shows other approaches to novaese-
262 THE TAXONOMY AND IDENTIFICATION OF PIPITS
elandiae in having the patterning above and below more clearly defined than is usual
in similis and the breast spotted rather than streaked ; the bill is also shorter than
is common in similis. The range of schoutedeni is from the middle Congo river
through the Kasai to Angola and north-western Rhodesia, but occasional specimens
of the more eastern myassae have either the short bill or the elongated tail-pattern of
schoutedeni.
Identification.—In Asia the plainer races of A. s¢milis bear a superficial resem-
blance to A. campestris, and the more heavily patterned races to migrants of A.
novaeseelandiae and A. godlewskii. They can all be distinguished by the blunter
wings and different tail pattern, and usually also by the length of the tail and hind
claw.
In Africa as in Asia there is the same superficial resemblance between many of the
races of A. similis and A. novaeseelandiae and through most of the country the same
specific differences of wing formula and tail pattern are diagnostic, in addition to the
more sharply patterned appearance of A. novaeseelandiae, the straighter hind claw
and usually shorter tail. It cannot, however, be emphasized too strongly that in
parts of central Africa, within or bordering the ranges of A. novaeseelandiae
lwenarum and A. similis schoutedent, all these distinctions are not diagnostic, for
these two races both show an approach in some characters to the other species. Thus
lwenayum has the dusky restricted tail pattern and ill-defined streaking above
typical elsewhere of A. similis, and schoutedeni has the extensive tail pattern, more
sharply defined pattern above and shorter bill typical elsewhere of A. novaeseelandiae.
In this area therefore the surest guide to identification is the blunter wing and longer
emarginated fifth primary of A. similis, with the shape of the hind claw as an
additional check.
Even the least patterned races of A. similis in fresh plumage are distinguished by
the amount of streaking on the mantle from the Plain-backed Pipits, A. vaalensis,
A. leucophrys and A. pallidiventris, but very worn birds present greater difficulty.
The wing formula is some help, but not a certain guide since the fifth primary of
some of the Plain-backed Pipits has some emargination and is frequently only 5 mm.
shorter than the fourth, though the difference is never less than that. The tail
pattern may also be diagnostic since the typical simlis triangle is found only rarely
in Plain-backed Pipits in southern Africa, in some specimens of A. vaalensis, or, in
northern Africa, as a very dusky and ill-defined pattern in some specimens of A.
leucophrys. Dimensions may be a guide as well, particularly the usually longer bill
and tail of A. similis, and many Plain-backed Pipits have a longer, straighter and
weaker hind claw.
5. Anthus vaalensis, A.leucophrys and A. pallidiventris—the Plain-backed Pipits
The Superspecies.—tThe relationship of the three plain backed species of African
pipit is so complex and still so little understood that it is convenient to consider them
as a superspecies and discuss them together. From the data at present available it
seems that in South Africa there are two sibling species, A. vaalensis and A. leuco-
phrys, which show some different ecological preferences and which can be dis-
WN
THE TAXONOMY AND IDENTIFICATION OF PIPITS
Map to Show Distribution of Plain-backed Pipits
A. pallidiventris.
Southern Africa.
A. leucophrys
(leucophrys, bohndorffi).
A. vaalensis
(vaalensis, chobiensis, neumanni).
Northern Africa. (A. leucophrys).
Dark races
(omoensis, zenkeri, ansorgei, gouldit)
Light races
(saphivoi, goodsoni).
. Area where zenkeri and
goodsoni have been
found together.
. Intergrade between
zenkeri and goodsoni.
. Intergrades between
zenkeri and saphiroi.
264 THE TAXONOMY AND IDENTIFICATION OF PIPITS
tinguished in the hand by colour, size and the relative lengths of the hind claw : there
is also some slight difference in tail pattern. Northwards, in Angola, Northern
Rhodesia and Nyasaland, the differences are less well marked but just apparent.
Northwards again there is a strip across Africa through the Belgian Congo and
Tanganyika from which A. vaalensis and A. leucophrys are absent but in the west of
which the long legged A. pallidiventris is found. From West Africa to Kenya, north
of this strip, there is no reliable evidence of two species being present, light and dark
populations of the lewcophrys/vaalensis types being alopatric and linked by inter-
grades: there is no corelation between lightness of colour, size and the length of the
hind claw, as in South Africa, and furthermore both types of tail pattern associated
with the different species in South Africa are found haphazard in the north among
individuals of varying colours. White (1948) hitherto has believed both A. vaalensis
and A. leucophrys to be present in the north, basing his conclusion on the record of
both light and dark birds being found together near Lake Naivasha in Kenya.
However, since this is the only area of overlap and lies between the ranges of darker
and paler populations it does not necessarily imply that the two forms breed along-
side : it is quite possible that some of these were non-breeding birds from neighbour-
ing areas, and if this is so only one species need be recognized in the north.
I suggest tentatively that, in the course of evolution, the Congo population was at
some time isolated and developed as a good species, A. pailidiventris ; elsewhere two
other species, A. vaalensis and A. leucophrys, developed through some ecological
preferences, but, before speciation was complete, some change in climate or vegeta-
tion in the north broke down the ecological barrier and the two re-united there,
forming a single semi-hybrid, species. Taxonomy cannot give a picture of these
relationships and I therefore propose for convenience to treat A. pallidiventris as a
distinct species and to recognize both A. vaalensis and A. leucophrys in southern
Africa, but refer all northern forms to A. leucophrys.
Characters of the Superspecies.—Large. Above, tawny to dark brown, with slight
obsolescent streaks on the head: below, light buff, with light, ill-defined streaking
confined to the upper breast. Hind claw variable, from fairly long and strong
(pallidiventris, and leucophrys in S. Africa) to short and weak (vaalensts in S. Africa)
The first four primaries longest and sub-equal with the fifth 5-10 mm. shorter than
the fourth: the second to fourth emarginated, and the fifth sometimes slightly so.
The tail pattern dusky or buff with the pattern on the second outermost rectrix
frequently reduced to a mere spot, occasionally a well-defined triangle near the tip
(some specimens of vaalensis in South Africa), occasionally an elongated streak along
the shaft (/ewcophrys in South Africa), all variations being found in northern Africa.
The Plain-backed Pipits do not appear to have any off-season or pre-nuptial moult.
The juveniles have scalloped plumage with distinct streaking on the breast.
Ranges (see Map.)—In southern Africa A. leucophrys ranges from Cape Province,
Natal, Transvaal through northern Bechuanaland and northern South West Africa
to Angola, Northern Rhodesia, southern Belgian Congo and Nyasaland. 4.
vaalensis ranges from Cape Province north through South West Africa, Bechuanaland
and the Transvaal to Angola, southern Belgian Congo, Nyasaland and Portuguese
East Africa. A. pallidiventris is found in Spanish Guinea, Gaboon, the Lower
THE TAXONOMY AND IDENTIFICATION OF PIPITS 265
Congo, and extreme northern Angola. In northern Africa A. leucophrys ranges from
Portuguese Guinea to British Somaliland south to the northern Belgian Congo and
Kenya.
Geographical variation—In South Africa A.v. vaalensis is large, sandy-coloured
with a short, weak hind claw, and sometimes with a small well-defined triangular
spot on the second outermost rectrix: it is replaced northwards from Angola to
Nyasaland by A.v. newmanni which is a smaller and less sandy race, variable in
colour with lighter and darker populations interspersed (Hall, 1959) : in newmanni
the tail pattern is invariably a mere spot. Birds from Southern Rhodesia are
intermediate. A.J. leucophrys in southern Africa is a smaller, darker bird than
A. v. vaalensis with a longer, straighter and stronger hind claw: it has commonly
an elongated streak up the shaft on the second outermost rectrix, and has also been
found sometimes to have a bright yellow lower mandible, in contrast to the invariably
duller bill of A. vaalensis. The variation in bill colour in A. leucophrys is not fully
understood but is probably seasonal. In central Angola and Northern Rhodesia
A.l. leucophrys is replaced by the darker A./. bohndorffi, which, like A.v. neumanni,
has little or no pattern on the second outermost rectrix. A single rather grey speci-
men of A. leucophrys has been examined from Duque de Braganc¢a in northern
Angola, and four very dark specimens were examined by White from Thysville,
Lower Congo, none of which can at present be referred to any race.
A. pallidiventris differs from A. leucophrys in its stronger, and usually longer,
leg, stronger foot with longer hind toe, and stronger hind claw. The tarsus measure-
ments show a slight overlap at 30 mm. but the relatively greater strength of the leg
of pallidiventris is always apparent. In addition there is some difference in the bill
structure, the nostrils of pallidiventris being more exposed, giving the bill the
appearance of being longer, although the measurements from the base of the skull
may be the same as in /eucophrys. A.p. pallidiventris in Gaboon and the Lower
Congo is darker than A.p. esobe which is found further up the river near Coquilhat-
ville: a single specimen examined from Luanda, northern Angola, matches closely
with esobe.
The forms of northern Africa ascribed to leucophrys vary from the dark and small
gouldi and ansorgei in West Africa, and the dark omoensis of northern Abyssinia, to
the light brown saphiroi of southern Abyssinia and the even lighter goodsoni of
Kenya. Most of the range from northern Nigeria to the borders of Kenya and south-
west Abyssinia is occupied by zenkeri which is a comparatively dark bird, varying
in different populations but browner than the other dark races. Intermediates
between zenkeri and saphiroi are found in south-west Abyssinia (Uba, Konso and
Mega), and one intermediate between zenkeri and goodsoni has been examined from
Eldoret in north-west Kenya: both goodsoni and zenkeri have been found between
Nakuru and the Mara River, as has already been noted.
In the paler races, goodsoni and saphiroi, there is some consistency in the hind
claw, which is never very long, and in the tail pattern which is never elongated : in
these respects these races show the characters of vaalensis. In the darker races
however, every variation of tail pattern is found, sometimes well-defined and some-
times so dark as to be almost indistinguishable, and the hind claw varies from 9-18
266 THE TAXONOMY AND IDENTIFICATION OF PIPITS
mm. It is this degree of variation in two characters which are so often specifically
diagnostic that makes me suggest that this is a hybrid population.
Identification.—Distinctions between the Plain-backed Pipits and worn specimens
of A. similis have been discussed under that species. Worn specimens of A.
novaeseelandiae are unlikely to lose all trace of patterning but can also usually be
recognized by the white and clearly defined tail pattern.
Distinctions between the three species of Plain-backed Pipit have been discussed
under geographical variation but can be summarized briefly as follows :—
South Africa.—A.v. vaalensis larger, paler and with shorter hind claw than 4.1.
leucophrys, with occasional differences in tail pattern.
Southern central Africa.—A. vaalensis neumanni less easily distinguished from A./.
leucophrys and A.l. bohndorffi owing to similarity in size, and variability in colour,
but paler in all variations than the latter, and with the hind claw weaker and usually
shorter. The lower mandible of A. leucophrys sometimes bright yellow.
West central Africa.—A. pallidiventris with a stronger and usually longer leg than
A. leucophrys and a more exposed bill.
6. Anthus pratensis—Meadow Pipit
Specific charvacters.—Medium sized. Above, olive brown, with clear streaking on
head and mantle: below, white or light buff, with spotting on the breast dark and
well-defined, changing on the lower breast and flanks to sparse streaks. The hind
claw fairly long and weak. The first three primaries longest and equal, the fourth
usually less than 1 mm. shorter, occasionally 2 mm.: the second, third and fourth
emarginated. The tail pattern white with a small triangle, spot or streak near the
tip of the second outermost rectrix, never very extensive: the primaries and
rectrices sometimes rather pointed.
The Meadow Pipit has a partial moult into similar plumage between January and
March. This is usually limited to the body, central rectrices, innnermost secondaries
and some wing coverts.
The juvenile is not scalloped and resembles the adult except that the streaking is
more extensive on the underparts and heavier above and below: the mantle is a
richer, redder brown, less olive than the adult, but the edges of the wings are olive
brown as in the adult.
Range.—Breeds from south-east Greenland to western Siberia, south to southern
France, northern Italy and the Balkans: winters in Europe, north Africa, the
Middle East and Turkestan.
Geographical V ariation.—There is a cline in colour from the richest birds in the west
to the greyest in the east of the range. The name ¢heresae was given to the richest
coloured birds, based on some collected in Ireland in autumn, and believed by
Williamson (1959) to belong to the breeding population of Iceland. It is possible to
identify as theresae a few exceptionally richly coloured specimens among winter
birds from other parts of Britain and western Europe and also to recognize in series
that the rest of the wintering birds of Britain are richer coloured than those of Europe
and North Africa. It may be assumed therefore that they are drawn from a breeding
THE TAXONOMY AND IDENTIFICATION OF PIPITS 267
population intermediate between theresae and pratensis, probably from Scotland and
the Hebrides. Ringing has shown that birds breeding in England move south to
winter.
Identification.—The combination of small size, short bill and olive brown edges to
the wings distinguish the Meadow Pipit from all the species that have been discussed
previously. It is most likely to be confused with the Tree Pipit, A. trivialis, but
has a finer bill and a longer and less curved hind claw : the markings on the breast of
A. pratensis are also usually rather less heavy and, in Europe, the difference between
the third and fourth primaries of A. trivialis is usually greater than 2 mm.
The Pechora Pipit, A. gustavi, and some female and young Red-throated Pipits,
A. cervinus, are similar in size and not unlike in colour to the Meadow Pipit, but have
lighter edges to the feathers of the mantle and head, streaked upper tail coverts,
whiter edges to the wing coverts, and plain brown, not olive brown, edges to the
wings. A. gustavi has, in addition, a distinctive tail pattern and wing formula.
7. Anthus trivialis—Tree Pipit
Specific characters —Medium sized. Above, light brown to olive brown, with clear
streaking on head and mantle : below, white or light buff, with spotting on the upper
breast dark and well-defined, changing on the lower breast to sparse, narrow streaks.
The hind claw short and curved. The first three primaries longest and equal, the
fourth commonly about 5 mm. shorter than the third in western birds, and 1-2 mm.
shorter in Indian birds: the second and third emarginated, the fourth slightly
emarginated in western birds and more clearly in Indian birds. The tail pattern
slightly off white with the pattern on the second outermost rectrix a small spot,
triangle or streak near the tip of the inner web, never very extensive : the rectrices
usually rather pointed.
The Tree Pipit has a partial moult of body feathers, taking place in January and
coming into similar plumage.
The juvenile is not scalloped and resembles the adult except that the streaking is
heavier below and the general colour above is slightly redder brown.
Range——Breeds in most of Europe and western Asia to Lake Baikal, between
latitudes 40° N. and 70° N.: winters throughout Africa, south to the Transvaal, in
the Mediterranean region, Persia and most of India.
Geographical variation.—Siberian breeding birds tend to be greyer than European,
especially on the upper tail coverts, and have been separated as sibirvica: they also
have frequently more white in the tail, the more elongated pattern being common :
the fourth primary is usually 2-3 mm. shorter than the third, against 4-5 mm. in
western birds of typical trivialis. None of these characters is constant and I do not
believe it is practical to attempt to differentiate between wintering birds of ¢rivialis
and sibivica though the names may be retained for the breeding populations.
There is also some clinal variation in size, the largest birds breeding in Russia,
where the wings of males may reach 95 mm. and Scandinavia ($ 87-90) : breeding
birds from Britain and France are smaller (3 84-87) and so is sibirica (3 81-88). No
wintering birds with wings over 90 mm. have been examined from West Africa or
268 THE TAXONOMY AND IDENTIFICATION OF PIPITS
India and it can therefore be assumed that the Russian population winters exclusively
in eastern Africa.
In Turkestan and the north-western Himalayas there is a very distinct race,
havingtoni, in which the markings on the head, mantle and breast are darker and
heavier, the bill is stouter and the difference between the third and fourth primaries
is less than 3 mm. No breeding birds examined show intergradation between
haringtoni and trivialis or sibirica but some wintering birds of northern India show
one or other of the characters, and may be presumed to belong to some intermediate
population. In winter havingtoni moves down to the plains of northern India but
does not undertake the vast migrations of tvivialis and sibirica.
Identification —The Tree Pipit is most likely, in Europe, to be confused with the
Meadow Pipit, A. pratensis, but has a stouter bill and a distinctive short, curved,
hind claw. The markings on the breast are usually more extensive and, in Europe,
the fourth primary is usually shorter.
Among other characters the stout bill and unstreaked upper tail coverts distinguish
the Tree Pipit from the young Red-throated Pipit, A. cervinus, and the Pechora
Pipit, A. gustavi. The lack of green tone in the plumage or green edges to the wings
distinguish it from the Indian Tree Pipit, A. hodgsonv.
In central and southern Africa the wintering Tree Pipit is best distinguished by
its short bill, legs and hind claw from the resident races of A. novaeseelandiae, and
by its short legs, clear streaking and pointed wing from those of A. szmilis.
8. Anthus hodgsoni—Indian Tree Pipit
Specific chavacters—Medium sized. Above, olive green with green edges to wing
and tail and with blackish streaking on head and mantle varying from very light
to heavy : below, white, with dark, broad, well-defined streaking variable in extent.
The hind claw short and curved, The first three primaries longest and sub-equal,
the fourth 1-4 mm. shorter: the second, third and fourth primaries emarginated.
The tail pattern slightly off-white with the pattern on the second outermost rectrix
in the form of a small spot or triangle near the tip, sometimes extending about 25
mm. up the shaft.
The Indian Tree Pipit has a partial moult of body plumage and some wing coverts
from February to April.
The juvenile is like the adult but more heavily streaked on the mantle and under-
parts, the streaks wider as well as more extensive: the greens of the plumage are
more bronzy, especially on the edges of the wings and wing coverts.
Range.—Breeds from the Pechora in north-eastern Russia, eastwards to the
Kurile Islands and Japan, southwards to the Himalayas and Szechwan. Winters
in India, Burma, Siam, Indo-China, Japan and the Philippine Islands.
Geographical variation—The most northern breeding birds are the least heavily
streaked, both above and below, the streaks in the mantle in fresh plumage being
narrow, faint and ill-defined and the streaks below heavily concentrated on the upper
breast, extending only sparsely on to the lower breast and flanks. Ripley (1948)
‘ has shown that these birds should be called yunnanensis. Southern birds, A. h.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 269
hodgsont, breeding from the Himalayas to central China, are more heavily streaked,
the streaks on the mantle being black and well-defined, narrow on the mantle and
rather broader on the head: the concentrated streaking on the breast extends to
the lower breast and there is more streaking on the abdomen. In yuwnnanensis the
fourth primary is usually 1-3 mm. shorter than the third, in hodgsoni the difference
is usually less than 1 mm. These two races therefore show similar differences in
pattern and wing formula to those that distinguish the northern and southern
populations of A. trivialis.
There is, in addition, a population breeding in Japan which is difficult to place
taxonomically since it hardly shows sufficiently distinct characters to warrant a name,
and yet is not truly typical of either race. It is slightly less heavily streaked than
hodgsoni, though closer in this character to hodgsoni than to yunnanensis : it has on
average a longer bill and shorter tail than either of the other races (Table 8): the
wing is usually similar to ywnnanensis and more pointed than hodgsoni. These
characters are trivial and do not readily identify individual specimens, but they
serve to show that most of the wintering birds of Formosa and the Philippines, as
well as some of those from Japan and Indo-China, belong to the Japanese breeding
population. These birds have sometimes been described as intermediates between
hodsoni and yunnanensis but are not truly intermediate in either the morphological
or geographical sense, and it seems preferable to refer to them as an atypical popula-
tion of hodgsoni. Specimens listed as this population in Table 8 include four summer
birds from Japan and winter birds from Japan, Formosa and the Philippines which
which are distinct from ywnnanensis on size and/or colour.
Ripley (op. cit.) believed also that there was a distinct population, A. h. berezow-
skit, of very heavily streaked, long billed birds breeding in south-east Tibet and
Sikang province, China. This view was based on twelve specimens: two of these
he has told me (in litt.) he has since found to be immature A. roseatus : through his
kindness it has been possible to re-assemble most of the remainder of the series :
these have been compared with the exceptionally good series in the British Museum
and it was found that all showing very wide streaks were young birds of either
hodgsoni or roseatus, and those with a long bill either vyoseatus or Japanese hodgsont.
There are therefore no apparent grounds for recognizing A.h. berezowskii as distinct
from A. h. hodgsont.
Identification —The green edges to the wings and the green in the upperparts
distinguish hodgsoni from all other species except A. voseatus. In autumn plumage
A. roseatus is superficially very similar to the adult hodgsoni and even more so to the
young bird. The two species can best be distinguished by the hind claw, which is
short and curved in hodgsoni and longer and weaker in voseatus : in addition roseatus
has a distinctive tuft of lemon yellow in the axillaries, is usually a larger bird with a
longer bill, darker legs, and less clear white underparts.
g. Anthus roseatus*—Hodgson’s Pipit
Specific characters —Medium to large sized. Above, upperparts in autumn olive
* This species may in future have to be known as A. pelopus Gray (see Deignan 1960, Bull.
Br. Orn. Cl. 80 : 120.)
270 THE TAXONOMY AND IDENTIFICATION OF PIPITS
brown, with dark, wide streaks on head and mantle, edges of wings green : in spring
and summer the upperparts are grey and heavily streaked: below, in autumn,
white with a faint wash of pink or buff, the breast heavily streaked with the streaking
extending to the lower breast and flanks : in spring and summer there is little or no
streaking and the chin to the lower breast is a vinous pink : axillaries lemon yellow.
The hind claw medium, weak and comparatively straight. The first four primaries
longest and sub-equal : the second, third and fourth emarginated. The tail pattern
slightly off white, the pattern on the second outermost rectrix confined to a medium
or small triangle near the tip.
Hodgson’s Pipit has a complete moult of body plumage between December and
March into the distinctive breeding dress.
The juvenile plumage is generally similar to that of the adult in autumn but is
browner above and less heavily streaked below, with no streaking on the abdomen.
Range.—Breeds in the mountains of central Asia from Afghanistan to China and
Tonkin, descending to the plains in winter.
Geographical variation —None apparent.
Identification —The green edges to the wing distinguish A. voseatus from all other
Asiatic species except A. hodgsoni. As has already been noted, autumn birds and
young birds of the two species can be confused but are distinguishable on the shape of
the hind claw, colour of the legs, the lemon yellow axillaries of A. voseatus, and some-
times also on size. The spring plumage of A. voseatus is quite distinctive since no
other pipits have pink on the underparts except the Water Pipit, A. spinoletta, in
which the pink is less vinous in tone, and the Red-throated Pipit, A. cervinus, in
which the pink is confined to the throat and upper breast. Furthermore neither of
these species have any green in the wings or yellow axillaries.
to. Anthus cervinus—Red-throated Pipit
Specific characters —Medium sized. Above, tawny brown in autumn, grey brown
in spring, distinctly streaked on head, mantle, rump and tail coverts, with some
indistinct white streaks on the mantle: wing coverts broadly edged with white :
below, pale creamy buff, in autumn clearly streaked with black on the breast, lower
breast and flanks, the throat either white or with some orange pink, the pink found
more commonly and more extensively in males: in spring males have the throat
and breast orange pink with little or no streaking except on the flanks and sides of the
lower breast : females usually have the pink confined to the throat with sparse
streaking on the upper breast as well as the lower breast and flanks. The hind claw
medium or long, weak and comparatively straight. The first three primaries longest,
the fourth between -5 and 2 mm. shorter than the third: the second and third
primaries emarginated, the fourth usually only slightly so. Tail pattern slightly
off white, the pattern on the second outermost rectrix confined to a small triangle at
the tip, rarely extending more than 10 mm. up the shaft.
The Red-throated Pipit has a complete moult of body plumage between January
_ and April into the distinctive breeding dress.
The juvenile plumage is similar to that of the adult female in autumn without
THE TAXONOMY AND IDENTIFICATION OF PIPITS 271
pink on the throat, but more rufous brown above with the streaks below longer and
less clearly defined.
Range.—Breeds in northern Europe and Asia from Scandinavia, north of lat. 67°
N., to north-eastern Siberia, and occasionally to Alaska. Winters in Africa south to
southern Nigeria, the Belgian Congo and Tanganyika, occasionally in Arabia, the
Maldive and Andaman Islands, Burma, Siam, Indo-China, Celebes, Borneo and the
Philippines, but not in the greater part of peninsular India.
Geographical variation—Some slight differences have been noted between the
eastern and western breeding populations. The eastern birds are slightly greyer
above, slightly less streaked below and average smaller (see Table 8). In addition the
wing tip is usually blunter, the fourth primary being nearly equal to the third and
more noticably emarginated than in western birds, in which the difference between
the third and fourth is usually about 2 mm. These differences do not seem great
enough to justify the recognition of two races, but the name vufogularis is available
for western birds if required.
Identification —Pink-throated birds are quite distinctive, the pink being richer,
more orange, and less extensive on the breast than in pink-breasted specimens of
A. roseatus and A. spinoletta. Young birds and some autumn females of A. cervinus
are easily confused with A. pratensis and A. trivialis but can be distinguished by the
streaked upper tail coverts, brown, rather than olive-brown, edges to the wings and
feathers of the mantle, the broader white edges to the wing coverts, and heavier
streaking below: A. cervinus has also a longer hind claw than A. trivialis. The
Pechora Pipit, A. gustavt, is similar to A. cervinus in colour and pattern above but
is smaller with a more pointed wing and a more extensive pattern on the tail ; below
the streaking is narrower and mostly confined to the upper breast ; the bill is heavier.
11. Anthus gustavi—Pechora Pipit
Specific characters—Small. Above, brown, heavily streaked on head, mantle,
rump and tail coverts, with two or three white-edged feathers to the mantle forming
an indistinct V on the back: below, white or pale creamy buff, with dark, clearly
defined streaks, heavy on the upper breast, rather sparse on the lower breast and
flanks. The hind claw of medium length and weak. The first three primaries
longest, the fourth about 4 mm. shorter than the third: the second and third pri-
maries emarginated. The tail pattern buff or dusky white, the pattern on the second
outermost rectrix usually a tapering streak extending about halfway up the shaft,
but occasionally restricted to a small elongated triangle at the tip: the rectrices
pointed.
The Pechora Pipit has a complete body moult between January and April into
similar plumage.
The juvenile is similar to the adult except that the streaking below is less clearly
defined but more extensive on the throat and abdomen.
Range.—Breeds in Eastern Europe and Siberia north of about lat. 64° N., from
the Pechora region to the Bering Strait. Winters in Borneo, Timor, Celebes and
Moluccas, migrating through Korea, eastern China and the Philippine Islands :
272 THE TAXONOMY AND IDENTIFICATION OF PIPITS
occasional stragglers travel westwards, and have been recorded at Fair Isle at different
times.
Geographical variation.—Three races are recognized : the nominate race over most
of the range, a slightly larger and possibly paler race, A. g. commandorensis,
in the Commander Islands, and a darker, smaller race, A. g. menzbieri, breeding in
south Ussuriland. The winter ranges of the respective races have not been defined
but there are in the British Museum specimens which, on measurement, appear to be
commandorensis from Celebes (2, undated, wing 85), Labuan (unsexed, undated,
wing 88) and Shaweishan (3, May, wing 86) : also some May birds which on colour
and size appear to be menzbiert from south China and the Philippines (wings 1 g 80, 12
74, 3 unsexed 73-79 mm.). As shown in Table 8 the few specimens available in the
British Museum indicate a wider range of measurements than quoted by Johansen
(1952 : 152) for the different races : his figures are quoted in brackets.
Identification.—In autumn the Pechora Pipit is easily confused with the female
Red-throated Pipit. The white streaks on the mantle of A. gustavi have been
quoted as a diagnostic character, but some white streaks are also found in A. cervinus,
though they are not usually so pronounced or in the indistinct V pattern. Other
differences between the two species have already been noted in the discussion on
A. cervinus, and include wing formula, tail pattern and size. In winter quarters
A. gustavi may be found in the same area as the Molucca race of Richard’s Pipit,
A. novaeseelandiae medius : this is also a small pipit but has heavy streaking above
and below, with the streaks above not extending to the tail coverts, and it has a less
pointed wing.
12. Anthus spinoletta—Rock and Water Pipits
A. spinoletta is divided into two ecological groups of coastal and inland races.
It is convenient in discussing the species to use the common name “ Rock Pipit ”’
for the coastal races of western Europe, petrosus, kleinschmidti and littoralis, and to
use “ Water Pipit ’’ for all other races.
Specific characters.—Medium sized. Above, varying from light chocolate or deep
olive brown in autumn to grey brown or grey in spring ; the streaking on head and
mantle ill-defined with no sharp contrast between the feather centres and the paler
edges : below, dusky white or buffish, usually suffused with pink in spring in variable
degree : in autumn extensively streaked often on the abdomen as well as the breast,
but the streaking ill-defined and often light in colour : in spring the streaking sparse
or absent except in some Rock Pipits which have no distinctive spring plumage.
The hind claw of medium length, weak and usually rather curved: the legs dark
except in young birds and some from eastern Asia. The first four primaries longest
and sub-equal: the second, third and fourth emarginated. The tail pattern clear
white in Water Pipits, dusky in Rock Pipits: in Water Pipits from Europe and
western Asia the pattern on the second outermost rectrix is usually confined to a
small triangle near the tip, but is more extensive in those from eastern Europe and
America : in Rock Pipits it is a mere speck at the tip or so dusky as to be indisting-
uishable.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 273
Most of the races of both Rock and Water Pipits have a body moult between
January and April into distinctive breeding dress, but Mayaud (1952) has shown
that this moult is absent or incomplete in Rock Pipits of Britain, coastal France
and the Atlantic islands.
The juvenile is similar to the adult in autumn except for the paler legs. It is a
plainer, more chocolate brown above than other young pipits.
Range.—Widespread in the Northern Hemisphere. The Rock Pipits breed on
the coasts of western Britain, northern France, the Faroe islands and Scandinavia,
the northern birds migrating south in autumn, sometimes as far as Portugal and Italy
but more usually to Britain and France. The Water Pipits breed inland in the
mountains of Europe and Asia Minor, Turkestan, northwards and eastwards to
Mongolia and the Bering Sea, across North America north of lat. 48° N. to western
Greenland, also in the Rocky Mts. south to California. All populations move south
in autumn reaching the Mediterranean, Egypt, Arabia, northern India, northern
Burma, Tonkin and the Gulf of Mexico. Stragglers have occured at even more
widespread localities.
A single juvenile specimen in the British Museum (No. 98.10.20.749), previously
identified as another species, was collected in the valley of the Yenisei at lat. 61°.30’
N. on 8th August 1877. This represents an extension of the range of the species as
shown by Dementiev and Ghladkov (1954: Map 121). The similarity in colour
of this specimen to young birds from North America suggests that it is probably
A. s. japonicus, which is closely allied to the American races, rather than the paler
A. s. blakistont.
Geographical variation—The Rock Pipits are more olive-brown than the Water
Pipits, this being particularly noticeable on the rump: below the streaking is more
extensive and the underparts are more washed with yellow-buff : the tail pattern is
dusky rather than pure white. Within this group there is a cline from the largest,
darkest and most heavily streaked race, kleinschmidti, in the Faroes and Hebrides,
to the less richly coloured race, petrosus, of Wales, Ireland, England and France,
and the shorter billed, paler race, littoralis, of Scandinavia. The most striking
variation in these populations is caused, however, by the degree of moult in the body
plumage that takes place from January onwards. In kleinschmidt: and fetrosus
there is little or no winter moult so that spring birds are still dark and heavily
streaked : in /ittoralis there is a fairly extensive winter moult varying individually
but giving all birds a distinctive breeding dress with usually some pink on the breast,
less streaking and a greyer back. Mayaud has noted that a fairly complete moult
is sometimes found also in birds of the population of petvosus breeding on Ushant,
giving them a /ittovalis-like appearance in spring. It is probable that there is some
mixing of /ittoralis with this population since large numbers of Scandinavian birds
winter on the coasts of northern France and a few, possibly birds coming early into
_breeding condition, may settle with the residents. There is also from Ushant an
apparently aberrent male bird in the Meinertzhagen collection (cited as the co-type
of A. s. ponens) collected 23rd September 1933, which is in fresh plumage similar
to littoralis in spring. In autumn plumage most individual specimens cannot be
named with certainty, but from series it is apparent that the majority of Rock Pipits
274 THE TAXONOMY AND IDENTIFICATION OF PIPITS
wintering on the eastern and southern coasts of Britain are migrants from Scandin-
avia, since there are few amongst them with bills of rg mm. which are common in
petvosus but not found in /ittoralis. An occasional very dark, large specimen can be
identified with some confidence as kleinschmidtt.
A number of names have been given to intermediate populations which do not
seem sufficiently distinct to warrant recognition on available material.
Opinions differ on the races to be recognized among the Asiatic populations of the
Water Pipits, and I am more in agreement with the ranges and races recognized
by Dementiev and Ghladkov (1954: map 121) than with Vaurie. A. s. spinoletta
of Europe is a fairly lightly streaked race with a pale pink flush in spring: the
breeding birds of central Asia and China, A. s. blakistont, are paler in all plumages :
wintering birds of Egypt, to which the name coutelli was given, average smaller and
have the streaking above more pronounced than either spznoletta or blakistoni ;
the marks on the breast in autumn are less streaky more spotty than spinoletta and
slightly heavier than blakistoni, and the rest of the underparts are washed with
pale orange buff ; in spring the pink wash is warmer and more orange in tone than in
either of the other two races. A. s. coutelli is believed to breed in the Caucasus and
Persia. It seems useful therefore to retain the two names, coutelli and blakistont, to
indicate the extremes of what is probably a cline across Asia. Winter birds are
hard to identify but throughout Persia, Afghanistan and north-western India the
few that can be named either on size or colour are mostly blakistoni. However in
Sind and United Provinces birds that are too small for blakistoni are common :
those in spring plumage are near in colour to coutelli. Some of these are exceptionally
small, even for coutell, and it is possible that they belong to an unlocated breeding
population in the Himalayas east of the range of typical coutelli. The lowest dimen-
sions of these exceptional birds are included in brackets with coutelli in Table 9.
The most eastern Asiatic race, A. s. japonicus, is more distinctive than the other
two. It breeds in eastern Siberia, possibly intergrading with American races in
the extreme north-east, and migrates chiefly to China and Japan with some stragglers
coming westwards to India and Burma. It is a dark race, with black, well-defined
spots on the breast which are extensive in autumn but also present, though sparse,
in spring: the wash on the underparts in spring is orange buff rather than pink :
the legs are paler than in other races and the white in the tail often more extensive.
Three American races are now recognized, the paler pacificus from the west, the
darker vubescens from the east, and a mountain population in Colorado, alticola,
said to have a richer spring plumage. All these are fairly close to japonicus but
differ in autumn in being a warmer brown above with less pronounced streaking,
and having the spots on the breast less clearly defined and browner : in spring they
are plainer in series, greyer and darker above ; below the streaking is much reduced
or absent : the white in the tail is usually extensive, as in japonicus, but the legs are
dark as in all other races. Vaurie believed that havmsz, based on migrants taken in
Turkestan, should be considered a synonym of vubescens, since a co-type matched
American birds. He has kindly sent me the specimen of Zarudny’s on which this
opinion was based. While I do not consider one can be dogmatic on single specimens,
to me this bird matches rather better with a series of japonicus than with American
THE TAXONOMY AND IDENTIFICATION OF PIPITS 275
birds. I would recommend that harms: is transferred to the synonymy of japonicus,
as this move has the added advantage of eliminating any question of whether or not
harmsi should be used instead of pacificus, which it antedates, for the western
American birds, now that vubescens is confined to the eastern populations.
| Identification—The differences between the two ecological groups of Rock and
Water Pipits have been discussed under geographical variation. The species as a
H whole is unlikely to be confused with other pipits though in size and plumage varia-
tions it appears to be closely related to the greenish A. voseatus. The dark, com-
paratively unstreaked back, and dark legs combined with the extensive but ill-defined
streaking or pale pink underparts of most races are quite distinctive. A. s. japonicus
is more like A. trivialis and A. pratensis below than the other Palaearctic races, but
has different dimensions and is greyer and less streaked above.
MEASUREMENTS OF SPECIES IN GROUP A
(based on a minimum of 15 ¢ 15 9 unless otherwise stated)
TABLE 2.—Australian, Melanesian and Philippine Forms of A. novaeseelandiae (pp. 253-254)
Wing Bill Tail*
—oOot — "(U7 o_o" Hind Tarsus
3 2 3 2 3 2 claw 3?
| All New Zealand races, 7 g, 89-99 84-90 16-18 16-17°5 67-72 63-68 II-13 23-26
692
steindachneri, 1 §,29. c 87 86-87 20 18-19 61 57 12-13 24-26
aucklandicus,3 35,12. 86-89 gl 18-23 I9 59-65 68 12-17 24-26
All Australian races, 12 ¢, 9 2 86-95 79-85 16-18 16-17 56-67 53-60 9-13 23-28
exiguus,3 6,49. 6 85-87 77-83 17-18 16:+5-18 57-60 52-56 10-12 25-27
medius,5 3,492. 3 - 79-80 77-80 17-175 17-18 51-55 55-50 10-12 24-26
albidus, 23,1 ve : F 80 77 17 18 56-57 54 II 25-26
lugubris : c - 78-83 75-79 17-18 16:5-18 52-58 51-55 12-19 27-29
* Seep: 249.
|
TABLE 3.—Asiatic Mainland, and Palaearctic Races of A. novaeseelandiae (pp. 254-256)
Wing Bill Tail*
ese —_—— — OOF Hind Tarsus
3 2 3 2 3 g claw 3?
vichardi (breeding), 7 3g, 2 2 91-99 93-94 18-5-19 18-19 64-72 71 15-20 29-33
(ror)
centralasiae (breeding), 4 g, 98-100 92 18-21 18-5 69-73 66 15-22 30-33
19 (96-102)
dauricus (breeding), 3 3,29. 90-96 87-92 18-19 17°5-18-5 63-69 64-69 14-19 28-31
ussuriensis feicedice), 53 +. 90-95 — 18-19 _— 63-70 =_ 15-18 30-31
vichardi subspp. (all year) . 90-102 87-94 18-21 17-19 63-73 62-71 14-22 28-33
simensis (breeding), 8 3,892. 87-91 81-88 17-18 16-5-18 58-64 55-62 12-19 27-30
Annam pop. (breeding), 6 g, 80-90 80-86 16:5-17 I6-17°5 57-62 54-59 10-18 26-29
59
malayensis, rufulus, and waitei 77-87 74-83 16-18 15-18 51-61 49-56 10-18 24-28
* See p. 249.
ZOOL. 7, 5. 20
276 THE TAXONOMY AND IDENTIFICATION OF PIPITS -
TABLE 4.—African Races of A. novaeseelandiae (pp. 256-258)
Wing Bill Tail*
ao" ——_ -——_ Hind Tarsus
3 2 3 2 3 9 claw 3?
cinnamomeus : 5 - 82-97 71 16-18-5 16-18 55-05 53-05 II-I7 24-29
bocaget : = - - 84-93 77-86 17-18-5 16-17 55-606 52-60 9-15 24-28
vufuloides . : . 87-94 84-93 16-18 16-17 59-64 57-61 11-15 24-28
Twenarum, 4 3,1 9 > - 93-95 97 17-19 19 65 67 11-13 28
editus,3 35,292 . 2 - 94-97 88-89 17:°5-18 17 63-65 62-64 13-15 26-29
hoeschi, t 9 (type) = : — 96 _ 17 _ —_ 14 29
cameroonensis, 4 gd, 22 - 91-95 93-95 17-19 18 57-68 64-05 Q-II 26-28
lynest, 43,39 - é - 95-99 90-92 17-18 17-18 65-71 63-66 g-10 25-27
* See p. 249.
TABLE 5.—Anthus godlewskii and A. campestris (pp. 258-260)
Wing Bill Tail*
oo" ——_ ———————" Hind Tarsus
3 2 3 2 3 2 claw 33
A. godlewshkii : 5 - 90-97 84-93 16°5-18 16-17'5 62-70 59-64 II-I5 24-28
A.c.campestris . ni - 88-101 82-91 18-5-20 17-20 61-67 59-66 9-14 24-28
A.c. kastschenkot 5 . 85-90 80-87 17-18 16-17 55-05 54-61 8-13 23-26
* See p. 249.
TABLE. 6.—Races and Populations of Anthus similis (pp. 261-262)
Wing Bill Tail*
A a a ——— ~ Hind Tarsus
3 g 3 g 3 fo) claw 3?
similis, travancoriensis, 7 3,2 ? 90-96 89-90 19-21 19 72-76 70-72 Q-II 26-28
yamethini, 8 3,42 : 87-92 84-89 18-19 18 67-73 66-67 8-11 24-26
decaplus, jerdont . 5 - 94-105 92-99 19-21 18-21 71-82 69-82 9-14 26-29
captus, avabicus . go-98 86-92 18-20 17-20 68-72 62-70 8-13 23-26
nivescens, jebelmarvae, asbenai- 88-103 87-100 17-20 17-20 57-75 58-71 8-11 24-28
cus, haravensis, hallae, nyas-
sae
schoutedent, 10 3, 3 9 86-97 85-92 15-17 15-17 57-65 58-60 8-10 23-25
nicholsoni and leucocraspedon gI-102 87-96 17-21 17-20 64-72 58-72 9-14 24-28
bannermani and josensis, 3 g 85-86 —_— 17-18 — 60-64 — 7-10 24-25
sokotrae, 15 specimens . c 82-91 19-22 56-71 IO-IL 24-26
* See p. 249.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 277
TaBLE 7. Anthus vaalensis, A. leucophrys and A. palidiventris (pp. 262-266)
Wing Bill Tail*
oo -—__ -o——_——_ Hind Tarsus
3 2 3 2 3 2 claw 3?
Southern Africa
A. v. vaalensis and daviesi, 101-111 —_92~103 18-20 17-19 67-76 68-75 8-12 28-32
15 5,109
uv. meumanni and cho- 92-105 89-102 17-20 16-20 62-73 59-69 8-13 26-30
biensis
A. 1. leucophrys : - 89-102 89-99 17-18:5 16-18 58-66 55-66 II-17 27-31
A.l.bohndorfi . : + 95-102 89-97 17-19 16-185 60-71 58-64 12-17 27-31
Northern Africa
A.l. saphiroi, 12 $,102 . 90-101 90-97 17-18 15-17°5 61-67 60-67 10-12 24-28
cA. 2. goodsont, BiGwe7- + 99-102 93-99 17 16-5-18 65-70 63-66 10-12 27-29
A. 1. omoensis, 13 8,82 . 98-108 97-102 17-19 17-18-5 65-71 67-70 10-18 26-30
A.l. zenkeri. . 89-101 85-97 16-18-5 16-18-5 59-69 58-68 9-18 24-29
A.1. ansorgei, 9 3,9 9 + 90-95 85-95 17-19 17-18 65-69 59-66 Q-12 23-28
A.1. gouldi, 11 3, 49 . 86-96 88-89 17-19 17-18-5 58-69 60-65 9-14 25-27
A.p. Pallidiventris, 43,3 : 95-99 93-96 19-20 19-20 61-64 55-59 13-16 31-33
A. p. esobe,2 g,19. 96-97 91 19-20 19 59 56 13-16 31-32
* See p. 249.
TABLE 8.—Anthus pratensis, A, trivialis, A. hodgsont, A. roseatus,
A. cervinus, A. gustavi (pp. 266-272)
Wing Bill Tail*
a Se, 2 A, —"—_ Hind Tarsus
3 & 3 2 3 2 claw de
A. pratensis : : - 77-85 73-83 14-16 14-15 51-58 49-56 9-15 20-23
A. 1. trivialis F - 84-95 80-90 14-16 14-16 50-61 51-59 8-10 20-23
A.t. sibivica, 15 3,8 Q . 81-88 79-85 13-15 14-15 52-57 52-57 8-10 20-21
A.t. haringtoni, 12g,62 . 84-89 83-87 14-15 14-15 54-60 54-58 71-9 20-22
Ah. hodgsoni (typical) - 79-86 77-85 13-16 14-16 53-61 50-59 8-9 20-22
A. h. hodgsoni (Japan, see p. 81-86 81-83 15-16-5 15-16 51-55 50-53 8-9 20-22
000) 10 g, 7 2 18 unsexed (81-87) (15-16-5) (47-54)
A. h. yunnanensis : . 81-90 77-83 14-16 14-15 51-61 52-56 8-9 20-21
A. yoseatus . 5 2 . 86-92 79-87 15-17 15-16 57-62 52-58 10-14 22-24
A. cervinus, Europe and W. 83-90 80-87 14-16 14-15 49-56 47-55 9-13 20-22
Siberia
A. a E. Siberia, 5 g, 83-85 79-83 14-15 14-15 51-55 48-51 9-13 21-22
5
A. g. gustavi, breeding 8362 81-86 77-82 16+5-17 15-16°5 947-51 47-51 10-13 20-22
(82-84) (78-81)
A. g. commandorensis, breed- 86-89 85 16-17 16 51-55 55 10-13 24-26
ing, 3d, 19 (83-86) (79-83)
A. g. menzbieri (winter), 1 3, 80 74 16 16 51 46 10-12 21-23
I 9, 3 unsexed (76-79) (73-77) (t5) (45-46)
* Seep. 240.
278 THE TAXONOMY AND IDENTIFICATION OF PIPITS
TABLE 9.—Races and Populations of Anthus spinoletta (pp. 272-275)
Wing Bill Tail*
ao -——_ ——— Hind Tarsus
3 g 3 2 3 2 claw 3?
Rock Pipits
kleinschmidti (Faroes and 88-95 83-89 18-19 19 58-62 58-59 II-12 23-25
Outer Hebrides)
petrosus (England, Wales, 88-04 83-90 17-19 18-20 55-64 52-60 8-14 22-25
Ireland)
littoralis (Scandinavia) 87-93 80-87 16-5-18 16:5-18 56-60 51-56 9-14 23-25 .
Water Pipits
spinoletta c : - 88-95 80-89 16-18 15-17 57-63 54-60 10-14 22-24
coutelli (Egypt and Cyprus, 85-92 80-87 16-17 16-17 55-61 54-59 10-13 23-25
5 6,9 9, and N. India, (83) (15) (54) (52) '
see p. 274)
blakistoni > 0 . 88-96 83-90 16-18 16-18 59-66 56-61 9-14 23-24
japonicus F : . 86-91 79-88 15-17 15-17 54-62 53-60 10-14 22-25
pacificus and rubescens . 80-90 78-86 14-17 14-16 55-64 53-57 9-13 22-24
* See p. 249.
GROUP B. DISTINCTIVE ASIAN, AFRICAN
AND AUSTRALASIAN SPECIES
None of the species in this group presents difficulty in identification to any student
with an appropriate regional handbook, since all have distinctive characters, many
have very restricted ranges, and none is a true migrant. They have therefore not
been illustrated : their characters have been summarized with particular reference to
their distinctive characteristics : the range and any geographical variation is out-
lined : as a guide to general size measurements have been given of specimens avail-
able although in some of the rarer species the series is not adequate to show the full
range of size.
ASIAN SPECIES
Anthus nilghiriensis—Nilgiri Pipit
Confined to high altitudes in the Nilgiri and Palni Hills of southern India, rarely
descending to the plains.
A medium sized pipit with short, blunt wings and a short bill. Above, rich tawny
brown, heavily streaked on head and mantle: below, rich buff, distinctly but
sparsely spotted on the upper breast with small spots and lightly streaked on the lower
breast and flanks. The hind claw of medium length and curved. The first four
primaries sub-equal with the fifth only 1-2 mm. shorter: the second to fifth emar-
ginated. The rectrices rather pointed, with the pattern buff: the pattern on the
second outermost a tapering triangle up the shaft, and the third outermost having a
small triangle at the tip. Measurements of 16 g 11 9: wing g¢ 76-80, 9 73-78:
bill g 15-16, 2 14-16: tail 9 53-61, 2 52-60: hind claw g 2 9-13: tarsus ¢ 2
24-25.
The well-defined streaking, short, blunt wing and extensive patterning on the tail
combine to distinguish the Nilgiri Pipit from all others likely to be found in the area.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 279
Anthus sylvanus—Upland Pipit
Confined to the mountains of central Asia from Afghanistan to Yunnan and eastern
Sikang, rarely descending to the plains.
A large pipit with short, blunt wings and a short heavy bill. Above, light pinkish
brown, heavily streaked on head, mantle, rump and tail coverts with dark brown :
below, pale buff or white, streaked with fine hair-streaks on the lower breast, flanks
and abdomen : these streaks are wider on the flanks and those on the breast divide
at the tip of the feather forming a small triangle. The hind claw short and strongly
curved. The first four primaries sub-equal with the fifth only 1-3 mm. shorter :
the second to fifth emarginated. The rectrices narrow and very pointed with the
tail pattern dusky and the same triangular pattern as in A. nilghiriensis on the second
and third outermost. Measurements 22 g 10 2: wing ¢ 78-84, 2 74-80: bill g 2
16-18 : tail J 59-60, 2 56-63: hind claw g 9 8-11: tarsus f 9 24-25.
There is a cline from paler birds, A. s. oveinus, in the west, to darker birds,
A. s. sylvanus, in the east.
The fine hair-streaks on the abdomen, heavy bill and pointed rectrices distinguish
the Upland Pipit from all others, but it can be seen that in the shape of the wing, the
pattern of the tail and conformation of the hind claw, it has many points of similarity
with the Nilgiri Pipit, which replaces it in the mountains of southern India.
AFRICAN SPECIES
Anthus berthelotii—Berthelot’s Pipit
Confined to the Canary Islands and Madeira.
A small pipit with a long bill. Above, dark brown, the streaking on the head and
mantle therefore not very distinct : below, white, with distinct spotting on the upper
breast and sparse streaks on the sides of the lower breast and flanks. The hind claw
fairly long and straight. The first four primaries sub-equal with the fifth about
6 mm. shorter: the second to fourth emarginated. The tail pattern white with the
pattern on the second outermost rectrix, as in A. campestris, usually extending up
the shaft in a tapering streak, sometimes reduced to a short streak near the tip.
Measurements of 35 ¢ 22 9: wing ¢ 2 69-79, bill, Canary Is. g 15-17, 2 14-16,
Madeira 3 16-18, 9 16-17: tail ¢ 2 48-56: hind claw g 9 8-16; tarsus g 9 23-24.
Birds of Madeira have rather longer bills than those of the Canary Islands and
have been separated as A. b. madeivensis. It has been suggested that there is some
variation in colour between the populations of other islands but sufficiently good
series of fresh plumaged birds are not available on which to establish this.
Size alone distinguishes Berthelot’s Pipit from any of the Palaearctic migrants that
might visit the islands. On field characters and voice it has been shown by Lack and
Southern (1949 : 619) and Volsge (1951 : 106) that this species has affinities with the
Tawny Pipit, A. campestris. Morphologically there is little to suggest closer affinities
with A. campestris than with some other species, the associations being dependent
on which characters are selected as being of most importance : the similarity of hind
claw, tail pattern and wing formula between A. berthelotii and A. campestris are off-
set by the considerable differences in pattern, colour, size, and in the lack of a
spring moult.
280 THE TAXONOMY AND IDENTIFICATION OF PIPITS
Anthus lineiventris—Striped Pipit
Found throughout most of Africa south of the Equator.
A large pipit with green edges to the wings. Above, dark brown, with heavy but
indistinct streaking on head, mantle, rump and tail coverts; the wings and tail
edged with green: below, creamy white, extensively streaked from the upper breast
to the tail coverts with well-defined dark brown streaks. The hind claw short,
curved and strong. The wing blunt, the first four primaries sub-equal and the fifth
only 1-3 mm. shorter : the second to fifth emarginated. The tail pattern clear white
and in the form of triangles of diminishing size on the inner webs of the three outer-
most rectrices. Measurements of 25 ¢ 22 2: wing ¢ 85-90, 2 82-88: bill g 2
18-20: tail $ 9 59-68, 2 58-64: hind claw $ 9 9-10: tarsus $ 9 28-30.
The green edges to the wings and tail, combined with the extensive streaking
below, make the Striped Pipit quite distinctive among African pipits, though with
a superficial resemblance to the Palaearctic A. voseatus in autumn.
Anthus brachyurus—Short-tailed Pipit
Sporadically distributed from Kenya to Angola and Natal.
A miniature, dark pipit. Above dark brown, with heavy but indistinct streaking
on head and mantle. Below creamy-white on the breast, with heavy, well-defined,
short streaks ; white on the abdomen and flanks with very sparse fine streaks. The
hind claw short and curved. The wing blunt, the first four primaries sub-equal and
the fifth 1-3 mm. shorter: the second to fourth emarginated. The tail pattern
dusky white on the outer rectrix and absent from or very small, on the second
outermost. Measurements of 12 f 12 2: wing ¢ 64-68, 2 60-65: bill 3 13-14,
9 12-13: tail 3 33-30, 2 32-36: hind claw $97: tarsus g 9 16-18.
Northern birds, A. b. leggei, are alleged to be smaller and darker than the southern,
A. b. brachyurus. The differences are just apparent but not very convincing and
it seems impossible to make a clear division between the ranges of the two races.
The Short-tailed Pipit is the smallest Old World Pipit: the only other small
pipits found in Africa are the following species, A. caffer and A. sokokensis, which
are a richer brown with longer tails.
Anthus caffer—Little Tawny Pipit
Sporadically distributed from southern Abyssinia to Angola and the Transvaal.
A small pipit with a misleading name since it is richer and less sandy in colour
than the Tawny Pipit. Above, light brown, heavily and distinctly streaked on
head and mantle: below, white, with dark brown streaks on the breast. The hind
claw short and curved. The wing blunt, the first four primaries sub-equal, the fifth
2-4 mm. shorter ; the second to fourth emarginated and the fifth slightly so. The
tail pattern usually clear white, with a small spot or triangle on the second outermost
rectrix : the pattern in Abyssinian birds is buffish and sometimes extends as a short
streak up the shaft. Measurements of 8 ¢ 8 2: wing g 67-77, 9 67-75: bill 32
12-16: tail ¢ 2 41-51: hind claw § 2 6-8: tarsus ¢ 2 17-19.
Four races are recognized on slight differences of size and colour, A. c. caffer of
THE TAXONOMY AND IDENTIFICATION OF PIPITS 281
southern Africa and A. c. mzimbaensis of Nyasaland being slightly larger and longer
billed than A. c. australoabyssinicus of Abyssinia and the paler A. c. blayneyi of
Tanganyika.
The Little Tawny Pipit is richer coloured and longer tailed than the Short-tailed
Pipit, with the richer brown above particularly noticeable on the rump in contrast
to the dark, almost blackish rump of A. brachyurus.
It is similar in many respects to the next species, A. sokokensis which, in parts of
East Africa, occurs in the same area, though not in the same type of country, but
which is less rich in colour above, has a different pattern on the breast and lacks the
pointed rectrices of A. sokokensis. Their relationship will be discussed later.
Anthus sokokensis—Sokoke Pipit
Confined to woodland clearings associated with surviving patches of forest in the
Sokoke forest near Mombasa, Moa at sea level one hundred miles south, and the
Pugu Hills near Dar-es-Salaam.
A small, richly coloured pipit with pointed rectrices. Above, rich orange brown,
with broad, dark streaks on head and mantle and light streaks on the rump and upper
tail coverts : below, creamy white, with large blotchy black spots confined to the
upper breast. Hind claw short and rather straight. The wing blunt, the first four
primaries sub-equal and the fifth only about 1 mm. shorter: the second to fourth
emarginated, the fifth slightly so. The rectrices pointed with the pattern clear white,
with a small, elongated triangle on the second outermost rectrix. Measurements of
Ig29Q: wing g 2 68-69: bill J 16, 9 15: tail f 49, 9 46: hind claw f 27-8:
tarsus 3 2 18-19.
The similarity between the Sokoke Pipit and the Little Tawny Pipit can be appre-
ciated by comparison of the descriptions and measurements. The chief differences
lie in the richer colour above of the Sokoke Pipit, the different pattern on the breast
and the shape of the tail feathers : they are similar in size and the general extent of
the pattern above and below, and in the wing formula and tail pattern. It seems
likely that A. sokokensis and A. caffer are derived from the same stock but have
diverged in different environments.
Anthus melindae—Malindi Pipit
Confined to coastal Kenya.
A medium sized, plain backed pipit. Above, plain brown: below, white, with
extensive light brown streaks on the breast extending sparsely to the abdomen and
flanks. The hind claw of medium length and fairly straight. The wing blunt, the
first four primaries sub-equal with the fifth about 3 mm. shorter: the second to
fifth emarginated. The tail pattern dusky white on the outermost rectrix and absent
from the second outermost in the few specimens examined. Measurements of
4519; wing ¢ 2 83-86: bill g 9 16-17: tail J 9 48-56: hind claw gf 9 10-11:
tarsus 3 2 25-27.
The combination of the plain back and the extensive brown streaking below
distinguish the Malindi Pipit from all others. It is also smaller than the Plain-
282 THE TAXONOMY AND IDENTIFICATION OF PIPITS
backed Pipits of the A. leucophrys/vaalensis group and larger than A. brachyurus,
the only other African pipit with a plain back.
Anthus chloris—Y ellow-breasted Pipit
Confined to the south-eastern districts of South Africa.
A medium sized pipit with some bright yellow on the underparts. Above, light
brown, heavily streaked on the head and scalloped rather than streaked on the
mantle with very dark brown : below, in breeding dress, lemon yellow from the throat
to the upper abdomen, with little or no streaking on the breast ; in non-breeding dress
the yellow replaced by tawny buff except for a yellow patch on the upper abdomen.
Hind claw long and weak. The wing blunt, the first four primaries sub-equal, the
fifth less than 2 mm. shorter: the second to fifth emarginated. The tail pattern
clear white with a small, elongated triangle on the second outermost rectrix and a
spot on the third. Measurements of 8 $5 9: wing ¢ 85-91, 2 82-85: bill f 17-18:
tail f 60-65, 9 56-59: hind claw g 9 12-17: tarsus § 9 24-27.
In colour and pattern the Yellow-breasted Pipit is distinct from all other members
of the genus Anthus. It has the appearance of a minature Longclaw but lacks the
rictal bristles that are considered a generic character of Macronyx. Birds in non-
breeding dress bear a superficial resemblance to the female Golden Pipit, Tmetothy-
lacus tenellus, but the Golden Pipit is easily distinguished by its yellow tail pattern
and less richly coloured mantle. The two species are not normally found together
since the Golden Pipit is primarily an East African species but there is one un-
substantiated record of its occurrence in the Transvaal.
Anthus crenatus—Cape Rock Pipit
Confined to hills and mountains from southern and eastern Cape Province to
Pondoland and eastern Transvaal.
A large almost plain, pipit with greenish edges to the wing, and rich buff under-
parts. Above, brown with faint streaks on head and mantle, a yellow-green shoulder
and greenish edges to the wing : below, the throat white, the rest of the underparts
light tawny brown with very faint streaking on the breast : axillaries yellow. The
hand claw short and strongly curved. The wing blunt, the first five primaries sub-
equal; the second to fifth emarginated. The tail pattern buff, very reduced on
the outermost rectrix and limited to a small spot at the tip of the second. Measure-
ments of 5 9 3 2: wing 3 88-91, 2 83-86: bill J 9 19-21: tail J 56-61, 9 56-58:
hind claw ¢ 2 10-12: tarsus ¢ 9 28-29.
The Cape Rock Pipit has a rather stocky build, heavy legs and bill giving an
un-pipit-like appearance, though it has some features in common with A. simuihs.
It is easily distinguished from the sympatric A. similis nicholsoni by the greenish
edges to the wing, yellow shoulder and axillaries, and the plainer pattern above and
below.
AUSTRALASIAN SPECIES
Anthus gutturalis—New Guinea Pipit
Confined to the mountains of New Guinea.
A large, dark pipit. Above, dark brown, with indistinct streaks on head and
THE TAXONOMY AND IDENTIFICATION OF PIPITS 283
mantle: below, the throat yellow buff constrasting with pale sepia brown on the
breast which merges into yellow buff on the abdomen ; the breast unspotted except
in young birds. The hind claw short and strongly curved. The wing blunt with
the second, third and fourth primaries sub-equal and the first and fifth about 2-3
mm. shorter: the second to fifth emarginated. The tail pattern very dusky and
limited on the second outermost rectrix to a small triangle at the tip. Measurements
of 6 35 2: wing J 99-102, 2 93-08: bill 9 17-18: tail g 64-77, 2 64-73: hind
claw ¢ ¢ 8-10; tarsus § 9 27-30.
Three races are recognized on slight differences of colour and size.
The New Guinea Pipit in its heavy structure is another un-pipit-like member of
the genus, but closest to the Cape Rock Pipit, A. crenatus, and A. similis. Its
structure and the brown, unstreaked underparts distinguish it from the other resi-
dent pipit of New Guinea, A. novaeseelandiae exiguus, and from any likely migrants.
GROUP C. AMERICAN AND SOUTH ATLANTIC SPECIES
American species are poorly represented in the British Museum and it has not
therefore been possible to make a detailed study of them. However it seems useful
to list their characters under the same formula as has been used for the Old World
pipits so that comparisons can be made easily between them. On the whole I do not
find it possible to associate many American species directly with those of the Old
World, especially without knowledge of their field characters, but I have noted a
few instances in which there seems some relationship. As with species of Group B,
members of this group have not been illustrated and the measurements, taken mostly
from inadequate samples, are provided only to give indication of the relative sizes.
It has not been possible to assess the degree of individual and geographical variation
or the ranges of the races. Hellmayr (1935) and Zimmer (1953) have been followed.
Anthus spragueii
The only endemic North American pipit : breeding in the central plains from east-
ern Montana to Manitoba, migrating as far south as Mexico.
A medium sized, rather light-coloured pipit. Above, tawny brown, with broad
but not very dark streaks on head and mantle: below, white on the abdomen, pale
buff on the breast and throat, lightly and sparsely streaked on the upper breast
with well-defined short streaks. The hind claw medium to long, rather weak and
sometimes rather straight. The first four primaries sub-equal with the fifth about
8 mm. shorter: the second to fourth emarginated. The rectrices slightly pointed,
with the pattern pure white extending in a long narrow streak up the shaft on the
second outermost rectrix. Measurements of Io g 5 2: wing ¢ 81-85, 2 79-82:
bill f 9 14-15: tail 5 51-57, 9 50-53: hind claw 3 2 10-14: tarsus f 9 22-24.
Morphologically I can see no reason to consider A. spragueii specifically distinct
from the following species, A. furcatus, of South America. The only differences
between them are in the degree of marking on the breast and a slight difference in
the size of the leg and foot as indicated by the length of the tarsus. Unless significant
differences can be demonstrated in their field characters, I would recommend that
Sprague’s Pipit be considered a race of A. furcatus. In structure the two forms ap-
284 THE TAXONOMY AND IDENTIFICATION OF PIPITS
pear to be the New World representatives of the A. campestris /godlewski |bertheloti
complex, but I cannot speak for their field characters.
Anthus furcatus
Confined to central South America from Peru and Bolivia south to Uruguay.
Similar in all characters to A. spragueii except that the buff of the upper breast
and throat is slightly darker and the streaks on the breast are broader, forming
brown, rather heavy, spots, instead of the narrow, short streaks. Measurements of
8 S19 2: wing 3 77-85, 9 74-80: bill g 2 13-15: tail J 48-55, 2 48-52: hind
claw ¢ 9 8-13: tarsus gf 9 20-22.
Birds from Peru and Bolivia have been separated as A. f. brevivostvis and can be
distinguished by slight differences in colour and size.
Anthus lutescens—(A. chi of Zimmer)
Widespread in South America from Panama to northern Chile, Argentine and
Paraguay.
A miniature pipit. Above, dark brown, heavily streaked on head, mantle, rump
and tail coverts : below, pale lemon yellow, with brown indistinct spotting confined
to the upper breast. Hind claw long and rather straight. The first four primaries
sub-equal with the fifth 4-6 mm. shorter: the second to fourth emarginated. The
tail pattern clear white, with the pattern extending in a long narrow streak up the
shaft on the second outermost rectrix. Measurements of 18 gj 19 9: wing 3 60-70,
2 59-69: bill f 9 13-15: tail g 2 39-46: hind claw ¢ 9 9-15: tarsus J 9 19-21.
Zimmer recognizes four races on slight differences of colour, A. 7. parvus from
Panama, A. /. abariensis from the north of South America, A. /. peruvianus, from
Peru and northern Chile, and A. /. lutescens from central South America.
It is tempting to associate A. dutescens with the miniature pipits of Africa, in
particular with the dark A. brachyurus, but, in fact, the two species have little in
common except their small size and dark appearance.
Anthus chacoensis
Confined to Argentine and Paraguay.
Similar to A. Jutescens, except that the streaking above and below is more clearly
defined and extends to the sides of the lower breast and flanks: the underparts
are whiter : the hind claw is short (7-8 mm.) : the pattern on the second outermost
rectrix is restricted to a small spot at the tip. Measurements of I 9: wing 65:
bill 13: tail 44: hind claw 8: tarsus 20.
Anthus correndera
Found throughout central and southern South America from Peru and southern
Brazil to Tierra del Fuego, and in the Falkland Islands.
A medium sized, heavily streaked pipit. Above, light brown, heavily streaked
on head, mantle, rump and tail coverts with dark brown, and with a few white
streaks in the mantle, similar to those in A. cervinus : below, white, heavily marked
on the whole breast and flanks with large spots or broad dark brown streaks. The
THE TAXONOMY AND IDENTIFICATION OF PIPITS 285
hind claw long, straight and weak. The first four primaries longest and sub-equal
with the fifth about 2-5 mm. shorter: the second to fourth emarginated. The tail
pattern is clear white, with the pattern on the second outermost rectrix varying from
a long narrow streak up the shaft to a small streak at the tip. Measurements of
37 36 17 2 from South America: wing ¢ 72-80, 9 71-78: bill 9 2 14-17: tail g
48-57, 2 47-52: hind claw g 2 10-20: tarsus g 9 21-24. Measurements of 8 3
from the Falkland Islands, A. c. grayi: wing 80-84: bill 15-16: tail 54-57: hind
claw 14-20: tarsus 22-23.
Apart from the larger A. c. grayi of the Falkland Is. Zimmer recognizes four
races: A. c. chilensis of Chile and Tierra del Fuego ; A. c. correndera from southern
Argentine, Uruguay and southern Brazil; A. c. catamarcae from northern Argen-
tine: and A. c. calcarvatus from Peru. The differences are not very well marked.
The superficial resemblance in colour and pattern between some specimens of
A. correndera and the Palaearctic A. gustavi is remarkable, but nevertheless I do not
think the two species are closely related as there is a significant difference in the
juvenile plumage as well as some differences in the hind claw, wing formula and tail
pattern. In A. gustavi the juvenile plumage is similar in most respects to that
of the adult, whereas in A. corvendera the juvenile has white edges to the mantle
feathers, giving a scalloped effect and a less brown, more black-and-white, appearance
than the adult.
The length of the hind claw and the tail pattern suggest that A. correndera may be
the American representative of A. novaeseelandiae though it has more streaking both
above and below.
Anthus antarcticus
Confined to South Georgia.
A large pipit, with extensive streaking below. Above, brown, heavily streaked
on head, mantle, rump and tail coverts with dark brown, and some whitish streaks.
Below, white washed with pale buff, heavily streaked on breast and flanks, with some
light streaking on throat and abdomen, heavier in young birds. The hind claw
long, and very heavy and straight. The wing blunt, the first four primaries sub-
equal with the fifth only 2-3 mm. shorter : the second to fourth emarginated and the
fifth slightly so. The tail pattern dusky white with little or no pattern on the inner
web of the second outermost rectrix. Measurements of 3 adults: wing 81-84:
bill 16-19: tail 58-62: hind claw 13-17: tarsus 25-26.
A. antarcticus appears to be the representative in South Georgia of A. correndera,
but has diverged sufficiently to be regarded as a distinct species.
Anthus nattereri
Confined to south-eastern Brazil and Paraguay.
A medium sized, richly coloured pipit. Above, rich tawny brown, heavily streaked
on head and mantle, and lightly streaked on the rump and tail coverts, with dark
brown: below, throat white, washed with yellow, breast and flanks washed with
rich orange buff and lightly streaked with brown, abdomen white. Hind claw long,
weak and straight. Wing blunt, the first four primaries sub-equal, the fifth 4 mm.
shorter: the second to fifth emarginated. Rectrices narrow and pointed, with the
286 THE TAXONOMY AND IDENTIFICATION OF PIPITS
tail pattern dusky with a long narrow streak up the shaft on the second outermost
rectrix and a small spot on the tip of the third. Measurements of type only (un-
sexed) : wing 76: bill 14: tail 57: hind claw 16: tarsus 25.
Anthus hellmayri
Confined to central and southern South America from Peru to the Argentine and
south-eastern Brazil.
A medium sized pipit, heavily streaked above, but lightly streaked below. Above,
light or rich brown heavily streaked on head, mantle and rump with dark brown :
below, pinkish buff, with narrow sparse streaks on the upper breast and flanks.
Hind claw medium to long, rather strong and usually rather curved. The wing
blunt, the first four primaries sub-equal, the fifth 1-2 mm. shorter: the second to
fifth emarginated. Rectrices rather pointed with the pattern dusky white or white
(A. h. dabbenet), and varying on the second outermost rectrix from a small spot or
streak near the tip (A. h. hellmayrt) to a narrow streak up the shaft in some specimens
of A. h. dabbenei and A. h. brasilianus. Measurements of 7 specimens : wing 71-80 :
bill 14-15: tail 46-57: hind claw 10-13: tarsus 22-24.
Zimmer recognizes three well-marked races ; hellmayri from the north-west ; the
paler dabbenei from western Argentine and the Chile border, which migrates north-
wards in winter ; and the richer coloured brasilianus from the east.
There are few records of A. h. hellmayri from Peru, and it therefore seems worth
noting that there is a specimen in the British Museum collected at Capachica, Lake
Titicaca, on 5th June 1937 by P. F. Holmes.
Anthus bogotensis
Confined to western South America from western Venezuela to north-western
Argentine.
A medium sized pipit, heavily streaked above. Above, rich or light brown
very heavily streaked on head, mantle, rump and tail coverts : below, light or
orange buff, sparsely spotted on the upper breast and very sparsely streaked on the
flanks. Hind claw medium to long, rather strong, and usually rather curved. The
wing blunt, the first five primaries almost equal: the second to fifth emarginated.
The tail pattern dusky usually restricted to a small spot or streak on the second
outermost rectrix, but occasionally a narrow streak up the shaft. Measurements
of Ir 9 15 2: wing ¢g 80-86, 2 76-83: bill gd 9 i5-17: tail J 50-55, 2 49-55: hind
claw § 9 9-17: tarsus 3 2 23-25.
Zimmer recognizes four races on small differences of colour, pattern and size ;
A. b. meridae from western Venezuela ; A. b. bogotensis from Colombia and Ecuador ;
A. b. immaculatus from Peru ; and A. b. shiptoni from Bolivia and Argentine.
ACKNOWLEDGMENTS
Many friends have earned my gratitude for their help in the preparation of this
paper but they cannot all be named. I must, however, mention particularly my
indebtedness to Mr. C. M. N. White for his advice on African pipits, to Dr. Charles
THE TAXONOMY AND IDENTIFICATION OF PIPITS 287
Vaurie for his help on Palaearctic species and the loan of specimens from the American
Museum of Natural History, to Col. R. Meinertzhagen for giving me access to his
collection, to Mr. Kenneth Williamson and Mr. Robert Spencer of the British Trust
for Ornithology for advice on some British pipits, and to Cdr. A. M. Hughes for
his drawings of tail feathers, wings and claws.
Other specimens have been borrowed from the Academy of Natural Sciences,
Philadelphia, the Chicago Natural History Museum, the Musée du Congo Belge,
Tervuren, the Peabody Museum, Yale University, the Royal Scottish Museum,
Edinburgh, and the Zoologishes Museum, Berlin. For these I am most grateful
to the Directors of the institutes concerned.
SUMMARY
Five diagnostic characters have been selected to aid in the specific recognition of
pipits : colour and pattern, size, the conformation of the hind claw, the tail pattern,
and the wing formula.
Variation in these characters is discussed with reference as well to some peculiarities
in moults of pipits.
The difficulties of subspecific definition and recognition are discussed in relation to
migration, ecological variation and clinal variation.
The pipits of the world are divided into three groups under which their characters,
ranges, geographical variation and identification are summarized with some notes on
the relationship between certain species. Group A includes old world species which
present difficulty in identification ; these are discussed fully and illustrated in Plates
56-61 ; their measurements are listed for comparison in Tables 2-9. Group B,
includes distinctive Old World and Australasian species, and Group C American
and South Atlantic species : species in these groups are discussed less fully and not
illustrated : the measurements of available specimens is included in the text.
BIBLIOGRAPHY AND REFERENCES
BANNERMAN, D. A. 1914. An ornithological expedition to the eastern Canary Islands, Pts.
Iand 2. Ibis (10), 2: 38-90, 228-293. (A. berthelotii.)
Benson, C. W., Irwin, M. P. Stuart & WuiTE, C.M.N. 1959. Some aspects of speciation in
the birds of Rhodesia and Nyasaland. Proc. First Pan-Afr. Orn. Congr., Ostrich suppl.
3: 397-414. (A. vaalensis and A. leucophrys.)
Brooks, W. E. 1873. Notes on some of the Indian pipits. Stray Feathers, 1 : 358-360.
(A. novaesaelandiae and A. godlewskii.)
Cuarin, J.P. 1937. The pipits of the Belgian Congo. Rev. Zool. et Bot. Afr. 29, 3 : 336-345.
Crancey, P. A. 1954. A revision of the South African races of Richard’s Pipit Anthus
vichardi Vieillot. Durb. Mus. Nov. 4, 9: 101-115.
1959. On the range and validity of Anthus lineiventris stygium Clancey, 1952. Durb.
Mus. Nov. 5, 18 : 247-248.
DEMENTIEV, G. P. & GutapKov, N. A. 1954. Birds of the Soviet Union, 5.
Grant, C. H. B. & MackworTH-PRAED, C. W. 1939. Notes on eastern African birds. Bull.
Br. Orn. Cl. 60 : 24-26. (A. similis.)
288 THE TAXONOMY AND IDENTIFICATION OF PIPITS
Hatt, B. P. 1957. Notes on specific identification in the Tawny Pipit (Anthus campestris),
Blyth’s Pipit (A. godlewskiz), and Richard’s Pipit (A. novaeseelandiae) in Asia. Journ.
Bomb. Nat. Hist. Soc. 54, 3 : 726-731.
—— 1959. The Plain-backed Pipits of Angola. Bull. Br. Orn. C!. 79 : 113-116.
HELiMayr, C. E. 1935. Catalogue of birds of the Americas, 8. Pub. Field Mus. Nat. Hist.
357, 13 : 1-541.
JOHANSEN, H. 1952. Die Vogelfauna Westsibiriens 2. Journ. f. Orn. 92, 1944 : 1-204.
Lack, D. & SouTHERN, H. N. 1949. Birds on Tenerife. Jbis, 91: 607-626. (A. berthelotii.)
Lynes, H. 1934. Contribution to the ornithology of southern Tanganyika Territory. Journ.
f. Oyn, 82, sonderh. : 1-147 (A. brachyurus.)
Mayaup, N. 1952. Le phylum marin d’Anthus spinoletta ses particularités écologiques et
morphologiques. Alauda, 20, 2 : 65-79.
Mayr, E., Linstrey, E. G. & Usincer, R. L. 1953. Methods and Principles of Systematic
Zoology. New York.
MEINERTZHAGEN, R. 1921. Notes on some birds from the Near East and from tropical East
Africa, Ibis (11) 3: 621-671. (A.campestris, A. similis, A. novaeseelandiae, A. leucophrys.)
Patterson, M. L. 1959. Richard’s Pipit, Anthus novaeseelandiae, in Southern Rhodesia.
Proc. First Pan-Afr. Orn. Congr. Ostrich suppl. 3 : 435-439.
Riptey, S. Ditton. 1948. Notes on Indian birds. 1. The races of Anthus hodgsoni. Journ.
Bomb. Nat. Hist. Soc. 47, 4 : 622-626.
SaviLLE, D. B. O. 1957. Adaptive evolution in the avian wing. Evolution 11, 2 : 212-224.
VAURIE, C. 1954. Systematic notes on Palearctic birds. 7. Alaudidae and Motacillidae
(genus Anthus). Amer. Mus. Nov. 1672 : 1-13.
1959. The Birds of the Palearctic Fauna. 1. London.
VaAuRIE, C., WHITE, C. M. N., Mayr, E. & GREENWAY, J. C. 1960. Family Motacillidae.
Check-List of Birds of the World, 9 ; 129-167.
VoLsoE, H. 1951. The breeding birds of the Canary Islands. Vidensk. Medd. fra. Dansk
Naturhist. Foren. Kbh. 113: 1-151. (A. berthelotii.)
WuitE, C. M. N. 1948. The African Plain-backed Pipits
90 : 547-553-
1957. Taxonomic notes on African pipits, with the description of a new race of Anthus
similis. Bull. By. Orn. Cl. 77 : 30-34.
Wiiiamson, K. 1959. Meadow Pipit migration. Bird Migration, 1, 2 : 88-91.
ZIMMER, J. T. 1953. Studies of Peruvian birds. 65. The Jays (Corvidae) and Pipits (Mota-
cillidae). Amer. Mus. Nov. 1649 : 1-27.
a case of sibling species. bis,
APPENDIX
Amendents proposed in this paper to the systematic list of Pipits in Check-List
of Birds of the World, 9, 1960.
Anthus novaeseelandiae ussuriensis. Here recognized as a good race breeding in
eastern Siberia, distinct from A. 7. sinensis of south China.
Anthus novaeseelandiae hoeschi. Here considered as distinct from A. n. bocaget,
and possibly will prove a good race allied to A. n. dwenarum and A. n. editus.
Anthus campestris griseus. Here considered a synonym of A. c. campestris.
Anthus campestris kastschenkot. Here considered a good race breeding between the
Ob and Yenisei rivers, and wintering’in India.
Anthus similis schoutedeni. Here considered a good race from the French Congo and
Angola to the Kasai and Northern Rhodesia, distinct from A. s. nyassae of
Nyasaland and Tanganyika.
THE TAXONOMY AND IDENTIFICATION OF PIPITS 289
Anthus vaalensis saphiroi and A. v. goodsoni. Here considered races of Anthus
leucophrys.
Anthus trivialis sibirica. Here considered a good race breeding in Siberia, distinct
from A. ¢. tvivialis of Europe in series but not in individual specimens.
Anthus hodgsoni berezowskii. Here considered a synonym of A. h. hodgsoni.
Anthus spinoletta meinertzhageni. Here considered a part of a cline between A. s.
petrosus and A. s. kleinschmidti, but closer to the latter, and therefore best listed
as a synonym of A. s. kleinschmidti.
Anthus spinoletta blakistoni. Here considered a good race breeding in Central Asia,
distinct from A. s. coutelli from the Caucasus.
Anthus spinoletta harmsi. Here considered as possibly indeterminate but best placed
as a synonym of A. s. japonicus and not of A. s. rubescens.
Anthus spragueii. Here considered possibly as a race of A. furcatus.
Anthus syluanus. The original author and reference should be :-—
Heterura syluana Hodgson, 1845, Proc. Zool. Soc. Lond. p- 33: Nepal. not
Heterura sylvana Blyth, 1845, Journ. Asiat. Soc. Bengal, 14, p. 556: Nepal.
Hodgson’s description was published in August 1845 (see P.Z.S. 1893 : 438).
Blyth’s paper, in which he quotes Hodgson’s description, must have been published
after August, since it is in the same part (number 164) of the J.A.S.B. as a paper
dated 2gth August 1845 (p. 602). This gives priority, as is fitting, to Hodgson’s
description.
12 Ara teat
PRESENTED
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
PLATE 56
SOME ASIATIC PIPITS
Gs
Richard’s Pipit
Anthus novaeseelandiae richardt.
Anthus novaeseelandiae waiter.
Anthus novaeseelandiae malayensis.
Tawny Pipit
Anthus campestris campestris.
Anthus campestris kastschenkot (young)
Blyth’s Pipit
Anthus godlewskii.
Long-billed Pipit
Anthus similis similis.
Anthus similis jerdoni.
Bull. B.M. (N.H.) Z00). 7, 5.
PLATE 56
ZOOL. 7, 5.
lic.
Tic.
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
Fic.
ie)
6.
I
10.
Pa AME By i577;
SOME AFRICAN PIPITS
Richard's Pipit
Anthus novaeseelandiae cinnamomeus (dark).
Anthus novaeseelandiae cinnamomeus (normal).
Anthus novaeseelandiae bocaget.
Anthus novaeseelandiae lwenarum.
Long-billed Pipit
Anthus similis schoutedent.
Anthus similis nicholsont.
Anthus similis jebelmarrae.
Plain-backed Pipits
Anthus leucophrys leucophrys.
Anthus vaalensis vaalensis.
Anthus pallidiventris pallidiventris.
Bull. B.M. (N.H.) Zool. 7, 5.
ZOOL. 7, 5.
SOME
EIG. as
ice 2:
RIG. 93:
lees 7
BIG. 5.
ImiteR Toy.
Fie. 7.
Bresee:
BIG, 10)
Fic, 10.
Fic. 22.
Fic, 12
PLATE 58
PALE ARG TUG WLP irs
Meadow Pipit
Anthus pratensis pratensis.
Anthus pratensis theresae.
Tree Pipit
Anthus trivialis trivialis.
Anthus trivialis haringtoni.
Indian Tree Pipit
Anthus hodgsoni hodgsoni.
Anthus hodgsonit yunnanensis.
Hodgson’s Pipit
Anthus voseatus (autumn).
Anthus roseatus (spring).
Red-throated Pipit
Anthus cervinus (spring 3).
Anthus cervinus (autumn ®).
Pechora Pipit
Anthus gustavi gustavt.
Anthus gustavi menzbiert.
Bull. B.M. (N.H.) Zool. 7, 5.
PLATE
55
PAIS SEG)
SOME ROCK AND WATER PIPITS
Water Pipits
Tlic. 1. Anthus spinoletta spinoletta (autumn).
"ic.
Anthus spinoletta spinoletta (spring).
Fic. 3. Anthus spinoletta blakistoni (autumn).
Fic. 4. Anthus spinoletta blakistont (spring).
Fic. 5. Anthis spinoletta japonicus (autumn).
Fic. 6. Anthus spinoletta japonicus (spring).
Rock Pipits
Fic. Anthus spinoletta petrosus (autumn).
“I
Fic. 8. Anthus spinoletta petrosus (spring).
Fic. 9. Anthus spinoletta littoralis (spring).
Bull. BAL. (N.H.) Zool. 7, 5
AL Na ta
5
PP Ade bio
Second outermost rectrices, wing tips and hind claws of Richard’s Pipit (4. novaeseelandiae),
the Tawny Pipit (A. campestris), Blyth’s Pipit (4. godlewski1), the Long-tailed Pipit (4. similis),
and the Plain-backed Pipits (A. vaalensis, A. leucophrys and A. pallidiventris).
Bull. B.M. (N.H.) Zool. 7, 5.
S Africa only - chiefly
Common Rare Iwenarum , editus ,hoeschi
novaeseelandiae
campestris
:
Wi ff
7
Rare except Common Africa only
in travancoriensis chiefly schoutedeni
Baslensie Ipgeoeuny & Gade dies
(v) LE
South Africa Se central attend
All species — (L) only
REA TAS
leucophrys
>see,
60
PAE on
Second outermost rectrices, wing tips and hind claws of the Meadow Pipit (A. pratensis),
the Tree Pipit (4. ¢vivialis), the Indian Tree Pipit (A. hodgsoni), Hodgson’s Pipit (A. roseatus),
the Red-throated Pipit (4. cervinus), the Pechora Pipit (A. gustavi), and the Rock and Water
Pipits (4. sprnoletta)
Bull. B.M. (N.H.) Zool. 7, 5. IPE NAD ID, Coys
trivialis
22... haringtoni
frivialis.
hodgsoni
{ Ny
\
hodgsoni (Japan)
Rare hasegoni (India) eres
cervinus
<— All races a Japonicus & Rock
<~—— _ Water Pipits eeLaMesicn only Pipits
- FREE-LIVING NEMATODES FROM
| SOUTH AFRICA
WILLIAM G. INGLIS
AND
P SEAWEED ON BRITISH BEACHES
WILLIAM G. INGLIS and JOHN W. COLES
acl
Es ES S3{ bate %
a BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
GY Vol. 7 No. 6
LONDON : 1961
FREE-LIVING NEMATODES FROM SOUTH
AFRICA
BY
WILLIAM G. INGLIS
Pp. 291-319 ; 37 Text-figures
AND
THE SPECIES OF RHABDITIS (NEMATODA)
FOUND IN ROTTING SEAWEED
ON BRITISH BEACHES
an
BY
WILLIAM G. INGLIS and JOHN W. COLES
Ph. 320-333 ; 4 Text-figures
= S MAY 196?
ORE SEATS: War wisi”
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 6
LONDON : 1961
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, 1s
issued in five series corresponding to the Departments
of the Museum, and an Historical Series.
Parts will appear at irregular intervals as they become
ready. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No. 6 of the Zoological series.
© Trustees of the British Museum, 1961
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM
Issued April, 1961 Price Fourteen Shillings
FREE-LIVING NEMATODES FROM SOUTH
AFRICA
By WILLIAM G. INGLIS
SYNOPSIS
Five new species of free-living nematodes are described from the mouth of the Greater
Kleinemonde River, Cape Province, South Africa. They are named: Trissonchulus janetae,
Mesonchium nini, Hypodontolaimus angelae, Polygastrophora omercooperi and Sphaerolaimus
antevides. Tvissonchulus Cobb, 1920 is accepted as a valid genus with six species: T. oceanus
Cobb, 1920 (type species) ; T. obtusus (Bresslau and Schuurmans Stekhoven, 1935) comb. nov. ;
T. nudus (Schuurmans Stekhoven, 1943) comb. nov.; T. reversus Chitwood, 1951; T. latus
(Wieser, 1953) comb. nov.; T. janetae sp. nov. Wieser’s (1954b) treatment of Pepsonema
Cobb, 1920 as a synonym of Mesonchium Cobb, 1920, is accepted but his treatment of Spilophora
canadensis Cobb, 1914, as a synonym of Hypodontolaimus geophila (de Man, 1876) is not.
S. canadensis is considered a species inquirendum. Bolbella cylindvicauda Allgén, 1959 is shown
to be a species of Polygastvophora and is treated as a synonym of P. hexabulba (Filipjev, 1918).
PROFESSOR J. OMER-COOPER made a small collection of free-living nematodes at the
mouth of the Greater Kleinemonde River in the Bathurst District of Cape Province,
Union of South Africa. Fuller details of this locality have been given by Omer-Cooper
(19574 ; 19576) but it may be noted here that the mouth of the river is closed by a
sandbar for much of each year and, sometimes, continuously for more than one year.
Behind the bar a lagoon is formed the salinity of which “ ... is normally between
23°3 and 34:0 per mille, but it has reached 41-2 per mille during along drought ... ”’
(Omer-Cooper, 19574). The nematodes were collected by sieving mud and, as their
collection was not the primary object of the survey, the majority of the specimens
are large. Nevertheless seven species (and genera) are represented, but two are
insufficiently preserved to warrant a full study. They could be identified to genera
but are not listed as the literature already contains too many references to genera
only. Further the genera are cosmopolitan and frequent in occurrence so that it is
not surprising that species referable to them should occur in South Africa and as the
species are almost certainly common they will be found again. The remaining five
species, all previously unknown, are described here as new, and are all referable to
existing genera.
The five species are :
Trissonchulus janetae sp. nov. (p. 294).
Mesonchium nini sp. nov. (pp. 301).
Hypodontolaimus angelae sp. nov. (pp. 305).
Polygastrophora omercooperi sp. nov. (pp. 309).
Sphaerolaimus anterides sp. nov. (pp. 313).
ZOOL. 7, 6. 22§
204 FREE-LIVING NEMATODES FROM SOUTH AFRICA
These species, although taken in brackish water, belong to genera which are other-
wise known only from wholly marine localities. This does not indicate anything of
importance since it is already fairly well established that characteristically marine
nematodes can occur in brackish water, such habitats usually having a mixture of
marine and fresh-water forms. That all five species are marine forms is not surprising
since they were collected by sieving mud and under such circumstances one would
expect only the larger forms to be gathered. The number of specimens in the collection
and their sizes support this. Since the marine species are generally larger than fresh-
water or soil forms their sole presence in the samples from Kleinemonde is a reflection
of the collecting method used rather than of the fauna present. No conclusions of a
zoo-geographical nature may be drawn since, as the present collection well demon-
strates, free-living marine nematodes are insufficiently known on a world basis to make
such an exercise either interesting or profitable (see also Chitwood (1951) who makes
the same point).
Trissonchulus janetae sp. nov.
Material Studied
60+ g¢; 60+ 9; 30+ larvae. B.M. (NH.), Reg. Nos. 1960.123-272. I g
selected as Holotype, 1960. 123.
Proportions and Measurements (mm.)
a b c Vv Body length
6g (- : 39°9 4°9 32°3 = 305
39°6 4°9 28°7 = 3°84
39°2 5:2 31-0 — 3°88
43°4 Hy 3rsr = 4°08
47°1 5°9 34°2 = 4°10
48-2 5.8 31-7 a 4°53
48°7 6-0 32-0 — 4°58
22s . 39°7 53 34°2 54°4 4°10
39°8 5°4 S05 56°1 4°10
36°6 5-3 3-5 Ait) 4°13
41°7 Hon 2:6 57°0 4°30
45°90 57 31°6 56-0 4°68
41-0 5°8 30°7 53°8 4°72
45°3 6°r 29°3 55°2 4°98
Larvae . 36-2 4:0 23°60 — 2°10
43°3 4°6 28-6 = 3°38
42°7 Bos} 29°1 = 3°54
Males (all measurements in the order of the body lengths) : Oesophagus length :
0°72 ; 0°78; 0:74; 0-71; 0:69; 0:78; 0-76. Pharyngeal-rod length : 0-092 ; 0-094 ;
0-097; 0:087; 0:098; 0-089; 0-087, Head diameter (level at anterior edge of
amphid) : 0:033; 0:034; 0:032; 0*034; 0:032; 0:033; 0-036. Amphid width
(head diameter /amphid width) : 0-090 (3-7) ; 0-090 (3:8) ; 0-010 (3:2) ; 0-00 (3-4) ;
FREE-LIVING NEMATODES FROM SOUTH AFRICA 295
0-009 (3:6); 0-010 (3:3); 0-009 (4:0). Amphid length: 0-010; 0-010; 0-010;
0-009 ; 0-010 ; 0-010; 0-011. Amphid from anterior end (=depth of cephalic cap) :
0:021; 0-019; 0-018; 0-019; 0-012 (teeth strongly retracted); 0-020; 0-022.
Excretory pore from anterior end: 0:024; ... ; 0:023; ... ; 0-021; :
0-029. Nerve ring from anterior end: 0:25 ; 0:23; 0:26; 0:28; 0:23; 0:31; 0:38.
Tail length (tail length/anal diameter): o-II0 (1-6); 0-133 (I-9); 0°I25 (I:7) ;
O-I3I (1-7) ; 0:120 (2:0) ; 0-143 (2:0) ; 0-143 (1-9). Spicule length: 0-093; 0-096;
0-097 ; 0-104; 0-097; 0-098; 0-099. Gubernaculum length : 0-047 ; 0-055 ; 0-055 ;
0-062 ; 0:056; 0-058 ; 0-060.
Females: Oecesophagus length: 0-78; 0:76; 0:78; 0:84; 0-82; 0-81; 0-82.
Pharyngeal rod length: o-091; 0:082; 0-097; 0:086; 0-087; 0:085; 0-097.
Head diameter (level at anterior edge of amphid): 0-031; 0:034; 0:030; 0-036;
0:034 ; 0:035; 0:034. Amphid width (head diameter/amphid width) : 0-009 (3-4) ;
0-010 (34); 0-009 (2:2); ... ( ... ); 0-0I0 (3:4); 0-009 (3:9); 0-0r0 (2:4).
Amphid length : 0-010; 0-011; 0-009; ... };0:010; 0-009; o-o1r. Amphid from
anterior end (= depth of cephalic cap): 0-019; 0-015; 0:018; 0-019; 0-022;
0-023; 0-017. Nerve ring from anterior end: 0:25; 0:36; ... ; ... }j 0°27;
0:29; 0:32. Excretory pore from anterior end: 0-020; ... ; ... 3 ... 3
0-021 ; 0-022; 0-022. Tail length (tail length/anal diameter) : 0-120 (1-7) ; 0-130
(I-9) ; 0-13 (I-9) ; 0:132 (1-8) ; 0-148 (2-1) ; 0°154 (1-9) ; 0-170 (2:2). Vulva from
anterior end: 2°2; 2:3; 2°3; 2:5; 2:6; 2:5; 2:8.
Larvae ; Oesophagus length: 0-52; 0:74; 0-67. Pharyngeal-rod length : 0-060 ;
0:074; 0-081. Head diameter (level at anterior edge of amphid) ; 0-033; 0-031 ;
0-044. Amphid width (head diameter/amphid width) ; 0-077 (4:7); 0-070 (4:4) ;
0-080 (5:6). Amphid length: 0-009; 0-009; 0-009. Amphid from anterior end
(= depth of cephalic cap): 0-014; 0-016; 0-017. Nerve ring from anterior end:
0-19; 0:25; 0-27. Excretory pore from anterior end: ... ; 0-024; 0-027. Tail
length (tail length /anal diameter) : 0-089 (2:0) ; 0-118 (2:1) : 0-122 (2:0). Secondary
teeth from anterior end: 0-019 ; 0:023; 0-016.
Cuticle
The cuticle is smooth without markings.
Head and Oesophagus
The head bears an inner circle of six small, sessile papillae and an outer circle of
ten prominent papillae of which four are markedly larger than the others (Text-figs.
2 and 4). Laterally, between the lateral papillae of the inner and outer circles, is
another structure, pore-like in appearance, which appears to correspond with the
cephalic slits found in the Enoploidea. Such slits do not appear to have been reported
from this genus before. The mouth opening is closed by three rather thin lip-flaps.
The anterior end of the oesophagus bears a pair of smallish, wholly cuticular teeth
dorsally and a single, larger, comparable tooth on each ventro-lateral sector (Text-
figs. 1, 3 and 5). The anterior edges of the lumen of the oesophagus bear a row of
small denticles exactly the same in appearance and distribution as the denticles
FREE-LIVING NEMATODES FROM SOUTH AFRICA 297
found within the mouth of species of the genus Enoplus. When the mouth is open the
teeth are pulled anteriorly so that they project through the mouth opening and the
lip-lobes are folded back over the head (Text-figs. 1, 2 and 3, 1.f.). When the mouth is
closed the two ventro-lateral teeth come together to lie between the two-dorsal
teeth (Text-fig. 4). The amphids are pouch-like and their anterior edges lie exactly
on the posterior edge of the cephalic cap.
The oesophagus expands evenly along its length so that there is no definite
posterior swelling or bulb. Anteriorly it is modified as a distinct pharynx lined by
very distinct cuticular rods, here called pharyngeal-rods. The posterior ends of the
pharyngeal-rods are very distinct and blunt (Text fig. 8). The musculature surrounding
the rods is directed antero-radially rather than wholly radially as it is in the remainder
of the oesophagus. The pharyngeal region is not markedly stouter than the rest of
the oesophagus in most specimens but it does swell out in some. It is probable that
the swollen condition is the more natural since the specimens appear to have been
stretched during fixation. The extreme anterior end of the pharynx, from about the
level of the amphids, is capped by cuticle (= pharyngeal capsule) and is fused to
the body-wall dorsally and ventro-laterally (i.e. at three points). A definite, although
indistinct, cephalic capsule is present which coincides posteriorly with the anterior
limits of the amphids but I have been unable to determine the anterior limits i.e.
there is no definite stomodaeal ring (terminology of Wieser, 1954a). Because of this
fusion of the pharynx with the body cuticle the pharynx is triangular in cross
section (Text-figs. 2 and 4).
In the larvae there is, in all the specimens studied (about twenty), a second set of
teeth lying about the level of the amphids (Text fig. 6). These teeth are identical in
structure and number with those found anteriorly. The dorsal are about 0-005 mm.
long while the ventro-lateral are about 0-008 mm. long. In one specimen which
appeared to be otherwise fully adult, with fully developed spicules, gubernaculum
and reproductive system (body length 4-08 mm.) such a second set of teeth was
present, 0-021 mm. from the anterior end. This I have interpreted as an abnormality
and have included the measurements of the specimen under the males.
Tail
The tail is relatively very short (c = 28-7 — 34:2 in the adults), and ends bluntly
posteriorly, particularly in the adults as there is a tendency for it to be more rounded
in the larvae and smaller adults. The spinerette opens dorsally (Text-figs. 11 and 13)
Fies. 1-6. Trissonchulus janetae sp. nov., the structure of the head. Fig. 1. Lateral
view of adult head with the dorsal side towards the right. The mouth is open and the
lip-flaps are folded back over the anterior end of the body. Fig. 2. En face view of adult
head with mouth open and lip-flaps folded back. Fig. 3. Head, as Fig. 1, from the
ventral aspect. Fig. 4. En face view of larval head. The mouth is closed, note the
telationships between the dorsal and ventro-lateral teeth. Fig. 5. Head, as Figs. 1
and 3, from the dorsal aspect. Fig. 6. Larval head from the lateral aspect with dorsal
side to the right. Note secondary teeth. (All figures to the same scale.) (lf.
= lip-flaps.)
ZOOL. 7, 6. 228§
298 FREE-LIVING NEMATODES FROM SOUTH AFRICA
FREE-LIVING NEMATODES FROM SOUTH AFRICA 299
and there are several sessile papillae scattered over the surface in both males and
females, but there are no setae.
Male
The spicules are short, equal in length, stout and complicated, with blunt posterior
tips. They show a distinct central bar of thickening from which alae appear to arise
when they are viewed from the ventral aspect (Text-fig. 7). The gubernaculum is
relatively short and is indistinct anteriorly. Posteriorly it is thick and is developed
into two claw-like structures which enfold the spicules and also appear to support the
posterior edge of the cloacal opening (Text-figs. 7 and g). There are no special caudal
papillae or pre-cloacal supplements but there is a series of muscle bands running
from the dorso-lateral part of the body ventrally and posteriorly. These bands occur
over a region equal in length to about one third of the length of the body.
There are two opposed testes of which the anterior is slightly longer than the
posterior. They lead into a pair of long narrow seminal vesicles from the junction of
which a very thick-walled vas deferens runs posteriorly to the cloaca (Text-fig. rz).
The seminal vesicles contain flagellate sperm (see Chitwood & Chitwood, 1951,
p- 156 and fig. 125m).
Female
The reproductive apparatus, which consists of two opposed uteri with associated
reflexed ovaries, is relatively short in proportion to the length of the body. Thus,
from four specimens the following lengths, in mm., of the entire length of the repro-
ductive tract were obtained: length of reproductive tract: body length (body
length/length reproductive tract): 1-2: 4°7 (3:9); 1:8:4:-7 (2:6); 1-2: 4-1 (3-4);
I-4 : 4-3 (3:1). The ovaries lead into relatively long narrow oviducts which are modi-
fied, just before they join the uteri, as seminal receptacles which generally contain
sperm. The eggs are very large, 0-29 mm. x 0:087 mm.; 0:22 mm. X 0-094 mm.;
0-26 mm. X 0-093 mm., and although two eggs have been seen in some specimens
there is generally only one present. It appears that the ovaries generally produce an
egg alternately since it has been noted that the last cell in the ovarian part of the
reproductive tract is generally much larger in the ovary opposite to that in which the
egg is present in the uterus (Text-figs. Io and 12). The eggs themselves appear to
have a line round them about the mid-point of their lengths although this has not
been seen in all the specimens. Its status is not clear since in all cases where such
a line was present only one nucleus could be found so that it does not appear to
represent the first division of the egg but may rather represent a modification of the
egg shell or simply be due to fixation.
Fics. 7-12. Tvrissonchulus janetae sp. nov. Fig. 7. Ventral view of spicules and
gubernaculum. Fig. 8. Lateral view of anterior end of body showing structure of
pharyngeal part of the oesophagus. Fig. 9. As Fig. 7, from the lateralaspect. Fig. ro.
Female reproductive apparatus. Note flagellate sperm in oviducts. Fig. 11. Whole
male. Fig. 12. Female reproductive apparatus. (Figs. 7 and 9; ro and 12 to the
same scale.)
300 FREE-LIVING NEMATODES FROM SOUTH AFRICA
Discussion
Schuurmans Stekhoven (1950) argues that Tvissonchulus Cobb, 1920 should not be
considered distinct from Dolicholaimus de Man, 1888, and Wieser (19530) accepts this,
since he could not see any difference between the two genera except the shape of the
tail, which is long and narrow in Dolicholaimus and short, wide and blunt in Tvis-
sonchulus. Gerlach (1954) apparently accepts this since he does not include Tvisson-
chulus in his key to the marine genera of the Ironidae. However, there does appear
to be a further difference between the species with long tails and those with short.
There is only a single dorsal tooth in those with long tails while some, at least, of
the short tailed species are known to have two teeth dorsally. Five short tailed species
have been described: T. oceanus Cobb, 1920 (type species of the genus) which was
described as having three teeth ; D. obtusa Bresslau and Schuurmans Stekhoven,
1935 (in Schuurmans Stekhoven, 1935) described as having two teeth dorsally and
two ventrally (Chitwood (in Chitwood & Chitwood, 1950) states that this species has
three double equal odontia but gives no figure and has probably misunderstood the
original description) ; D. nudus Schuurmans Stekhoven, 1943 has been described as
having “‘ three spears with biuncinate apex ’’ (Schuurmans Stekhoven, 1950) but the
figures do not support this interpretation and suggest that two teeth are present on
the dorsal side of the head only; D. Jatus Wieser, 19530, in which the written
description is very short, suffers because of Wieser’s declared policy that ‘* No organs
will be described morphologically in the text if their structure can be inferred from
the figure.’’ (Wieser, 19530, p. 8). Unfortunately Wieser only mentions three teeth
and gives a figure which is on such a small scale that it is impossible to obtain any
information about the structure or arrangement of the teeth. Finally Chitwood
(951) described T. veversus from a single juvenile, the teeth are not mentioned and
the figure of the head does not allow the number of teeth to be established (see also
Chitwood and Timm (1954) where Chitwood’s 1951 figures are reproduced). In spite
of this uncertainty about the number and arrangement of the teeth in the various
short tailed species I think that the genus Trissonchulus should be recognized for
the species with short, stout, blunt tails since I suspect that adequate morphological
studies will demonstrate the presence of two dorsal teeth in them all. Even if this
should not be so the difference between the tail shapes in the two groups certainly
warrants generic separation. The genus Tvissonchulus may be diagnosed thus :
Trissonchulus Cobb, 1920
Ironidae : sense organs of head papilliform ; mouth opening bounded by three
lip-flaps ; two small teeth, identical in structure present on anterior end of dorsal
sector of pharynx (?) ; one large tooth on each ventro-lateral sector (?) ; tail short,
stout and blunt.
Type species : Tvissonchulus oceanus Cobb, 1920.
Other Species: J. obtusus (Bresslau and Schuurmans Stekhoven in Schuurmans
Stekhoven, 1935) comb. nov.; 7. nudus (Schuurmans Stekhoven, 1943) comb. nov.;
T. veversus Chitwood, 1951; T. latus (Wieser, 1953) comb. nov.; T. janetae sp. nov.
T. janetae is easily distinguished from all the other species of the genus Tisson-
FREE-LIVING NEMATODES FROM SOUTH AFRICA 301
chulus, except T. reversus; by the dorsal opening of the spinerette. Chitwood
reports the same condition in T. reversus together with a figure of the tail and a
figure of the anterior end of the body. The written description, which was based on
one juvenile specimen, is otherwise restricted to the body length (r:16 mm.), the ratios
a (29), b (3-2), c (16) and the length of the stoma (0-040 mm.) (= length of pharyngeal
rods ?). Although this description leaves much to be desired the value for “a’’ is
much lower than the values obtained for T. janetae larvae even when the differences
a b iS d
|
0-1 mm.
Fic. 13. Outlines of the tails of various specimens: a and }, adult females, c, adult male
and d, larva. (All to same scale.)
between the lengths of the bodies is considered. The differences between the “5”
values are probably not significant but “c’’ does appear to be sufficiently low to be
significant. Nevertheless it is impossible to be sure of the relationship between
T. janetae and T. reversus and I have considered it better to name the specimens from
South Africa as new until the developmental stages of both nominal species are
known.
Mesonchium nini sp. nov.
Material Studied
Ig,29B.M. (N.H.), Reg. Nos. 1960.297-299. J selected as Holotype. The speci-
mens are in a rather poor condition.
Proportions and Measurements (mm.).
a b c Vv Body length
3 5 36-4 A 9°5 6 13°9 : — 2 1°93
Oe. 0 34°2 8-5 c III F 43°3 : 1-78
45°2 ; 8-2 ' II-3 ; 48-6 ' 2:08
302 FREE-LIVING NEMATODES FROM SOUTH AFRICA
Male (Holotype) : Oesophagus length: 0-204. Head diameter: 0-o10. Pharynx
depth: 0-021. Distance from anterior end to anterior edge of amphids: 0-006.
Amphid diameter : 0:007. Diameter of head at amphid : 0-013. Diameter of amphid
as percentage of head diameter : 53-8. Nerve ring from anterior end: 0-097. Excre-
tory pore not seen. Tail length (tail length/anal diameter) : 0-139 (3:6). Spicule
length : 0-082. Gubernaculum length (= length posterior apophosis) : 0-036.
Females (in order of body lengths): Oesophagus length: 0-210; 0-253. Head
diameter: 0-012; 0-010. Pharynx depth: 0-020; 0:023. Distance from anterior
end to anterior edge of amphids: 0-004; 0-006. Amphid diameter: 0-008 ; 0-008.
Diameter of head at amphid: 0-015; 0-016. Diameter of amphid as percentage of
head diameter : 53:3 ; 50:0. Nerve ring from anterior end : 0-082 ; 0-089. Excretory
pore not seen. Tail length (tail length/anal diameter) : 0-160 (4:3); 0-184 (4:7).
Vulva from anterior end: 0-77; I-0I.
Cuticle
The surface of the body, dorsally and ventrally is marked by fine striations while
the cuticle is differentiated laterally by a series of dots. This differentiation, from
about the level of the posterior end of the oesophagus to just anterior to the cloacal
opening or anus takes the form of two files* of large, rectangular, spectacularly distinct
dots which lie in a strip of otherwise undifferentiated cuticle. There is, therefore, a
clear space on each side of the files of dots. This clear strip is roughly twice as wide
as the distance between the two files of dots so that the zones flanking the files of dots
are roughly half the distance between two files in width. The clear space is bordered
on both sides by a region, roughly the same width as the clear strip, in which the
cuticle is differentiated by small dots of which one row corresponds with each set
of large rectangular dots and one row corresponds with the space between each
contiguous set of rectangles (Text-fig. 16). The clear space, which is about 0-007 mm.
in width in all the specimens, is delimited from the outer small dots by a distinct line
which may be an artifact. Anteriorly and posteriorly there are four files of smaller,
squarer dots which lie equidistant from each other transversely, are not set off from
the remainder of the cuticular markings by a clear space and are flanked by rather
elongate cuticular markings arranged in rows which correspond one to each row of
the larger lateral markings. The smaller elongate markings continue round the body
so that there are no dorsal and ventral zones in which the cuticle is undifferentiated
as there are on the body opposite the two files of large markings. Four files are
present anteriorly from just posterior to the amphids to about the posterior end of
the oesophagus (Text-fig. 18) and posteriorly from about the anus, or cloaca, almost
to the tip of the tail. The transition from the four files to the two files is remarkably
regular. Anteriorly the four files begin to approach each other in pairs until the
individual elements of the four files fuse to produce the two files of larger rectangles
characteristic of the middle region of the body (Text-fig. 16). At the same time the
nature of the markings external to the files changes from the elongate form, in which
* Files refers to the arrangement of the dots in lines running antero-posteriorly and Rows refers to
lines of dots running transversely on the body.
FREE-LIVING NEMATODES FROM SOUTH AFRICA 303
each row corresponds with each set of lateral markings, to the punctate form in
which there is one row corresponding to each row of larger rectangles and one row
between each row of rectangles. The lines bordering the undifferentiated strip in
which the two files lie correspond exactly with the outer limits of the outer files of the
four file zone. This explains why the large rectangles are separated from each other,
radially, by a distance twice as great as the width of the clear zones which flank
them. Because the four files have fused with perfect symmetry the two files lie
exactly midway between the files of each pair in the four file zone (Text-fig. 16). The
interpretation of the large dots as representing two fused small dots is confirmed by
the presence among the former of many in which only one half is well developed or
in which one half has completely failed to develop. The rate at which the four rows
approach each other in pairs may vary so that in some cases there are three rows
for a short distance. Posteriorly the same change occurs, except that it is reversed,
the two files dividing into four as one passes posteriorly.
There are two files of relatively long setae running down each side of the body, one
file on each side of the lateral differentiation.
Head and Oesophagus
The amphids are spiral and lie relatively far posterior to the anterior end of the
body. Both on one female have three and three quarter spirals (Text-fig. 18), both
on the male have three and a quarter (Text-fig. 17) while on the second female the
left amphid has three and three quarter spirals and the right has three and a quarter.
It should be noted that the difference is restricted to the central part of the spiral.
The amphidial spiral, which is an open groove, leads into a covered pouch from which
the amphidial nerve leaves, so that the innervation of the amphid is posterior.
The mouth opening is bounded by three lip-flaps which are slightly incised centrally
so that they are partly bi-lobed (Text-fig. 14). There are two circles of six small
sessile papillae and more posteriorly there is a set of four long setae, 0-007—0-008 mm.
in length.
The oesophagus is roughly the same width along its whole length except for a
slight even swelling at the posterior end (Text-fig. 15). Anteriorly there are three
teeth of which the two ventro-lateral are stouter than the dorsal and project further
anteriorly (? artifact) (Text-fig. 18). The thickened cuticle which forms these teeth is
continued posteriorly for about 0-020 mm. (see above, pharynx depth) as a lining to
the anterior end of the oesophagus.
Male
The spicules are slightly curved, simple, identical without alae or other elabora-
tions and terminate posteriorly in sharp points. The gubernaculum has a distinct
posterior apophosis and appears to curve round the spicules proximally. The outline
of the part of the gubernaculum which enfolds the spicules is irregular (see Text-fig.
20) and while I am sure that the large mass at the cloacal opening end of the guber-
naculum is accurate the presence of the other two protuberances is less certain. There
are no pre-cloacal supplements and there do not appear to be any special caudal
setae. This is however, most uncertain since many of the setae on the body of the
304 FREE-LIVING NEMATODES FROM SOUTH AFRICA
i
_ Fics. 14-20. Mesonchiumninisp.nov. Fig.14. En face view ofhead. Fig. 15. Whole
body of female. Fig. 16. Lateral differentiation of body about level of posterior end
of oesophagus (semi-diagrammatic). Fig. 17. One form of amphid. Fig. 18. Lateral
view of head, dorsal side to the right, showing another variation of the amphid.
Fig. 19. Lateral view of female tail, arrow indicates point at which lateral differentia-
tion stops. Fig. 20. Structure of the spicules and gubernaculum from the lateral
aspect. (Figs. 14, 17, 18 and 20 to the same scale.)
FREE-LIVING NEMATODES FROM SOUTH AFRICA 305
male specimen appear to have been broken off. Anterior to the cloacal opening are
about 25-26 oblique, dorso-ventral muscle strands.
Female
The female tail is identical in outline with that of the male (Text-fig. 19). There are
two opposed uteri (Text-fig. 15) and the ovaries are not reflexed. The eggs are
0:069 X 0:032 mm. and there are three in each uterus.
Discussion
This species appears to be very similar to Mesonchium poriferum Cobb, 1920, the
type species of Mesonchium, particularly in the structure of the head, the form of the
amphids, the structure of the spicules and gubernaculum and the type of lateral
differentiation. In M. poriferum Cobb (1920) reports the presence of two rows of
lateral gland pores lying outside the lateral differentiation which takes the form of
three rows of round cuticular elements in the female and two in the male. The so
called lateral gland pores may, in fact, have been the bases of lateral rows of setae
which had become broken. Wieser (19540) treats Pebsonema Cobb, 1920 as a synonym
of Mesonchium which appears reasonable. The great similarity between the descrip-
tions of M. poriferum and P. pellucidum is also clear from the characters by which
Chitwood (1951) attempted to separate the two species in his key, M. poriferum :
Ovaries reflexed ; P. pellucidum: ovaries outstretched, in spite of Cobb’s statement
that in the latter species ‘‘ The ovaries may be reflexed for a short distance near their
blind ends.”’ while in the former “‘ An unusual feature is that the ovaries are reflexed
only near their blind ends.’’ P. pellucidum appears to differ from M. poriferum
mainly in the form of the lateral differentiation of the cuticle which is described
as ‘‘ ... of medium thickness. Anteriorly the number of the longitudinal rows of
“beads ’’ appears to be fewer than near the tail, where there are sometimes six or
possibly eight rows.”’
Mesonchium nini can, therefore, be distinguished by the form of the lateral differen-
tiation and possibly by other characters but the descriptions of Cobb’s species are
insufficient to allow this to be established.
Hypodontolaimus angelae sp. nov.
Material Studied
4 & (one badly damaged, no head), 2 9. B.M. (N.H.), Reg. Nos. 1960, 304-309.
I g, 1960, 304 selected as Holotype.
Proportions and Measurements (mm.)
a b c Wi Body length
3d : : 22:6 7°9 5 9:1 $ — r 1-04
25°8 : TB 5 8-2 6 — é 0-98
22°3 6.3 9°9 : — : 1-07
Clore ei 24°7 d Gfaat é 8-1 j 43°6 5 I-O1
(2? 4th larva)
25°9 < 8-1 > 9:2 : 45°4 : I-19
ZOOL, 7, 6. 2288§
306 FREE-LIVING NEMATODES FROM SOUTH AFRICA
Males (measurements in same order as above): Oesophagus length: 0-132 ;
0-134; 0-170. Head diameter: 0-014; 0-013; 0-014. Oesophageal bulb, length :
0°03I ; 0:031; 0:039. Oesophageal bulb, breadth: 0-024; 0-024; 0-023. Nerve
ring from anterior end: 0-079; 0-082; ... Excretory pore: not seen. Tail
length (tail length/anal diameter) : 0-114 (3:9); 0-120 (3-9) ; 0-108 (3-2). Spicule
length, across chord: 0-038 ; 0:037 ; 0:036. Gubernaculum length : 0-030; 0-027 ;
0-028.
Females; Oesophagus length: 0-142; 0-147. Head diameter: 0-014; 0-014.
Oesophageal bulb, length: 0:033; 0-041. Oesophageal bulb, breadth: 0-023 ;
0-026. Nerve ring from anterior end: 0-079; 0-076. Excretory pore: not seen.
Tail length (tail length/anal diameter) : 0-124 (4-7) ; 0-129 (4:6). Vulva from anterior
end: 0°44; 0°54.
Cuticle
The lateral differentiation starts relatively close to the head and between the head
and this point the body is marked by a few rows of circular punctations. Passing
posteriorly the cuticle becomes laterally differentiated, with lateral bars which are
flanked by large circular dots, one on each side. The remainder of the body is covered
by rows of smaller dots (Text-fig. 22, a). The main dots become gradually smaller
posteriorly while those outside them become narrower and elongate in an antero-
posterior direction. From about the level of the posterior end of the oesophagus to
just anterior to the level of the anus or cloacal opening the punctations are restricted
to a strip on either side of the lateral bars, each strip being roughly the same width as
the barred strip (Text-fig. 22, 6) which varies from 0-003-0-004 mm. just posterior to
the head; to 0-004—-0:006 mm. about the middle of the body length and becomes
narrower again about the level of the anus or cloacal opening where it is 0:003—0-004
mm. in width. The lateral fields are distinctly raised above the remainder of the body
surface (Text fig. 21).
There are two files of setae down each side of the body of which the setae are much
closer together anteriorly, where they are 0-:007—0:008 mm. in length (that is they are
longer than the cephalic setae which are 0-006 mm. long), than they are more
posteriorly.
Head and Oesophagus
The head is somewhat contracted in all the specimens and, perhaps because of this,
an inner circle of papillae has not been seen. One circle of six small, sessile papillae
has been seen and there are four long cephalic setae dorso- and ventro-lateral in
position (Text-fig. 21). The amphids are latero-subdorsal in position but they are
difficult to see and their shape is not clear. The mouth opening is surrounded by the
usual twelve ribs which are in two parts, a thick posterior part and an anterior thin
part.
The oesophagus has a distinct posterior bulb (Text-fig. 23) and is slightly swollen
anteriorly, particularly on the dorsal side, by the muscles which supply the oeso-
FREE-LIVING NEMATODES FROM SOUTH AFRICA
397
Fics. 21-28. Hypodontolaimus angelae sp. nov. Fig. 21. En face view of head Fig. 22.
Detail of lateral differentiation. a, Anterior end of body. b. Middle part of body
(semi-diagrammatic). Fig. 23. Lateral view of oesophagus. Fig. 24. Whole male,
note single gonad. Fig. 25. Detail of extreme tip of tail showing shape of spinerette.
Fig. 26. Lateral view of head, dorsal surface to the right. Fig. 27. Male tail from the
lateral aspect. Fig. 28. Details of spicules and gubernaculum from the lateral aspect.
(Figs. 21 and 26; 23 and 27; 25 and 28, to same scale.)
308 FREE-LIVING NEMATODES FROM SOUTH AFRICA
phageal teeth. There is one small, solid (?) tooth developed from each ventro-lateral
sector and a large, hollow S-shaped dorsal tooth (Text-fig. 26). In addition there is a
series of denticles, apparently developed along the anterior edge of the ventral radius
of the oesophageal lumen and also along the more ventral of the edges of the dorso-
lateral radii. Whether such a series is also present along the dorsal edge of the dorso-
lateral radii is not clear but probably it is not since the dorsal tooth appears to be
due to a thickening of the cuticle along the inner edge of the dorsal sector while the
ventro-lateral teeth appear to be due to the thickening of the cuticle at the apex only
of each ventro-lateral sector.
Tail
The tail is relatively long and thin with a very long, narrow spinneret (Text-figs.
25 and 27).
Male
The spicules are fairly strongly curved and are roughly the same width along most
of their length. Anteriorly there is a distinct swelling for the attachment of the
retractor muscles and just posterior to this the spicule narrows rather suddenly. The
posterior ends of the spicules are bluntly rounded. The spicules appear to bear thin
alae running from the tip to the point near the anterior end where the shaft suddenly
narrows but this is uncertain. The gubernaculum is simple (Text-fig. 28). There is
one testis with a distinct seminal vesicle (Text-fig. 24).
Female
There are two opposed uteri but due to the poor condition of the specimens the
arrangement of the ovaries could not be definitely determined although they appear
to be reflexed. The eggs, of which the maximum number seen in one specimen is two,
one in each uterus, are spherical, 0-028 mm. in diameter.
Discussion
Hypodontolaimus angelae appears to be most similar to Hypodontolaimus geophila
(de Man, 1876) in possessing a gubernaculum without an apophysis and in having two
longitudinal rows of large dots separated by bars. The shape of the spicules in
H. angelae is different with the definite constriction near the anterior end, which is
not present in H. geophila, and with bluntly rounded posterior tips, these being
sharply pointed in H. geophila. These differences have been confirmed by comparing
the specimens of H. angelae with some of H. geophila. The position is, however,
complicated by the somewhat unsatisfactory nature of the classification within the
subfamily Chromadorinae, particularly the separation of the genera Hypodontolaimus
and Dichromadora. Wieser (19546) separates them almost wholly on the shape of the
dorsal tooth, S-shaped in Hypodontolaimus and not so shaped in Dichromadora.
Such a character, although clear in a specimen with a large tooth, is not at all clear in
species in which the tooth is small. While I recognize that a character is not invalid
because it is difficult to establish, the published descriptions of the species which
FREE-LIVING NEMATODES FROM SOUTH AFRICA 309
Wieser distributes between these two genera do not convince me that this is a
satisfactory basis for a classification. However I am unable to suggest a better
grouping now but, because of this difficulty, I have also compared H. angelae with the
species referred to Dichromadora. Among them H. angelae appears to be most similar
to D. punctata Schuurmans Stekhoven, 1950. As Wieser (19546) points out the
description given by Schuurmans Stekhoven is poor but H. angelae differs from D.
punctata in the shape and position of the amphids and the shape of the spicules.
Wieser (19540) treats Spilophora canadensis Cobb, T1914 as a synonym of H. geophila
but this I cannot accept. The description given by Cobb is insufficient to determine
either the systematic position or the specific validity of his species and until specimens
from a comparable locality have been studied S. canadensis should be considered a
species inquirendum.
Polygastrophora Omercooperi sp. noy.
Material Studied
15 3 (I without a head) ; 7 2 (x immature) ; 1 4th stage 2 larva. B.M. (N.H.),
Reg. Nos. 1960, 273-206. Holotype 3 selected, 1960, 273.
Proportions and Measurements (mm.)
a b c Vv Body length
Si) : 34°4 4°5 17°8 a 3°24
35°4 5-1 cn 16°1 é —_— c 2°90
220 4°I r 15°0 : — 5 2°60
36°7 5°2 163 = 3°30
37°0 4-5 17°8 = 3°55)
ao : 32-0 4-7 057 : 2°5 3°14
34°3 4°I j 14°7 F 59°6 2-92
3I°1 4°2 a 16-0 : 55°7 3°05
2°4 : 4°9 7 15°4 - 56-2 - 3°13
Males (measurements in order of body lengths) : Oesophagus length : 0-72 ;
0°59 ; 0:63; 0-64; 0-79. Buccal cavity depth : ——: ; 0°017 ; 0-016; o-or8.
Buccal cavity width : —— : ; 07005 ; 0-006; 0-006. Refractive bodies from
anterior end : ——; ——; 0-018; 0-016; 0-019. Nerve ring from anterior end:
i > 0:278 ; 0:340; 0-371. Excretory pore from anterior end : only seen
in the 3°55 mm. long specimen, 0-077. Tail length (tail length/anal diameter) :
0-186 (3:5) ; 0-180 (—); 0-173 (3-4); 0-203 (4:2) ; 0-199 (3-8). Spicule length :
0:28; 0:26; 0-26; 0:26; 0-28. Gubernaculum length : 0-045 ; 0:039; 0-041 ;
0-036 ; 0-046.
Females (all measurements in order of body lengths) : Oesophagus length : 0-67 ;
0°72; 0°74; 0-64. Buccal cavity depth: 0-016; o-o15; 0-016 ; 0-016. Buccal
Cavity width : 0-006; 0°005 ; 0-006; 0-007. Refractive bodies from anterior end :
0-018 ; 0-019 ; 0-019; 0-org. Nerve ring from anterior end : O-04I ; 0-039; 0-036;
0-038. Excretory pore from anterior end : 0°074 ; 0°072 ; ——; 0-074. Tail length
(tail length/anal diameter) : 0-200 (4:1) ; O-IQI (4:0); 0-198 (4:3); 0-203 (3:9).
Vulva from anterior end : 1-65; I-70; 1°74; 1-76,
FREE-LIVING NEMATODES FROM SOUTH AFRICA
0-02mm.
Fics. 29-32. Polygastvophora omercooperi sp. nov. Fig. 29. Dorsal view of female
head. Note the recessed amphids. Fig. 30. Lateral view of female head, dorsal side
to the right. Fig. 31. Lateral view of the oesophagus, note nine bulbs. Fig. 32. En
face view of female head. Note large tooth is right ventro-lateral in position. (Figs.
29, 30 and 32 to the same scale.)
FREE-LIVING NEMATODES FROM SOUTH AFRICA 311
Head and Oesophagus
The anterior end of the body narrows rapidly from about the posterior end of the
oesophagus forward so that the head, in spite of the length of the body, is small,
0:0I0—0-01I mm. in diameter. There are many setae scattered over the anterior end
of the body but they become progressively less common posteriorly until they are
very rare posterior to the nerve ring. The mouth opening is circular, 0-004 mm. in
diameter (in a male specimen 3-30 mm. long) and leads into a typical long, relatively
narrow buccal cavity with parallel sides, except for the first chamber which is wider
than the posterior chamber. The first chamber is 0-007 mm. in diameter, the second
is 0:006 mm. The buccal cavity is divided into four parts by transverse rings, one at
the opening of the swollen anterior chamber, one at the junction of that chamber and
the narrower posterior chamber and two in the narrow chamber itself (Text-figs. 29
and 30). The small size of the head makes study difficult so that although small
teeth appeared to be present on all three of the more anterior rings—on only one
ring in some specimens, on two in others and on all three in some—I cannot be sure
that they are a constant character of the species or whether in fact the serrated
appearance is not an artifact. The transverse rings are therefore shown untoothed in
the figures of the head (Text-figs. 29 and 30). Three teeth are developed from the
base of the second chamber of the buccal cavity. The largest springs from the right
ventro-lateral sector and the other two, which are much less prominent and equal in
length, spring from the left ventro-lateral and the dorsal sectors of the oesophagus.
Although in the en face figure of the head (Text-fig. 32) the dorsal tooth appears to be
dorso-lateral in position and the left ventro-lateral appears to be lateral this is due to
a slight spiralling of the teeth as they pass anteriorly. This is shown in the figure of
the head from the dorsal aspect (taken from a different specimen from that used for
the en face preparation) where it can be seen that their origins are wholly dorsal and
ventro-lateral. The transverse rings appear to represent, from the anterior end to the
posterior end (x) the junction of the mouth with the expanded anterior chamber ;
(2) the junction of the expanded chamber with the narrow chamber ; (3) the level at
which the dorsal and left ventro-lateral teeth become free at their anterior ends from
the wall of the narrow chamber and (4) the level at which the large right ventro-
lateral tooth becomes free from the narrow chamber. It follows from this that, as
described above, there are only two true chambers the other rings only being apparent
from certain angles as has been confirmed by rolling some of the specimens. This
probably explains some of the discrepances between some of the descriptions of the
species of this genus.
The mouth is surrounded by six small, sessile papillae and the head bears five pairs
of long setae which originate about the level of the junction between the anterior and
posterior chambers of the buccal cavity. Of these setae three pairs are long, 0-008
mm. in all the specimens measured, and two pairs are short, about 0-006 mm. The
distribution of the setae is most easily understood from the figure (Text-fig. 32). The
amphids are located about the level at which the cephalic setae originate and are
dorso-lateral in position. They are semi-circular recesses which lead into pouches at
the bases of which are the amphidial nerves (Text-figs. 29 and 30).
The oesophagus (Text-fig. 31) is very narrow anteriorly without any muscle bands
312 FREE-LIVING NEMATODES FROM SOUTH AFRICA
which only become obvious just anterior to the nerve ring. Approximately the
posterior third of the oesophagus is developed into nine bulbs each of which contains
a central lenticular cuticularization from which radiate stands of muscles. In some
specimens a tenth, very small and poorly developed bulb appears to be present but
it is probably that this is simply an artifact.
The usual pair of lenticular refractive bodies is present about the posterior end of
the buccal cavity. The bodies show some variation in their positions relative to the
buccal cavity, both from specimen to specimen and between the two sides of the same
specimen but in no case were they seen anterior to the posterior end of the buccal
cavity.
Male
All the specimens appear to be larvae (4th stage: but see below, page 312) since
the structure of the head is identical with that of the female. The tail is relatively
long and the three caudal glands are located relatively far anterior to the cloacal
opening. The spicules are long and narrow, equal in length and identical in structure.
There is a small, simple gubernaculum. Anterior to the cloacal opening, on the ventral
surface of the body, are six pairs of relatively evenly spaced papillae, although in
some specimens they are further apart anteriorly than posteriorly. Also anterior to
the cloacal opening is a series of oblique muscle strands running from the dorsal to
the ventral surface of the body over a length of 0-89-0-92 mm. from the cloacal
opening. There are two opposed testes, which are restricted to the anterior half of
the body, and a heavily muscled ejaculatory duct.
Female
The tail is similar in outline to that of the male. There are two opposed uteri
which are not (?) reflexed. The eggs are 0-041 X 0:024 mm. to 0:043 X 0-025 mm.
in size and the greatest number seen in one specimen was one in each uterus.
Discussion
Polygastrophora omercoopert is distinct from all the other species referred to the genus
by the presence of nine bulbs in the posterior end of the oesophagus.
Wieser (99534 and b) suggests that all the genera referred to the subfamily Enchili-
diinae may be characterized by sexual dimorphism and points out that it is definitely
known to occur in three of the genera of that subfamily, one of the genera in question
being Polygastrophora. However, I find it difficult to believe that all the male speci-
mens I have seen are fourth stage larvae as in many of them the reproductive organs
appear to be fully developed and the spicules are frequently protruded from the cloacal
opening. In addition it is difficult to believe that among nineteen male specimens
found in association with gravid females none of the males is fully adult but that
many of them are fourth stage larvae just about to moult to the adult condition.
I therefore suggest that it is more probable that sexual dimorphism, involving a
~ highly modified head in the male, does not necessarily occur in all the species of the
FREE-LIVING NEMATODES FROM SOUTH AFRICA 313
genus Polygastrophora but only in some of them. In fact such a male is only known
in P. quinquebulba Micoletzky, 1930.
Allgén (1959) describes a new species of Bolbella, B. cylindricauda, based on one
female specimen. Although the description is extremely poor, without measurements
other than a statement of the length of the body and the values of a, 6 and c (‘The
vulva was not to be stated.”’), it is clearly a species of Polygastrophora since Allgén
refers to ‘‘ light-refracting small bodies behind the buccal cavity ’’. Such bodies are
characteristic of Polygastrophora but do not occur in Bolbella as Wieser points out
(19530, p. 132). Further Allgén draws attention to the similarities between his new
species and the redescription of Polygastrophora hexabulba (Filipjev, 1918)—which
Allgén attributes to Wieser—given by Wieser (19536). While acknowledging that
Allgén’s description is insufficient and that his figures are virtually impossible to
analyze, I have little doubt that B. cylindricauda is the same species as that described
by Wieser as P. hexabulba, since the characters on which Allgén considers them
distinct are such as could be due to poor preservation. Certainly the figure of the tail
(Allgén, 1959, fig. 83c) could only have been drawn from a distorted specimen. [
therefore propose that B. cylindricauda Allgén, 1959 be treated as a synonym of
P. hexabulba (Filipjev, 1918).
Sphaerolaimus anterides sp. nov.
Material Studied
03; 42 (2 adult, 2 4th stage larvae). B.M. (N.H.), Reg. Nos. 1960. 300-303. One
adult female selected as Holotype, 1960. 300.
Proportions and Measurements (mm.)
a b c Vv Body length
19°7 4:0 : 9°9 5 82:8 é 2°38
19-6 : 4:6 : 10°5 é 83-2 f 2°74
16°4 3°9 97 . 83°3 . 1-74 (larva)
Adult (in order of body lengths) : Oesophagus length : 0°59; 0°59. Head diameter
at “A”’ (see Text-fig. 33) : 0°04I ; 0°037, at “B’’: 0-057; 0-053, at “C”’: 0-068:
0-071. Amphid diameter (percentage of corresponding head diameter) : 0-006 (I0°5) ;
*0-006 (11-3). Buccal capsule diameter : 0:027; ... . Buccal capsule depth:
0-015; ... . Nerveringfromanteriorend: ... ; 0-19. Excretory pore from
anterior end: 0:21; .... Tail length (tail length/anal diameter) : 0-24 (3-1) ;
0-26 (3-8) Vulva from anterior end : I-97; 2:28.
Larva: Oesophagus length: 0-45. Head diameter at “A”: 0:037, at “B”:
0050, at “C”’: 0-061. Amphid diameter (percentage of head diameter) : 0-007
(14:0). Nerve ring not seen. Excretory pore from anterior end: 0-18. Tail length
(tail length/anal diameter) : 0-18 (2-1). Vulva from anterior end : I-45.
Cuticle
The cuticle bears very fine, close-set transverse striations, about 0-oor mm. apart,
over most of the body, which resolve into series of small rectangular blocks (Text-fig,
314
FREE-LIVING NEMATODES FROM SOUTH AFRICA
Fics. 33-37. Sphaerolaimus antevides sp. nov. Fig. 33. Lateral view of head.
Dorsal side to the right. Fig. 34. The same from the dorsal surface. Fig. 35. Whole
body. Note posterior position of vulva and only one ovary. a = cuticular markings
on anterior end of body. b= cuticular markings on middle part of body.
¢ = irregular markings about level of anus (semi-diagrammatic). Fig. 36. En face
view of head. Fig. 37. Optical section through oesophageal funnel showing ventro-
lateral teeth. (Figs. 33, 34, 36 and 37 tothe same scale.) (A A, B———B and
C C indicate levels referred to in the text. lc. = leaf crown; n = nerves
supplying cephalic sense organs ; bu = buttresses of buccal capsule; f = foramina ;
m.l. = muscular lobes developed on the ventro-lateral sides of the oesophageal
funnel ; d.m. = dorsal muscle fibres of oesophageal funnel; d.o.g. = duct of dorsal
oesophageal gland ; f,-f; = foramina.)
FREE-LIVING NEMATODES FROM SOUTH AFRICA 315
35, 6). The markings start anteriorly about the level of the anterior edge of the buccal
capsule (Text-fig. 33, level ““A’’) where they are regular and slightly more elongate
than those on the major part of the body. More posteriorly, particularly around the
amphid, the blocks on the lateral fields become longer, more prominent and slightly
irregular both in shape and distribution (Text-fig. 35, a), although never to the same
extent as the markings on the posterior end of the body (see below). This anterior
zone of larger markings continues posteriorly, narrowing evenly until it disappears
about the level of the posterior end of the oesophagus, the smaller blocks flanking the
lateral zone becoming smaller and squarer concomitantly. On the posterior end of the
body, about the level of the anus, the regular arrangement is also lost and is replaced
by blocks along the lateral fields which are very irregular in arrangement and shape.
The area so covered is V-shaped with the wider part anteriorly. The regular arrange-
ment persists dorsally and ventrally (Text-fig. 35, c).
There are many longish setae, about 0-006 mm. long, arranged in sixteen evenly
spaced files. The setae are relatively close together anteriorly but become further
apart posteriorly until they cease about the level of the posterior end of the oesophagus
The remainder of the body bears only a few setae but they become more frequent
again on the tail (Text-fig. 35).
Head and Oesophagus
The head bears two circles of six sessile papillae of which those of the inner circle
are small and inconspicuous while those of the outer are fairly prominent, but are
not setiform (Text-fig. 36). Slightly posterior to the outer circle of papillae is a circle
of four sets of setae of which one seta is much longer (0-012-0-013 mm. on the adults
0-orI mm. on the larvae) than the other three and is the most lateral in all four
groups. The other three setae are of different lengths, becoming shorter the more
dorsal or ventral (depending on the group to which they belong) their position. These
four groups are dorso- and ventro-lateral in position (using the terminology of de
Coninck (1942) and Hyman (1951), p. 201, fig. 94). Immediately posterior to this
circle is another, also consisting ot four groups of setae, but of only two setae per
group. In this case also the more lateral seta is longer than the other in each group.
There are further small setae which appear to correspond to those covering the general
surface of the anterior end of the body except that the first circle consists of eight
setae instead of sixteen as on the remainder of the body. In addition there are two
small setae immediately anterior to each amphid.
The mouth opening is circular in shape and is closed by six fleshy lip-lobes which
appear to be striated radially, but it is possible that this appearance is due to the
underlying longitudinal striations of the cavity anterior to the leaf elements (= vesti-
bule) (see below). The mouth Jeads through the vestibule into a capacious, globular
buccal cavity which is bordered anteriorly by a set of leaf elements forming a leaf
crown (I am applying the terminology used in the strongyloids, a group of parasitic
nematodes, see below, page 317). Posterior to the leaf crown the buccal cavity consists
of two distinct parts the more anterior of which, between levels “‘A’’ and ‘‘B’’(see
Text-figs. 33 and 34) will be referred to as the buccal capsule while the more posterior
316 FREE-LIVING NEMATODES FROM SOUTH AFRICA
will be referred to as the oesophageal funnel (another term applied to the strongyloids).
The buccal capsule is circular in cross section and the leaf crown (Text-fig. 36, l.c.)
is composed of twenty five leaf elements which arise as thin cuticular strips from the
inner surface of the buccal capsule just posterior to its extreme anterior edge. An-
terior to the leaf crown there appears to be a second leaf crown consisting of much
smaller leaf elements but this effect is due to the longitudinal folding of the cuticle
lining the vestibule whih produces longitudinal striations (see Cobb, 1929). The pos-
terior end of the buccal capsule lies over the wall of the oesophageal funnel as twelve
“buttresses ’’ (Text-figs. 33 and 34, bw) which are the only sclerotized parts of the
buccal capsule i.e. they show up distinctly even under very low powers and appear
to be covered by small dots. These buttresses are extremely prominent and appear
to be characteristic of this species. Further, the buccal capsule is fused to the body
wall by these butttresses and the nerves which supply the cephalic setae and papillae
can be seen passing through the spaces between them (‘‘’’). These spaces are
represented on the en face view of the head (Text-fig. 36) by somewhat oval spaces
enclosed by dashes (‘‘ f’’), since this is the impression they give, although a more
detailed study shows that they are in fact bounded internally by the buccal capsule
and/or the wall of the oesophageal funnel and externally by the cuticle covering the
body. The oesophageal funnel is massive and appears to be divided into two parts.
There are two well developed teeth at the base of the funnel, one on each ventro-
lateral sector (Text-fig. 37). There is no corresponding tooth dorsally but there is a
marked thickening of the dorsal wall of the oesophageal funnel through which passes
the duct of the dorsal oesophageal gland (Text-fig. 36, d.o.g.). The musculature of the
ventro-lateral sectors of the oesophagus continues anteriorly as two lobes (Text-fig.
33, m.l.) which stop about the middle of the oesophageal funnel. There are no lobes
dorsally although there is a slight development of muscles in two separate blocks
(Text-fig. 34, d.m.). The oesophageal funnel is circular in cross section anteriorly but
becomes hexagonal in cross section internally towards the bottom (Text-fig. 37).
The amphids lie anterior to the base of the oesophageal funnel, roughly half way
between the posterior and anterior ends. They are circular in outline and the opening
is a small circle leading into a larger cavity. Most figures show only a large circle
which may have been due to the authors overlooking the small circle of the opening,
but there may in fact be a difference in the form of the amphids. The amphidial
nerve appears to enter from the posterior side but a sight break in the outer periphery
in one specimen suggests that the nerve may in fact enter from the dorsal side, but I
cannot be sure owing to the difficulty of seeing the nerves.
The oesophagus is stout without a posterior swelling and is lined by thick cuticle
along its whole length.
Tail
The tail narrows suddenly about two-thirds of its length posterior to the anus and
bears several rows of relatively long setae. There are three very distinct, stout setae
on the extreme tip of the tail which are about 0-014 mm. long in the adults and 0-009
. mm. long in the larvae. The three caudal glands are located immediately posterior
to the anus (Text-fig. 35).
FREE-LIVING NEMATODES FROM SOUTH AFRICA 317
Reproductive Apparatus
There is a single ovary which is not reflexed and there does not appear to be a
distinct oviduct. The eggs, of which the greatest number seen in one specimen was
four, measure 0:063 x 0:05I mm. and 0-069 x 0-056 mm. The vulva lies relatively
far posterior to the head, V = 83, and there is no post-vulvar sack (Text-fig. 35).
Discussion
Sphaerolaimus anterides belongs to what may be called the Parasphaerolaimus-
group of the genus Sphaerolaimus, a group characterized by a reduced buccal capsule
(in the nomenclature used here ; “ sclerotized portion ’’ of Wieser (z956) ; ‘“ chagri-
nierter Teil ’’ in German literature ; ‘“‘ chagrinated cuticularized plates ’’ of Schuur-
mans Stekhoven (1950)). This group contains three species, according to Wieser
(1956), S. dispar Filipjev, 1918; S. paradoxus Ditlevsen, 1919 and S. tslandicus.
Ditlevsen, 1926; from all of which S. anterides differs in the form of the buccal
capsule, perhaps in the presence of cuticular differentiation on the body (this character
is doubtful since such markings may have been overlooked) and, apparently, in the
length and distribution of the cephalic setae. The position is complicated, however,
by the unsatisfactory nature of some of the descriptions and figures. One further
species referable to the Parasphaerolaimus-group has been described since Wieser,
S. lodosus Gerlach, 1954. Gerlach’s full description brings out the many resemblances
between his species and S. anterides but they differ in the cuticular pattern and the
structure of the buttresses of the buccal capsule.
The use of the terms “‘ leaf crown ’’ and “‘ oesophageal funnel ’’ is not to be taken
as indicating any homology between the structures so named in Sphaerolaimus and
in the strongyloids. They are used solely as descriptive terms since there is a marked
similarity in appearance between the two head forms. Such descriptions are used in
preference to more specific terms such as cheilorhabdions, a term employed by
Chitwood (in Chitwood and Chitwood, 1951) and by Wieser (1956) for what are referred
to above as leaf elements, since such a term carries a concept of homology which
may be unfounded and certainly is not satisfactorily established.
The great depth and diameter of the buccal cavity (i.e. the entire cavity stretching
from the mouth opening to the posterior end of the oesophageal funnel) must intro-
duce serious mechanical weaknesses which have been overcome by the attachment
of the buccal capsule to the body wall by means of the buttresses. Since some provision
must be made for the passage of the nerves which supply the sense organs of the head
this fusion is incomplete leaving ten foramina (Text-figs. 33, 34 and 36, f) through
which the nerves pass. The foramina being flanked by the buttresses. Thus the nerves
which supply the four sets of four setae pass through the dorsal and ventral foramina
of each lateral set of three (fz and 4, Text-fig. 36). The nerves which supply the four
sets of two setae pass through the dorso- and ventro-lateral foramina (f1 and /5) and
the nerves which supply the dorso- and ventro-lateral papillae of the inner and outer
circles pass through the same foramina (i.e. ft and 5) while the nerves supplying the
lateral papillae of both circles pass through the lateral foramina (/3). Several minor
nerves supplying the various supernumerary setae of the head also pass through the
318 FREE-LIVING NEMATODES FROM SOUTH AFRICA
foramina. Such foramina appear to be present in all species of Sphaerolaimus but
appear to be much more prominent in the species of the Parasphaerolaimus-group
(see, for example, Schuurmans Stekhoven (1950), figs. 127 and 128 ; Gerlach (1954)
Tafel XVII, Abb. 24a, b,c; and Filipjev (1918) figs. 69a, b, f). The foramina should
not, however, be confused with the fenestrae which occur in some of the species of
the Sphaerolaimus-group of species and which appear to represent a tendency towards
the lightening of the buccal capsule.
REFERENCES
ALtGiN, CARL A. 1959. Freeliving marine nematodes. Further zool. Res. Swed. Antarct.
Exped. 5 (2) : 1-293.
Bressiau, E. & SCHUURMANS STEKHOVEN, J. H. 1940. Marine freilebende Nematoden aus
dev Nordsee. Musée Royal d’Historie Naturelle de Belgique.
Cuitwoop, B.G. 1951. North American marine nematodes. Texas J. Sct. 3: 617-672.
Cuitwoop, B. G. & Cuitwoop, M. B. 1950. An Introduction to Nematology. Section I.
Anatomy, with contributions by R. O. Christenson, L. Jacobs and F. G. Wallace. B. G.
Chitwood, Baltimore.
Cuitwoop, B. G. & Timm, R. W. 1954. Free-living nematodes of the Gulf of Mexico in
Chapter IX. Free-living flatworms, nemerteans, nematodes, tardigrades, and chaetog-
naths. In Gulf of Mexico, its origin, waters, and marine life (Co-ordinated by Paul S.
Galsoff). Fish. Bull. U.S. 55 : 313-323.
Cops, N. A. 1920. One hundred new nemas. (Type species of 100 new genera.) Contr. Sci.
Nemat. 9 : 217-343.
1929. The nemic genus Sphaerolaimus Bastian composed of carnivorous forms. Proc.
helm. Soc. Wash. in J. Parasit. 15 : 284.
De Coninck, A. P. 1942. De Symmetrie-verhoudingen aan het Vooreinde (vrijlevende)
Nematoden. Natuurwet. Wijdschr. 24 : 29-68.
DiItLEVSEN, Hyatmar. 1919. Marine freeliving nematodes from Danish waters. Videmsk.
Medd. dansk. naturh. Kbh. 70 : 147-214.
— 1926. Free-living nematodes. Danish Ingolf-Exped. 4 (6): -42. Plates I-XV. Map
and table of stations.
Fiuipjev, I. N. trg918. [Free-living nematodes from the region of Sevastopol. I.} Tvav.
Lab. Zool. Sébastopol, 2 (4) : 1-350.
Gervacn, S. A. 1954. Brasilianische Meeresnematoden. I. Bol. Inst. Ocean. Univ. Sao
Paulo, 5 : 3-69.
Hyman, Lirppre HENRIETTA. 1951. The invertebrates: Acanthocephala, Aschelminthes, and
Entoprocta. The pseudocoelomate bilateria. Volume III, pp. i-vii, 1-572. Figs. 1-223.
McGraw-Hill Book Company, Inc., New York, Toronto, London.
DE Man, J. G. 1888. Sur quelques nématodes libres de la Mer du Nord, nouveaux ou peu
connus. Mém. Soc. zool. Fy. 1: 1-51.
MIcoLetzky, HEINRICH. 1930. Papers from Dr. Th. Mortensen’s Pacific Expedition, 1914-16.
LIII. Freilebende marine Nematoden von den Sunda-Inseln. I. Enoplidae. (Edited
by Hans A. Kreis). Vidensk. Medd. dansk. naturh. Foren. Kbh. 87 : 243-3309.
OmER-CoopER, J. 1957a. Pyvotohydva and Kinorhyncha in Africa. Nature, 179 : 486.
19570. Deux nouvelles especes de Kinorhyncha en provenance de l'Afrique du Sud.
Bull, mens. Soc. linn. Lyon. 8 : 213-216.
SCHUURMANS STEKHOVEN, J.H. 1935. Nematodaerrantia. Tierw. N.-w. Ostsee. 5b : 1-173.
1943. Freilebende marine Nematoden aus Mittelmeeres, IV. Freilebende marine
Nematoden der Fischereigriinde bei Alexandrien. Zool. Jb. (Syst. etc.) 76 : 323-380.
1950. ‘The freeliving marine nemas of the Mediterranean. I. The bay of Villefranche.
Mém. Inst. Sci. nat, Belg. (2ieme Sér.), 37 : 1-220.
FREE-LIVING NEMATODES FROM SOUTH AFRICA 319
_ WIESER, WOLFGANG. 1953a. Der Sexualdimorphismus der Enchelidiidae (freilebende marine
‘a Nematoden) als taxonomisches Problem. Zool. Anz. 150: 152-170.
—— 1953). Reports of the Lund University Chile Expedition, 1948-1949. 10. Free-living
marine nematodes. I. Enoploidea. Acta Univ. lund. n.s. 49 (6) : 1-155.
—— 19544. On the morphology of the head in the family Leptosomatidae (marine free-
living nematodes). With a key to all the genera described. Ark. Zool. 6: 69-74.
—— 1954). Reports of the Lund University Chile Expedition, 1948-49. 17. Free-living
marine nematodes. II. Chromadoroidea. Acta Univ. lund. n.s. 50 (16) : 1-148.
1956. Reports of the Lund University Chile Expedition, 1948-49. 26. Free-living
Marine nematodes. III. Axonolaimoidea and Monhysteroidea. Acta Univ. lund. n.s. 53
(13) : I-115.
THE SPECIES OF RHABDITIS (NEMATODA)
FOUND IN ROTTING SEAWEED
ON BRITISH BEACHES
By WILLIAM G. INGLIS anp JOHN W. COLES
SYNOPSIS
Rhabditis marina Bastian, 1865, is reported from several localities on the South Coast of
England and from Aberdeen, Scotland. Although this species has been reported from several
localities in Europe and in North and South America these are the first records of its occurrence
in Britain since it was originally described from Falmouth. Rhabditis ehrenbaumi Bresslau
and Schuurmans Stekhoven, 1935, originally reported from Heligoland, is reported from the
South and West Coasts of England and Wales: these are the first records of this species since the
original description. Both speciesare fully redescribed and none of the varieties of Rh. marina which
have been described or named are accepted with the exception of Rh. m. var. bengalensis Timm,
1956, which is considered to represent a distinct species Rh. bengalensis. Rh. m. var. nidvo-
stensis Allgén, 1933, is considered to be a nomen dubium. Rh. velata Bresslau and Schuurmans
Stekhoven, 1935, is considered to be a synonym of Rh. marina and further evidence is presented
supporting the treatment of Rh. fluviatilis Biitschli, 1876, as a synonym of Rh. mavina. The
occurrence of Rh. marina is discussed and it is considered to be a form which, although found
away from beaches, must be considered a normal member of the beach fauna, typically occurring
in rotting seaweed and that its occurrence in beach pools must be considered accidental. It
is suggested, tentatively, that Rh. ehrenbaumi is probably not a typical beach form but insuffi-
cient is known about its distribution for any definite conclusions to be drawn.
THE species of Rhabditis most frequently reported from marine habitats is Rhabditis
mayina which was described by Bastian (1865) from specimens found in sand from
tide-pools at Falmouth, England. Subsequently six varieties of this species have
been described or named, and it has been reported, in one form or another, from the
coasts of Europe, the Atlantic coast of the United States of America, the coast of
Brazil, the coast of Pakistan, from the South Pacific (Campbell Island) and from the
Falkland Islands. It has not, however, been reported from the coast of Britain
since the original description. Although we have been unable to find it at Falmouth,
we have found specimens at several localities on the South and West Coast of England
and have received specimens from Scotland. A full redescription of Rh. marina is
given below and we are able to demonstrate that some at least of the characters used
to differentiate the various varieties are simply due to intraspecific variation.
Two further ‘“‘ marine ’’ species of Rhabditis (Rh. ehrenbaumi and Rh. velata) were
described by Bresslau & Schuurmans Stekhoven (in Schuurmans Stekhoven, 1935 ;
Bresslau & Schuurmans Stekhoven, 1940) from Heligoland and neither has been
reported since. We have found specimens of the first species on the South and West
Coast of England and the South Coast of Wales and a redescription of it is given below.
One male specimen which at first sight appeared to belong to the second species was
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 321
received from Scotland, but a detailed study demonstrated that the apparently
distinguishing characters were in fact due to poor preservation and we consider
Rh. velata a synonym of Rh. marina.
Rhabditis (Pellioditis) marina Bastian, 1865
Synonymy :
Rhabditis marina Bastian, 1865. Tvans. Linn. Soc. Lond. 25,129. Pl. to, Figs. 60-62.
Rhabditis fluviatilis Biitschli, 1876. Z. wiss. Zool. 26: 365. Taf. XXIV, fig. 8.
Rhabditis marina var. septentrionalis Steiner, 1921. Zool. Jb. (Syst. etc.) 44: 10 (= Rh. marina
of Steiner, 1916. Zool. Jb. (Syst. etc.) 39: 518. Taf. 18, figs. 1a—g.)
Rhabditis marina var. kielensis Schulz, 1932. Zool. Jb. (Syst. etc.) 62: 419. Fig. 49a-e.
Rhabditis marina var. danica Allgén, 1933. Capita Zool. 4: 123 (= Rh. marina of Ditlevsen,
1912. Vidensk. Medd. naturh. Foren. Kbh. 64: 240. PI. II, figs. 1-5, 7.)
Rhabditis velata Bresslau & Schuurmans Stekhoven, in Schuurmans Stekhoven, 1935. Tierwelt
N. -u. Ostsee.5:155. Fig. 338.
Rhabditis (Choriorhabditis) fluviatilis, Osche, 1952. Zool. Jb. (Syst. etc.) 81 : 263.
Rhabditis (Choriorhabditis) velata, Osche, 1952. Zool. Jb. (Syst. etc.) 81: 264.
Rhabditis (Caenorhabditis) marina, Osche, 1952. Zool. Jb. (Syst. etc.) 81 : 265.
Rhabditis (Choriorhabditis) marina marina, Osche, 1954. Zool. Anz. 152: 247.
Rhabditis (Pellioditis) fluviatilis, Dougherty, 1955. J. Helminth. 29 : 131.
Rhabditis (Pellioditis) velata, Dougherty, 1955. J. Helminth. 29 : 131.
Rhabditis (Pellioditis) marina, Dougherty, 1955. J. Helminth. 29 : 132.
nec Fhabditis (Choriorhabditis) marina var. bengalensis Timm, 1956. J. Bombay nat. Hist.
Soc. 54:87. Figs. A and B (= Rh. bengalensis).
Type locality: In sand from tide-pools, Falmouth, south coast of England.
Material studied
Fifty-nine specimens (B.M. (N.H.) Reg. Nos. 1958.12.5.31-60; 1960.2~-30)
from rotting sea-weed on beach at Downderry, Cornwall (11 3, 11 9 measured).
Other specimens have been studied, but not measured, from the following localities :
Littlehampton, Sussex; West Wittering, Sussex; Parson and Clerk Rock, nr.
Holcombe (between Dawlish and Teignmouth), Devon ; Sunny Cove, East Portle-
mouth (Salcombe Estuary), S. Devon; Sennen Cove, Sennen (near Land’s End),
Cornwall (larvae only) ; Weston-Super-Mare, Somerset; Aberdeen, Scotland. All
these specimens were found in association with rotting sea-weed.
Geographical distribution
Barents Sea (Steiner, 1916) ; Denmark, coast of (Ditlevsen, 1912) ; Germany,
Baltic coast (Schulz, 1932); Kiel Bay, Germany (Otto, 1936; Gerlach, 1954) ;
Ostend (De Coninck & Schuurmans Stekhoven, 1933) and Zeebrugge (Schuurmans
Stekhoven, 19352), Belgium; West Sweden (Allgén, 1950); Heligoland, North
Sea (Bresslau & Schuurmans Stekhoven, 1940) ; Mediterranean—Italy and Algeria
(Osche, 1954) ; Coast of Algeria (Gerlach, 1954b) ; Woods Hole (Timm, 1956) and
Long Island, N.Y., Atlantic Coast of the U.S.A. (Chitwood, 1951) ; Pernambuco,
Brazil (Gerlach, 1956) ; ? Campbell Island, South Pacific (Allgén, 1932) ; Falkland
Islands, Port William (Allgén, 1959) ; Falmouth (Bastian, 1865), and other localities
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
322
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 323
in England and Scotland listed above (present authors). Several localities (not
beaches) in Germany (Biitschli, 1876; Hirschmann, 1952; Meyl, 1955) and from
Hungary (Andrassy, 1958).
Measurements (specimens fixed in ‘“‘ Taf ’’ and mounted in glycerine).
Males—(n = 11). L. =1-40-1°75 (1°59 + 0-112). @ = 13°2-23°8 (19°55 + 3°03).
b = 5°6-6'9 (0°43 + 0:482). c = 17°6-23°4 (20-20 + 2:12).
Females—(n = 11). L. = 1-61-2-42 (1:90 + 0-262). a@ = 14:6-21°7 (185 +
I-97). b = 6:2-8-6 (6:9 + 0°89). c = 12-4-18-6 (15:2 + 1°89). V. = 50-56
(53) =: 1°55).
MORPHOLOGY
General
The body is relatively narrow and terminates in a relatively long tail in both
sexes ; laterally it carries well defined lateral fields which have eight incisures about
the middle part of the body length where the fields are about one fifth the diameter
of the body in width. The oesophagus is typical of Rhabditis with a distinct middle
bulb and a poorly developed posterior bulb, the valves of which bear a series of semi-
elliptical concentric ridges. The oesophagus anterior to the middle bulb is markedly
wider than the part posterior to that bulb.
Head
The head appears to carry a full complement of sixteen papillae which are
arranged in three circles (Text-fig. 2e); two pairs, dorso- and ventro-lateral in
position, in an outer circle ; three pairs in an intermediate circle and (?) three pairs
in aninner circle. The papillae of the outer and intermediate circles are setiform and
have been seen very clearly particularly in some of the specimens from Scotland,
but those of the inner circle appear to be sessile and it is not certain that they do in
fact exist. The amphids are slightly dorso-lateral in position and are prominent
with large openings (Text-fig. 2e and f). The mouth opening is bounded by six-lip-
lobes which are not off-set from the body and are free from each other at their ends
nearer the central axis of the body, but pass backwards onto the surrounding head
where they form six prominences on which are located the papillae and the amphids.
The buccal cavity (cheilostome) is circular in cross section and is divided anteriorly
into six pointed processes, one of which corresponds with each lip-lobe. The pro-
stome is triangular in cross section, this being the triangular structure shown in
Text-fig. 2e. The metastome bears a series of five tubercle-like structures and the
base of the stoma is surrounded by an oesophageal “sleeve ’’, i.e. muscular tissue
extends anteriorly around the posterior part of the stoma.
Male
The tail is relatively long and narrow with broad caudal alae which continue
round the posterior tip, i.e. the tail is peloderan. The alae are supported by nine
Fic. 1. Rhabditis marina, female containing eggs and larvae (a), male (d) ; Rhabditis
ehvenbaumi, female (b), male (c). All figures tosame scale. (Scale line = 0-5 mm.)
324 RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
Scale _a
Scale _b
Fic. 2. Rhabditis marina, posterior end of male (lateral view) (a), ventral view of spicules
and gubernaculum (b), en face view of head () (e), lateral view of head with the dorsal
surface to the right (f), optical section through buccal cavity and anterior end of
oesophagus (g); Rhabditis ehrenbaumi, en face view of head (c), dorsal view of head
showing five tubercules on the metastome (d), semi-ventral view of male tail showing
the distribution of the caudal papillae in detail on one side only (h), posterior end of female
(k) ; Rhabditis bengalensis sp. nov., structure of oesophagus (redrawn after Timm),
note particularly the lack of a distinct median bulb (7). (a, g and k to same scale a ;
b, c, d, e, f and h to same scale, b; both scale lines = 0-05 mm.)
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 325
pairs of long narrow caudal papillae, or rays, arranged in definite groups: one pair
far anterior, a group of two pairs mid-way between the most anterior pair and the
cloacal opening, a group of three pairs very close together just posterior to the cloacal
opening and a final group of three pairs just anterior to the posterior tip of the tail
(Text-fig. 2a). The two anterior pairs of papillae in the more anterior group of
three are very close together and can frequently be resolved only with great difficulty.
The phasmids open on the ventral surface of the tail just anterior to the most posterior
group of papillae. There is, in addition, at least one pair of sessile papillae on the
anterior lip of the cloacal opening and possibily a second pair on the posterior lip.
The spicules are equal in length, 0-40-0-70 mm., identical in structure and are not
Fic. 3. Rhabditis marina, variation in female tail. (Scale line = o-I mm.)
fused. They terminate posteriorly in “‘ doubled ’’ swollen ends (Text-figs. 2a and 0)
and bear broad double alae which are slightly folded over the main central shaft
forming open tubes in all the specimens studied. The gubernaculum is broader
posteriorly than it is anteriorly and is about half as long as the spicules. There is
only one testis, which is flexed, and posteriorly there appears to be a pair of rather
short ejaculatory glands.
Female
The vulva opens on the ventral surface of the body slightly posterior to the middle
of the body length, V varying from 50-54%. The tail is long and somewhat variable
in shape. It ranges from a very long, narrow form with a fine tip in the immature
females to a relatively short stout form without such a tip in mature specimens.
The range of variation is illustrated in Text-fig. 3 and it appears that as the width of
the body increases with the appearance and development of eggs the tail becomes
326 RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
wider and shorter, with the result that a constriction appears slightly anterior to the
end ; this is the tail form that Osche considered to be diagnostic of the subspecies
Rh. m. septentrionalis. Finally the extreme posterior tip of the tail may become lost.
The shape of the female tail has been used as the distinguishing character separating
the two subspecies, marina and septentrionalis (see Osche, 1954), but it is clear that
the reliance put on it has been misplaced. The reproductive system is amphi-
delphic and didelphic (as defined by Chitwood and Chitwood, 1950) (Text-fig. ra).
The ovaries are reflexed and there are short oviducts which are swollen just before
the uteri to form large sacks which appear to function as spermathecae ; there is no
indication of spermathecae in the uteri. The uteri are large; in maturefemales
they are packed with a large number of eggs and in the most mature specimens
larvae are also present (Text-fig. ta). The eggs are relatively small and spherical,
0:036-0-045 mm. in diameter.
Discussion
Six varieties of Rh. marina have been named of which one appears to represent a
distinct species, one—possibly two—should be treated as a nomen dubiwm and the
remaining four (or three) are indistinguishable, thus var. danica Allgén, 1933 (a
name proposed for the description of Rh. marina given by Ditlevsen, 1912) has,
according to the description, nine pairs of caudal papillae, or rays, on the male tail,
arranged in groups of 2, 2, 3, 2 (from the figure of the lateral aspect) or I, 2, 3, 2
(from the ventral view) ; var. kvelensis Schulz, 1932 was described as having seven
pairs arranged I, 2, 3, 1; var. nidrosiensis Allgén, 1933 was proposed for one male
specimen which apparently had seven pairs of papillae, but as the description is
insufficient for identification we propose to treat this as a nomen dubium; var.
norwegica Allgén, 1933 was proposed for one female specimen which was probably a
young female of Ri. marina and, in spite of the very poor description and figures, we
propose to treat it as a synonym of Rh. marina (it might be better to treat this as
another nomen dubium) ; var. septentrionalis Steiner, 1921 was a name proposed
by Steiner for the specimens described by him in 1916 and was based on females
only. The arrangement of the papillae on the male tail typical of Ah. marina is
I, 2, 3, 3, of which one of the pairs in the last group can be easily overlooked as has
probably been done by Ditlevsen (1912) (we consider his lateral view of the male
tail showing two papillae anteriorly to be faulty), Schulz (1932) and de Coninck and
Schuurmans Stekhoven (1933) where fewer than three pairs of papillae are shown
in the terminal group. Osche (1954) has suggested that these reported differences
may represent natural variation but, while agreeing that this is possible, we feel
it more probable that the papillae have simply been overlooked, particularly as
we have found no variation in all the specimens we have studied.
Osche (1954) reviewed all the varieties and concluded that there were only two
sub-groups which he treated as subspecies, Rh. marina marina and Rh. m. septentrio-
nalis. He referred all the varieties listed above to the second sub-species which he
considered to differ from the first in that the female tail ended in a relatively long,
sharply pointed tip in septentrionalis and was stouter and blunter in marina. We
agree with Osche that the various varieties are indistinguishable, with the reservation
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 327
that var. nidvosiensis cannot be placed, but we cannot accept the separation into
two subspecies. That such a separation is unacceptable is shown by the outlines
of the female tails reproduced in Text fig 3 from which it can be seen that the range of
variation includes both types of tail and also some which have not been graced with
varietal names. We therefore recognize none of the varieties or subspecies and
treat all the names proposed—with the exception of Rh. marina var. bengalensis
(see below, page 327)—as synonyms of Rh. marina.
Rh. marina has been reported from many localities on the coasts of Europe and
we have been able to find it almost everywhere we have looked on the South and West
Coast of England (always in association with rotting sea-weed) while Mr. Douglas
Bremner, who at our request looked for it at Aberdeen, had no difficulty in finding it
there also. There are six reports of its occurance outside Europe, twice from the
U.S.A. (Chitwood, 1951 ; Timm, 1956), once from the Southern Pacific (Allgén, 1932),
once from the Falkland Islands (Allgén, 1959), once from the Bay of Bengal,
Pakistan (Timm, 1956) and several times from the beach at Pernambuco, Brazil
(Gerlach, 1956). Chitwood recorded one female from Long Island, N.Y.,
and Timm (1956) mentions that he found males at Woods Hole. Gerlach’s speci-
mens were identified by Dr. Arwed H. Meyl who has studied European specimens
(see Meyl, 1955) and it cannot be doubted that Rh. marina occurs on both sides of
the Atlantic Ocean. Allgén (1932) reported Rh. marina from Campbell Island,
South Pacific (52° 34’ S. 169° 12’ E.) but the validity of the identification, which
was based on one female specimen, must be considered very doubtful although
Osche (1954) apparently accepts it. The record of Rh. marina, by the same author
(Aligén, 1959), from the Falkland Islands appears to be slightly more reliable
although the figure of the male tail is too poor to allow us to be certain.
The position of the remaining variety, Rh. m. bengalensis Timm, 1956 (referred to
as Pellioditis marina var. bengalensis, n. comb. by Timm (1960)) is different. It was
based on one male specimen (collected from “‘ Sonadia Island, Cox’s Bazar, Bay of
Bengal, East Pakistan ’’) which Timm considered to be distinct in having nine
pairs of caudal papillae arranged I, I, I, 3, 3, since, as he rightly points out, the
typical marina arrangement is with the second and third pairs (from the anterior
end) very close together, while in his specimen they are far apart. This distribution
is clearly shown in his figure. Also the figure of the oesophagus shows it to be
different in outline from that typical of Rh. marina, so much so that we feel it probable
that, unless the figure is completely inaccurate, Timm was dealing with a different
species. The corpus of the oesophagus is the same width all along its length so that
there is no distinct middle bulb (See Text-fig. 23—-Timm’s figure redrawn) and we
feel that this, in conjunction with the distribution of the caudal papillae and the
apparently sharp posterior points to the spicules (although this is possibly an un-
reliable character since Timm’s figure of the male tail is clearly somewhat diagram-
matic) warrants the treatment of this variety as a distinct species, Rh. bengalensis
Timm, 1956.
Bresslau and Schuurmans Stekhoven, in Schuurmans Stekhoven (1935) described
a new species, Rh. velata, from Heligoland. The description was based on one male
and one female, the male apparently differing from Rh. marina particularly in the
328 RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
form of the spicules and the shape of the tail. We have seen one male specimen which
on first examination appeared to belong to, and was initially referred to this species,
but a more careful study showed it to be a poorly preserved specimen of Rh. marina,
or a late fourth-stage larva, in which the caudal alae appeared to be more extensive
than usual and in which the form of the spicules could only be established with
difficulty. The appearance of the specimen is so very similar to the figure given by
Bresslau and Schuurmans Stekhoven for Rh. velata that we have no hesitation in
referring that name to the synonymy of Rh. marina.
Rhabditis fluviatilis Biitschli, 1876 was redescribed by Hirschmann (1952) ; Osche
(1954) then drew attention to the great similarity between it and Rh. marina but
said that he was unable to decide whether or not they were indistinguishable since
his specimens of Rh. marina were in such a poor condition that he was unable to
determine the form of the amphids or to establish the presence of lateral fields.
Meyl (1955), however, considered Rh. fluviatilis, from Magdeburg, to be indistinguish-
able from Rh. marina var septentrionalis, also reporting Rh. m. var. marina from
the same area. We are able to confirm the validity of this synonymization since
our specimens agree in all particulars with the descriptions given by both Biistchli
and Hirschmann. Further evidence in support of this conclusion, and also our
refusal to accept two subspecies, is given by Andrassy (1958) who figures the range
of variation in the shape of the female tail in Rh. fluviatilis (see Andrassy, 1958.
Text-fig. II, C-E).
The records of Rh. marina show it to be widespread on the coasts of Europe and
the Mediterranean (see records from the coast of Algeria in Gerlach, 19540). It also
appears probable that it is common on the Atlantic coasts of both North and South
America but there are no wholly reliable records of it occurring anywhere else,
although it may later be shown to be cosmopolitan. The records from “ non-
marine ’’ localities, all of which are European, generally refer to it as a rare species
from habitats characterized by extreme decomposition (Hirschmann, 1952 and,
probably, Biitschli, 1876). Hirschmann records it at Regnitz and Pegnitz, Bavaria
from ‘‘ Wasser ... triib und stinkend ... ”’ while Meyl (1955) reports it,
also as a rare species, from several localities of fairly high salinity (Salzbiotopen)
near Magdeburg and Andrassy (1958) reports it from Hungary as a rare species
in heavily manured soil.
As Osche (1954) has pointed out, many of the records of so called marine species
of Rhabditis clearly represent species which have been swept into such localities
by accident and cannot be considered true marine forms. The position with Kh.
marina seems to be slightly different but we would still consider it a terrestrial
saprophagous form which is able to survive under conditions of fairly high salinity.
Many of the records of this species refer to specimens found in association with sea-
weeds in the littoral zone, but in most cases very few specimens have been found.
On the other hand Ditlevsen (1912) obtained relatively large numbers of specimens
from putrefying sea-weed and we also found large numbers under similar conditions.
It appears that Rh. marina is characteristic of such conditions of fairly extreme
decomposition and it is clear that the specimens found in the littoral zones have been
swept there by accident and almost certainly cannot live and reproduce under such
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 329
conditions. Nevertheless Rh. marina is unusual in being the species of Rhabditis
most commonly found on beaches so that it can be considered to represent a form
which is adapted to living under semi-marine conditions and must be treated as a
typical member of the beach fauna.
Rhabditis (Pellioditis) ehrenbaumi Bresslau and
Schuurmans Stekhoven, 1935
Synonymy :
Rhabditis ehvenbaumi Breslau & Schuurmans Stekhoven, in Schuurmans Stekhoven, 1935.
Tierw. N. -u. Ostsee 5 (b): 155. Figs. 3392-c; Bresslau & Schuurmans Stekhoven, 1940.
Marine Freilebende Nematoda aus der Nordsee, Bruxelles, p. 70. Taf. XIV, Abb. 80-81.
Rhabditis (Choriorhabditis) ehrenbaumi, Osche, Zool. Jb. (Syst. etc.) 81 : 263.
Rhabditis (Pellioditis) ehrenbaumi, Dougherty, 1955. J. Helminth. 29: 1 31.
Type locality: among Ceramium rubrum, Heligoland (no more precise locality
given).
Material studied
5 d, 8 9. (BM. (N.H.) Reg. Nos. 1960.32-41) from among rotting sea-weed
and other plant matter cast up on beach, just above high water mark, at Neyland,
Pembrokeshire, South Wales (August, 1959).
6 3, 6 9, 3 4th-stage larvae. (B.M. (N.H.) Reg. Nos. 1960.1213-1227) from
among very rotten and strong smelling sea-weed and other plant matter on beach at
bottom of cliff path, Jennicliffe Bay, Plymouth (July, 1960).
A few specimens were also found in rotting sea-weed mixed with other plant matter,
high on the beach at Weston-Super-Mare, Somerset. Rh. marina was also present
(see record above), (November, 1960).
Measurements : (specimens fixed in cold formalin and mounted in glycerine).
From Neyland
Males (5)
Body length
(mm.) a b c Vv
0-89 - 17-0 471 32°0 —
0-96 F 13°8 ; 3°4 3 27°4 —
1:05 9 16°8 3°2 c 25°3 —_
1-28 17:0 4°1 32-0 —
T2228 S 18-3 3°9 2-0 —
Females (8)
I-OI-1I-+45 14°2-18-2 3°6-4°6 17 *5-22°7 53-60
(1-271--0-145) (16-0841 -45) (4:01--0-118) (20-09-11 - 382) (56-12-21)
330 RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
From Jennicliffe Bay
Males (6)
Body length
(mm.) a b c Vv
1-33 . 16-6 4:0 B8E3 =
1-34 . 16°7 4°2 355 =
1°47 : 21-0 3°8 49°0 —_—
I-50 : 18-9 4°3 Svan S57
1-60 : 17°8 4°7 593 =
1-64 c 20°5 4°3 41:0 —
Females (6)
1-38 : 5/3 3°6 19°7 52°9
1°49 . 14-9 4:0 24-8 52°3
+56 c 19°5 4°2 22°3 55°8
1:62 4 20°3 41 18-0 53°7
I-62 5 20°3 4°2 20°3 54°3
1°64 4 18-2 3°9 18-2 56-7
Larvae
O75, 150 3°4 9° =
0:89 Pde 3°4 1a ae =
0-97 19-4 3°6 9°7 =
MORPHOLOGY
General
The body is relatively stout and terminates posteriorly in a very short tail in
both sexes. The specimens are in rather poor condition; they were killed and
fixed in cold formalin. There are no lateral fields but there appear to be distinct
narrow lateral alae running almost the full length of the body in both sexes. The
oesophagus is typical with the anterior part roughly the same width as the posterior
isthmus. The valves in the posterior bulb are marked with concentric semi-
elliptical ridges as in Rh. marina and the metastome bears five tubercles.
Head
The head is very similar to that of Rh. marina and the distribution of the cephalic
papillae seems to be the same, except that we have been unable to find any indication
of an inner circle of papillae. Although the outer two pairs of papillae are slightly
setiform, those of the inner circle appear to be wholly sessile. The amphids are
relatively prominent and the structure of the lip-lobes and the underlying lining of
the buccal cavity is identical with that of Rh. marina (Text-fig. 2c).
Male
The tail is short and broad, with very narrow caudal alae beyond which the
terminal spike of the tail does not project. There are ten pairs of narrow papillae,
or rays, supporting the alae, of which the most anterior pair lies alone, slightly
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 331
anterior to the cloacal opening. followed by a group of seven pairs which are all
roughly the same size except for those making up the second pair from the posterior
end which are distinctly longer and narrower than the others. The phasmids open
on the ventral surface of the tail just anterior to the long pair of papillae (Text-fig.
2h). The spicules are equal in length, identical in structure and are not fused.
They terminate posteriorly in simple sharp points and bear rather broad double
alae. The gubernaculum is about one third the length of the spicules and widens
anteriorly. There is a single testis which is reflexed and which does not appear
to have any ejaculatory glands (Text-fig. 1c).
Female
The reproductive apparatus is amphidelphic and didelphic with oviducts modified
as spermathecae as in Rh. marina. The eggs are relatively large and are spherical
Fic. 4. Rhabditis ehrenbaumi, outline of tail: a and b, larvae; c and d, adults.
(Scale line = 0-05 mm.)
|
in shape, about 0:035-0°045 mm. X 0°070-0:095 mm. in size. The greatest number
seen in the uteri at one time is six (Text-fig. 15). The tail is short and very stout
with a fine evenly narrowing terminal spike (Text-fig. 2k and Text-fig. 4). The
phasmids open just anteriorly to the commencement of the terminal spike. The
vulva opens slightly posteriorly to the middle of the body, V = 52-68.
Larva
The fourth-stage larva is very similar to the adults, the only marked difference,
other than those shown by the reproductive organs, is in the shape and proportions
332 RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES
of the tail. In the larvae it is much less stout, is relatively longer and tapers more
evenly than in the adult (Text-fig. 4). This is shown most clearly by the low value
of “c’’ (body length/tail length) in the larvae compared with the adults.
Discussion
This species, like Rh. marina, appears to be a terrestrial saprophagous form whose
presence among Ceramium rubrum at Heligoland was accidental, since the de-
composing matter among which we found it, although largely composed of sea-weed.
contained straw and other rotting terrestrial plant remains at all localities,
Further, the habitats at the localities in which it was found were relatively much
higher up the beach than those from which Rh. marina alone was obtained and it is
doubtful if this species may even be considered a typical member of the beach
fauna as Rh. marina certainly can be. The whole question cannot be resolved at
this time as our records are the first reports of this species since the original
description.
ACKNOWLEDGEMENTS
Our thanks are due to Mrs. W. P. C. Tenison for translations from Hungarian ;
to the Director, Dr. F. S. Russell, C.B.E., F.R.S., and staff of the Marine Laboratory,
Plymouth for the facilities made available to us at Plymouth during June, 1958
(J. W. C.) and July, 1960 (W. G. I.) and to Mr. Douglas Bremner, B.Sc., University
of Aberdeen for sending us specimens.
REFERENCES
ALLGEN, C. A. 1932. Weitere Beitrage zur Kenntnis der marinen Nematodenfauna de Camp-
bellinsel. Nytt. Mag. Naturv. 70 : 97-108.
1933. Freilebende Nematoden aus dem Trondhjemsfjord. Capita Zool. 4, Afl. 2 : 1-162.
— 1950. Westschwedische marine litorale und terrestrische Nematoden. Ark. f. Zoologi,
Ser. 2, 1: 301-344. :
— 1959. Free-living marine nematodes. Further zool. Res. Swed. Antarct. Exped. 5 (2):
1-293.
Anprassy, IstvAN. 1958. Szabadoneto fondlfergek Nematoda Libera. [Fauna Hung. 36]
Mag. Allatvil. 3 (1) : 1-362.
Bastian, H.C. 1865. Monograph on the Anguillulidae, or Free Nematodes, marine, land and
freshwater with descriptions of 100 new species. Tvans. Linn. Soc. Lond. 25 : 73-184.
BrESSLAU, E. & SCHUURMANS STEKHOVEN, J. H., Jr. 1940. Marine Freilebende Nematoden
aus dey Nordsee. 74 pp. Bruxelles: Musée royal d'Histoire naturelle de Belgique.
Birscuii, O. 1876. Untersuchungen iiber freilebende Nematoden und die Gattung Chaeto-
notus. Z. wiss. Zool. 26 : 363-413.
Cuitwoop, B.G. 1951. North American Marine Nematodes. Texas J. Sci. 4: 617-672.
Cuitwoop, B. G. & Cuitwoop, M. B. 1950. An Introduction to Nematology. Section I.
Anatomy. Revised edition.
De Coninck, L. A. P. & SCHUURMANS STEKHOVEN, J. H. Jr. 1933. The freeliving marine
nemas of the Belgian coast. II. Mém. Mus. Hist. nat. Belg. 58 : 1-163.
DITLEVSEN, H. 1912. Danish freeliving nematodes. Vidensk. Medd. naturh. Foren. Kbh.
63 : 213-256.
Geriacn, S. A. 1954a. Die freilebenden Nematoden der schleswigholsteinischen Kusten.
Schr. naturw. Ver. 27 : 44-69.
:
RHABDITIS (NEMATODA) FOUND ON BRITISH BEACHES 333
Gerwacu, S.A. 1954b. Nematodes marins libres des eaux Souterraines Littorales de Tunisie
et d’Algeri. Vie et Mileu, 4 : 221-237.
1956. Die Nematodenbesiedlung des tropischen Brandungsstrandes von Pernambuco.
Brasilianische Meeres-Nematoden II. Kieley Meeresforsch. 12 : 202-218.
HirscuMann, H. 1952. Die Nematoden der Wassergrenze mittelfrankischer GewdAsser.
Zool. Jb. (Syst. &c.) 81 : 313-407.
Mey, N. H. 1955. Freilebende Nematoden aus binnenland Salzbiotopen zwischen Braun-
schweig Magdeburg. Aych. Hydrobiol. 50 : 569-614.
OscHE, G. 1954. Ein Beitrag zur Kenntnis mariner Rhabditis-Arten. Zool. Anz. 152: 242—
251.
Otto, G. 1936. Die Fauna der Enteromorpha Zone der Kieler Bucht. Kieley Meevesforsch.
1: 1-48.
ScHuLze, E. 1932. Beitrage zur Kenntnis mariner Nematoden aus der Kieler Bucht. Zool.
Jb. (Syst. &c.) 62 : 331-430.
SCHUURMANS STEKHOVEN, J. H., Jr. 1935. Nematoda errantia. Tierw. N.-u. Ostsee, 5b: 173 pp.
(Lief. 28).
STEINER, G. 1916. Freilebende Nematoden aus der Barentssee. Zool. Jb. (Syst. &c.), 39:
511-676.
1921. Beitrage zur Kenntnis mariner Nematoden. Zool. Jb. (Syst. &c.) 44 : 1-68.
Timm, R. W. 1956. Marine nematodes from the Bay of Bengal. I. Phasmidea. J. Bombay
nat. Hist. Soc. 54 : 87-90.
1960. The widespread occurrence of the hemizonid. Nematologica, 5 : 150.
ayy AGH MUSE,
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PRINTED IN GREAT BRITAIN BY
ADLARD AND SON LIMITED
BARTHOLOMEW PRESS, DORKING
THE DEALFISHES (TRACHIPTERIDAE)
OF THE MEDITERRANEAN AND
NORTH-EAST ATLANTIC
= JUN 1969
PRESENTED
be: G. PALMER
s BULLETIN OF
E BRITISH MUSEUM (NATURAL HISTORY)
Vol. 7 No. 7
LONDON: 1961
| THE DEALFISHES (TRACHIPTERIDAE) OF THE
MEDITERRANEAN AND NORTH-EAST
ATLANTIC
BY
G. PALMER
Department of Zoology, Brit. Mus. (Nat. Hist.)
Pp. 335-351 (with Pl. 62; 1 Text-fig.)
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 7
LONDON : 1961
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, is
issued in five series corresponding to the Departments
of the Museum, and an Historical Series.
Parts will appear at irregular intervals as they
become ready. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
within one calendar year.
This paper is Vol. 7, No. 7 of the Zoological series.
© Trustees of the British Museum, 1961
PRINTED BY ORDER OF THE TRUSTEES OF
THE BRITISH MUSEUM
Issued May, 1961 Price Eight Shillings
@HE DEALFISHES (TRACHIPTERIDAE) OF THE
MEDITERRANEAN AND NORTH-EAST
ATLANTIC
By G. PALMER,
Department of Zoology, Brit. Mus. (Nat. Hist.).
(With 3 Text-figs.)
SUMMARY
Sees VO peas
+
1. The species of Tvachipterus occurring in the Mediterranean and north-east Atlantic are
Teviewed.
2. Tvachipterus cristatus is considered to be generically distinct and is placed in a separate
genus.
3. Trachipterus gryphurus Lowe is regarded as a synonym of T. arcticus and T. pentastigma
Norman as a synonym of T. tvachypterus.
4. Comments are made on the young stages, sexual dimorphism and food of Trachipterids.
5. A brief description of the swim bladder is given.
INTRODUCTION
THE systematics of the fishes of the genus Tvachipterus (s.l.) are in a somewhat
confused state, the main reason for this being that these fishes are comparatively
rare in museum collections. Their fragility is such that few unmutilated examples
have been available for study, and many of the nominal species have been described
from single specimens. Furthermore, it is known that allometric growth occurs at
certain stages, the extent of which has not been fully investigated.
The present paper has resulted from the difficulty experienced in identifying a
juvenile example from the Orkneys.*
The Dealfishes are widely distributed and are known to occur in the Arctic,
_ Atlantic, Indo-Pacific and Mediterranean regions. Some thirty nominal species
_ have been described, but the work I have done on this family suggests that there
_ may be comparatively few species, each having a fairly wide geographical range.
In r86r Giinther listed nine species of Tvachipterus, eight of which were said to
occur in the Mediterranean and north east Atlantic. Since that time an additional
_ fifteen species have been described from various localities, including two from the
area under consideration, these latter being T. filicauda Costa (1862) and T. gavardi
Bounhiol (1923).
* For a comprehensive study of the order Allotriognathi, reference should be made to a series of
Papers to be published by Walters and others.
ZOOL. 7, 7. 23
338 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
In his work on the young stages of T. taenia, Emery (1878-79) was able to
demonstrate for the first time the changes that take place in these fishes during
successive growth stages and on the basis of this work came to the conclusion that
T. filicauda, T. spinolae, T. taenia and T. trachypterus were synonymous, being
different growth stages of the same form.
Liitken (1881) reduced still further the number of species and to-day it is generally
accepted that only three taxons should be recognized from the Mediterranean and
NE. Atlantic areas. These are T. arcticus, a northern form, and 7. trachypterus
and T. cristatus, both more southerly species. T. cvistatus differs so markedly from
the other two species that it warrants generic status. Walters and Fitch (1960)
have reached the same conclusion and I shall consequently be using their name in
preference to that which I was proposing to use.
The only other species which has been recorded from the North Atlantic is T.
trachyurus, described by Poey (1856-58). This is known only from the type, taken
off Cuba, and one other specimen taken off Florida in 1952, and appears to be con-
fined to the western North Atlantic. This species is quite distinct from both T.
arcticus and T. trachypterus, differing in the lower dorsal ray count (82) and in the
form of the gill-rakers, which in T. trachyurus lack the fringe of bristle-like setae
found in the other species.
In the past, the keys which have been provided for the distinction of the species
have been based largely on descriptions and not on an examination of actual speci-
mens. As an example, Goode and Bean (1896) ignored the work of Emery and
Liitken and gave a key to a number of species, which had been adapted from an
earlier work by Moreau (88x). More recently, Lozano y Rey (1947) and Smith
(1949) have given keys for the three forms currently recognized from this area.
As the species of the genus Tvachipterus (s.1.) here considered are now placed in
two genera, the following key for their separation has been included.
Key To THE MEDITERRANEAN AND N.E. ATLANTIC GENERA
1. Body scaleless; ventral profile not constricted behind vent. Lower rays of caudal
fin reduced to stumps in adults. Vertebrae 84 to 102. No bulbous flaps on fin-
rays at any stage. Colour pattern uniform silvery or brown, with usually 1 to 5
large dark blotches along sides of body A 3 a Trachipterus |
2. Deciduous cycloid scales present on body. Ventral profile crenulate and sharply |
constricted behind the vent. Lower caudal rays not so reduced as in Tvachipterus.
Vertebrae 62 to 69. Bulbous flaps present cn dorsal and pelvic rays in young
stages. Anumber of dark transverse markings along the trunk and caudal regions Zu
Trachipterus Gouan
Tvachipterus Gouan, 1770. Hist. Pisc. : r04 and 153 (Cepola trachypteva Gmelin).
Gymnogastey Briinnich, 1788. K. Dansk. vid Selsk. 3: 408 (arcticus).
Tvachypterus Schneider, 1801. Blochii Syst. Ichth. : 480 (taenia).
Bogmarus Schneider, 1801. Blochii Syst. Ichth. : 518 (islandicus).
Argyctius Rafinesque, 1810. Caratt. nuov. Gen. : 55 (quadvimaculatus).
Cephalepis Rafinesque, 1810. Ind. Ittiol. Siciliana : 54 (octomaculatus).
Epidesmus Ranzani, 1818. Opusc. Sci. Bologna : 137 (maculatus).
> I
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 339
Body elongate, compressed, scaleless ; dorsal and ventral outlines tapering more
or less evenly from head to caudal fin. Recurved, pointed teeth in both jaws,
6 to 12 in the upper, 6 to ro in the lower. Vomer with 1 to 2 median teeth. Palatine
teeth, if present, feeble. Nostrils single. One dorsal fin, consisting of 145 to 190
rays, the first 5 or 6 elongate, at least in the young. Pectorals of 9 to 12 rays.
Pelvics 3 to g, long and filamentous in young stages but reduced to stumps in adults.
No anal fin. Caudal fin in two parts; the upper lobe of 6 to 10 well developed
trays, often set at right angles to the longitudinal axis of the body; the lower lobe
of 2 to 7 rudimentary rays in adults. Lateral line straight, running the length of
the body, armed with small forwardly directed spines which become larger posteriorly.
Gill rakers on first arch 3 to 4+ 7 to 10. Branchiostegal rays 6. Vertebrae 84
to 102. Swim bladder present, much reduced in adults.
Key to MEDITERRANEAN AND N.E. ATLANTIC SPECIES
1. Greatest depth of body } to 4 of the way along its length, except in specimens of less
than 300 mm.; depth of caudal peduncle contained more than twice in depth of
body at roth lateral line spine forward from the caudal fin. Body axis approxi-
mately a straight line in adults (see Pl. 62, fig. 1) 5 ¢ 5 : : arcticus
2. Greatest depth of body immediately behind head; depth of caudal peduncle con-
tained less than twice in depth of body at roth lateral line spine forward from caudal
fin. Body axis upcurved in the posterior caudal region in adults (see Pl. 62, fig. 2)
trachypterus
Trachipterus arcticus (Brinnich)
Trichiurus lepturus Mohr, 1786 (nec Linnaeus). Forsog til en Islandsk Naturhist. Copen-
hagen : 63 (Iceland) ; Palsson, 1791-97 (1945). J. Naturf. Reise Island : 36 and 187 (Iceland)
(fide Saemundsson, 1949); Hoy, 1815. Tvans. Linn. Soc. Lond. 11: 210 (Moray Firth).
Gymnogaster arcticus Briinnich, 1788. K. Dansk. Selssky. N. Saml. 3: 408 tab. B, figs. 1-3
(Iceland) ; Faber, 1829. Naturg. Fische Islands : 66 (general) ; Cuvier, 1829. Regn. Anim.
Ed. 2: 219 (description) ; Fleming, 1831. Ann. Mag. nat. Hist. 4: 215, fig. 34 (Orkneys);
Nilsson, 1832. Prod. Ichth. Scand.: 107 (synonymy, distribution); Jenyns, 1835. Brit.
Vert. : 372 (synonymy, description) ; Swainson, 1839. Nat. Hist. Fishes, Amphib., Rept.
2: 258 (generic diagnoses) ; Duduid, 1851. Proc. zool. Soc. Lond. : 116 (Orkneys).
Bogmarus islandicus Schneider, 1801. Blochii Syst. Ichth. 2: 518, pl. ror (Iceland).
Trachypterus aycticus, Nilsson, 1855. Skand. Faun. Fisk. 4: 162 (Scandinavia); Giinther,
1861. Cat. Fish. Brit. Mus. 3 : 305-306 (synonymy, description) ; Collett, 1875. Norges
Fiske, Christiania: 78 (Norway); Newman, 1875. Zoologist (2) 10: 434 (Donegal Bay) ;
Edwards, 1879. Zoologist (3) 3: 220 (Banffshire coast); Day, 1880-84. Fishes of Great
Britain and Iveland 1: 217, pl. 63 (synonymy, description); Liitken, 1882. Vid. Selsk.
Forh. : 206-216 (synonymy) (translated in Ann. Mag. nat. Hist. (5) 11: 176-184, 1883) ;
Schneider, 1882. Vid. Selsk. Forh. No. 15: 1-6 fig. (Scandinavia) ; Collett, 1885. Norges
Fiske, Christiania (2nd suppl.) : 69 (Norway); Meek, 1890. Stud. Dundee Mus. 1, No. 6:
I-24, 2 pls., 9 figs. (anatomy); Lilljeborg, 1891. Sver. Norges Fiskay. Uppsala 1: 462
(synonymy, description) ; Smitt, 1893. Scandinavian Fishes 1 : 315, fig. (general) ; Goode
and Bean, 1895. Oceanic Ichth.: 479, fig. (synonymy); Traquair, 1896. Amn. Scot. nat.
Hist.:159 (Shetland Isl.) ; Cursiter, 1896. Amn. Scot. nat. Hist.: 160 (Orkneys); Clarke,
1900. Ann. Scot. nat. Hist.: 13 (Firth of Forth); Collett, 1902-05. Norges Fiske, Christiania
(3rd suppl.), No. 1:99 (Norway); Lemmon, 1905. Ann. Scot. nat. Hist. :184 (Banffshire
340 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
coast); Evans, 1909. Ann. Scot. nat. Hist.: 20 (Scottish coast); Cole, 1913. Nature,
91: 607 (Grimsby Mkt); Thompson, 1918. Scot. Nat.: 67-68 (Rockall and St. Kilda) ;
Wolleback, 1924. Norges Fiske, Christiania: 218 (distribution); ? Barnard, 1925. Ann.
S. Afr. Mus. 21, Pt. 1 : 353, fig. (doubtful S. African record) ; Saemundsson, 1926. Fiskarnir,
Reykjavik : 155 (Iceland) ; Matheson, 1930. Ann. Mag. nat. Hist. (10) 6: 683-685 (west of
Treland) ; Buen, 1935. Inst. esp. Oceanogr. Not. y Res. (2) No. 88:78 (Atlantic) ; Nobre,
1935. Peixes de Portugal, 1: 162, fig. (Portugal); Ehrenbaum, 1936. Naturg. Wirtsch.
Bedeutung Seefische Nord-Europas, Stuttgart : 153, fig. 129 (description, distribution) ; Lozano
y Rey, 1947. Fauna Ibevica, Peces, 2 : 693, fig. (key to species) ; Smith, 1949. Sea Fishes
of S. Africa : 142 (S. African record and key to species) ; Went, 1952. Irish Nat. J. 10: 302
(Ireland) ; Andryashev, 1954. Tabl. anal. Faune URSS No. 53: 207, fig. (description,
distribution).
Trachypterus bogmarus Cuv. and Val., 1835. Hist. nat. Poissons, 10 : 346 (synonymy, Norway) ;
Reinhardt, 1835-1836 (1837). K. dansk. vid. Selsk.: 3 (Faroe Isl.); Bonaparte, 1846.
Cat. met. Pesci Euvopei : 79 (synonymy).
Gymnetrus aycticus, Yarrell, 1836. Brit. Fishes, 1: 191 (description).
Trachypterus vogmarus Reinhardt, 1838. KK. dansk. vid Selsk. 7: 67 (Denmark) ; Hallgrimsson,
c. 1845 (1936). Islenzk Dyr, 3, Pt. 3-5: 98 (fide Saemundsson, 1949); Grondal, 1891.
Pisces Islandiae : 46 (fide Saemundsson, 1949).
Vogmarus islandicus, Reid, 1849. Ann. Mag. nat. Hist. (2) 3: 456 (Scotland).
Trachypterus gryphurus Lowe, 1850. Proc. Zool. Soc. Lond. : 248 (Madeira) ; Giinther, 1861.
Cat. Fish. Brit. Mus. 3: 301 (description) ; Goode and Bean, 1895. Oceanic Ichth.: 478
(description).
Tvachypterus ivis Priol. (nec Walbaum), 1944. Rev. Tvav. Off. Péche marit. 13 : 432, fig. (from
Germo stomach, off coast of Spain).
D. 150-190; A. 0; V. 5-6; P. 9-11; C. 8+ 5-6. Branchiostegal rays 6.
Vertebrae 99 to 102.
Body strongly compressed, greatest depth about midway between occiput and
vent in adults, from which point the body tapers more or less evenly dorsally and
ventrally to the caudal fin. Ventral profile conspicuously armed with wart-like
tubercles, especially in large specimens. Anterior profile of head straight, sharply
declivous in young when mouth is retracted. Eye of moderate size. Teeth in
upper jaw slender, almost horizontal, their distal ends pointing backwards. Usually
6 to 12 in number. Those in the lower jaw stronger, slightly recurved, 6 to 9 in
number. Three to 5 teeth on the vomer, none on the palatines. Gill rakers on
first arch 3 to 4+ 7to1o. A single dorsal fin, the first 5 or 6 rays greatly prolonged
in young stages, but never with bulbous flaps. Pelvics extremely elongate in
young stages, but vestigial in adults. Caudal fin in two parts, the upper lobe of
8 well developed rays, the lower lobe of 5 or 6 rudimentary rays. The upper lobe
of this fin is usually set at right angles to the body axis in adults. Scales absent,
except for a modified series along the lateral line, each of which is armed with a
small forwardly directed spine. These spines increase in size towards the posterior
end of the body. Scattered over the body are numerous small pit-like depressions,
the structure and function of which have not been studied. Stiiwitz (1840) figures
both the lateral line scales and the pit-like depressions.
Eighteen specimens have been examined, ranging in length from 32 to 1,630 mm.
The largest specimen to have been recorded in recent years is one of 2,515 mm. length,
trawled near the Porcupine Bank off the west coast of Ireland.
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 341
Colour: Silvery, with usually from 1 to 5 dark spots along the body. These
may completely disappear in large examples and the overall body colour become
brownish. In life, the dorsal fin is red.
I have examined Lowe’s unique example of T. gryphurus described by him in
1850 from Madeira. Although in a poor state of preservation, this specimen appears
to be conspecific with examples of T. arcticus. The accompanying table indicates
that T. gryphurus agrees more closely with T. arcticus than with T. trachypterus.
eryphurus arcticus tvachypterus
Average number of dorsal rays 2 170 (1) 5 169-5 (18) : 164-8 (44)
£ », vertebrae a 100 (I) 5 99 =«((18) : 90 (44)
Depth of caudal peduncle into depth
of body at roth lateral line spine
forward from caudal 5 5 2-5 (1) 2 2-2-5 (18) : I+3-2 (44)
The number of specimens of each species examined is indicated in brackets.
The type of T. gryphurus is here figured for the first time.
In younger stages of T. arcticus (i.e. specimens below 300 mm. in length) the
greatest depth of the body is immediately behind the head as in T. trachypterus,
but whereas in 7. arcticus this depth remains more or less constant to about 4} of
the way along the body length before the gradual tapering to the caudal begins, in
young examples of T. trachypterus this tapering commences immediately behind the
occiput.
T. arcticus is a north-eastern Atlantic species which does not seem to occur in the
western North Atlantic. It has not been possible to ascertain satisfactorily its
southerly limits from existing records, but it has not been reported from the Medi-
terranean.* There is one record from Madeiran waters and Priol (1944) figures and
describes ten juvenile examples of what he calls T. ivis from the stomach of an
albacore (Germo alalunga), which was captured north west of Finisterre. From
the information given, however, it is clear that these fishes are examples of T.
arcticus.
The breeding areas of this species do not appear to be known, but it is probable
that spawning occurs at considerable depths in off-shore waters. Andryashev
(1954) states that shoals of several hundreds of these fishes may be observed off the
north-east coast of Iceland, varying in length from 900 to 2,060 mm. Unfortunately,
no indication is given as to whether or not this is a seasonal occurrence. In this
connection, it is of interest to note the comparatively large influx of this species
into Scottish waters in the year 1954 when fifteen specimens were recorded, none
being less than 830 mm. in length.
It has been reported on a number of occasions by Scandinavian fishermen that
they have seen these fishes floating on their sides at or near the surface. A more
recent report of a similar occurrence has been made by Mr. S. Willis. In November,
* Since this paper went to press, I have seen a report by Planas and Vives (1956) which records the
Occurrence in the Mediterranean of three specimens of T. arcticus, 425-529 mm. in length.
342 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
1955, some 200 miles west of Lands End, he saw seven or eight objects of varying
size floating on the surface. Closer inspection showed that they were fishes and
from his description they were almost certainly examples of T. arcticus. He states
that they were floating on their sides, moving feebly as though stunned. The
reason for this behaviour is not apparent, but may be abnormal.
A juvenile example of this species has recently been received from Dr. J. H.
Fraser of Aberdeen. It was taken off the west coast of Ireland (54° 10’ N., 12° 10’
W.) in an oblique haul from 250 to o metres. A brief description of the specimen
is given below.
It is 32 mm. in standard length and appears to be one of the smallest examples of
this species reported on. At this stage it is apparent that ossification of the finrays
is not yet completed as the dorsal count is considerably lower than the mean for an
adult of this species. Similarly, only eight pectoral rays are at present ossified.
Caudad to the last stained dorsal ray and continuous with it is a lobe containing a
number of thin filamentous structures, which may be actinotrichia. There is also
a similar structure on the ventral surface, which is not present in the adult. The
vertebral count of 99, of which 45 are pre-caudal, places this specimen as an example
of T. arcticus. At this stage all the vertebrae are of approximately the same length.
The caudal fin consists of eight rays in the upper lobe and six on the ventral lobe.
The rays in this lower lobe are well developed in this specimen, although in the
adult they become obsolescent, as is the case with the pelvic rays. The pectorals
have eight ossified rays plus three or four which are still unossified.
Measurements and counts for this specimen are as follows :
Standard length: 32 mm.
D: 143 + unossified rays. The first five rays are elongate.
At 0,
Pectorals : 8 + 3 or 4 which are not yet ossified.
Pelvics: 8.
Caudal: 8 + 6.
Vertebrae : 99 (of which 45 are pre-caudal).
Greatest depth, which is immediately behind the occiput, 4 in the length.
DistTRIBUTION. Eastern North Atlantic from Iceland to Madeira and into the
North Sea.
Trachipterus trachypterus (Gmelin)
Cepola trachyptera Gmelin, 1788. Syst. Nat. 1, Pt. 3: 1187 (Adriatic).
Cepola iris Walbaum, 1792. Avrtedi Bibl. Philos. Ichth. 3: 617.
Trachypterus taenia Schneider, 1801. Blochii Syst. Ichth. 2: 480 (Adriatic) ; Bonaparte, 1846.
Cat. met. Pesci Euvopei No. 711: 78 (synonymy); Costa, 1850. Faun. régn. Napoli, 2: 3,
pl. ix; Erhard, 1858. Faun. dey Cycladen, Leipzig: 89 (Greek waters); Giinther, 1861.
Cat. Fish. Brit. Mus. 3: 302 (description) ; Canestrini, 1872. Fauna d’Italia, Pt. 3: 193
(description) ; Heldreich, 1878. La faune de Gréce, Athens: 87 (Greek waters); Emery,
1879. Mem. Atti R. Accad. Lincei, 3: 390 (growth stages); Emery, 1879. Mitt. zool. Sta.
..
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 343
Naples, 1: 581 (growth stages); Giglioli, 1880. Elenco det Mammiferi, etc.: 92 (Nice and
Elba) ; Gogorza, 1883. Ann. Soc. esp. Hist. nat. 12:75, 78 (Mediterranean) ; Apostolides,
1883. La péche en Gréce, Athens: 11, 23 (Greece); Carus, 1889. Pyvod. Faun. medit. : 699
(description and distribution) ; Apostolides, 1907. La péche en Gréce (2nd Ed.):8, 16
(Greece) ; Fage, 1907. Arch. zool. exp. gen. (4) 7: 73 (listed from Balearic Isl.) ; Lo Bianco,
1908-1909. Mitt. zool. Sta. Naples, 19:1, figs. (eggs and larvae); Jacino, 1909. Arch.
zool. Naples, 3, Fasc. 4: 479 (eggs and larvae); Kaschkaroff, 1913. Anat. Anz. 44: 214
(structure of epidermis) ; Devedjian, 1926. Péches et pécheries en Turquie : 144, fig. (Turkish
coast); Bertin, 1929. Bull. Soc. zool. Fy. 54: 164 (description) ; Sparta, 1931. Fauna e
flora del Golfo di Napoli, 38: 267 (young stages) ; Dieuzeide and Goeau-Brissoniere, 1940.
Bull. Sta. Aquic. Péche, Castiglione (N.s.), No. 1: 81, figs. (Algeria) ; Dieuzeide, Novella
and Roland, 1954. Bull. Sta. Aquic. Péche, Castiglione (N.s.), No. 5: 146, figs. (description,
distribution).
Gymnetrus cepedianus Risso, 1810. Ichth. Nice, Paris: 146, fig. (Mediterranean) ; Risso, 1826.
Hist. nat. Europ. mérid. 3 : 295 (description).
Argyctius quadrimaculatus Rafinesque, 1810. Caratt. alcun. nuov. Gen. Siciliana : 55 (Sicily).
Cephalepis octomaculatus Rafinesque, 1810. Indice ittiol. Siciliana: 55 (Messina) ; Swainson,
1839. Fishes, Amphib. Rept. 2: 404 (description)
Epidesmus maculatus Ranzani, 1818. Opusc. Sci. Bologna, 2: 133, pl. 6 (Adriatic).
B(v)ogmarus aristotelis Risso, 1820. J. Phys. Chim. Hist. nat. Paris, 91 : 249 (Nice).
Bogmarus mediterraneus Otto, 1821. Conspic. Anim. : 6 (Mediterranean).
Regalecus maculatus, Nardo, 1824. Guiorn. Fisica, Pavie, 8: 116 (not seen; fide Costa, Faune
Régne Napoli).
Trichiurus trimaculatus Giovene, 1829. Mem. Soc. ital. 20, Pt. 1: 25 (Mediterranean).
Trachypterus spinolae Cuvier and Valenciennes, 1835. Hist. nat. Poissons, 10: 328 (Nice) ;
Bonaparte, 1846. Cat. met. Pesci Europei, No. 712:79 (synonymy; Mediterranean) ;
Canestrini, 1861. Aych. Zool. Anat. Fis. Genova, 1, Fasc. 1 : 26 (Gulf of Genoa) ; Giinther,
1861. Cat. Fish. Brit. Mus. 3 : 300 (description and distribution) ; Canestrini, 1872. Fauna
d'Italia, Pt. 3: 193 (Naples, Sicily); Giglioli, 1880. Elenco dei Mammiferi, etc. : 91 (Nice,
Elba, Naples) ; Moreau, 1881. Hist. nat. Poissons, 2 : 565, fig. (description and synonymy) ;
Bertin, 1946. Petit Atlas des Poissons, 1: 81, fig. (brief diagnosis).
Trachypterus falx Cuvier and Valenciennes, 1835. Hist. nat. Poissons, 10 : 333 (Spain) ; Moreau,
1881. Hist. nat. Poissons, 2: 558 (description and synonymy); Fage, 1907. Arch. Zool.
exp. gén. (4) 7: 73 (listed from Balearic Islands).
Trachypterus ivis, Cuvier and Valenciennes, 1835. Hist. nat. Poissons, 10: 341, pl. (Adriatic) ;
Giinther, 1861. Cat. Fish. Brit. Mus. 3 : 303 (description, distribution) ; Canestrini, 1861.
Arch. Zool Anat. Fis. Genova, 1, Fasc. 1 : 262 (Gulf of Genoa) ; Carruccio, 1870. Cat. degli
Anim. Sicilia: 32 (Cagliari); Emery, 1879. Zool. Sta. Napoli, 1: 581 (young stages) ;
Giglioli, 1880. Elenco dei Mammiferi, etc. : 92 (Livorno, Elba and Cagliari) ; Moreau, 1881.
Hist. nat. Poissons, 2: 561 (description, synonymy); Goode and Bean, 1895. Oceanic
Ichth. : 477, fig. (description, synonymy) ; Damiani, 1896. iv. ital. Sci. nat. Siena, 16 : 132
(Genoa) ; Parona, 1898. Atti Soc. Ligust. Sci. Genova, 9: 350 (Ligurian Sea); Barnard,
1925. Ann. S. Afr. Mus., 21: 353 (S. Africa); Buen, F. de, 1926. Res. Camp. Inst. esp.
Oceanogr. No. 2: 72 (Catalan Sea, Balearic Isl.) ; Mourgue, 1931. Bull. Soc. Linn. Lyon,
10: 39 (abundance in Mediterranean) ; Kamohara, 1934. Zool. Mag. Tokyo, 46: 462, fig.
(Japan); Buen, F. de, Inst. esp. Oceanogr. Not. y Res. (2), No. 88:78 (Mediterranean) ;
Ninni, 1939. Ati Soc. ital. Milan, 78 : 224 (synonymy); Matsubara, 1941. Suisan Kenkiu-
shi Japan, 36, No. 2: 34 (Japan) ; Lozano y Rey, Fauna Iberica Peces, 2 : 686, figs. (descrip-
tion, synonymy) ; ? Barnard, 1947. A pictorial guide to S. African fishes, Cape Town: 84,
pl. X, fig. 2 (Table Bay; the figure is that of T. avcticus) ; King and Ikehara, 1956. Pac.
Sci. 10 : 22-23 (Central Pacific).
Trachypterus leiopterus Cuvier and Valenciennes, 1835. Hist. nat. Poissons, 10: 342 (Naples
and Nice); Giinther, 1861. Cat. Fish. Brit. Mus. 3: 304 (description, distribution) ;
Giglioli, 1880, Elenco dei Mammiferi, etc.:92 (Nice, Genoa, Messina); Moreau, 1881.
344 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
Hist. nat. Poissons, 2: 563 (description, synonymy); Carus, 1889-1893. Prod. Faun.
Médit. : 700 (description, distribution) ; Goode and Bean, 1895. Oceanic Ichth. : 479 (general
notes); Damiani, 1896. Riv. ital. Sci. nat. Siena, 16: 132 (Genoa); Parona, 1898. Ath
Soc. Ligust. Sci. Genova, 9: 350 (Ligurian Sea); Tortonese and Trotti, 1950. Atti Acad.
Ligure, 6 : 99 (Ligurian Sea).
Trvachypterus costae Cocco, 1838. Giorn. Il Faro, 4, Anno 6: 4, figs. ta and b. (Messina).
Cephalepis swainsonii Rafinesque in Swainson, 1839. Fishes, Amphib. Rept. 2: 404 (Sicily).
Trachypterus vondeletii Costa, 1850. Fauna Regn. Napoli, 2: 10, fig. 1X bis (Naples).
Trachypterus viippellii Giinther, 1861. Cat. Fish. Brit. Mus. 3: 304 (Mediterranean) ; Carus,
1889-93. Prod. Faun. Médit. : 700 (description) ; Goode and Bean, 1895. Oceanic Ichth. :
479 (references copied).
Trachypterus trachypterus, Hamilton, 1916. Tvans. Proc. N.Z. Inst. 48 : 374, figs. (review of
New Zealand species) ; Pietschmann, 1925. Veroff. naturhist. Mus. Wien, 5: 6, figs. (popular
account) ; Phillipps, 1927. Fish. Bull. Wellington, N.Z., No. 1 : 26 (listed from New Zealand) ;
Fowler, 1936. Bull. Amey. Mus. nat. Hist. 70: 492 (description) ; Tortonese, 1948. Bol.
Pesca Piscic. Idvobiol. 23 (N.S.) 2:19 (Aegean Sea); Tortonese and Trotti, 1950. Ath
Accad. Ligure, 6:99 (Ligurian Sea); Tortonese, 1952. Natura, Milan, 43:28 (Ligurian
Sea).
Trachypterus pentastigma Norman, 1922. Ann. Mag. nat. Hist. (9) 10: 217 (Japan) ; Matsubara,
1941. Suisan Kenkui-shi, 36, No. 2: 34 (affinities).
Trachypterus arcticus, Barnard (nec Briinnich), 1948. Ann. S. Afr. Mus. 36: 359, fig. (S.
Africa).
D. 145-185; A. 0; V.5; P. 9-11; C.8+5 rudiments; branchiostegal, rays
6; Vertebrae, 84-06.
This species occurs in large numbers in the Mediterranean, which appears to be
one of its main spawning areas. Eggs and larvae, as well as adults, have been
recorded from this sea on many occasions. It has also been recorded from Japan
(Norman, 1922 ; Kamohara, 1934 and Matsubara, 1941) and New Zealand (Hamilton,
1916; Phillipps, 1927).
I have examined the type of 7. pentastigma described by Norman (1922) from
Misaki, Japan, and have come to the conclusion that Matsubara (1941) was correct
in synonymizing this species with T. trachypterus. A comparison of this specimen
with one of equal length from the Mediterranean shows that there is no significant
difference in vertebral or fin-ray counts. There is a difference in the proportional
body depth of the two examples, the Mediterranean specimen having a slightly
deeper body. This character, however, is a known variable in this group of fishes
and it is also obvious from the proportions given by Norman that the Japanese
example has shrunk appreciably since being examined by him. This specimen has
a pattern of five dark blotches along the side of the body, whereas T. trachypterus
has usually three to four of these markings. This is not constant, however, as
several of the Mediterranean specimens which I have examined also show a pattern
of five dark blotches.
It may be noted that 7. pentastigma appears to be very similar, both in meristic
counts and in markings, to T. vex-salmonorum described from San Francisco Bay
by Jordan and Gilbert (1894) of which 7. selenivis Snyder (1908) from Monterey
Bay, California isasynonym. T. arawatae Clark (1880) from New Zealand may well
be synonymous with the above, but these records are all outside the area covered in
this paper.
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 345
There is an important error in the original description of T. pentastigma, Norman
stating that the jaws of the specimen are without teeth. A careful examination of
the holotype, however, reveals the presence of slender teeth in both jaws, the number
and form of which are similar to those found in other specimens of Tvachipterus.
The large specimen from the Mediterranean described by Giinther (1861) as T.
vuippelliz, although in a poor state of preservation, is undoubtedly an adult example
of T. trachypterus. I have been unable to find any characters that could warrant
this specimen being considered specifically distinct.
Barnard (1947) mentions and figures specimens from South Africa, which he
considers to be examples of 7. tvachypterus. I include these records with some
hesitation as I believe that they are more properly referable to the Australian
species T. jacksonensis. The same author (1948) lists a fully grown female under
the name T. arcticus. It is clear from the figure that this specimen is an example
of T. trachypterus and Barnard himself indicates some doubt as to the specific
identity of this fish. King and Ikehara (1956) record an example of T. trachypterus
from the Central Pacific.
Fourty-four specimens have been examined, ranging in length from 81 to 1,700 mm.
The coloration and markings are similar to those of the previous species.
DISTRIBUTION. Mediterranean, S. Africa, Central Pacific, Japan, New Zealand.
Zu Walters and Fitch
Zu Walters and Fitch, 1960. Calif. Fish Game, 46: 445
Body elongate, laterally compressed. The caudal region sharply constricted
dorso-ventrally behind the vent. Twelve to 18 strong caniniform teeth in the
upper jaw, 8 to 12 in the lower jaw, with smaller teeth at the symphysis. omer
with 4 strong teeth, both palatines with 3 teeth. Nostrils as in Tvachipterus.
Dorsal fin consisting of 120 to 150 rays, the first 5 elongate. Pectorals with 11 to
IZ rays, pelvics with 3 to 6 rays, present at all stages. No anal fin. Caudal fin in
two parts, the upper fan-like of 8 to 12 rays, the lower of 1 to 5 rays. These latter
are reduced, but are not rudimentary as in Tvachipterus. Ventral edge of body not
covered with wart-like tubercles. Lateral line armed, straight as far as the ventral
constriction where it joins the lower edge of the body. Posteriorly from this point
the ventral edge of the caudal region is armed with an additional paired series of
downwardly directed spines, one on either side of the body. Deciduous cycloid
scales present. Gill-rakers on first arch 3+1-+ 8. Branchiostegal rays, 6.
Vertebrae, 64-65. Swim bladder present, though much reduced in adults. In
young stages bulbous flaps are present on the elongate dorsal and pelvic rays.
Type: Trachypterus cristatus Bonelli, 1820.
DisTRIBUTION. Mediterranean; S. Atlantic; Indo-Pacific; Japan.
Closely related to Trachipterus, from which it differs in having fewer vertebrae
and a stronger dentition, in the presence of scales and in the shape of the ventral
profile of the body and of the caudal fin.
346 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
Zu cristatus (Bonelli)
Trachypterus cristatus Bonelli, 1820. Mem. Acad. Sci. Turin, 24: 487 (Gulf of Spezia) ;
Giinther, 1861. Cat. Fish. Brit. Mus. 3: 301 (description); Giglioli, 1880. Elenco dei
Mammiferi, etc.: 91 (Nice); Moreau, 1881. Hist. nat. Poissons, 2: 567 (description, dis-
tribution) ; Carus, 1889-1893. Pyvod. Faun. Médit.: 700 (description, distribution) ; Goode
and Bean, 1895. Oceanic Ichth.: 479 (description, distribution) ; Parona, 1898. Ati Soc.
Ligur. Sci. Genova, 9 : 350 (Ligurian Sea) ; Fage, 1907. Avrch. Zool. exp. gén. (4) 7: 73 (listed
from Balearic Islands) ; Sanzo, 1918. Mem. R. Como Talass. ital. Venice, 64: 1-15 (eggs and
larvae); Argilas, 1928. Bull. Sta. Aquic. Péche Castiglione Fasc. 1:27, 2 figs. (Algeria) ;
Sparta, 1931. Fauna e Flora del Golfo di Napoli, 38: 272 (young stages); Stephanidis,
1939. Acta Inst. Mus. zool, Univ. Athens, 2: 246, fig. (Greek waters) ; Lozano y Rey, 1947.
Mem. R. Acad. Cienc. Madrid, 9 : 689 (description, distribution) ; Smith, 1949. Ann. Mag.
nat. Hist. (12) 2:99 (Durban); Smith, 1949. Sea Fishes of Southern Africa: 142, fig.
(description, distribution) ; Tortonese and Trotti, 1950. Atti Acad. Ligure, 6:99 (Gulf of
Spezia) ; Dieuzeide, Novella and Roland, 1954. Bull. Sta. Aquic. Péche Castighone (N.S.),
No. 5: 151, figs. (Algeria) ; Tortonese, 1958. Doriana, 2, No. 89: 1-5 (Ligurian Sea).
Gymnetrus vepandus Metaxa, 1833. Ann. Med. Chirug. Roma Fasc. 1 : 53 (Gulf of Naples).
Trachypterus bonelli Cuvier and Valenciennes, 1835. Hist. nat. Poissons, 10: 331 (Mediter-
ranean) ; Canestrini, 1862. Arch. Zool. Anat. Fis. Genova, 1, Fasc. 1 : 266 (Gulf of Genoa).
Gymnetrus miillerianus Risso, 1840. Arch. naturgesch. Berlin, 6 : 13 (Nice).
Trachypterus repandus, Costa, 1850. Fauna Regn. Napoli, 2: 11, pl. (Mediterranean) ; Bona-
parte, 1846. Cat. met. Pesci Euvopei: 79 (synonymy); Steindachner, 1868. S.K. Akad.
Wiss. Wien, 57: 676 (Alicante) ; Canestrini, 1871-72. Fauna d'Italia Pesci: 194 (descrip-
tion) ; Giglioli, 1880. Elenco dei Mammiferi, etc.: 92 (Naples); Goode and Bean, 1895.
Oceanic Ichth. : 480 (description) ; Pietschmann, 1925. Verdéff. naturhist. Mus. Wien, 5: figs.
I-3.
Trachypterus ivis Buen (nec Walbaum), 1917. Bol. Pesca Madrid, 2 : 23-26, 2 figs. (description,
distribution).
Trachypterus gavavdi Bounhiol in Bounhiol and Gavard, 1923. Bull. Inst. Oceanogr. Monaco,
No. 432 : 1-4 (Bay of Algiers) ; Weber and de Beaufort, 1929. Fishes of the Indo-Australian
Archipelago, 5: ot (references).
D. 120-150; A.o; V.6; P.11; C.8+ 4; Branchiostegal rays 6; Vertebrae
64-65; Gill rakers 3 + 1 -+ 8.
This species is markedly different from both species of Tvachipterus, as indicated
in the generic description. The most obvious character is the shape of the ventral
profile, which is scalloped and sharply constricted at the vent in this species, a
difference which is present in specimens of 30 mm. length upwards. It would
appear to attain to the same length as T. trachypterus, the longest specimen I have
seen recorded being 1,105 mm. in total length. This specimen was captured near
Genoa and reported on by Tortonese (1958). The body in this species is more
robust and the dentition stronger than in Tvachipterus.
Zu cristatus is found in the Mediterranean, from which area all stages have been
taken on numerous occasions. Outside the Mediterranean it has been reported
from Madeira and the Azores, with one record from Durban, S. Africa.
I have examined a larval form 32 mm. in standard length, taken by the “ Chal-
lenger ’’ near the Philippines and reported on by Giinther (1887) and another speci-
men 3I mm. in standard length, taken by the “‘ Discovery ’’ off the Cape of Good
Hope (33° 30’ S., 17° 29’ E.). Both these specimens are morphometrically indis-
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 347
tinguishable from Zu cristatus, and it may be that the genus Zw is monotypic.
Confirmation of this fact, however, must be left for Walters ef al. It is for this
reason that I have not included T. ijimae Jordan and Snyder 1gor from Japan or
T. semiphorus Bleeker 1868 from Amboina in the synonymy of Zu cristatus.
The colour pattern of this species is quite distinctive and consists of six or seven
incomplete dark wavy vertical bars dorsally, with three or four similar markings
on the ventral edge of the body. On the caudal region there are six or seven entire
vertical dark bands. The body is silvery, as in Tvachipterus, but with the addition
of deciduous cycloid scales. The caudal fin is usually dark brown to black in pre-
served material.
Twenty-six specimens have been examined, ranging in length from 31 to 655 mm.
DistRIBuTION. Mediterranean, Madeira, Azores, Durban, ? Cape of Good Hope,
? Philippines, ? New Zealand.
Young stages of Trachipterid fishes
Having had the opportunity of examining a number of young examples of each
of the three species dealt with here, it is evident that the characters present in the
young of this group persist until a definite developmental stage is attained. This
does not appear to be directly correlated with size alone, as in some instances smaller
sized individuals show fewer juvenile characters than other specimens of larger
size. In the majority of specimens examined, this change takes place within the
size limits of 50 and 70 mm. On the other hand, there is an example of the genus
Zu from the Philippines of 38 mm. length in which almost all trace of the juvenile
characters has already been lost. This suggests that the post larvae are pelagic
and that a triggering process is needed to set in motion this partial metamorphosis.
In specimens prior to this stage, the first 5 or 6 dorsal rays and the first 3 or 4
pelvic rays are greatly elongated, the caudal fin is still parallel to the body axis and
has not yet separated into the distinct upper and lower lobes found in the adult.
Not all the pectoral rays are fully ossified and this applies also to the rays of the
dorsal fin. Posteriorly there is a fin fold supported by actinotrichia. On the
ventral surface, opposite this posterior part of the dorsal fin, is a similar lobe. As
members of the family Trachipteridae do not possess an anal fin, the very numerous
and closely aggregated structures present in this ventral lobe, which show no basal
supports, are probably actinotrichia giving added strength to this structure whilst
it is of use to the larvae. Later, during the transitional stage from larva to adult,
the lobe is probably sloughed off or resorbed.
This is the condition mentioned by Clarke (1880) in his description of T. avawatae
from New Zealand. These two lobes, which he describes as dorsal and anal adipose
fins, are the main characters used to distinguish this form from related species.
Tt should be noted that these larval characters were still present in Clarke’s specimen,
which had attained a length of 65 mm. Ehrenbaum (1905) mentions the presence
of these lobes and both Emery (1879) and Smitt (1893) indicate the presence of a
similar structure in their figures of the young stages of T. trachypterus.
348 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
Finally, there is the growth that occurs in the vertebral column. In the juvenile
stages the caudal vertebrae are the same length as those anteriorly, but with growth
they elongate until in the adult they become two to four times as long as the anterior
vertebrae.
Sexual dimorphism in the Trachipteridae
Although sexual dimorphism may be present in this group of fishes, I have not
been able to show its occurrence from the material available to me. Attention
must be drawn, however, to the statement made by McCann (1953) in which he
says that such dimorphism does occur, as he has based these remarks on quite
erroneous grounds. He figures two undoubted examples of the genus Zu and com-
ments on other previously described specimens of the same genus, all of which he
regards as males of Tvachipterus arcticus, on the basis of a dissection made on one
example of what he terms an aberrant juvenile form.
Food of Trachipterid Fishes
A few authors have commented on the food of these fishes, although the majority
of those captured usually have an empty gut. It is clear, however, that they are
carnivorous. Moreau (1881) states that they feed on molluscs and small crustaceans.
McCann (i.c.) states that he has found the “‘ whitebait ’’ stage of other fishes in
stomach contents of Tvachipterus taken in New Zealand waters. Of the fifty or so
specimens which I have had the opportunity of examining, only three contained
identifiable remains in the gut. These consisted of a fairly complete example of an
isospondylid fish, Microstoma sp., from a specimen taken off Madeira; a mass of
penaeid prawns, Penaeus duodecimalis, and several squid beaks, probably Loligo,
from two further specimens taken in the Mediterranean.
Swim Bladder
It is known that the fishes of the order Allotriognathi possess a physoclistic swim
bladder (Regan, 1907 and Berg, 1947) and this condition has been verified in the
genera Lophotes and Velifer. The position appears to be somewhat uncertain,
however, so far as the Trachipteridae are concerned. Of the several authors who
have published accounts of the anatomy of these fishes Meek (1890), in describing
an example of T. arcticus, makes no mention of the presence of a swim bladder.
Other authors, notably Reid (1849), Smitt (1893) and Andryashev (1954), state
quite definitely that this organ is absent. As already mentioned Regan and Berg,
in their definition of the order, state that a swim bladder is present but make no
further reference to it in the diagnosis of the family.
In view of these conflicting statements I have examined two or three half-grown
and adult specimens of 7. arcticus, T. trachypterus and Zu cristatus of varying sizes,
together with a large example of Regalecus and have found that a swim bladder
has been present in each specimen. It is a small rudimentary structure, having
the appearance of a sac-like swelling, which lies dorsal to the oesophagus and a little
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 349
thelium; pv. lumen; E. gas gland; F. retia mirabilia.
Fic. 3. Composite T.S. of swim bladder. a. tunica externa; B. submucosa; c. inner epi-
|
|
350 MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES
to the right of the median line. In a specimen of T. trachypterus of 1,075 mm.
length, the swim bladder is approximately 8 mm. long. It is, therefore, not readily
visible except when dissecting the fish from the right-hand side. Stained transverse
sections of this structure show quite clearly, despite the regressed condition, the
presence of a gas gland with six or seven retia entering it. A small lumen is also
present (Text-fig. 3).
ACKNOWLEDGMENTS
My thanks are due to the following individuals and institutions for the loan of
material and for information and help given on numerous occasions.
Dr. V. Walters of the American Museum of Natural History ; Dr. P. Kahsbauer
of the Vienna Natural History Museum; Mr. G. P. Whitley of the Australian
Museum ; Dr. J. H. Fraser, Dr. B. B. Rae and Mr. E. Wilson of the Marine Labora-
tory, Aberdeen, Mr. F. Williams of Zanzibar, Dr. H. O. Bull of the Dove Marine
Laboratory, Cullercoats, and Mr. S. Willis. I am very grateful to my colleagues
in the Fish Section for their generous help and advice given during the preparation
of this paper.
REFERENCES
ANDRYASHEV, A. P. 1954. Fishes of the northern seas of the USSR. Tabl. Anal. Faune
URSS. No. 53 : 206-208.
BarnarD, K. H. 1947. A pictorial guide to South African fishes, Capetown : 84.
1948. Further notes on South African marine fishes. Ann. S. Afr. Mus. 36: 359,
fig. 17.
Bere, L.S. 1947. Classification of fishes both recent and fossil. Leningrad : 463.
BLEEKER, P. 1868. Description et figure d’une nouvelle espece de Tvachypterus de 1|'Ile
d’Amboine. Arch. neerl. Sci. nat. 3 : 279-280, fig.
Bounuiot, J. P. & Gavarp, —. 1923. Une espéce nouvelle de Trachypterus Gouan: le
Trachypterus gavardi Bounhiol. Bull. Inst. Oceanogr. Monaco. No. 432 : 1-4, I fig.
CLarRKE, F. E. 1880 (1881). Description of a new species of Tvachypterus (T. arawatae).
Trans. New Zealand Inst. 13 : 195-199, fig.
Costa, A. 1862. Diun piccolo Trachiptero. Ann. Mus. zool. Napoli, 1: 50-54, fig.
EHRENBAUM, E. 1905. Nordisches Plankton. Ever und Larven von Fischen, 4: 125-128
3 figs.
Emery, C. 1879. Le metamorfosi del Tvachypterus taenia. Mutt. zool. Sta. Neapel, 1 : 581-
588, 1 pl.
1879. Le metamorfosi del Tvachypterus taenia. Atti Accad. Rom. Mem. Sct. Fis. (3)
3 : 390-395.
Goober, G. B. & Bean, T. H. 1896. Oceanic Ichthyology. Mem. Mus. comp. Zool. Harvard.
22 : 476-480.
GuntHer, A. 1861. Cat. Fish. Brit. Mus. 3 : 300-306.
1887. Report on the deep-sea fishes collected by H.M.S. “‘ Challenger ’’ during the years
1873-1876. Rep. sci. Res. ‘ Challenger’ Zool. 22: 72.
Hamitton, H. 1916. Notes on the occurrence of the genus Tvachipterus in New Zealand.
Trans. Proc. N. Zealand Inst. 48 : 370-382, figs.
Jorpan, D. S. & Girpert, C.H. 1894. Description of a new species of ribbon fish (Tvachyp-
terus vex-salmonorum) from San Francisco. Proc. Calif. Acad. Sci. (2) 4: 144-146.
GAB WUE
ey ,aR4
MEDITERRANEAN AND NORTH-EAST ATLANTIC DEALFISHES 351
Jorpan, D. S. & SNypER, J.O. 1g01. Description of nine new species of fishes contained in
museums of Japan. J. Coll. Sci. imp. Univ. Tokyo, 15 : 310.
Kamouara, T. 1934. Supplementary notes on the fishes collected in the vicinity of Koti
(vii). Zool. Mag. Tokyo, 46: 462.
Kine, J. E. & Ikenara, I. I. 1956. Some unusual fishes from the Central Pacific. Pacific
Sci. 10 : 17-24, figs.
Lowe, R. T. 1850. An account of fishes discovered or observed in Madeira since the year
1842. Proc. zool. Soc. Lond. : 248.
Lozano y. Rey, L. 1947. Ictiologia iberica. Peces ganoideos y fisostomos. Mem. R. Acad.
Madrid, 2 : 681-694.
LitKen, C. F. 1882. Nogle bemaerkninger om vaagmaeren (Tvachypterus aycticus) og
sildetusten (Gymnetrus banksit). Overs. Dansk. vid. Selsk. Copenhagen, No. 2 : 206-216.
McCann, C.1953. Ichthyological notes, with special reference to sexual dimorphism in some
New Zealand fishes. Rec. Dom. Mus. Wellington, N.Z. 2 : 21-23, figs.
Matsupara, K. 1941. Studies on the deep sea fishes of Japan. XIII. On Professor Naka-
zawa’s collection of fishes referable to Isospondyli, Iniomi and Allotriognathi. Suisan
Kenkiu-shi, Japan, 36 : 34-37.
Meek, A. 1890. On the structure of Tvachypterus arcticus (the northern ribbon fish). Stud.
Dundee Mus. 1, No. 6: 1-24, figs.
Moreau, E. 1881. Hist. nat. Poissons de France, 2 : 558-570.
Norman, J. R. 1922. Two new fishes from New Britain and Japan. Ann. Mag. nat. Hist.
(9) 10: 217.
Puitirers, W. J. 1927. A check list of the fishes of New Zealand. J. Pan. Pac. res. Inst.
2:12.
1942-44. An immature Tvachipterus from French Pass. Rec. Dom. Mus. Wellington,
N.Z. 1, No. 2: 120-122, r pl.
Pranas, A. & Vives, F. 1956. Sobre la presencia de Trachypterus arctius (Briinn.) en el
Mediterraneo. Invest. Pesqg. Barcelona, 5: 135-138, 2 figs.
Pory, F. 1856-58. Mem. Hist. nat. Cuba, 2: 420.
Priot, E. P. 1944. Remarques sur quelques poissons recueillis dans l’estomac des thons.
Rev. Trav. Pech. marit. Paris, 13 : 432.
Recan, C.T. 1907. On the anatomy, classification and systematic position of the teleostean
fishes of the suborder Allotriognathi. Proc. zool. Soc. Lond. : 634-643, figs.
Rei, J. 1849. An account of a specimen of the vaagmaer or Vogmarus islandicus (Trachy-
plerus bogmarus of Cuvier and Valenciennes) thrown ashore in the Firth of Forth. Ann.
Mag. nat. Hist. (2) 3: 456-477, pl.
SaEMuUNDsSON, B. 1949. Zoology of Iceland, 4, Pt. 72 : 1-150.
SmitH, J. L. B. 1949. Forty-two fishes new to S. Africa, with notes on others. Ann. Mag.
nat. Hist. (12) 2:99.
SmitH, J. L. B. 1949. Sea fishes of Southern Africa : 141-142, 2 figs.
Smitt, F. A. 1893. A history of Scandinavian fishes (2nd Ed.) : 309-321, figs.
Snyper, J.O. 1908. Description of Tvachypterus selenivis, a new species of ribbon fish from
Monterey Bay, California. Proc. Acad. nat. Sci. Philadelphia, 60 : 319-320.
Sparta, A. 1933. Fauna e flora del Golfo di Napoli. Uove, larve e stadi giovanili di teleostet.
Monogr. 38 : 266-275, 1 pl., 6 figs.
Sttwitz, P. 1840. Efterretninger om en til Bergens Museum fra Nordland indsendt Tva-
chypterus. Nyt Mag. naturvidansk. Christiania, 2 : 277-296, 6 figs.
TorTONESE, E. 1958. Cattura di Tvachypterus cristatus Bon. e note sui Trachypteridae del
mare Ligure. Doriana, 11, No. 89: 1-5.
Watters, V. & Fitcu, J. E. 1960. The families and genera of the Lampridiform (Allo-
triognath) suborder Trachipteroidei. Calif. Fish. Game, 46: 441-451.
ZOOL. 7, 7. 24
PLATE 62
Fic. 1. Tvachipterus arcticus. Photograph of the holotype of Trachipterus gryphurus Lowe.
x +.
Fic. 2. Tvachipterus trachypterus. Photograph of the holotype of Tvachipterus pentastigma
Norman. x 14.
29) Hy Dick
19007 (H'N) ‘W'd 1"
PRINTED IN GREAT BRITAIN BY
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BARTHOLOMEW PRESS, DORKING
<4
A YOUNG MACRISTIUM AND
N. B. MARSHALL
~ 3 JU 1961
PRESENTED
= BULLETIN OF
BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 8
LONDON : 1961
A YOUNG MACRISTIUM AND
THE GX ENODTHRISSID FISHES
BY
N. B. MARSHALL
hi SEN] ED
Ph. 353-370; 4 Text-figures
BULLETIN OF
THE BRITISH MUSEUM (NATURAL HISTORY)
ZOOLOGY Vol. 7 No. 8
LONDON: 1961
THE BULLETIN OF THE BRITISH MUSEUM
(NATURAL HISTORY), instituted in 1949, is
issued in five series corresponding to the Departments
of the Museum, and an Historical series.
Parts will appear at irregular intervals as they become
veady. Volumes will contain about three or four
hundred pages, and will not necessarily be completed
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This paper is Vol. 7, No. 8 of the Zoological series.
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A YOUNG MACRISTIUM AND THE
CTENOTHRISSID FISHES
By N. B. MARSHALL
SYNOPSIS
A young fish, taken by ‘‘Discovery Investigations’ in the Bay of Biscay, has proved to be the
second known representative of Macristium chavesi Regan (1903), a species belonging to the
order Isospondyli (family Macristiidae). In fin pattern, which is unique among isospondylous
fishes gill cover structure, and branchiostegal ray complement, this species is very close to
the ctenothrissid fishes of Cretaceous strata.
Consideration of the functional design of the fins of “ lower ” teoleosts with thoracic (or near
thoracic) pelvic members suggests that the similarities between Macristium and the ctenothrissids
are not likely to be due to convergent evolution. Macristium would thus appear to be a modern
ctenothrissoid fish, a supposition to be fully tested when an adult specimen becomes available.
INTRODUCTION
In 1903, Mr. C. Tate Regan wrote a short report on some fishes brought back from the
Azores by Mr. W. R. Ogilvie Grant. One fish had a quite unusual appearance, but
Regan (1903) believed it to be most nearly related to Giinther’s genus Bathysaurus,
«« __. which it resembles in the position of the fins and the number of rays, but
with the mouth only moderately wide, the dentition weaker, the maxillary dilated
posteriorly, the fin rays much prolonged, and the ventrals still more anterior in
position.” Regan described the fish as a new genus and species, Macristium chavesi,
and placed it in the family Scopelidae.
When he came to revise the order Iniomi, Regan decided that closer scrutiny of the
fish (which was housed in the Punta Delgada Museum in the Azores), was desirable.
Having obtained the fish from Major F. A. Chaves, Regan (1911) revised his judge-
ment of its systematic position. These were his conclusions : “ Originally I believed
that Macristium was related to Bathysaurus Giinth, which it resembles in the position
of the fins and the number of rays. I am now of the opinion that this resemblance is
misleading, for I think that in all probability the praemaxillaries would not exclude
the maxillaries from the gape. In any case, Macristiwm must be made the type of a
distinct family, Macristiidae, probably related to the Alepocephalidae.””*
It is clear, then, that Regan believed Macristiwm to be an isospondylous fish. In
his classification of fishes, Berg (1947) puts this genus in the order Clupeiformes
(=Isospondyli), suborder Clupeoidei and places it immediately after the superfamily
Alepocephaloidae. But he remarks that the systematic position of the Macristiidae
is uncertain. This is also Gosline’s (1960) view.
1 Regan continues ; ‘‘ Before returning the fish to the Ponta Delgada Museum it seems best to make a
figure of it and to reinforce my original description.” But recent correspondence has revealed that the
type of Macristium chavesi is missing from this Museum,
ZOOL 7, 8. 25
356 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
When working on the Miripinnati (Bertelsen & Marshall, 1956), we were naturally
interested in the “ lower ’’, soft-rayed teleosts that have large pelvic fins set close to
the pectorals. We considered Macristium and two Upper Cretaceous families, the
Ctenothrissidae and the Chirothricidae, but concluded that the similarities in fin
pattern, which are certainly not very striking, could be convergent. (We might also
have included Pantodon, and would, no doubt, have come to the same conclusion.)
But this survey not only revealed that the Miripinnati are a natural and somewhat
isolated group within an “ iniomous complex ’’. It lead me to realize that there are
striking similarities between the fin patterns of Macristiwm and the ctenothrissid
fishes, which I discussed when reading a paper (unpublished) on the Miripinnati
(“ Some new oceanic fishes ’’) to the Challenger Society on 26th October, 1955.
Closer consideration can now be given to these possible, even probable indications
of a relationship between Macristiwm and the Ctenothrissidae. Recently when
looking through the unnamed Discovery Collections, I found a young Macristiwm
(taken in the middle part of the Bay of Biscay (Station 2072, 46° 31-6’ N., 07° 42-9’ W.,
TYFH, 170 (—o) m., 22.v.1937). Making due allowance for its immaturity, the
form and meristic features of this young fish are close to those of the type specimen
(Regan, 1903: 345; IgII: 204-205). Treatment of these aspects must obviously
form the first part of this paper. Then follows an assessment of the affinity between
Macristium and the ctenothrissids, an enquiry which has involved some consideration
of the functional significance of fin pattern in the lower soft-rayed teleosts with
thoracic (or near thoracic) pelvic fins.
A young Macristium chavesi Regan
(Text-figs. 1-3)
Locality : Discovery Station 2072 ; 22.v.1937; 46° 31-6’ N., 07° 42:9’ W. (middle
part of Bay of Biscay) ; TYFH 170 (—o) m.
Standard length of fish, 33-0 mm.; total length, 41-5 mm.
MerIstTic FEATURES
Dorsal rays, 17, the first ray a small splint closely applied to the next ray.
Anal rays, 13, the first ray splint-like.
Pectoral rays (left), 15, the uppermost ray a small splint.
Pelvic rays, 7.
Principal caudal rays, 10 + 9.
(None of the fin-rays is branched.)
Branchiostegal rays, Io.
Gill rakers on first arch, 3 + 1 + 13.
Number of myotomes, 61.
MEASUREMENTS (mm.) and proportions (in parentheses and expressed as percentages
of the standard length).
1. Head. Length, 6-5 mm. (19-7) ; length of snout, 2-1 (6-4) ; interorbital width,
c. 2:0 (6:0) ; horizontal diameter of eye, 1-4 (4:2) ; length of premaxillae, 1-3 (3:9) ;
length of maxillae, 2-0 (6-1) ; length of mandible, 3-3 (10-0).
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 357
2. Body (trunk and tail). Depth of body at origin of pelvic fins, 4-0 (12-1) ; depth
at origin of anal fin, 2-8 (8-5) ; depth of caudal peduncle, 1-5 (4:5) ; length of caudal
peduncle, 5-5 (16:7).
Fic. 1. Macristium chavesi Regan. Young fish from Discovery Station 2072 (x3).
3. Fin positions. Length between tip of snout and origin of dorsal fin, 10-0
(30:3) ; snout to origin of anal fin, 23-5 (71:2) ; snout to origin of pectoral fins, 7-5
(22-7) ; snout to origin of pelvic fins, 9-0 (27-2).
4. Fin size. Length of base of dorsal fin, 12-0 (37-9) ; length of longest dorsal ray
(and), 27-0 (81-8) ; length of base of anal fin, 5-0 (15-2) ; length of longest anal ray
(5th), 9-0 (27:3) ; length of longest pectoral rays (middle), 10-0 (30-3) ; length of
longest caudal rays, 8-5 (25-8); length of longest pelvic rays (2nd to 4th), 21-0
(63-7).
358 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
FIN PATTERN
The most striking features are the high, sail-like dorsal fin and the very extended
pelvic fins, which have a thoracic setting (in this young fish there appears to be no
attachment of pelvic to pectoral girdle). There is a regular and fairly sharp decrease
in the height of the dorsal fin after the longest (2nd) ray, the length of which is
about four-fifths of the standard length. The base of the fin extends along the greater
part of the trunk region (along rather less than half the combined extent of trunk and
tail). The longest rays of the pelvic fins (2nd to 4th) are just over three-quarters the
length of the second dorsal ray, and when applied along the body, extend to about
the middle of the caudal peduncle. The dorsal and pelvic fins arise at precisely
opposite points. A line joining their origins would come just behind the muscular
Fic. 2. Jaws of Discovery Macristium chavesi (x28). pmx, premaxilla; mx, maxilla ;
mxt, maxillary tooth.
bases of the pectoral fins, the rays of which are closely associated, forming relatively
long, paddle-shaped fins. The triangular anal fin originates 7 myotomes behind the
last dorsal ray, but this separation may be reduced when the dorsal fin is fully formed
(see p. 361). The longest rays of the anal and caudal fins are about equal in length and
are slightly shorter than the longest pectoral rays.
SCALES
The skin is without any trace of scaling.
JAWS AND DENTITION
The premaxillae and maxillae together form the biting edge of the upper jaw, their
contributions being about equal in extent (see Text-fig. 2). The maxillae are paddle-
shaped, the greatest width of the blade being about one-third the length of the bone.
——
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 359
They end just before the most forward parts of the eyes. The hinge between the
lower jaw and the suspensorium lies vertically under the middle region of the eyes.
The width of the jaw at the coronoid process is about one-third the length of the
mandible. Upper and lower jaw bones meet in a gape that is directed upwards and
makes an angle of about 40° with the long axis of the body.
Teeth are formed on the premaxillae, maxillae, dentaries, vomer, palatines and
tongue. They are pointed and recurved and are fairly large compared to the bones
that bear them. Each premaxilla has about 6 teeth. There is about the samen umber
of larger recurved teeth forming an inner row on each dentary. The outer row consists
of about ro teeth, which are about half the size of the inner members, A few teeth
can just be seen emerging from the dental lamina of each maxilla. The vomer bears
6 teeth (3 on each side), these being slightly larger than the premaxillary teeth. Each
palatine carries 3 teeth. The spatulate tongue is armed with a transverse row of 3
pointed, retrorse teeth, which emerge fairly close to the anterior border of this organ.
PSEUDOBRANCHIAE
Present.
BRAIN AND SENSE ORGANS
The mid-brain is large compared to the forebrain, which contains the olfactory
bulbs. The cerebellum is moderately well developed (Text-fig. 3).
The opening into each nasal sac is a single keyhole-shaped aperture. (As Regan,
Ig1I definitely states that there are 2 nostrils on either side of the snout, these
must be formed at a later stage.)
INTERNAL ORGANS
The intestine is quite straight except for a turn just before the anus (see Text-fig.
1). There is no evidence of a swimbladder.
MUSCULATURE
Except for the uppermost parts of the hypaxial myotomes (which arch over the
body cavity) this lower part of the body musculature is quite undeveloped. The lateral
and ventral walls of the body cavity are thus perfectly transparent (for the pigmenta-
tion is also in a larval condition).
PIGMENTATION
The most conspicuous features are 7 narrow, vertical bars of pigment, 3 being on
the trunk and 4 on the tail. The first bar, which does not extend above the horizontal
septum, is vertically under the 7th dorsal ray ; the second under the gth, the third
under 12th, and the fourth under the last dorsal ray. The fifth pigment bar is
opposite the 2nd anal ray, the sixth between the 8th and gth anal rays, and the
seventh is not far behind the last anal ray. There is also a narrow horizontal tract
of melanophores running just below the horizontal septum. (It begins just behind the
head and ends just before the anus.) There are 3 patches of pigment on the pelvic
X
360 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
fins (see Text-fig. 1) and scattered cells on the webs between the 3rd and 4th anal
rays. There is a fine peppering of small melanophores over the bases of the caudal
rays.
Fic. 3. Dorsal view of head of Discovery Macristium chavesi (X21). pmx, premaxilla ;
mx, maxilla; no, nostril; on, olfactory nerve; ob, olfactory bulb; fb, forebrain; so,
supraoccipital bone ; fy, frontal bone ; op, optic tectum ; cm, cerebellum ; pa, parietal
bone ; sc, semicircular canal; pt, post-temporal bone.
Comparison of this description with those given by Regan (1903 and 1911) indicates
that this young fish belongs to the genus Macristium and, most likely, to the species
‘ chavesi, Relevant comparative data will be found in Table I.
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 361
TaBLE I.—Comparison of Type of Macristium chavesi Regan with Discovery Specimen
Type specimen
(Regan, 1903 and ro1t) Discovery specimen
Standard length (S.L.) : P 110 mm. 33 mm.
Fin-ray formula : o . D.18; A. 12; Pct. 16; Pv. 8. D. 17; A. 13; Pct. 14; Pv. 7.
Principal caudal rays Principal caudal rays
10+9 10+9
Number of myotomes F 5 About 62 61
Number of branchiostegal rays . About 8 Io
Proportions :
Depth body intoS.L. . : 74 8}
Length head into S.L. : 5 5
Eye diameter into head . c Nearly 8 4%
Interorbital width into head . 34 G3
Base of dorsal fin intoS.L. . 24 23
Posterior extent of maxillae . To anterior quarter of eye To anterior rim of orbit
Origin of anal fin : ; . Just behind last dorsal ray Well behind (6 myotomes)
last dorsal ray
Scrutiny of this Table will reveal that the fin-ray and myotome numbers of the type
are quite close to those of the Discovery specimen. The one outstanding difference
in the proportional data concerns the eye diameter, which is slightly less than one-
eighth of the head length in the type and almost equal to one-quarter of this dimension
in the Discovery fish. However, the type (standard length, 110 mm.) is more than
three times as large as the present specimen (S.L., 33 mm.), and it is a general rule
that the relative size of the eyes decreases with growth, particularly during the earlier
life-history of fishes. Even so, the difference is more than that usually found within
any given species.
Reference to Text-fig. 4 will also show that the eyes of the type specimen are set
well below the interorbital level (not projecting above, as in the Discovery specimen).
Yet Regan (r911) states that the frontals are slightly raised above the eyes, which
may well be a structural indication of the earlier position and proportionately greater
size of these sense organs. If we also consider the damaged, and presumably shrunken,
condition of the type specimen, which Regan (1911) thought might have been washed
ashore, the divergence between the relative eye sizes seems more comprehensible.
The type specimen of Macristium chavesi is also somewhat deeper bodied than the
Discovery fish and has a relatively longer base to the dorsal fin. This last difference
may be coupled with another : according to Regan’s (1911) figure the last dorsal ray
appears to be no more than one myotome in advance of the first anal ray, whereas
in the Discovery specimen the separation between these 2 rays is about 6 myotomes.
However, Regan (1903) remarks that the anal fin begins “’ ... directly behind
the vent, which is slightly posterior to the last dorsal ray.” The separation between
the last dorsal and the first anal ray may thus be somewhat greater than that shown
in his (rg1r) figure. Furthermore, the last few dorsal rays of the Discovery fish
are in a very early stage of development, and it may well be that at a later stage the
gap between the 2 fins will close. Considerable changes in fin pattern, involving both
position and extension of a fin base are not uncommon during the early life-history
362 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
sei
:
ANY
N
\
YY
ae
\
ON
x»
SX
SA
SA
AY
SAR
NY
=
SS
Ly
Lf,
A
(a) Macristium chavesi Type specimen (from Regan, 1911). Reproduced by kind
Fic. 4.
permission of Taylor & Francis, Ltd. (b) Ctenothrissa radians (Agassiz) (from Woodward,
1903). Reproduced by kind permission of the Council of the Palaeontographical Society.
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 363
of teleosts. (In the sprat (Sprattus sprattus), for instance, the gap between the last
dorsal ray and the first anal ray decreases by 3 or 4 myotomes between post-larval
and adolescent stages.)
Apart from this dorsal-anal gap, there is very close agreement between the fin
position of both fishes (see Text-fig. 4). There are, however, differences in fin form.
In the type the posterior parts of the dorsal and anal fins are far better developed
than those of the Discovery fish. Yet, as already stated, the last few dorsal fin rays,
and also the last few anal rays, are in a very early stage of formation. The 5th pelvic
ray of the type, which appears to be complete, extends beyond the caudal peduncle,
being thus much “‘ in advance ”’ of the corresponding ray of the other fish. But again
the difference may be no more than that associated with particular phases of develop-
ment.
To conclude, having an awareness that the Discovery fish is little more than post-
larval in phase, there is no good reason for considering it to represent a second species
of Macristium. When the life-history of M. chavesi is adequately known we may
expect this young fish to fall into place in the earlier and more active phases, times
during which there are trenchant changes in form and function.
MACRISTIUM AND THE CTENOTHRISSID FISHES
Despite the thoracic position of their pelvic fins, Woodward (1903), considered the
Ctenothrissidae to be closely related to the existing Clupeidae. In his (rgor) Catalogue
of the Fossil Fishes in the British Museum (Natural History), the synopsis of Cretaceous
and Tertiary Isospondyli (p. 5) shows that besides the difference in position of the
pelvic fins, the two families can be distinguished in that the abdominal vertebrae of
-the ctenothrissids lack transverse processes. Reference to the definitions of the families
(Ctenothrissidae, p. 19 ; Clupeidae, p. 128) also reveals that there is some median
contact between the parietal bones of the first-named fishes. In the clupeids these
two skull bones are completely separated by a well-formed supraoccipital. The out-
standing common features of the two families (taken from these definitions) are as
follows: “ Premaxilla small and maxilla relatively large and loose, both these bones
entering the upper border of the mouth ; two supramaxillaries ; teeth acuminate, but
feeble. Opercular apparatus complete, but few branchiostegal rays and no gular
plate. Vertebral centra well ossified ; ribs nearly or completely encircling the abdomi-
nal cavity. Fin fulcra absent. Post-temporal bones in contact with postero-lateral
angles of cranium ; post-clavicular plate (post-cleithrum) overlapping the clavicle
(cleithrum).”
Berg (1947) must have been more impressed by the difference in fin pattern,
for in proposing a new suborder Ctenothrissoidei (p. 422) he states that these fishes
are “ As Clupeidae but with very large ventral fins situated below the pectorals ”’
(his italics). This would seem a reasonable proposal, but whatever the opinion, we
can at least agree that the ctenothrissids are isospondylous fishes, having soft-rayed
fins, a caudal fin with 19 principal rays and an upper jaw bordered by both premaxillae
and maxillae. By the same combination of characters. Macristium can also be placed
in the Isospondyli. Indeed, as already quoted (p. 355) Regan (1911) considered this
3644 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
genus to be most closely related to the Alepocephalidae, a family that can be reason-
ably assigned to the suborder Clupeoidea.
Concerning closer comparisons, the most striking resemblance between Macristium
and the Ctenothrissidae is in fin pattern (see Text-fig. 4). The tall sail-like dorsal
fin, extending over the greater part of the trunk ; the long, wing-shaped pelvic fins,
which arise at points opposite, or nearly opposite to the origin of the dorsal fin ;
the smaller pectoral fins, set laterally on the shoulders between the lateral line and the
base of the pelvics ; the rather prominent anal fin, beginning close behind the last
dorsal ray and spanning about half the length of the tail; the well-formed shallow-
forked caudal fin—these are the outstanding similarities.
This precise form of fin pattern is unique within the order Isospondyli (the nearest,
but not very close, approach is with Pantodon). Indeed it is almost without parallel
among the entire complex of “ lower ’’, soft-rayed teleosts (Isospondyli, Ostariophysi,
Haplomi, Iniomi, Cetunculi, Miripinnati, Chondobrachii, Giganturoidea and Lyomeri).
One striking convergence of fin pattern is with Bathysaurus , a congruence that first
led Regan (1903) to suspect a relationship between Macristiwm and this genus (now
assigned to the order Iniomi, suborder Myctophoidea, family Bathysauridae). In
fact, the Macristiwm-ctenothrissid fin pattern most nearly resembles that of one
particular species, Bathysaurus ferox. But the term fin pattern, as used by Harris
(1953), includes both fin position and fin form. Now the fin positions of B. ferox
are like those of Macristiwm and Ctenothrissa (except that the origin of the dorsal
fin is behind the pelvic insertions in the former). In fin form, however, B. ferox has
less accentuated dorsal and pelvic fins.
There is also a close resemblance between the fin pattern of another iniomous
species, Latropiscus purpurissatus (Aulopidae) and that of Macristiuwm and Ctenothrissa.
In this aulopid the pelvic fins do arise at points opposite to the origin of the dorsal
fin, but again, both kinds of fins are less expansive than those of the two genera in
question. The aulopids also have an adipose dorsal fin, which is certainly absent in
Macristium.
Macristium and Ctenothrissa are not only alike in fin pattern, but also in fin-ray
numbers, which are listed below in Table II. The figures for Ctenothrissa are taken
from Woodward (1901 and 1903).
TaBLe II.—Fin-ray Numbers of Macristium chavesi and Ctenothrissa spp.
Species Dorsal Anal Pectoral Pelvic
Macristium chavesi 6 17-18 12-13 16-18 7-8
Ctenothrissa radians c 20-25 12+ Io-12 7-8
C. vexillifer . : + |18=20 13-14 ? 8
C. microcephala c : ? c. 10 c. 10 8-9
It will be evident that there is a close correspondence between the numbers of anal
and pelvic rays and a fairly near match in dorsal ray complements. There is a bigger
gap in the numbers of pectoral rays, but in Ctenothrvissa the pectorals are rather weakly
developed. Azlolepis, the other known genus of ctenothrissid fishes, also had small
and delicate pectoral fins, each with about 12 rays, while there are 9 rays in the pelvics
(Woodward, 1903).
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 365
Apart from upper jaws bordered by both the premaxillae and maxillae, there are
numerous other similarities between the head structure of Macristium and the
Ctenothrissidae. The underlying structural congruence is in the markedly forward
inclination of the suspensoria. The jaws are thus relatively short, the hinges of the
mandible and the ends of the maxillae lying below the orbits. The mandible is not
only short but deep, the width at the coronoid process being about a third of the
mandibular length in Macristium and nearly one-half this dimension in Ctenothrissa.
Conforming to the inclination of the suspensoria, the preopercular bones are
shaped. The divisions between the large opercular and much smaller subopercular
bones run backwards and upwards from the angles of the preopercula. The inter-
opercular bones lie below the horizontal preopercular limbs (see Text-fig. 1). There
is, in fact, a close correspondence between the gill-cover bone patterns of all three
genera, Macristium, Ctenothrissa and Aulolepis. (see also Text-fig. 4).
Macristium and Ctenothrissa also have much the same number of branchiostegal
rays. Regan (1911) stated that there are about 8 on either side of the type of
Macristium chavesi : the Discovery specimen has 10. In his descriptions of Ctenothrissa
yadians, Woodward (1903 : 81) remarks that “ the number of branchiostegal rays is
uncertain, but there cannot have been less than eight, perhaps ten.”
Turning now to differences, the most obvious one is the lack of scales in Macristium.
In the ctenothrissids the scales are large and regularly arranged, their edges being
pectinated in Ctenothrissa but smooth in Aulolepis. A second striking difference is the
development of 2 well-formed supramaxillae in the Ctenothrissidae, whereas in
Macristium the paddle-shaped maxilla is apparently a single bone. Furthermore,
the large blade-like maxillae of the ctenothrissids form two-thirds to three-quarters
of the biting edge of the upper jaw, but in the Discovery Macristium the fraction is no
more than one half. Thirdly, except for the first 4 dorsal rays, the upper pectoral ray,
the outer pelvic ray, the Ist anal ray and the outer principal caudal rays, the fin rays
of Ctenothrissa are branched. In the Discovery Macristiwm none of the fin-rays is
branched, and the same appears to be true of the type specimen (Regan, IQIt).
Lastly there is one appreciable meristic difference. In Ctenothrissa and Aulolepis the
vertebral numbers are from about 30 to 40 ; in Macristium there are about 60.
The significance of these contrasting features can only be properly assessed with an
awareness that the Discovery and type specimens are young fishes. In both the skull
is at an early stage of development (see Text-figs. 3 and 4) and in the former specimen,
at least, this is also true of the hypaxial musculature of the trunk region. Regarding
the type specimen, Regan (rg11) noticed that the abdomen appeared to be very
distensible, which either suggests incomplete development of the investing muscula-
ture or a poor state of preservation.
Finally, the melanophore pattern of the Discovery fish seems to be in a post-larval
condition, there being no general pigmentation of the skin, such as appears at meta-
morphosis.
Considering now the first difference, the complete lack of scales in young Macristium
need not imply their absence in the adult. In the Scopelarchidae and certain Para-
lepididae, for instance, the scales do not begin to form until a relatively late stage in
366 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
the life-history. At first sight, indeed, young Macristiwm remind one of the Benthal-
bella larvae of scopelarchids. But it is not the absence of scales in relatively large
young that provokes the reminiscence, but rather the translucent, muscle-lacking
walls of the abdominal cavity. It is reasonable to assume that in fishes with this large
type of post-larva the early part of the life-history is prolonged, the rate of differenti-
ation of the organ systems being slow compared to the growth in size. In fact, young
Macristium may not reach the adolescent stage until they are about 6 inches in
length. This could well account for the non-branched condition of the fin rays of
the two specimens of Macristiwm (in Benthalbella larvae almost all of the fin rays
are in this stage of development).
The relatively small (half) share of the maxillae in the biting edge of the upper jaw
could also be a larval feature. In just metamorphosed larvae of Elops, for instance,
this maxillary fraction is between a half and two-thirds, whereas in the adult it is
somewhat greater than two-thirds. Could the absence of supramaxillae simply be
due to the fact that they have not yet ossified? There is no trace of supramaxillae in
the above larvae of Elops. If, as seems likely, the early (pre-adolescent) development
of Macristium is much protracted, the relatively late appearance of certain adult
jaw features is by no means impossible. But we can only await the capture of
further stages in what is clearly a most interesting kind of life-history.
Lastly, the marked difference in vertebral numbers (about 60 in Macristiwm,
30-40 in the Ctenothrissidae) need not imply marked genetic separation. Instances
of a wide range of vertebral numbers within one family are not uncommon and, as in
the fishes under review, this may be coupled with relatively small variations in the
numbers of fin rays. In the Chlorophthalmidae of the Western North Atlantic the
fin formula is D. ro-11, A. 7-9, Pct. 15-17, Pv. 8-9, but the vertebrae vary from 38
to 49 (Mead, in the press). There are 45-66 vertebrae in the Scopelosauridae but the
usual numbers of rays are: D. 10-12, A. 17-20, Pct. 10-12, Pv. 8-10 (Marshall, in
the press).
FIN PATTERNS OF * LOWER ”’ SOFT-RAYED TELEOSTS WITH
THORACIC (OR NEAR THORACIC) PELVIC FINS:
FUNCTIONAL ASPECTS AND CONVERGENCE
Macristiwm and the Ctenothrissidae are thus closely similar in head structure
and fin pattern, the latter being unique within the order Isospondyli. But could these
common features be simply due to convergence? More precisely, have these features
been independently acquired? And could they be adaptations to a particular way
of life? If such questions could be answered in the negative, one could feel more
certain of the genetic affinity between the two.
We have already seen that the Macristium type of fin pattern is found in two iniom-
ous fishes, Bathysaurus ferox and Latropiscus purpurissatus. There is also a remarkable
resemblance in the numbers of fin rays, which are as follows :
Macristium chavesi. ‘ : ; . D.17-18, A. 12-13, Pet. 15-16, Pv. 7-8
Bathysaurus ferox (Type) 3 : aD aro AR Te SP CtaarAnibvae
Latropiscus purpurissatus (one specimen) . D. 20, A. 12, Pct. 14, Pv. 9
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 367
Concerning the two iniomous species, the differences between them, particularly
in head structure, are no less striking than the foregoing resemblances. The Bathy-
sauridae and Aulopidae have clearly diverged considerably from their point of common
origin, which must be close to the origin (or origins) of the iniomous fishes. Now the
fin pattern of most Iniomi suggests that the ancestral fish(es) would have had a short
based dorsal fin and abdominal pelvics. If this is so, then the fin array of the two
above species could well have been acquired independently (and not be an instance
of parallelism). Could the same be true of Macristium and Ctenothrissa? Before
trying to answer this question, some consideration of certain functional aspects of
fin pattern in isospondylous and iniomous fishes with thoracic (or near thoracic)
pelvic fins will be relevant.
All the members of one suborder of Iniomi, the Alepisauroidea, have abdominal
pelvic fins. In the other suborder, the Myctophoidea, only the Myctophidae, the
Harpadontidae and the Scopelosauridae can be said to have typically abdominal
pelvic fins. In the remaining families, the Aulopidae, the Chlorophthalmidae, the
Bathypteroidea, the Ipnopidae, the Bathysauridae and the Synodontidae, these
fins are either thoracic in position or inserted well forward on the abdomen, close to
the bases of the pectorals. There would thus appear to be a correlation between
pelvic fin position and habit. The bathypelagic Iniomi have abdominal pelvics
whereas in all but one of the benthic groups (the Harpadontidae), the pelvics have
moved near or very near to the pectorals, which have a lateral setting.
In the percoid fishes Harris (1953) has shown that lateral pectoral fins, acting in
concert with thoracic pelvics, form an extremely efficient and stable braking system.
He also writes : ‘‘ It is interesting to find that the percoid facies has been evolved at
least three times over, since it appears in the Permian Palaeoniscoid, Dorypterus,
possibly in some Holostei (Dapedius) and also in the isospondyl Ctenothrissa ; all
are short, thin, deep-bodied forms where pitching motions would be liable to become
excessive during braking if it were not for this pelvic fin migration.”
But this disposition of the paired fins is not necessaily an invariable indication of
a braking system. Keeping to the Iniomi, the lizard-fishes (Synodontidae) have the
habit of lying on the sea floor, propped up by their pelvic fins, which are inserted
well forward, between the origins of the pectoral and dorsal fins. A Trachinocephalus
in just this posture is figured by Ray & Ciampi (1958 : 190, fig. 96). As these authors
remark (p. 189) : ‘‘ All the lizard fishes are fiercely predatory. They sit on the bottom,
resting on their ventral (pelvic) fins until some unsuspecting fish or crustacean swims
by. Then they rush so quickly at the prey that the movement can hardly be seen.
They prefer sand bottoms but many may be found about reefs and rocks as well as
over mud and grass.
“ This is one of the groups in which the normal swimming pattern has been altered.
For sudden rushes the tail fin is used, but lizard fishes do not often swim when at
leisure, preferring to creep about on the bottom on their very large pelvic fins. The
pectorals are held out as wings and are probably used as planing devices in their
sudden rushes after prey.”
Like the Synodontidae and other benthic myctophoids, the Bathypteroidae are
without a swimbladder. Having a firmly ossified skeleton and a well-developed
368 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
muscular system, they must be denser than their surroundings. And as Houot &
Willm (1955) first observed, Benthosaurus actually rests on the bottom, supported
by its elongated pelvic and caudal rays, which form a tripod.
These supporting rays have a special structure. In the Bathypteroidae the two
lowermost, principal caudal rays, which may be much prolonged, are stiffened through
being composed of short, closely interlocking, lepidotrichia, these elements being
much shorter than those of the other caudal rays. The outermost 2 (or 3 ) rays of
each pelvic fin are also made of very short segments. The same kind of fin-ray
modification occurs in the Synodontidae. The two lowermost principal caudal rays
are usually comprised of shortened lepidotrichia and certain of the outer pelvic rays
also have this special structure (in Tvachinocephalus myops, the outer 5 pelvic rays ;
in Synodus the outer 4 or 5 rays and in Saurida the outer 2 pelvic rays.
All three “legs” of this fin-tripod are thus specially modified, presumably to
support the weight of the resting or creeping fish. The other significant feature is that
the insertions of the pelvic fins are definitely in advance of the centre of gravity.
The tripod rest is thus quite stable, which would not be so if the pelvics were inserted
further back along the abdomen (in a typically “‘ abdominal ”’ setting). The forward
migration of the pelvic fins would thus seem to be simply related to the formation of a
stable undercarriage.
It is clear that the lizard-fishes get a quick take-off from this undercarriage, while
observers have seen Benthosaurus dart forward from a resting position. Perhaps the
raising of the body above the substratum also enhances sensory appreciation of the
immediate environment. If, for instance, a fish is flattened against sand or ooze
the lower parts of the lateral line system of the head and of the visual field are out of
action. The tips of the fin-ray tripod may also give tactile information of local
movements of invertebrate food in the deposits.
The other benthic myctophoids, the Aulopidae, Chlorophthalmidae, Ipnopidae
and Bathysauridae have also lost the swimbladder. Again, certain of the outer pelvic
rays and (usudlly) the lowermost principal caudal rays are relatively stout and
composed of short segments. (In Aulopus filamentosus and Latropiscus purpurissatus
the outer 4 pelvic rays and the 2 lowest caudal rays have this special structure. In
Chlorophthalmus agassizi and C. nigripinnis this applies to the outer 2 or 3 pelvic
rays and the lowermost caudal ray, but in C. punctatus no single ray of these fins is so
differentiated. Concerning Ipnops murray: and Bathysaurus ferox, the modification
is confined to the pelvic fins, to the outer 3 pelvic rays in the former and to the outer
2 rays in the latter.) Lastly, the pelvic fins of all these fishes are inserted in advance
of the centre of gravity.
These fin features are surely close enough to those of lizard-fishes and bathyp-
teroids to suggest that the fishes of the above four families use their pelvic and caudal
fins as a mobile tripod-undercarriage.1_ There is no observational evidence to support
this view, and indeed, little is known of the biology of these fishes. But the close
1 It is interesting that the one crossopterygian fish (Laugia grénlandica, Stensid, 1932) with thoracic
pelvic fins has specially modified pelvic rays. Like the iniomous fishes described above, some of the pelvic
Tays are much stouter and composed of shorter lepidotrichia than the other fin rays. Did Laugia use
its pelvic fins as supports and/or for walking along the bottom?
A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES 369
structural congruence of fin form, to which may be added the common possession
of a well-shaped muscular body ending ina forked tail fin, are features suggestive of a
darting, synodontid-like habit (based on a “ tripod ”’ rest, allowing of a quick take-off.
Aside from these features of fin pattern and form, the benthic myctophoids have
few characters in common. Evidently they are not closely related, except perhaps
for the Synodontidae and Bathysauridae. In fact, the Chlorophthalmidae are more
closely allied to a pelagic family, the Scopelosauridae (Marshall, in the press), than to
any of the benthic groups. The similar pelvic and caudal characters of these groups
may thus be due to (adaptive) convergent evolution rather than to inheritance from
a common ancestor.
As in the Synodontidae, the pelvic fins of the Ctenothrissidae are considerably
larger than the pectorals and composed of much stouter rays. Woodward (1903)
described the pelvic fins of Ctenothrissa radians as follows: “‘ Each of them consists
of seven or eight very stout rays all articulated and all, except for the foremost,
finely divided in their distal half.’ If these fins were part of a “ percoid’’ type of
braking system, they seem disproportionately large for such a function. But their
robust structure may well point to their use as supports when the fish was resting on
the bottom. The fact that they have a forward, thoracic setting could then be related
to the requirement of an insertion anterior to the centre of gravity. In deep bodied,
large-headed fishes, such as Ctenothrissa spp., this centre comes close behind the bases
of the pectoral fins. In fact, the deeper the body the nearer to the head will be the
point of balance. To take an apt example, comparison of Aulopus filamentosus with
Latropiscus purpurissatus reveals that in the former, which is the slimmer bodied,
the insertions of the pelvic fins are appreciably behind those of the pectorals. In
the deeper bodied Latropiscus the pelvics originate just behind the vertical level of
the pectoral bases.
Are the adults of Macristium chavesi also bottom-living fishes that use their long
pelvic fins as two legs of a tripod undercarriage? In the Discovery specimen there is no
sign of a swimbladder, the lack of which is a particular feature of fishes that spend
most of their adult life actually resting on the bottom.
To return to our original question, the foregoing discussion might suggest that the
resemblance between the fin patterns of Macristium and the ctenothrissids are due
to convergent evolution. But our functional analysis of fishes with synodontid-like
habits of resting on the bottom simply refers to the paired fins. Nevertheless the
striking resemblances between the fin patterns and fin-ray numbers of Latropiscus
purpurissatus and Bathysaurus ferox shows what “Nature can do” by way of
convergence. Yet the aulopids and Bathysaurus are quite unlike in head structure,
whereas Macristium and the ctenothrissids have a cluster of head characters in
common. The pattern of gill cover bones might, of course, be simply correlated with
the forwardly inclined suspension of comparatively small jaws (see p. 365). If so, the
convergent features of these fishes would reside in both fin and gill cover pattern.
Against such considerations must be set the correspondence in number of branchio-
stegal rays and the fact that the Macristiwm-ctenothrissoid fin pattern is unique
within the order Isospondyli (p. 364). Furthermore, no single feature or combination
of features, precludes the consideration of Macristiwm as a ctenothrissoid fish. The
ZOOL. 7, 8. 26
370 A YOUNG MACRISTIUM AND THE CTENOTHRISSID FISHES
absence of supramaxillae in Macristiwm seems the most outstanding difference, but
these bones may be quite late in ossifying (p. 366). Certainly, the paddle-shaped
bone that appears to be the maxilla has a most unusual shape if it is going to be no
more than a maxilla.
In conclusion, these problems can only be resolved when an adult Macristium
becomes available. We shall then know whether each maxilla carries two supra-
maxillae and whether the parietals meet in the middle line. If the answers are in
the affirmative it would seem that Macristiwm can be regarded as a modern survivor
of the ctenothrissoid fishes. Meantime the purpose of this paper is to suggest that
this outcome is at least possible, perhaps even probable.
ACKNOWLEDGEMENTS. Thanks are due to Dr. N. A. Mackintosh for placing this
material at our disposal.
REFERENCES
Bere, L.S. 1947. Classification of fishes, both recent and fossil. Tvav. Inst. zool. Acad. Sci.
U.R.S.S. 5 (2) : 1-517 (English and Russian). J. W. Edwards, Ann Arbor, Michigan.
BERTELSEN, E. & Marsuati, N. B. 1956. The Miripinnati, a new order of teleost fishes.
Dana Rep. No. 42 : 1-33.
GosLINE, W. A. 1960. Contributions toward a classification of modern isospondylous fishes.
Bull. Brit. Mus. Nat. Hist. Zool. 6 (6) : 325-365.
Harris, J. E. 1952. Fin Patterns and Mode of Life of Fishes. Essays in Marine Biology :
17-28. Oliver and Boyd, Edinburgh, 144 pp.
Houot, G. & Witt, P. 1955. Two Thousand Fathoms Down. Hamish Hamilton, London,
256 pp.
MarsHALL, N. B. (in the press). The Scopelosauridae : in Fishes of the Western North Atlantic.
Sears Foundation for Marine Research. No. 2.
Meap,G. W. (in the press). The Chlorophthalmidae : in Fishes of the Western North Atlantic.
Sears Foundation for Marine Research. No. 2.
Ray, C. & Ciampi, E. 1958. The Underwater Guide to Marine Life. Nicholas Kaye, London,
338 pp.
Recan, C. T. 1903. Ona collection of fishes from the Azores. Ann. Mag. nat. Hist. Ser. 7,
12 : 344-348.
t911. On the systematic position of Macristium chavesi. Ibid. Ser. 8. 7 : 204-205.
StEnsI0, E.A. 1932. Triassic fishes from East Greenland collected by the Danish Expeditions
in 1929-1931. Medd. Gronl. 83 (3) : 1-305.
Woopwarp, A. S. rgo1. Catalogue of the Fossil Fishes in the British Museum (Natural
History). Part 4, 636 pp.
— 1903. Fossil Fishes of the English Chalk. Palaeontogr. Soc. (Monog.) London. Part II:
57-96.
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THE DISTRIBUTION OF PELAGIC
» POLYCHAETES. ACROSS THE
NORTH PACIFIC OCEAN
NORMAN TEBBLE
«23 FEBING
” PRESENTED.
ZOOLOGY Vol. 7 Noi 9
Ss LONDON : 1962
THE DISTRIBUTION OF PELAGIC POLYCHAETES
ACROSS THE NORTH PACIFIC
BY
NORMAN TEBBLE
Pp. 371-492 ; 55 Text-figures
BULLETIN OF
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ZOOLOGY Vol. 7 No. 9
LONDON : 1962
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THE DISTRIBUTION OF PELAGIC POLYCHAETES
ACROSS THE NORTH PACIFIC OCEAN
By NORMAN TEBBLE
THE principal purpose of this report is to examine the extent to which pelagic poly-
chaetes are restricted in their distribution in the North Pacific Ocean at the northern
boundary of the Sub-Tropical Zone and the southern boundary of the Sub-Arctic
Zone. Previously reported collections from this region have been confined to
material from small areas, or from a few stations scattered over the ocean. The
essential requirements for such a study, abundant samples from stations made
across the major hydrological boundaries of the region, were provided by the col-
lections of the University of California, Scripps Institution of Oceanography, La
Jolla, California. It is principally on an examination of these collections that this
study is based.
It is a pleasure to record my gratitude to the Royal Society of London for the
award of the John Murray Travelling Studentship in 1958 which made possible my
visit to the Scripps Institution of Oceanography, and also to that Institution for
providing facilities during the first year of study. To Dr. Martin Johnson, Professor
of Marine Biology at La Jolla, I am particularly grateful for inviting me to make
this report, and for encouragement and criticism throughout its preparation ; other
colleagues at Scripps, including Dr. J. A. McGowan and Dr. L. Berner, also provided
invaluable advice. Miss Dorothy Tyler was responsible for sorting the plankton
samples, and, for her sedulous work, I am very much indebted. Mr. Bob Winsett
has prepared the drawings of complete specimens (Text-figs. 4-6, 13, 19, 21-23)
and it is a pleasure to pay tribute to his artistic ability. Dr. Warren Wooster and
Mr. Bruce Taft provided guidance in the interpretation of hydrological data. At
the British Museum (Natural History) the Keeper of Zoology, Dr. F. C. Fraser,
has given continual support and encouragement to this work and Miss A. C. Edwards
has been very helpful in the preparation of drawings and charts.
MATERIAL AND METHODS
The plankton samples examined in this report were collected by ships of the
Scripps Institution of Oceanography on the Trans-Pacific Expedition, 1953 ;
Northern Holiday Expedition, 1951; Chinook Expedition, 1956; and by the
Pacific Oceanic Fisheries Investigations of the U.S. Fish and Wild Life Service,
Honolulu, Hugh M. Smith Cruise 30, 1955. The positions of the stations at which
the samples were collected are shown in Text-fig. 1, and the number of samples
examined tabulated according to Expedition, Zoogeographical location and depth
in Table I.
ZOOL. 7. 9. 27
ES
OF PELAGIC POLYCHAET
STRIBUTION
THE DI
374
‘peulmrexa useq aAey sefdures uozHURId YoIyM Woy suoT}E}s Jo suoMIsod oy} Surmoys zIeYD
9561 “dX3 NOONIHD &
$561 ‘DVdYON “I'd'O'd ¥
£561 ‘dX3 DISIDVdSNVUL
1861 “dX3 AVGIIOH NY3HLYON ©
THE DISTRIBUTION OF PELAGIC POLYCHAETES 375
TaBLE I.—Number of Samples Examined, According to Expedition,
Zoogeographical Location and Depth
Depth of tow Sub-Tropical Transition Sub-Arctic
(metres) Zone Zone Zone Totals
TRANS-PaciFic Exp.—
190-0. : 6 72 10 52
Between 530 and 190-0 2 38 3 II
Between 1,280 and 530-0 ° 9 a 2 : 6
150-35 - 0 a ° c ° é 2
385-75 . . 38 7 30
720-210 (Mainly 500— 18 3 13
300)
680-495 .- 5 3 5 2 . 2
850-680 . . é 2 4 fo) 5 fo)
1,175-525 - fo) ° I
Subtotals 6 0 ° 180 c 27 c 117 c 324
NorTHERN HoLipay Exp.—
Between 227 and 118-0 . 5 31 5 6 0 18 6 55
P.O.F.I. H. M. S. CRuIsE 30—
145-0 . 6 : © 13 9 6 28
CHINOOK ExP.—
Between 130 and 85-0. 5 5 0 4 5 3 9
Totals. 6 0 < 229 45 5 142 o 416
These samples represent the material which was sorted for pelagic polychaetes.
Both negative and positive results from them are recorded on the distribution maps
for the various species except for the maps recording quantitative distribution on
which Hugh M. Smith cruise 30 results have not been plotted. No details of the
amount of water filtered by each net are available for this cruise but this information
is available for the other expeditions. Details of number of specimens of all species
collected are tabulated in Appendix I, Tables I and II.
Except for the University of Washington collections, which were made with a
mid-water trawl, all the samples were collected with 1-metre nets, which have a
mesh of 0:65 mm. (29 to the inch) of 30 xxx, silkgrit gauze. This net appears to be
most efficient for catching pelagic polychaetes, the majority of which fall within the
5 to 35 mm. size range. Use of this net helps to explain the large number of records
made here and by Dales (1957) for species not previously known to occur in abun-
dance. For example, in the South Atlantic collections of Discovery from the Tropical
and Sub-Tropical Zones (Tebble, 1960), when 1-metre nets were comparatively
rarely used and the TYF (with a 2-metre frame and 10-12 meshes to the inch)
normally in operation, no catches of Sagitella kowalewskii were reported, although
it is known to occur there (Friedrich, 1950). In the North Pacific this species
376 THE DISTRIBUTION OF PELAGIC POLYCHAETES
has been collected with persistant regularity (Text-fig. 48). On the other hand
there were many more records for the larger 7. msseni (up to 70 mm. in length)
from Discovery collections, than from the North Pacific, because it was more easily
caught by the larger net. Nevertheless, for most pelagic polychaetes measuring
less than 35 m. long, the 1-metre net appears to provide a better chance of catching
a larger number of species.
This question of net efficiency is a debatable point (it is clearly associated with
comparative abundance, type of tow, etc.) yet its importance cannot be overlooked,
and the success of the Scripps Institution’s Expeditions and of CCOFI (Dales, 1957)
in catching pelagic polychaetes with the 1-metre net warrants comment.
Details of how the nets were operated on the Trans-Pacific Expedition, in both
open and closed tows, have been given by McGowan (1960).
The collections made by the University of Washington were kindly provided by
Mr. William Aron whose research is supported by the National Science Foundation
and by the Office of Naval Research, Contract 477 (10). The mesh size of the nets
used in making these collections and the method of towing is such that the smaller
beasts are bound to be squeezed out of the net. For this reason I have not plotted
the negative records from this collection on the distribution maps in this paper.
The positive records, however, have been plotted, and details are tabulated in
Appendix I, Table III.
Hereafter the report is divided into four sections :
(1) Hydrological Environment, a brief account only ; the reader is referred to the
relevant parts of Chapter XV, in Sverdrup e¢ al., 1946 for greater detail ;
(2) Systematic Account ;
(3) Distribution ;
(4) Zoogeographical Review, in which the principal features of the distribution are
examined in relation to other oceans and other animal groups, etc.
HYDROLOGICAL ENVIRONMENT
The collections reported here were made principally in the two major water
masses of the North Pacific Ocean, the Sub-Arctic water mass in the Sub-Arctic
Zone and the North Pacific Central water mass in the Sub-Tropical Zone. Between
these there is generally a broad belt of water with intermediate hydrological charac-
teristics in the Transition Zone from which samples have also been examined
(Text-fig. 3).
The term Sub-Arctic water should be strictly applied only to the top 1,000 m.
of water north of 45° N. (Sverdrup e¢ al., 1946) and it is principally in this sense
that the term is used in this paper. No attempt is made here to interpret, in detail,
distribution along the western coast of the U.S.A., between 48°N., and 23°N.,
where a southward flow of modified Sub-Arctic water, the California Current, exists
prior to converging with Equatorial water.!
The hydrological data obtained on the Trans-Pacific Expedition has been inter-
1 Dales (1957) has reported on the distribution of pelagic polychaetes in the California Current (1949—
50) within 75 metres of the surface: his data will be referred to here in terms of general oceanic dis-
tribution only.
377
THE DISTRIBUTION OF PELAGIC POLYCHAETES
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cd UHON 04} ur 197M Jo JrOdsueI} 0Y} Jo UOTOeNp oyeuNxoIdde oy} Surmoys yey
JOLYVNOS Hie
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378 THE DISTRIBUTION OF PELAGIC POLYCHAETES
preted by Warren Wooster and Bruce Taft and the T/S diagram (Text-fig. 3) prepared
by them. This diagram differs from that in Sverdrup et al. (1946, fig. 209B) in
that no differentiation has been made between Eastern and Western North Pacific
Central water. In a schematic sense, however, it does indicate clearly the charac-
teristics of the Sub-Arctic water mass, the broad belt of Transition water and the
North Pacific Central water as sampled in 1953 by the Trans-Pacific Expedition.
18
10
s TRANSITION
= WATER
=
SUB -ARCTIC
WATER
33 34 35
SALINITY %o
Fic. 3. Temperature/salinity diagram for the North Pacific Ocean from data
obtained by the Trans-Pacific Expedition, 1953.
From the T/S diagram Wooster and Taft have interpreted the positions of stations
from which samples have been examined ; these positions have been plotted on all
distribution maps. Normally positions of the stations in relation to the water
masses are comparatively clear but, in the region off the north-east coast of Japan,
where the warm Kurushio current meets the cold Oyashio (Text-fig. 2), the condi-
tions are more complicated. Thus Stations 71, 72, 73 and 78 were essentially Sub-
Arctic in character but had a layer of Transition water at the surface, and Stations
74 and 77 Sub-Arctic below 450 metres but in North Pacific Central water above
this depth.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 379
SYSTEMATIC ACCOUNT
This section deals with descriptions of the species collected and with a re-examina-
tion of the taxonomic status of some of them. A short note on general distribution
is appended to each description, but reference should be made to the section on
Distribution (below, pp. 428-469) for a more detailed consideration of this aspect
of the work.
Recent systematic analyses of pelagic polychaetes by Step-Bowitz (1948), Dales
(1957) and Tebble (1960) make repetition of lengthy lists of synonyms unnecessary.
References to descriptions of species have therefore been restricted to these three
works, original descriptions and Fauvel (1923) except where necessary. The
spelling of specific names in these lists of synonyms follows that used in each
particular reference.
The material collected by the research ships of the University of California has
been deposited in the British Museum (Natural History) collections, Reg. No.
1960.6.1. I-11,186, and the Scripps Institution of Oceanography, La Jolla, Cali-
fornia ; material collected by the Pacific Oceanic Fisheries Investigations in the
Smithsonian Institution, Washington D.C., and by the University of Washington,
is in the University Dept. of Oceanography, Seattle.
Family ToMOPTERIDAE
Exclusively pelagic. Prostomium with a pair of laterally directed antennae which
together form its anterior border, a pair of nuchal organs and normally a pair of
eyes. There may be two pairs of lateral processes just behind the eyes of which
the anterior and smaller pair is often not present (the first pair of chaetigers) whereas
the posterior pair is always present (the second pair of chaetigers). Parapodia are
biramous and achaetous with notopodia and neuropodia modified into paddle-
shaped pinnules. These pinnules may carry glands which have been given the
following names: (a) chromophil glands, these are large glands which normally
appear only in neuropodia and stain deeply with haematoxylin ; (6) hyaline glands,
small glands which occur in either notopodia or neuropodia, they may be pigmented
or appear only as crystalline spots; they do not stain with haematoxylin; (c)
rosette glands, very small glands which occur on the trunks of the parapodia or on
notopodia and neuropodia, they do not stain with haematoxylin ; (d) spur glands,
these are small, normally subsidiary to the chromophil glands, and occur only on
neuropodia, they stain with haematoxylin. Posteriorly the body may be prolonged
into a tail, bearing rudimentary parapodia.
Genus TOMOPTERIS Eschscholtz, 1825
Notopodial and neuropodial pinnules always completely surrounding the para-
podial trunk.
Type species. Tomopteris onisciformis Eschscholtz, 1825.
Type locality. South Seas (Pacific).
I have given elsewhere (Tebble, 1960) my reasons for not accepting the subgeneric
division of Tomopteris into Tomopteris (sensu stricto) and Johnstonella.
380 THE DISTRIBUTION OF PELAGIC POLYCHAETES
TABLE II.—In this Table the Presence (x) or Absence (—) of the More Important
Diagnostic Characters in Some Species of Tomopteris is Indicated
Hyaline glands
eee
oe Se
On 3rd Chromophil glands _— Pinnules
First On and 4th oc _"——— ___ extend
chae- most feet Rosette Com- With to body
tigers Apical Dorsal feet only glands pact Diffuse spur wall Tai
T. planktonis . = D x — x — — x — = = 4
T. septentrionalis — — x x = = - x — _ =
T. ligulata b — = x — - x = = x s
T. elegans . a és _— x = x = x
T. nisseni . : — x — x — - x — _ = x
T. krampi : x x — x = = x = = = x
T. apsteini : x : _— — - — 3 x qe. = x = x
T. pacifica P x . x x = = = x
* Of the species listed T. kvampi was not present in the collections but was reported in the North Pacific fron
Monterey Bay by Dales (1955).
Tomopteris elegans Chun, 1887
(Text-fig. 4a, 5)
Type locality. Canary Islands, 500—1,300 m.
Tomopteris elegans Chun, 1887, pp. 18-19, pl. 3, figs. 4-9.
Tomopteris (Tomopteris) elegans : Fauvel, 1923, p. 223, fig. 84, b, c.
Tomopteris (Tomopteris) elegans : Stop-Bowitz, 1948, pp. 46-48, fig. 33a—b.
Tomopteris elegans : Uschakov, 19574, pp. 283-284, Chart 3, fig. 7a-c.
Tomopteris (Tomopteris) elegans: Dales, 1957, pp. 142-143, figs. 51a, 52a, 53.
Tomopteris elegans: Tebble, 1960, pp. 179-180, fig. 11, a-c; pp. 250-252, fig. 48.
DESCRIPTION. This species varies between I-5 mm. in length for ten pairs of
parapodia and 6-5 mm. for fifteen pairs, with most specimens having fourteen pairs.
The anterior border of the antennae has a pronounced central indentation and
there is a pair of pale brown eye spots on the prostomium. (These may not be |
well preserved.) The first pair of chaetigers is always present ; the second pair
varies in length but normally reaches to almost the total length of the body (though
frequently broken off, as in the specimens shown in Text-fig. 4). Pigmented hyaline
glands are present on the notopodial pinnules of the third and fourth parapodia
only; they are absent from all other feet. Compact chromophil glands appear
from the fourth neuropodial pinnule on all parapodia up to the end of the body ;
they are ventral in position just below the apex of the parapodial trunk. There is
no tail in this species.
Discussion. Dales (1957 : 160) notes that 7. elegans has, “‘ Gonads present in
the 3rd to 8th pairs of parapodia’’; by gonads he must mean gonadial products,
but I have never found these restricted to particular segments in this species. Text-
fig. 4a shows them occurring in every foot from the first to the tenth and I have
seen them in all and in only onet.
1 Dales uses this character to separate T. elegans from T. kefersteini Greeff, 1879, which he considers
has “‘ gonads present in the 3rd to 9th parapodia ’’. In fact T. kefersteini has itself been described with
gonads in all feet (Fauvel, 1923); and although a little-known species it can be distinguished from
T. elegans by characters noted in its original description (Greeff, 1879).
THE DISTRIBUTION OF PELAGIC POLYCHAETES
a __LOmm._,
b
Fic. 4. Tomopteris elegans : (a) with and (b) without eggs in the body cavity. Both
specimens are from Stn. 17A of the Trans-Pacific Expedition, and have had the tips
of the second pair of chaetigers broken off.
382 THE DISTRIBUTION OF PELAGIC POLYCHAETES
GENERAL DISTRIBUTION. T. elegans is known only from Tropical and Sub-
Tropical waters (see below, pp. 428-434).
Tomopteris septentrionalis Quatrefages, 1865
(Text-fig. 5)
Type locality. “‘ ... les mers du Danemark ”’.
Tomopteris septentrionalis Steenstrup, 1849, p. iv (nomen nudum).
Tomopteris septentrionalis Quatrefages, 1865, p. 229.
Tomopteris (Tomopteris) septentrionalis : Stop-Bowitz, 1948, pp. 49-51, figs. 36-37.
Tomopteris septentrionalis : Uschakov, 19574, pp. 282-283, Chart 3.
Tomopteris (Tomopteris) septentrionalis: Dales, 1957, p. 145, figs. 51f, 52g, 54.
Tomopteris septentrionalis : Tebble, 1960, pp. 176-177, fig. 8a, b; pp. 228-231, figs. 32, 33.
DESCRIPTION. The specimens of this species collected vary in length between
1-5 mm. for twelve pairs of parapodia and 20-28 mm. for twenty to twenty-four
ey)
Fic. 5. Tomopteris septentrionalis : complete specimen from Stn. 1B of the Trans-Pacific
Expedition.
pairs. The anterior border of the antennae has a prominent central indentation
and there is a pair of eye spots on the prostomium. The first pair of chaetigers is
never present ; the second pair extends almost as far as the body length. The
hyaline gland is normally clearly pigmented a red-brown, and appears dorsally on
THE DISTRIBUTION OF PELAGIC POLYCHAETES 383
the neuropodial pinnule from the first parapodia, although it may not be distinct
on all feet. The chromophil gland appears first on the third pair of parapodia and
subsequently on all feet ; it is not a compact gland but consists of a series of ramify-
ing tubules situated between the ventral and apical surfaces. There is no tail in
this species.
Discussion. The largest specimens of T. septentrionalis from the South Atlantic
(Tebble, 1960) are 15 mm. in length, much smaller than the largest reported here
from the North Pacific, which are between 20 mm. and 28 mm.,a similar size range
to that reported by Uschakov (1955) and Berkeley and Berkeley (1957). In general
these larger specimens appeared more often in the Sub-Arctic water mass than else-
where, but more material from warmer waters will have to be examined before
the possibility that the Sub-Arctic Zone harbours a distinct population can be
sustained.
GENERAL DISTRIBUTION. T. septentrionalis has been reported from all explored
water masses throughout the world (see below pp. 430-434).
Tomopteris planktonis Apstein, 1900
Original localities. In the Atlantic Ocean between Ascension Island and Brazil,
Ascension Island and Cape Verde Islands and between Newfoundland and Iceland.
Tomopteris planktonis Apstein, 1900, p. 42, pl. 11, figs. 21, 22 and pl. 12.
Tomopteris (Tomopteris) planktonis : Fauvel, 1923, pp. 224-225, fig. 84, d.
Tomopteris (Tomopteris) planktonis : Stop-Bowitz, 1948, pp. 52-54 (in part), fig. 39.
Tomopteris (Tomopteris) cavallii: Dales, 1957, pp. 144-145, figs. 510, 520.
Tomopteris planktonis : Tebble, 1960, pp. 171-174, fig. 6, a-f; pp. 228-231, fig. 31.
DEscRIPTION. The smallest specimens of this species in the collection measure
2 mm. in length for twelve pairs of parapodia and the largest 9 mm. for eighteen
pairs. The anterior border of the antennae is entire and there is a pair of eyes on
the prostomium. The first pair of chaetigers is never present. The second pair
teaches to about two-thirds the length of the body. Small hyaline glands appear
apically on the neuropodial pinnule of all parapodia but they are frequently in-
distinct. Compact chromophil glands appear on all neuropodial pinnules from the
fourth, they are ventral in position and when fully developed extend right into the
angle between the pinnule and the ramus. In some specimens there are tubules,
like those which make up the chromophil gland, in the dorsal region of the neuro-
podium and ventral in the notopodium. Bands of brown pigment appear on some
specimens either encircling the body or confined to the dorsal or ventral surfaces.
There appears to be no particular pattern manifest in the occurrence of these.
There is no tail in this species.
Discussion. This material is identical with that reported from the California
Current by Dales (1957) as T. cavallii; this species differs from T. planktonis in
having no hyaline glands but these are present in the material reported here, and
by Dales which has been deposited in the British Museum (Natural History).
The appearance of chromophil gland tubules in a dorsal position in neuropodia
and ventrally in notopodia in some specimens was noted by Dales (1957, as in T.
3384 THE DISTRIBUTION OF PELAGIC POLYCHAETES
cavallii) and my observations confirm this. There is no regularity about the ap-
pearance of these tubules ; they appear on specimens from widely separated stations,
and at one station some specimens may have them and some not. Bands of brown
pigment have not, to my knowledge, previously been seen on T. planktonis ; these
again appear to occur in no regular manner. The extent, and importance, of this
variation may become more apparent when comprehensive collections to the south
of the area now investigated have been examined.
GENERAL DISTRIBUTION. T. planktonis has been widely reported throughout the
world from all explored water masses but in the North Pacific it has not been col-
lected in the Sub-Arctic Zone (see below, pp. 434-435).
Tomopteris ligulata Rosa, 1908
Original localities. Atlantic Ocean, 22°N., 35° W., 33°S., 30° W.; Pacific
Ocean, 31°S., 84° W.
Tomopteris ligulata Rosa, 1908a, p. 1.
Tomopteris ligulata: Rosa, 19086, pp. 302-304, pl. 12, figs. 18-19.
Tomopteris (Tomopteris) ligulata: Fauvel, 1923, p. 224, fig. 84e.
Tomopteris ligulata: Tebble, 1960, pp. 177-179, figs. 9, 10; p. 248, fig. 47.
DeEscrIPTION. The smallest specimen of this species in the collection measures
2 mm. in length for twelve pairs of parapodia and the largest 7 mm. for eighteen
pairs. The anterior border of the antennae is entire and there is a pair of eyes on
the prostomium, these are normally distinct but on occasion may be difficult to
see. There is no first pair of chaetigers, the second pair reaches to about two-thirds
of the body length. The hyaline gland is distinctly pigmented—normally a red-
brown and appears in a dorsal position from the third neuropodial pinnule up to
the end of the body. The chromophil gland is compact and appears ventrally
from the fourth neuropodial pinnule. The pinnules border the parapodia almost to
the junction with the body wall. There is no tail in this species.
GENERAL DISTRIBUTION. This appears to be the first record of 7. igulata from
the North Pacific Ocean (see below, pp. 437, 438). In the Atlantic Ocean it is
known only from Tropical and Sub-Tropical waters.
Tomopteris nisseni Rosa, 1908
Type locality. Atlantic Ocean 20°S., 27° W.
Tomopteris Nisseni Rosa, 1908a, p. I.
Tomopteris (Tomopteris) Nisseni: Rosa, 1908), pp. 292-294.
Tomopteris (Tomopteris) Nisseni: Fauvel, 1923, p. 222, fig. 82e, g.
Tomopteris (Tomopteris) Nisseni : Stop-Bowitz, 1948, pp. 44-46, figs. 29-30.
Tomopteris nissent: Tebble, 1960, pp. 180-181, pp. 246-248, fig. 46.
DESCRIPTION. All the specimens collected are in a poor condition of preservation,
making examination difficult. In addition they are probably all young forms, the
glands are not developed on all feet and the largest measures only 12 mm. in length
for fourteen pairs of parapodia. Adult specimens of this species may measure up
to 60 mm. in length. The antennae are long and thin and have a prominent central
indentation. A first pair of chaetigers is never present ; the second pair is exceed-
THE DISTRIBUTION OF PELAGIC POLYCHAETES 385
ingly long-reaching in young forms to four or five times the length of the body.
Parapodial pinnules are reduced to a fringe bordering the rami. Apical hyaline
glands appear first on the neuropodial pinnules of the third parapodia and in noto-
podia from about the eighth. Compact chromophil glands appear on the ventral
part of the neuropodial pinnules in all parapodia from the fourth. A tail is present
in this species but in most of the specimens examined here it has broken off.
Discussion. There are no eye spots visible in any of these specimens ; this is
either because they are juveniles, or because of the poor state of preservation.
In well-preserved adult 7. nissent I would certainly expect a pair of eye spots to be
present.
GENERAL DISTRIBUTION. In the Atlantic Ocean 7. nissenit has been reported
from all explored water masses except south of the Sub-Tropical Convergence in
the South Atlantic; in the North Pacific it has not been collected north of the
Sub-Tropical Zone (see below pp. 437, 439).
Tomopteris apsteini Rosa, 1908
Type locality. Messina, Mediterranean Sea.
Tomopteris (Tomopteris) Apsteini Rosa, 1908), pp. 288-292, pl. 12, figs. 10-13.
Tomopteris (Johnstonella) Apsteini: Fauvel, 1923, pp. 220-221, fig. 83, a-d.
Tomopteris (Johnstonella) Apsteini : Stop-Bowitz, 1948, pp. 39-42, figs. 26-27.
Tomopteris apsteini: Tebble, 1960, p. 183; p. 252, fig. 48.
DEscRIPTION. The smallest specimen of this species in the collection measures
8 mm. in length for nineteen pairs of parapodia and the largest 18 mm. also for
nineteen pairs. The anterior border of the antennae carries a central indentation.
There is a pair of eye spots on the prostomium. The first pair of chaetigers is
present extending almost to the length of the antennae ; the second pair reaches to
about two-thirds of the length of the body. Rosette glands appear on all para-
podia ; on the first two there is one present near the ventral surface within the
ramus ; thereafter one is present on all notopodial and neuropodial pinnules near
the apex of the parapodial trunk. The characteristic “ spur ’’ glands may appear
in the first neuropodia projecting prominently from the ventral border of the pin-
nules. They are always present from the second parapodia and from the third are
associated with the large compact chromophil gland. A prominent tail is present
normally carrying rudimentary parapodia.
GENERAL DISTRIBUTION. T. apsteini is known only from Tropical and Sub-
Tropical waters (see below, pp. 437, 439)-
Tomopteris pacifica Izuka, 1914
(Text-fig. 6)
Type locality. Misaki, Japan.
Tomopteris pacifica Izuka, 1914, pp. 11-12, figs. 1-4.
Tomopteris elegans Berkeley, 1924, pp. 5-6, pl. 1, figs. 1-2 (name preoccupied).
Tomopteris renata Berkeley, 1930, pp. 11-12 (new name to replace T. elegans Berkeley, 1924).
Tomopteris venata: Berkeley & Berkeley, 1948, p. 26, figs. 31-32.
Tomopteris (Johnstonella) pacifica : Uschakov, 1955, p. 109.
386 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Tomopteris (Johnstonella) renata: Uschakov, 1955, p. 110.
Tomopteris (Johnstonella) pacifica: Dales, 1955, p. 440.
Tomopteris (Johnstonella) renata: Uschakov, 19574, p. 285, Chart 3.
Tomopfteris (Johnstonella) pacifica: Uschakov, 19574, pp. 285-286, Chart 3.
Tomopteris (Johnstonella) pacifica: Dales, 1957, p. 141, fig. 51e, fig. 52f.
Tomopfteris (Johnstonella) renata: Berkeley & Berkeley, 1957, p. 576.
Tomopteris (Johnstonella) renata: Berkeley & Berkeley, 1960, p. 791.
DESCRIPTION. This species measures between 8 mm. long for fourteen pairs of
parapodia and 50 mm. for twenty-four pairs!. The antennae are long and thin
l'1G. 6. Tomopteris pacifica : specimen from Stn. 46B of the Trans-Pacific Expedition,
the first pair of chaetigers has been lost.
and carry a central indentation. There is a pair of black eye spots on the pro-
stomium. The first pair of chaetigers is normally present but may be broken off ;
the stumps, however, are always visible on the ventral surface, just beside the inner
edge of the nuchal lobes. The second pair of chaetigers reaches to about two-
thirds of the body length. Rosette glands appear on all parapodia; on the first
two they are within the parapodial trunk thereafter on the pinnules immediately
ventral to the ramus in the notopodium and dorsal in the neuropodium. Chromophil
1 One very poorly preserved specimen from Northern Holiday Expedition Station 23, which could
be T. pacifica measures 135 mm, in length. This identification, however, cannot be confirmed and
has neither been plotted on a chart nor recorded in the appendices of this report.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 387
glands are compact and appear ventrally on the neuropodia of all parapodia from
the third backwards. All glands, except the rosettes on the first two parapodia,
are always well preserved and clearly visible. A prominent tail with rudimentary
parapodia is normally present though it may be broken off.
Discussion. After examining co-type material of T. venata Berkeley in the
collections of the B.M. (N.H.) (Reg. No. 1938.11.29.6-8) I have no doubt that this
species is identical with T. pacifica. Berkeley & Berkeley (1957 and 1960) reject
the possibility of such synonymy mainly on the grounds that T. renata is much the
larger, with an abrupt transition from the body to the tail region. I can find no
evidence for supporting such a conclusion. The principal difficulty in accepting
these two species as identical results from the ease with which the first pair of
chaetigers becomes detached from the body. These are almost certainly lost acci-
dentally and not, as suggested by Berkeley (1930), naturally, in the course of the
life history of the animal. There are no observations on living tomopterids which
substantiate Berkeley’s suggestion. Of the specimens examined in this survey over
half have lost the first chaetigers and have only the stumps remaining. At some
stations some specimens have retained them and others lost them, and at Trans-
Pacific Station 50B, the chaetiger is present on one side and missing on the other.
In all other characters these specimens are identical with those in which the first
chaetigers are present. There is no doubt that identification is difficult when
situations of this type arise and confusion between 7. pacifica and T. nissent and
T. kempzi is possible in this present case.
Text-fig. 6, of T. pacifica, has been prepared from a specimen which has lost the
first pair of chaetigers.
GENERAL DISTRIBUTION. From the evidence obtained in this survey T. pacifica
appears to be restricted to the Sub-Arctic water mass in the North Pacific Ocean
(see below, pp. 434-437). The fact that it was first recorded from Misaki, just
outside Tokyo Bay, with a number of other species which are certainly not Sub-
Arctic forms, is also discussed below, p. 437.
Family ALCIOPIDAE
Exclusively pelagic. Body normally elongate with numerous segments: ex-
ceptionally short and wide with comparatively few segments. Prostomium small
with two very large eyes and four, five or six antennae. There are three, four or
five pairs of tentacular cirri. Proboscis eversible, with long terminal horns and/or
short papillae. Uniramous parapodia, with simple and/or compound chaetae, often
with pigmented segmental glands. In mature females some anterior dorsal cirri
may be modified into receptacula seminis. Anal cirri present.
Table III below has been prepared to show the principal diagnostic characters of
the parapodia which are used in separating genera in the Alciopidae.
Some authors, in particular Dales (1957), have used the angle subtended by the
axes of the eyes as a character of value in separating species ; in no specimen have
I found evidence to support such use. It appears reasonable to assume that a
character of this type will vary considerably with the method of fixation of the
ZOOL. 7, 9. 28
388 THE DISTRIBUTION OF PELAGIC POLYCHAETES
TABLE III
Acicular
chaetae . Absent . Absent . Simple . Simple . Compound
Capillary
Number \chaetae . Simple . Compound . Simple . Compound . Compound
of cirriform
pedal
appendages
Nil . Naiades . Torrea* . Alciopina* . Plotohelmis . Not known
One . Wateliot . Vamnadis . Krohnia . Rhynchonerella
Two . Alciopa* . Not known . Not known . Not known . Not known
* Not reported here.
specimens. Of the Alciopidae reported here only Natades cantrainit and Rhyncho-
nerella angelint are normally complete when collected, the remaining species being
almost always broken into fragments. In identifying fragments it is generally
necessary to have at least the head and anterior parapodia to make a reliable deter-
mination. With two species, however, Vanadis longissima and Krohmnia lepidota,
the body is characterized by an ornamentation which allows a specific determination
to be made with some certainty, even when the head is missing. It will be appre-
ciated, however, that identification of fragments is an unsatisfactory state of affairs,
although it is one which workers on polychaetes have to deal with frequently.
In the Appendices the presence or absence of alciopid fragments has been noted as
an indication of the occurrence of this family even when species were not identifiable.
The zoogeographical importance of these results is discussed below, p. 440.
Genus NAIADES Delle Chiaje, 1830
Body elongate. Prostomium with five antennae. Three pairs of tentacular cirri.
Proboscis bell-shaped with two short terminal lobes between which are small papillae.
Parapodia with simple chaetae only ; the pedal lobe is without an appendage.
Type species. Naiades cantrainii Delle Chiaje, 1830.
Type locality. Naples.
Naiades cantrainii Delle Chiaje, 1830
Naiades cantrainii Delle Chiaje, 1830, pl. 82, figs. 14, 18, 21.
Alciopa cantrainii : Izuka, 1914, pp. 2-3, pl. 1, fig. 9.
Alciopa cantrainii : Fauvel, 1923, pp. 203-204, fig. 76.
Alciopa distorta Treadwell, 1943, p. 35, Ppl. 1, figs. 16,17; pl. 11, fig. 18.
Naiades cantrainii : Stop-Bowitz, 1948, pp. 24-25, figs. 15-16.
Naiades cantrainii : Dales, 1957, pp. 113-115, figs. 18-20.
Naiades cantrainii : Tebble, 1960, p. 184, p. 257, fig. 51.
DESCRIPTION. Complete specimens of this species may measure up to IIo mm.
in length. The body is sharply terminated anteriorly, the eyes projecting forward
THE DISTRIBUTION OF PELAGIC POLYCHAETES 389
prominently with the small prostomium between them. There are two pairs of
antennae on the anterior edge of the prostomium and an unpaired median antenna
on the dorsal surface between the eyes; the latter is in fact a crest with a free
anterior edge. There is one pair of tentacular cirri on each of three successive
segments behind the head; the most anterior of these is very long, the posterior
two minute. The first three pairs of parapodia are reduced, with no chaetae but
with aciculae ; in mature females the cirri of the second pair are modified as recep-
tacular seminis. The remaining parapodia, up to the end of the body, each have a
large foliaceous dorsal cirrus, a slightly smaller ventral cirrus, a prominent pro-
jecting acicula, long simple capillary chaetae and a strongly pigmented dorsal
segmental gland.
Discussion. I have examined the type specimen of Alciopa distorta Treadwell,
1943, in the Smithsonian Institution, No. 20084, and it is identical with N. can-
traint.
GENERAL DISTRIBUTION. NN. cantrainii is known only from Tropical and Sub-
Tropical waters (see below, pp. 440-441).
Genus VANADIS Claparéde, 1870
Body elongate. Prostomium with two large eyes and with four, five or six
antennae. There are three to five pairs of tentacular cirri. Parapodia with long
compound chaetae ; pedal lobe with terminal appendage. Proboscis with terminal
horns and/or papillae.
Type species. Vanadis formosa Claparéde, 1870.
Type locality. Gulf of Naples.}
Key To Species oF Vanadis
1. With six antennae (Text-fig. 9) . : 5 - E . 0 S V. tagensis
—. With four or five antennae 5 6 - c ‘ c : S : c 2
2. With four antennae (Text-fig. 7) . : ; : : : : : V. minuta
—. With five antennae (Text-fig. 8) . : fe 3 c 3
3. Proboscis terminated by twelve equal small papillae 5 6 v. longissima
—. Proboscis terminated by two long horns and a varying number of small papillae 4
4. Parapodia well developed and with chaetae from the third foot posteriorly V. formosa
. Parapodia well developed and with chaetae from the seventh to tenth feet posteriorly
V. crystallina
Vanadis formosa Claparéde, 1870
Vanadis formosa Claparéde, 1870, pp. 480-484, pl. 10, fig. 3.
Vanadis formosa: Fauvel, 1923, pp. 305-306, fig. 77, a—c.
Vanadis formosa: Treadwell, 1943, p. 36, pl. II, figs. 23-24.
Vanadis formosa: Stop-Bowitz, 1948, pp. 25-26, fig. 17, Chart 18.
Vanadis formosa: Dales, 1957, p. 117, figs. 21-24.
Vanadis formosa: Tebble, 1960, pp. 185-186; pp. 252-255, fig. 49.
DEscrIPTION. No complete specimens of this species were collected ; the largest
head-fragment measures 73 mm. long for seventy-two chaetigers but. most pieces
? Not the Island of Formosa (Taiwan) as in Dales (1957, p. 117, and fig. 63).
390 THE DISTRIBUTION OF PELAGIC POLYCHAETES
are less than 20 mm. in length. Wesenberg-Lung (1939) reports complete speci-
mens up to 300 mm. long from the Mediterranean. All five antennae are small, the
dorsal and ventral pairs on the anterior edge of the prostomium and the unpaired
in the median line between the large eyes. The proboscis carries two long terminal
horns each with a pair of basal ailerons continuous with rows of four to six papillae.
There are three pairs of tentacular cirri, one on each of successive segments behind
the head; the first pair is the longest and joined by bulbous basal ceratophores
continuous under the ventral surface ; the posterior pairs are equal in length and
project out about half the distance of the anterior pair. In mature females the
first two pairs of parapodia are reduced, with the dorsal cirri modified as receptacula
seminis. In the male these parapodia are reduced but never modified. In both
sexes, all parapodia from the third are well developed, with large foliaceous dorsal
and smaller ventral cirri, with pedal mamelon and projecting acicula, and with
cirriform appendage and compound chaetae with short terminal articles. Darkly
pigmented segmental glands appear on each foot after the first three, except in
mature females when they may appear in the first two modified parapodia.
GENERAL DISTRIBUTION. V. formosa is known only from Tropical and Sub-
Tropical waters (see below, pp. 442, 447).
Vanadis crystallina Greeff, 1876
Type locality. Gulf of Naples.
Vanadis crystallina Greeff, 1876, pp. 68-69, pl. 4, figs. 35-39.
Vanadis crystallina: Fauvel, 1923, pp. 206-207, fig. 77, d, e.
Vanadis crystallina: Stop-Bowitz, 1948, pp. 27-29, figs. 19-20.
Vanadis crystallina: Dales, 1957, pp. 118-119, figs. 25-28.
Vanadis crystallina : Tebble, 1960, pp. 186-187, pp. 252-255.
DEscRIPTION. No complete specimens of this species were collected ; the longest
head-fragment is only 9 mm. long for twenty-five pairs of parapodia, but in Dis-
covery collections from the South Atlantic (Tebble, 1960) a complete specimen was
143 mm. in length. V. crystallina differs from V. formosa in having the first seven
to ten pairs of parapodia rudimentary, with no chaetae and only very small cirri ;
in V. formosa fully developed parapodia are present from the third foot.
GENERAL DISTRIBUTION. V. crystallina is known only from Tropical and Sub-
Tropical waters (see below, pp. 442, 445).
Vanadis minuta Treadwell, 1906
(Text-fig. 7)
Type locality. Off Hawaii.
Vanadis minuta Treadwell, 1906, pp. 1158-1159, figs. 25-278.
nec. Vanadis fusca-punctata Treadwell, 1906, pp. 1159-1160, figs. 29-31.
Vanadis minuta: Dales, 1957, pp. 119-121, figs. 28-30.
~ tOmm.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 391
DEscRIPTION. No complete specimens of this species were collected ; the longest
head-fragment is 15 mm. in length. Treadwell’s original material does not appear
to have been complete, the first twenty-one segments measuring 8 mm. The
proboscis has two long terminal processes, each carrying a pair of basal ailerons
between which there are no papillae. There are three pairs of small tentacular
cirri, one on each of successive segments behind the head ; the first of these pairs
is the largest and joined ventrally by basal ceratophores ; the second and third are
equal in size. There are only four antennae, all on the anterior border of the pro-
stomium arranged in dorsal and ventral pairs ; of these the ventral pair is sharply
pointed and noticeably the longer, being always at least twice as long as the blunt
dorsal pair. No median unpaired antenna is present in this species: on the top
of the prostomium, between the eyes (where the unpaired antenna is present in all
other species of Vanadis) there is a pronounced crest but this cannot be called an
antenna. The anterior seven pairs of parapodia are achaetous with very small
cirri; thereafter parapodia are fully developed ; chaetae are long and compound,
cirri ovate, and the pedal lobe carries a cirriform appendage. In mature females
Fic. 7. Vanadis minuta : lateral view of head and extruded proboscis of
specimen from Stn. 63 of the Northern Holiday Expedition.
the dorsal cirri of the second parapodia are modified as receptacula seminis. None
of the specimens examined has the pigmented segmental glands preserved suffi-
ciently well to allow accurate examination.
Discussion. Dales (1957) was the first to record V. minuta after its original
discovery ; I have examined some of his specimens in the B.M. (N.H.) collections,
and they are identical in all respects with those described here including having
four antennae. In suggesting however, that V. fusca-punctata is synonymous with
V. minuta, both he and Treadwell (1943) allow for the possibility that the latter
species has a fifth unpaired median antenna as Treadwell’s (1906) drawing of the
type of V. fusca-punctata clearly shows this organ present, and his description
mentions it. There is no precedent for suggesting any species of Alciopidae has a
variable number of antennae ; no work on the life history of any species of the
family suggests this as likely. Indeed it is a basic tenet of the systematic analysis
of adult polychaetes, that the number of antennae within a species is constant.
GENERAL DISTRIBUTION. V. minuta is known only from the Pacific Ocean where
it has been collected in Tropical and Sub-Tropical waters (see below, pp. 440-443).
392 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Vanadis longissima (Levinsen), 1885
(Text-fig. 8)
Type locality. 26° 0’N., 26° 0’ W.
Rhynchonerella longissima Levinsen, 1885, pp. 330-331, figs. 7-10.
Vanadis grandis Izuka, 1914, pp. 5-7, pl. 1, figs. 1-7.
Vanadis longissima: Fauvel, 1923, p. 207, figs. 77f—g.
Vanadis pacifica Uschakov, 19574, pp. 275-277, Chart 2, fig. 4a~d.
Vanadis longissima: Dales, 1957, pp. 121-123, figs. 31-33.
Vanadis longissima: Tebble, 1960, pp. 187-188; p. 224, fig. 27.
DescriPTIon. No complete specimens of this species were collected ; the longest
head-fragment measures 160 mm. in length. There are four anterior antennae, in
dorsal and ventral pairs on the front edge of the prostomium and a median unpaired
antenna between the large eyes ; irregular black spots may be present on the eyes
in some specimens. The proboscis carries twelve small terminal papillae. There
are three pairs of tentacular cirri, one on each of successive segments behind the
head ; all are approximately equal in length, the foremost pair being joined ventrally
by basal ceratophores. The first pair of parapodia is achaetous with small foliaceous
dorsal cirri and minute ventral cirri. In mature females the dorsal cirri of the ,
second and third parapodia are converted into darkly pigmented receptacula
seminis. From the fourth chaetiger parapodia gradually increase in size to a constant
width from about the tenth ; pedal lobes project about twice as far as the dorsal
cirri and carry a prominent cirriform appendage; dorsal cirri are foliaceous and
ventral cirri conical; chaetae are long and compound. On specimens other than
mature females the second and third parapodia are achaetous with small cirri.
Pigmented segmental glands appear at irregular intervals along the body, variously
grouped over two to eight segments, with the pigment often extending over the
ventral and dorsal surface, giving a striped appearance to the specimens. The
first group of pigmented glands may appear on any of the first ten parapodia.
Discussion. In reporting on the Discovery collections (Tebble, 1960) from the
South Atlantic I noted that V. longissima and V. antarctica could be separated with
certainty only from complete specimens. Because no complete specimens have
been found in the present survey it follows that, theoretically, none of the deter-
minations of V. longissima made here can be absolutely certain. In the Atlantic,
and Pacific Oceans however, V. antarctica has never been reported north of the
Antarctic Convergence and it is reasonable to assume that in the North Pacific
Sub-Tropical Zone the material examined is V. longissima.
I do not think that V. pacifica Uschakov (1957a) is a valid species. Uschakov
separates it from V. grandis (= V. longissima) on a combination of the different
number of tentacular cirri and poorly developed anterior parapodia. Because
tentacular cirri are frequently lost, and chaetae may be missing, either accidentally,
or through normal development, on anterior feet, it is easy to mistake parapodial
cirri for tentacular cirri. This Izuka (1914) did in his original account of V. grandis,
and has led Uschakov to establish V. pacifica as a separate species.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 393
Specimens of V. longissima from five localities, Trans-Pacific Exp., Stns. 51A,
54A, and 56A, and Hugh M. Smith Cruise 30, Stns. 74 and 96 have irregular black
spots on the eyes and surrounding areas. Stn. 51A is from the Transition Zone,
and the other four stations are from close to the boundary separating it from the
Sub-Tropical Zone! and although these records are few the presence of specimens
with this unusual character (the first time it has been recorded) in and near the
O-Smm.
Wc. 8. Vanadis longissima : dorsal view of head and extruded proboscis, showing marking on
the eyes ; specimen from Stn. 74, of Hugh M. Smith Cruise 30.
Transition Zone should be noted as possibly indicative of a distinct population
inhabiting this region. It is shown below, Pp. 442, that the northern boundary
of the Transition Zone is the northerly limit of the distribution of V. longissima in
the North Pacific and it is of interest that at its southern limit in the South Atlantic
at the Antarctic Convergence it meets the endemic antarctic form Vanadis antarctica,
which it was suggested in Tebble (1960), may be a geographical race rather than a
separate species. This suggestion may now be taken a little further. It is possible
that, at the extremities of its range in higher latitudes, V. longissima has developed,
or is developing, separate populations capable of establishing themselves in dis-
1 Specimens of V. longissima from Trans-Pacific Stns. 70E, 76A and H. M. Smith Cruise 30, Stn. 29
also near this boundary, are without heads.
394 THE DISTRIBUTION OF PELAGIC POLYCHAETES
tinctive hydrological environments. In the case of V. longissima-V. antarctica
about the Antarctic Convergence, semi-sympatric speciation, involving ecological
allopatry and genetical continguity (Cain, 1954) may have taken place, whereas
near the Transition Zone in the North Pacific V. longissima may be developing a
physiological race.
GENERAL DISTRIBUTION. In the North Pacific and North Atlantic V. longissima
has never been found in Arctic or Sub-Arctic waters (see below, p. 442); in
the South Atlantic, however, it penetrates the Sub-Antarctic Zone as far as the
Antarctic Convergence, and in the Antarctic Zone it may be represented by V.
antarctica.
Vanadis tagensis Dales, 1955 (characters emended)
(Text-fig. 9)
Type locality. Monterey Bay, California, in a depth of 1,000 to 500 metres.
Vanadis tagensis Dales, 1955, pp. 436-439, figs. ta, b, c.
DESCRIPTION. No complete specimens of this species were collected ; the longest
head fragment is 51 mm. in length for sixty pairs of parapodia. There are six
antennae in this species not five as noted in the original description. Text-fig. 9
has been prepared from a paratype in the B.M. (N.H.) collections, Reg. No.
1955-9.30.4 and shows, apart from the anterior dorsal and ventral pairs, and the
fifth unpaired on the top of the prostomium, a sixth antenna in the anterior region
of the prostomium above and between the ventral pair. This sixth antenna is small
and, after preservation in formalin, may be difficult to see. There are twelve
terminal papillae on the proboscis of which two lateral pairs are the longest, being
about twice as long as the dorsal and ventral groups of four. There are four pairs
of tentacular cirri on three successive segments behind the head arranged thus
1+1-+ 1/1. The most anterior of these is almost joined ventrally by basal
ceratophores. The anterior seven parapodia are much reduced with small cirri and
aciculae ; they may have a few chaetae present. Thereafter cirri are well developed
and ovate, the dorsal twice as long as the ventral and the pedal lobe prominent.
In mature females the dorsal cirri of the first two parapodia are modified as recep-
tacula seminis. Chaetae are long and compound. None of the specimens avail-
able is sufficiently well preserved to permit a critical diagnosis of the arrangement
of the pigmented segmental glands.
Discussion. This species presents two characteristics met nowhere else in the
genus, six antennae and four pairs of tentacular cirri, and should be considered
quite distinct from known species. It may be that its distinctive habitat (it is the
only Vanadis known to inhabit deep water exclusively, see below p. 442) provides
a key to this disposition of normally stable features.
GENERAL DISTRIBUTION. V. ¢agensis is at present known only from deep water
in the North Pacific Ocean, south of the Sub-Arctic Zone (see below, pp. 442, 446—
447).
THE DISTRIBUTION OF PELAGIC POLYCHAETES 395
(O33 mm.
Fic. 9. Vanadis tagensis : ventral view of head showing six antennae :
Paratype, B.M. (N.H.), Reg. No. 1955.9.30.4.
Genus RHYNCHONERELLA Costa, 1862
(Emended Claparéde, 1868 pro Rhynchonereella Costa, 1862)
Body normally elongate. Prostomium extending beyond the eyes and carrying
fiveantennae. Five pairs of tentacular cirri. Parapodia with a cirriform appendage
on the pedal lobe; acicular chaetae simple or compound ; long slender chaetae
(capillaries) always compound.
Type species. Rhynchonerella gracilis Costa, 1862.
Type locality. Gulf of Naples.
Key TO SPECIES
1. With simple acicular chaetae c ° ° . “ c e ¢ 2 : 2
—. With compound acicular chaetae c 3
2. Simple acicular chaetae present on the first six “to ten chaetigers, but compound
capillaries absent (Text-fig. 11) ; both types of chaetae on remaining feet. Acicular
chaetae with a few distal spines (Text-fig. 11) . . R. mobii
—. Simple acicular chaetae and compound capillary chaetae present from the first para-
podia (Text-fig. toa). Acicular chaetae smooth c . R. gracilis
3. Compound acicular chaetae with a large, serrated terminal article (lext fie 12a-c)
R. petersii
—. Compound acicular chaetae with a small, sooth terminal article (Text-fig. 14c) R. angelini
306 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Rhynchonerella gracilis Costa, 1862
(Text-fig. roa, b)
Rhynchonereella gracilis Costa, 1862, p. 168, pl. 4, figs. 13-15.
Callizona nasuta Greeff, 1876, p. 72, pl. VI, figs. 60-62.
Callizona japonica Izuka, 1914, pp. 7-8, pl. 1, fig. 8.
Callizona nasuta: Fauvel, 1923, pp. 215-216, fig. 81a—c.
Rhynchonerella gracilis : Stap-Bowitz, 1948, p. 36.
Callizona nasuta : Uschakov, 19574, pp. 279-281, Chart 2, fig. 6a—d.
DESCRIPTION. Most specimens collected were anterior pieces rarely measuring
more than 8 mm. in length but one complete specimen, from Stn. 112A of the Trans-
Pacific Expedition is 20-5 mm. long for 116 chaetigers. The specimen reported by
Izuka, (1914 as C. japonica) from Misaki measured 36 mm. for about 190 segments.
The proboscis is covered with small papillae, all of the same size; there are no
terminal papillae. The prostomium protrudes prominently in front of the eyes and
carries two pairs of anterior foliaceous antennae with a smaller unpaired antenna
between the eyes. Two parallel lines of light brown pigment run down the middle
of the protruding prostomium (these may not always be well preserved). The
five pairs of tentacular cirri are arranged on three successive segments behind the
head thus 1 + 1/1 + 1/1; of these the dorsal are the longest and the posterior the
longer. Pigmented segmental glands are present on every chaetiger from the first
(these are only rarely not visible). One or two simple acicular chaetae appear on
anterior feet with a bundle of long compound capillaries. On posterior feet there
is only one acicular chaeta. There is a very prominent cirriform pedal lobe on all
feet. The body is terminated by an unpaired anal cirrus.
GENERAL DISTRIBUTION. R. gracilis is known only from Tropical and Sub-
Tropical waters (see below, pp. 446, 450-451).
Rhynchonerella mobii (Apstein), 1893
(Text-fig. 11)
Type locality. Mediterranean Sea.
Callizona Mobii Apstein, 1893, p. 147.
Callizona Moebii: Fauvel, 1923, pp. 213-214, fig. 80a—d.
Rhynchonerella Mobii : Stop-Bowitz, 1948, p. 34.
Rhynchonerella mobii : Dales, 1957, pp. 131-132, figs. 39, 40-43.
DEscrIPTION. The majority of specimens collected are incomplete anterior
fragments, less than 15 mm. in length, but from Northern Holiday Expedition
Stn. 54 there is an almost complete specimen measuring 45 mm. in length for ap-
proximately 170 chaetigers. The prostomium protrudes in front of the eyes and
Fic. 10. Rhynchonerella gracilis : parapodia, (a) from second chaetiger of specimen
from Stn. 107A or the Trans-Pacific Exp., (b) from ninetieth chaetiger of specimen
from Stn. 117A.
397
THE DISTRIBUTION OF PELAGIC POLYCHAETES
398 THE DISTRIBUTION OF PELAGIC POLYCHAETES
carries two pairs of stout anterior antennae and a single small, unpaired, antenna
between the large eyes. The five pairs of tentacular cirri are arranged on three
successive segments behind the head thus r + 1/1 + 1/1: of these the anterior is
short and fat ; the two dorsal are strap-like, equal in length and the longest of all ;
the anterior ventral very short and fat ; the posterior ventral broadly foliaceous.
uso
Fic. 11. Rhynchonerella mobii : parapodium from the fifth chaetiger of specimen from Stn,
86B of the Trans-Pacific Exp., with acicular chaeta enlarged.
Pigmented segmental glands appear on every foot from the seventh on the few
specimens in which they are visible. Anterior parapodia have three to six simple
acicular chaetae only; from the tenth to the twelfth foot compound capillary
chaetae appear and acicular chaetae are gradually reduced until there is only one in
each foot. The distal ends of the acicular chaetae are slightly serrated; this
serration is visible only at high magnifications. Dorsal and ventral cirri are broadly
foliaceous, the former being the larger. There is a very prominent pedal lobe on all
parapodia.
GENERAL DISTRIBUTION. R. mobii is known only from Tropical and Sub-Tropical
waters (see below, pp. 446-449).
(Text-fig. 12a, b, c)
Type locality. Madeira.
Alciopa (Halodora) Petersii Langerhans, 1880, p. 312, pl. XVII,fig. 49.
Callizona setosa: Fauvel, 1923, p. 214, fig. 80c, f.
Rhynchonerella petersii : Stop-Bowitz, 1948, p. 34.
Callizona setosa: Uschakov, 19574, p. 281, chart 2, fig. 6e-7.
Rhynchonerella petersii (Langerhans), 1880*
* See Addenda, p. 492.
THE DISTRIBUTION OF PELAGIC POLYCHAETES
Fic. 12. Rhynchonerella petersii : (a) parapodium, from the fourth chaetiger of speci-
men from Stn. 11A of the Trans-Pacific Exp., (b) compound acicular chaeta from
anterior chaetiger of specimen from Stn. 129B, (c) parapodium from the fourteenth
chaetiger of specimen from Stn. 12E.
399
400 THE DISTRIBUTION OF PELAGIC POLYCHAETES
DEscRIPTION. Only fragments of this species were collected, the largest measuring
10 mm. in length for forty-two chaetigers. The prostomium projects only a little
way in front of the eyes and carries four bulbous terminal antennae and one very
small median antenna between the eyes. The prostomium, antennae and interior
edge of the eyes may be sprinkled with light brown spots. The five pairs of tentacular
cirri are arranged on three successive segments between the head thus r + 1/1 + 1/1;
the anterior one is long and strap-like; the two dorsals are the longest and the
posterior one the longer, both pointed; the anterior ventral is very short and
digitiform ; the posterior ventral small and foliaceous. The proboscis carries
twelve small terminal papillae. On anterior parapodia dorsal cirri are large and
broadly foliaceous, ventral cirri smaller but of similar shape. On the first four to
six parapodia acicular chaetae are much more numerous than compound capillary
chaetae ; on a specimen from Trans-Pacific Expedition Stn. 3A, for example, there
are twelve compound acicular chaetae and one compound capillary chaeta on the
first parapodia—see also Text-fig. 12a for a specimen from Stn. 1rA, which has
these chaetae in the proportion of 6: 1 respectively. From the fourth to sixth feet
posteriorly there is a reduction in the number of compound acicular chaetae and an
increase in the compound capillaries. The terminal article of all the compound
acicular chaetae is denticulated and at high magnification the distal end of the
main stem is seen to bear spines. All parapodia carry a prominent cirriform pedal
appendage. Pigmented segmental glands may appear on every chaetiger from the
third but they are frequently not distinctly preserved.
Discussion. This is the first time that spines have been reported on the distal
end of the main stem of acicular chaetae in R. petersit. I have checked a specimen
of the same species deposited in the B.M. (N.H.) Fauvel Collection (Reg. No.
1928.4.26.746 from the Balearic Islands, Fauvel, 1916 as Callizona setosa) and find
it identical with the above in this and all other respects.
GENERAL DISTRIBUTION. R. petersiti is known only from Tropical and Sub-
Tropical waters (see below, pp. 446, 448).
Rhynchonerella angelini (Kinberg), 1866
(Text-figs. 13, 14, a, b, c)
Type locality. China Sea, 20°S., 107° E.
Krohnia Angelini Kinberg, 1866, p. 242.
Callizona Angeliin: Fauvel, 1923, p. 215, fig. 81d-1.
Callizona angelini: Berkeley & Berkeley, 1948, pp. 40-41, fig. 56.
Rhynchonerella Angelini : Stap-Bowitz, 1948, pp. 34-36.
Rhynchonerella angelini : Dales, 1957, p. 113, figs. 44-46.
Rhynchonerella angelini : Tebble, 1960, p. 192; p. 255, fig. 50.
DESCRIPTION. This is the only species of Riynchonerella which is normally com-
plete when collected ; it is comparatively large and robust, the longest specimens
‘+Omm.
Ly
yea
MS
4] ie H Aas
i
Fic. 13. Rhynchonerella angelini : specimen from Stn. 117B of the Trans-
Pacific Exp.
AES ANQOG
oe tye
Me
\
ay.
SS
402 THE DISTRIBUTION OF PELAGIC POLYCHAETES
measuring 70 mm. in length and the smallest 10 mm. The prostomium protrudes
in front of the eyes and carries two pairs of anterior short, dumpy antennae, and a
small unpaired antenna immediately behind this prostomial extension, between the
WWSOO.
{a
wus
“yf
Fic. 14. Rhynchonerella angelini : (a) parapodium from the fourth chaetiger of speci-
men from Stn. 50B of the Trans-Pacific Exp., (b) the same from the eighteenth chae-
tiger, (c) compound acicular chaeta of specimen from Stn. 117B.
large eyes. The prostomium, tentacular cirri, antennae and anterior parapodia are
normally covered with a brown pigment. The proboscis is covered with papillae
between which there are longitudinal grooves on the anterior half and lateral grooves
on the posterior half. The five pairs of tentacular cirri are arranged on three suc-
THE DISTRIBUTION OF PELAGIC POLYCHAETES 403
cessive segments between the head thus r + 1/1 + 1/1 of these the anterior is
short and pointed and the two dorsal long and pointed, the two ventral are short
and tend to be foliaceous; all are thick at the base. Over the anterior three-
quarters of the body parapodia have broadly foliaceous dorsal cirri which become
elongate posteriorly and smaller but still large foliaceous ventral cirri. The first
six to ten parapodia have two types of chaetae, an inferior group of stout acicular
bristles with short terminal articles and a superior group of compound capillary
chaetae with long terminal articles. The acicular chaetae decrease rapidly in
number after these first parapodia and are absent over the greater part of the body.
On all parapodia there is a prominent cirriform pedal appendage. Posteriorly the
body width is considerably reduced assuming the appearance of a whip-cord-like
tail.
GENERAL DISTRIBUTION. R. angelini is confined to Tropical and Sub-Tropical
waters in the southern hemisphere but in the northern extends into higher latitudes
(see below, pp. 450, 452).
Genus PLOTOHELMIS Chamberlin, 1919
Body elongate. Prostomium extending beyond the eyes and carrying five
antennae. Five pairs of tentacular cirri. Parapodia without a cirriform appendage
on the pedal lobe ; acicular chaetae simple, capillary chaetae compound.
Type species. Plotohelmis alata Chamberlin, 1919.
Type locality. South Pacific Ocean.
Plotohelmis tenuis (Apstein), 1900
(Text-figs. 15a, b; 16, 17)
Original localities. Tropical Atlantic Ocean.
Corynocephalus tenuis Apstein, 1900, p. 14, pl. 2, figs. 14-16.
Corynocephalus tenuis : Chamberlin, 1919, p. 141.
Plotohelmis tenuis: Dales, 1957, pp. 125-128, figs. 36-39.
DEscriPTIoN. No complete specimens of this species were collected ; the longest
fragment measures 25 mm. in length. The prostomium projects forward between
the eyes as a bulbous outgrowth divided into hemispheres by a median groove ;
there are four terminal antennae on this outgrowth, two dorsal and two ventral, all
are small ; the dorsal pair are fat and the ventral thin. There isa pit at the anterior
end of the prostomium in which the antennae have their bases. (This pit, which
may be filled with extraneous material, should not be confused with the opening of
the proboscis which may, or may not, be extruded.) A fifth unpaired antenna is
situated on top of the prostomium between the large eyes. When fully extruded
the proboscis carries numerous small papillae terminally. There are five pairs of
tentacular cirri arranged on successive segments behind the head thus 1 + 1/r + 1/r.
ZOOL, 7, 9. 29
404 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Of these the posterior ventrals are very small and foliaceous, the posterior dorsals
very long and thin, and the anterior lanceolate, of medium length. Parapodia
have no cirriform appendage on the pedal lobe, dorsal cirri are large, broadly
O5mm.
Fic. 15. Plotohelmis tenuis : (a) lateral view of head and anterior segments of specimen from
Stn. 1A of the Trans-Pacific Exp., (b) the same, ventral view.
Fic. 16. Plotohelmis tenuis : parapodium of the fourth chaetiger of specimen from
Stn. 1A of the Trans-Pacific Exp.
foliaceous, and ventral cirri cirriform, smaller than the pedal lobe; chaetae are
simple aciculars and compound capillaries with long thin terminal articles. Pig-
mented segmental glands, when preserved, appear at about the ninth foot, becoming
larger posteriorly so that they extend along the body wall as a lateral band. An-
terior parapodia may have up to a dozen stout acicular chaetae, and no compound
THE DISTRIBUTION OF PELAGIC POLYCHAETES 405
capillaries, but from about the sixth foot the latter begin to replace the former till
there may be only one acicular chaetae present, always in the most ventral position.
Discussion. Dales (1957) was the first to establish that this species is Ploto-
helmis but I have found no specimens which support his separating the three species
within the genus P. tenuis, P. alata and P. capitata, on relative lengths of tentacular
cirri.
—~
wugO
——__—_—_________
Ree
Fic. 17. Plotohelmis tenuis : parapodium of the thirtieth chaetiger of specimen from
Stn. 1A of the Trans-Pacific Exp.
GENERAL DISTRIBUTION. P. tenuis occurs mainly in Tropical and Sub-Tropical
waters but may occasionally be found in higher latitudes (see below, pp. 450, 453-4).
Genus KROHNIA OQuatrefages, 1865
Body elongate. Five pairs of tentacular cirri. Parapodia with a cirriform
appendage on the pedal lobe, with simple capillary and acicular chaetae only.
Type species. Alciopa lepidota Krohn, 1845.
Type locality. Messina, Mediterranean Sea.
406 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Krohnia lepidota (Krohn), 1845
(Text-fig. 18)
Alciopa lepidota Krohn, 1845, p. 175.
Krohnia lepidota: Quatrefages, 1865, pp. 158-159.
Rhynchonerella cincinnata Chamberlin, 1919, pp. 146-147.
Callizona lepidota: Fauvel, 1923, pp. 211-212, fig. 79e-h.
Krohnia lepidota : Stop-Bowitz, 1948, p. 33.
Callizonella lepidota : Uschakov, 1957a, p. 278, Chart 2, fig. 5.
Krohnia lepidota: Dales, 1957, p. 129.
Krohnia lepidota: Tebble, 1960, p. 193; p. 255, fig. 50.
Fic. 18. Kyvohnia lepidota : parapodium of the second chaetiger of specimen from
Stn. 120A of the Trans-Pacific Exp.
DEscRIPTION. No complete specimens of this species were collected. The largest
fragments rarely measure more than 15 mm. long ; Fauvel (1923) gives a maximum
of 100 mm. for the length of a complete specimen. Two pairs of small but stout
conical antennae are situated on the anterior border of the prostomium and an un-
paired antenna occurs dorsally between the eyes. The proboscis is smooth, except
for a broad group of small terminal papillae. The five pairs of tentacular cirri
© ae mera ee yee oe
THE DISTRIBUTION OF PELAGIC POLYCHAETES 407
appear on successive segments behind the head thus r + 1/1 + 1/1; of these the
anterior is long, strap-like and pointed; the two ventrals foliaceous and a little
smaller ; the anterior dorsal long and thin and the posterior dorsal exceedingly long,
reaching out as far again as the total body width. Few of the parapodial cirri
have been retained but on one anterior foot the dorsal cirrus is very large and
foliaceous and the ventral smaller, and broadly foliaceous. Chaetae are of two
types, simple stout acicular chaetae and simple capillaries, the former are more
numerous anteriorly and are gradually replaced by the latter posteriorly. The
whole body surface is sprinkled with black spots, which run in lines along the antennae
and tentacular cirri and are scattered over the eyes and prostomium ; they are
arranged in a linear series at the dorsal edge of the parapodia and ventrally at the
base of the feet and in pairs on the mid-ventral line ; the anterior surface of each
pedal lobe has a single black spot in its centre. These spots show clearly only in
well preserved specimens, but in all material they are present and even when some
have disappeared, an overall pattern similar to that described can be visualized.
Discussion. Chamberlin’s (1919) records of Rhynchonerella cincinnata Greeff,
1876, from the Pacific must be considered as K. lepidota for although he does not
describe the pigment spots he refers to the very long posterior tentacular cirri,
which appear to be characteristic. Dales (1957) reports Callizona pigmenta Tread-
well, 1943, as synonymous with K. lepidota.
GENERAL DISTRIBUTION. K. lepidota is known only from Tropical and Sub-
Tropical waters (see below pp. 454-455).
Family TyPHLOSCOLECIDAE
Exclusively pelagic. Body spindle-shaped or cylindrical. Prostomium not
distinctly marked off from the rest of the body. Nuchal organs well developed.
Peristomium indistinct bearing one pair of cirri; the two succeeding segments also
bear only one pair but thereafter there are two representing the dorsal and ventral
cirri of the parapodia. Pedal mamelon reduced with an acicula and a few small
simple chaetae sometimes present.
Kry To GENERA
1. Prostomium with dorsal and ventral ciliated epaulettes . : : TYPHLOSCOLEX
—. Prostomium without ciliated epaulettes c 2
2. With a pair of nuchal organs which are attached to the jbady. only plone their aatedien
border ; a caruncle may or may not be present “ TRAVISIOPSIS
—. With nuchal organs entirely attached to the body surface : 5 SAGITELLA
Genus TYPHLOSCOLEX Busch, 1851
Body spindle-shaped. Prostomium with dorsal and ventral ciliated epaulettes,
the dorsal epaulettes carrying two lateral basal wings. Chaetae begin on the fifth
parapodia. Protrusible proboscis.
Type species. Typhloscolex miilleri Busch, 1851.*
Type locality. Trieste.
* See Addenda, p. 492.
408 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Typhloscolex miilleri Busch, 1851
Typhloscolex miilleri Busch, 1851, pp. 115-116, pl. 11, figs. 1-6.
Typhloscolex Miillert :
Typhloscolex Miilleri :
Typhloscolex miillert :
Typhloscolex miilleri :
Typhloscolex miilleri :
Typhloscolex miilleri :
DESCRIPTION.
Fauvel, 1923, pp. 226-227, fig. 85, (-h.
Stop-Bowitz, 1948, pp. 17-18, fig. 8.
Uschakov, 1955, p. 112, figs. a—c.
Uschakov, 19574, p. 286, Chart 4.
Dales, 1957, pp. 146-147, fig. 55, a—b.
Tebble, 1960, pp. 195-196 and pp. 231-236, figs. 34-36, Tables 16, 17.
In Table IV the size range of specimens of 7. miilleri collected
on the Trans-Pacific Expedition at Stations 12A to 21B have been listed. This
TaBLE 1V.—Typhloscolex miilleri*
Number of specimens between
and 14°09 mm.
in length
Sub-Arctic Zone
Transition Zone
H HN AH NNR D
Sub-Tropical Zone
* This Table also shows the increase in numbers of T. miélleri caught in the Sub-Arctic Zone and that
an ecotypic form of this species inhabits this zone ; these points are examined in greater detail later.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 409
line of stations crosses from the Sub-Tropical Zone through the Transition Zone
into the Sub-Arctic Zone.
A finely pointed prostomial palpode projects between the dorsal and ventral
ciliated epaulettes ; the latter are always as wide as the body width. The dorsal
epaulette carries two basal wings which are proportionally larger in the bigger
specimens. On each side of the peristomium are the first cirri, large and kidney-
shaped, covering the epaulettes laterally. The next two segments carry one oval
cirrus on each side; thereafter foliaceous dorsal and ventral cirri are present on all
segments up to the end of the body. Simple chaetae appear on the fifth parapodia.
There is a pair of elliptical anal cirri.
Discussion. A most striking feature of the systematic analysis of these collec-
tions was the occurrence of specimens of T. muilleri, measuring up to 13-21 mm.
in length, at stations made in the Sub-Arctic Zone. Samples from this zone were
recognizable immediately through their presence ; they have been reported from
nowhere else in the world. Almost all previous authorities accepted 2-7 mm. as
the approximate size range of T. miillert, only Uschakov (1955 and 1957a) having
previously reported a larger size, 2-15 mm., and these from the Bering Sea, the
Sea of Okhotsk and off the south-east coast of Kamchatka, within the Sub-Arctic
Zone of the North Pacific.
Statistical analysis! of the data in Table IV indicated that the animals from the
Sub-Arctic Zone on the one hand and the Transition and Sub-Tropical Zones on
the other did not belong to the same population (F = 21-2; d.f. 2,156; P < 0-001)
and that the Sub-Arctic Zone general mean (7-51 mm.) was significantly greater
than the Transition Zone (4:57 mm.) which was non-significantly greater than the
Sub-Tropical Zone (4:04 mm.). This final analysis also indicated that the Transi-
tional and Sub-Tropical Zone data were homogenous whilst the sub-arctic data
could be resolved into two populations the one with smaller individuals (4:2 mm.)
being closely similar to that from the other zones, whilst the other had significantly
greater (9:I mm.) individuals.
As isolated specimens the larger forms in the Sub-Arctic Zone could have been
described as separate species, relating specific characteristics only to gross size, but
the presence of typical small forms is against this. The evidence from statistical
analysis, however, suggests that there are two distinct populations, a population of
small individuals, which is part of a population occurring in all three zones, and a
population of large forms which is confined to the Sub-Arctic Zone. Presumably
we have here an ecotypic variation (large forms adapted to the sub-arctic environ-
ment) mixed with members of a more widely distributed continuous series of con-
tiguous populations.
GENERAL DISTRIBUTION. T. miilleri is a cosmopolitan species, having been
reported from all explored water masses (see below, pp. 454, 456).
* These analyses were carried out by Mr. D. E. Davies and involved in order, an analysis of variance,
@ sequential means test based on the error of variance derived from the first analysis, and tabulated
upper 5% range tests followed by a polymodal graphical analysis due to Harding (1949). Statistical
So of these data was first suggested by Dr. E. W. Fager of the Scripps Institution of Oceano-
graphy.
410 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Genus SAGITELLA Wagner, 1872
Body spindle-shaped. Prostomium with nuchal organs which are entirely fixed
to the body surface. Caruncle absent. Simple chaetae appearing from about the
third to fifth parapodia.
Type species. Sagitella kowalewskii forme A. Wagner, 1872.
Type locality. Tropical Atlantic Ocean.
The second w in kowalewskii has frequently been altered to av; there is no valid
reason for altering the original orthography in this case and I therefore use the
spelling howalewskit.
Sagitella kowalewskii Wagner, 1872
Sagitella kowalewskii forme A Wagner, 1872, pp. 342-347, figs. A-c.
Sagitella kowalewskui : Fauvel, 1923, p. 228, fig. 85, a-—c.
Sagitella kowalevskit : Stop-Bowitz, 1948, pp. 56-57, fig. 43.
Plotobia paucichaeta: Treadwell, 1943, p. 38, pl. 11, fig. 26.
Sagitella kowalewskii : Uschakov, 19574, pp. 288-289, Chart 4.
Sagitella kowalevskii: Dales, 1957, pp. 147-148, figs. 56, 57, 60
DESCRIPTION. The largest specimen collected measures 19 mm. in length for
about sixty pairs of parapodia and the smallest 2-0 mm. for thirty. The prostomium
has a finely pointed palpode projecting anteriorly. The first three segments carry
one foliaceous cirrus on each side. Between the first and second of these, on the
dorsal surface, the nuchal organs form two boomerang-shaped ridges. Parapodia
carry a pair of dorsal and ventral cirri, with simple chaetae first appearing on the
third to fifth feet ; these are clearly visible only on posterior segments where the
segmentation is more clearly marked. The pygidium carries two spatulate anal
cirri.
Discussion. I have examined a syntype of Plotobia paucichaeta Treadwell 1943,
in the collections of the U.S.N.M., No. 130492, from 14° 52’ S., 126° 07’ W., and find
it is a Sagitella kowalewskti: this confirms the opinion of Dales (1957). From
Treadwell’s description of Plotobia paucichaeta I thought it might be Tvavisiopsis
dubia (q.v.).
GENERAL DISTRIBUTION. S. kowalewskii is known only from Tropical and Sub-
Tropical waters (see below, pp. 454, 457-8).
Genus TRAVISIOPSIS Levinsen, 1885 (characters emended)
Body cylindrical or spindle-shaped. Prostomium with nuchal lobes which are
free from the body over the greater part of their length ; these normally flank a
caruncle but in one species (7. dubia) a true caruncle is absent. The first three
segments behind the head with single foliaceous cirrus on each side; thereafter
parapodia with paired foliaceous cirri; only a few simple chaetae present on some
parapodia.
Type species. Tvavisiopsis lobifera Levinsen, 1885.
Type locality. 42° 50’ N., 46° 10’ W.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 41
This description of Travisiopsis is emended to include Travisiopsis dubia Stop-
Bowitz, 1948, which was first described from two specimens collected by the Michael
Sars in the North Atlantic. Sixteen more are reported here, and it is clear that
this species though without a true caruncle (but only a thickening of the dorsal
surface of the prostomium) is a Tvavisiopsis because it has two nuchal lobes which
are free from the body over the greater part of their length. It differs, therefore,
fundamentally from the closely related Sagitella, which has neither caruncle, nor
free nuchal lobes, but has these latter organs entirely attached, forming distinct
ridges.
Kery TO SPECIES
1. Caruncle absent : , : 3 5 2 ¢ 5 é . TT. dubia
—. Caruncle present : : , 2 5 ; : . c < 2
2. Nuchal lobes branches 5 c ; : 5 : : 4 3 T. coniceps
—. Nuchal lobes not branched é A : ; : ¢ . © 3
3. Nuchal lobes long, finger-shaped . : é 4 : : 3 3 T. lanceolata
—. Nuchal lobes short c 3 : A : é 5 : 5 4
4. Caruncle round ; twenty-one segments : é ‘ ; : : . T. lobifera
—. Caruncle rectangular, twenty-five segments . : : F : ; T. levinseni
Travisiopsis lobifera Levinsen, 1885
(Text-fig. 19)
Travisiopsis lobifera Levinsen, 1885, pp. 336-340, figs. 17-20.
Travisiopsis lobifera: Fauvel, 1923, p. 229, fig. 86a—d.
Travisiopsis lobifera : Stop-Bowitz, 1948, pp. 57-58, fig. 44.
Travisiopsis lobifera : Uschakov, 19574, pp. 286-287, Chart 4, fig. 7, d—g.
Travisiopsis lobifera: Berkeley & Berkeley, 1957, pp. 577-578.
Tyravisiopsis lobifera: Dales, 1957, pp. 148-149, figs. 58—60 (in part).
Travisiopsis lobifera : Tebble, 1960, pp. 196-197, fig. 134; p. 245, fig. 45.
DEscripTIon. This species is cylindrical in shape and may measure up to 25 mm.
long for a constant twenty-one segments. The median dorsal caruncle, attached
on a level with the first cirri, is characteristically oval. Paired nuchal lobes sur-
round the caruncle in the form of fixed processes anteriorly, and laterally, with
free projecting lobes posteriorly which reach as far as the second cirri. The single
cirri of the first three segments are circular—except for the incision at the point of
attachment—thereafter the parapodial cirri are approximately heart-shaped.
Simple acicular chaetae may appear from the fifth segment ; there are rarely more
than three of these in a group and there may be only one. Anal cirri are elongate
oval to rectangular in form.
Discussion. Dales (1957) refers Plotobia simplex Chamberlin (1919) to T.
lobifera but I agree with Stop-Bowitz (1948) that it is probably T. lanceolata (see
below, p. 413).
GENERAL DISTRIBUTION. TJ. lobifera is known only from Tropical and Sub-
Tropical waters (see below, pp. 458-459).
412 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Fic. 19. Tvavisiopsis lobifera : specimen from Stn. 13B of the Trans-Pacific
Expedition.
Travisiopsis levinseni Southern, 1910
Type locality. 53° 07’ N., 15° 09’ W., 650-750 fathoms (= 1,188-7-1,371-6 m.).
Travisiopsis levinseni Southern, 1910, p. 429.
Travisiopsis levinseni : Southern, 1911, pp. 32-33, pl. 2, figs. 7-10.
Travisiopsis levinsent : Fauvel, 1923, pp. 229-230.
Travisiopsis levinseni : Stop-Bowitz, 1948, pp. 59-60, fig. 46, fig. 47a~-b.
Travisiopsis levinseni : Uschakov, 1955, p. 114, fig. 14d-g.
Travisiopsis levinseni : Uschakov, 19574, p. 288, Chart 4.
- Travisiopsis levinseni: Dales, 1957, p. 150.
Travisiopsis levinseni: Tebble, 1960, pp. 197-198, fig. 13); pp. 236-237, fig. 30.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 413
DESCRIPTION. This species is spindle-shaped and may measure up to 35 mm.
in length for a constant twenty-five segments. The median dorsal caruncle is
attached on a level with the first cirri and is characteristically rectangular. Paired
nuchal lobes border the caruncle laterally with free projecting semicircular lobes
posteriorly, which reach as far as the second cirri. The single cirri of the first three
segments are foliaceous; thereafter the paired parapodial cirri are rectangular,
becoming lanceolate posteriorly. Simple acicular chaetae may appear from the
sixth foot, with rarely more than three in a group. Anal cirm are long and
oval.
GENERAL DISTRIBUTION. The records of this species from the North Pacific
Ocean are too few to warrant drawing any firm conclusions about its distribution
(see below, pp. 458, 461). In the South Atlantic Ocean T. /evinseni has been reported
in all hydrological zones (Tebble, 1960) ; its distribution in the North Atlantic
Ocean has not been fully investigated.
Travisiopsis lanceolata Southern, 1910
Type locality. 51° 12’ N., 11° 55’ W., 500 fathoms (914-4 m.).
Travisiopsis lanceolata Southern, 1910, p. 429.
Tyavisiopsis lanceolata: Southern, 1911, pp. 30-32, pl. I, figs. 3, 5, 6.
Plotobia simplex Chamberlin, 1919, pp. 155-156, pl. 65, figs. 6-11; pl. 66, fig. 1.
Travisiopsis lanceolata: Fauvel, 1923, p. 229, fig. 86, e-g.
Plotobia simplex: Treadwell, 1943, p. 38.
Travisiopsis lanceolata : Stop-Bowitz, 1948, pp. 58-59, figs. 45-46.
Travisiopsis lobifera: Dales, 1957, pp. 148-150, figs. 58-60 (in part).
Travisiopsis lanceolata: Tebble, 1960, pp. 198-199, fig. 13¢; p. 246, fig. 45.
DESCRIPTION. This spindle-shaped species may measure up to 38 mm. in length
for a constant twenty-two segments. The median dorsal caruncle is V in shape ;
the anterior part is attached at the level of the first cirri, the posterior portion is
free. Two long, finger-shaped, nuchal lobes surround the caruncle anteriorly, are
free posteriorly and may reach to the fourth segment. Cirri on the first three
segments are reniform, thereafter they are almost square becoming lanceolate
posteriorly.
Discussion. There can be little doubt that Plotobia simplex Chamberlin (1919)
is synonymous with T. lanceolata as suggested by Stop-Bowitz (1948). Dales
(1957) considers P. simplex synonymous with T. lobifera but Chamberlin’s drawing
(1919, pl. 66, fig. r) shows the characteristic finger-shaped nuchal processes clearly.
GENERAL DISTRIBUTION. Chamberlin’s (1919) record of P. simplex appears to be
the first for 7. lanceolata from the North Pacific where it is known from few records
(see below, pp. 458, 461). In the South Atlantic Ocean T. lanceolata does not occur
south of the Sub-Tropical Convergence but in the North Atlantic it has been reported
from boreal waters, Wesenberg-Lund (1950, 1951).
414 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Travisiopsis dubia Stop-Bowitz, 1948
(Text-fig. 20, a, b, c)
Type locality. North Atlantic Ocean, 39° 30’ N., 49° 42’ W.
Travisiopsis dubia Stop-Bowitz, 1948, pp. 60-61, fig. 48, a-e.
Travisiopsis dubia: Dales, 1960, p. 485.
DESCRIPTION. The holotype of this species measures 6 mm. in length for twenty-
eight segments and the paratype 10 mm. for twenty-three segments (Step-Bowitz,
1948, both specimens in the Bergen Museum, Norway).
Of the sixteen specimens reported here the smallest measures 2-5 mm. in length
for eighteen segments and the longest 6:5 mm. for twenty-six.
O25mm.
Fic. 20. Tyvavisiopsis dubia : specimen from Stn. 92A of the Trans-Pacific Exp., (a) side
view of head and anterior segments with the anterior pair of cirri omitted, (b) dorsal
view of head and anterior segments, (c) dorsal view of posterior segments.
The slender body terminates anteriorly in a bulbous point. The dorsal nuchal
lobes are attached along their anterior edge only, on a level with the anterior border
of the second cirri; they are oval to semicircular with a rim along the outer edge.
They do not border a caruncle but the dorsal surface of the prostomium in front of
them is considerably thicker than elsewhere. The cirri on the first segments are
circular and cover the front of the prostomium laterally, on the second segment
they are elongate, broadly oval, with the long axis horizontal, and on the third
segment also elongate, broadly oval but with the long axis vertical. The first
group of paired parapodial cirri are lanceolate but from the middle body region
become gradually quadrate up to the end of the body. Simple acicular chaetae
appear between some parapodial cirri; there are never more than three of these
THE DISTRIBUTION OF PELAGIC POLYCHAETES 415
in a group and they may not penetrate the body wall in posterior segments. Anal
cirri are elongate, and curved at their free ends.
Discussion. This is the first record of this species since its original discovery.
Dr. C. Stop-Bowitz kindly compared specimens I sent him with the type material
and was able to confirm that they are T. dubia. There is no doubt that this species
is superficially much closer to Sagitella than to Travisiopsis but it must be included
in the latter species because of the free nuchal lobes. Stop-Bowitz (1948) notes this
similarity but refers the species to Tvavisiopsis because of the possession of a caruncle.
However, it is noted above that T. dubia does not have a true caruncle, merely a
thickening of the dorsal surface of the prostomium and this character brings it
closer still to Sagitella. Nevertheless, the possession of nuchal lobes, attached only
along their anterior borders, but free posteriorly and not completely attached to
form ridges as in Sagitella, is a distinctive generic difference and unequivocally
establishes the species as a Tvaviopsis.
GENERAL DISTRIBUTION. T. dubia is known from very few records all of which
are from Tropical and Sub-Tropical waters (see below, pp. 460, 461).
Family PHYLLODOCIDAE
Not exclusively pelagic. Body normally long and slender with numerous seg-
ments except in the pelagic genera in which it is short and wide and the number of
segments may be fixed within narrow limits. Prostomium normally with eyes and
antennae. Tentacular cirri present. Parapodia uniramous or biramous, with
simple and/or compound chaetae ; cirri normally present. Proboscis protrusible,
usually with papillae, exceptionally with chitinous jaws. Anal cirri normally
present.
Representatives of two subfamilies, all members of which are exclusively pelagic,
have been collected ; they may be separated as follows :
1. With no antennae. Two pairs of tentacular cirri. Proboscis may have chitinous
jaws. Chaetae always compound . F . IOSPILINAE
2. With four antennae. Two or three pairs of tentacular cirri. Proboscis never with
chitinous jaws. Chaetae compound and simple . LopaDORHYNCHINAE
Subfamily LOPADORHYNCHINAE
KEy TO GENERA
rt. Anterior parapodia modified See the chaetigers into two distinct regions (Text-
fig. 21) : 5 i 5 3 LOPADORHYNCHUS
—. Anterior oaceppadd tee saeartaedl 3 5 é c c ; 6 0 ; 2
2. With four pairs of tentacular cirri (Text-fig. 23 0 0 A 5 R MAUPASIA
—. With two pairs of tentacular cirri (Text-figs. 22 and 25) : : : 3
3. Tentacular cirri with chaetae (Text-fig. 22) . 5 : 0 PELAGOBIA
—. Tentacular cirri without chaetae (Text-fig. 25) c : . . . PEDINOSOMA
1 In 1959 Dr. R. P. Dales sought my opinion about some specimens he had from the Malacca Straits
which were identical with material I had already identified from the Scripps Collections as Tvavisiopsis
dubia. Dr. Dales’ paper was published whilst this present work was in manuscript (see Dales, 1960).
416 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Genus LOPADORHYNCHUS Grube, 1855
(Emended Malaquin & Dehorne, 1907 pro Lopadorrhynchus Grube, 1855)
Prostomium with four antennae, two dorsal, which appear as anterior extensions
of the lateral border, and two ventral, close to the mouth. Three pairs of tentacular
cirri. Parapodia uniramous and modified anteriorly so that the chaetigers are
divided into two distinct regions ; simple and compound chaetae are present sup-
ported by a prominent pedal lobe with acicula. Dorsal cirri present on all para-
podia, ventral cirri may be absent on anterior feet. Proboscis smooth or papillate.
Type species. Lopadorhynchus brevis Grube, 1855.
Type locality. Mediterranean.
I have given elsewhere (Tebble, 1960) my reasons for not accepting the division
of this genus into the subgenera Lopadorhynchus sensu stricto and Prolopadorhynchus.
Key TO SPECIES
1. The first three parapodia modified ; with simple chaetae only and no ventral cirri
L. brevis
—. The first two parapodia modified: no ventral cirri 2
2. The first two parapodia robust and stout, with strong mnidentate hooks surrounded
by a “‘ruff’’, orcollar . 2 L. uncinatus
. The first two parapodia not robust or stout : with simple unidentate hooks, without
a ruff or collar c : 5 : : : : 5 : . . L. krohnii
Lopadorhynchus brevis Grube, 1855
Lopadorrhynchus brevis Grube, 1855, p. 100, pl. 3, fig. 15.
Lopadorrhynchus parvum Chamberlin, 1919, pp. 114-116, pl. 17, figs. 6, 7.
Lopadorhynchus brevis : Fauvel, 1923, p. 184, fig. 69k.
Lopadorhynchus (Lopadorhynchus) brevis: Dales, 1957, pp. 104-105, figs. 7-8.
Lopadorhynchus brevis : Tebble, 1960, pp. 200-201 ; pp. 259-261, fig. 52.
DescripTION. The largest specimen collected measures 7 mm. in length for
twenty-two chaetigers and the smallest 2-5 mm. for sixteen. The parapodia are
divided into two separate regions at the posterior border of the third chaetiger.
The prostomium is wider than long, with a straight anterior border with two long
dorsal and two ventral antennae. Two eyes may be present but are not always
clearly visible. There are three pairs of tentacular cirri, one dorsal and one ventral
just behind the antennae and the third very small almost an appendage of the lower
of these. The first three parapodia have no ventral cirri ; up to seven stout simple
chaetae project, fan-wise, from a spatulate pedal lobe. Thereafter, compound
chaetae, with oval terminal pieces on a pronounced heterogomph articulating surface,
appear on all feet, with simple chaetae grouped ventrally becoming less numerous.
On the fourth chaetiger there may be five to eight simple chaetae but on far posterior
feet there may be none or only one. Dorsal cirri are foliaceous, ventral cirri smaller
and subulate.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 417
Discussion. The largest of the specimens reported here is smaller than those
reported by Dales (1957) from the California Current, which measure up to 17 mm.
in length, or by Tebble (1960) from the South Atlantic which reach 20 mm. in length.
They differ from these also in other characters which would normally be associated
with differences in stages of growth ; chaetae are neither as large nor so numerous,
cirri are less well formed, and there are fewer chaetigers.
In my Discovery report (Tebble, 1960) I suggested that L. mans Chamberlin, rgr9,
was synonymous with L. brevis although Step-Bowitz (1948) suggested it might be
a synonym of L. nationalis Reibisch, 1895. In July, 1959, I examined the type
specimen of L. nans in the Smithsonian Institution, Washington, U.S.N.M. No.
19402, and found it in poor condition and am unable to confirm either my own or
Stop-Bowitz’s opinion. At the same time I examined the type specimen of L.
parvum Chamberlin, 1919, U.S.N.M. No. 19403 and found it similar to L. brevis.
GENERAL DISTRIBUTION. L. brevis is known only from Tropical and Sub-Tropical
waters (see below, pp. 463, 465).
Lopadorhynchus uncinatus Fauvel, 1915
Original localities. From off the Azores and Monaco.
Lopadorhynchus uncinatus Fauvel, 1915, p. 3, fig. 2.
Lopadorhynchus uncinatus : Fauvel, 1923, pp. 184-185, fig. 67, a—y.
Lopadorhynchus varius Treadwell, 1943, pp. 32-33, pl. 1, figs. 7-10.
Lopadorhynchus (Lopadorhynchus) uncinatus : Stop-Bowitz, 1948, pp. 17-18, fig. 11.
Lopadorhynchus (Lopadorhynchus) uncinatus : Dales, 1957, pp. 101-104, figs. 1-6.
Lopadorhynchus uncinatus: Tebble, 1960, p. 201; pp. 259-261, fig. 52.
DESCRIPTION. The largest specimen measures 2I mm. in length for twenty-six
chaetigers and the smallest 6 mm. for twenty-four. The parapodia are divided into
two separate regions at the posterior border of the second chaetiger. The pro-
stomium is wider than long, pointed anteriorly with two long dorsal and two short
ventral antennae. Two eyes may be present but they are not always clearly visible.
The first two tentacular cirri are long and cirriform lying dorsally and ventrally
just behind the antennae, the third is very small and subulate, situated on the
ceratophore which supports the ventral pair. The first two parapodia are much
more prominant than the rest, they are large, stout, and directed laterally, with up
to seven strong unidentate simple hooks, surrounded by a ruff or collar and with a
small dorsal cirrus but no true ventral cirrus. The succeeding feet are thin and
paddle-shaped, and directed backwards, with chaetae grouped fan-wise about the
pedal lobe. From the third parapodia both simple and compound chaetae are
present but the latter gradually replace the former. The terminal article of the
compound chaetae is ovate with serrations on one side ; the articulation is hetero-
gomph. Dorsal cirri are short and conical, ventral cirri are smaller and subulate.
Discussion. As Dales (1957) notes L. varius Treadwell, 1943, is almost certainly
synonymous with L. uncinatus.
GENERAL DISTRIBUTION. L. uncinatus is known only from Tropical and Sub-
tropical waters (see below, pp. 463, 465).
418 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Lopadorhynchus krohnii (Claparéde), 1870*
(Text-fig. 21)
Type locality. Naples.
Hydrophanes krohnii Claparéde, 1870, pp. 464-466, pl. 11, fig. 2.
Lopadorhynchus krohnii : Fauvel, 1923, pp. 185-186, fig. 69a-d.
Lopadorhynchus (Lopadorhynchus) krohnii : Dales, 1957, pp. 105-106, figs. 9, 10.
Lopadorhynchus krohnii : Tebble, 1960, p. 202; pp. 259-261, fig. 52.
O5 mm.
Lopadorhynchus krohnii : specimen from Stn. 123A of the Trans-
Fic. 21.
Pacific Exp.
The largest specimen collected measures 9 mm. in length for
The parapodia are divided
DESCRIPTION.
The
twenty chaetigers and the smallest 1-5 mm. for eleven.
into two distinct regions at the posterior border of the second chaetiger.
* See Addenda, p. 492.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 419
prostomium is twice as wide as long, with a rounded anterior border and two long
dorsal and two short ventral antennae. No eyes are visible in any of the specimens.
There are two long, dorsal and ventral pairs of tentacular cirri, and on the cerato-
phore at the base of the ventral pair there is a minute pimple, which must be regarded
as a third tentacular cirrus. The first two chaetigers are directed laterally and are
shorter and stouter than the rest ; they have simple hooked chaetae and a dorsal
cirrus but no ventral cirrus. The remaining parapodia are directed posteriorly and
are thin and paddle-shaped with small dorsal and ventral cirri; chaetae are com-
pound, with heterogomph articulation and serrated ovate terminal pieces, grouped
fan-wise about the pedal lobe.
Discussion. This description differs from that in all previous descriptions of
this species in noting the presence of a minute third tentacular cirrus. In re-
examining the specimens of L. krohni reported in Tebble (1960) from the South
Atlantic I see that these also have this organ, as do those reported by Dales (1957),
from the California Current, and material in the University Museum, Copenhagen
from the North Atlantic.
GENERAL DISTRIBUTION. L. krohnii is known only from Tropical and Sub-
Tropical waters (see below, pp. 463, 464).
Genus PELAGOBIA Greeff, 1879
Prostomium with four antennae. Two pairs of tentacular cirri with chaetae.
Parapodia uniramous with dorsal and ventral cirri cylindrical (dorsal cirrus reduced
or absent on the second chaetiger) and compound chaetae. Proboscis smooth.
Pygidium with two cirri.
Type species. Pelagobia longicirrata Greef{, 1879.
Type locality. Arrecife, Canary Islands.
Pelagobia longicirrata Greeff, 1879
(Text-fig. 22)
Pelagobia longicirrata Greeff, 1879, pp. 247-249, pl. 14, figs. 23-25.
Pelagobia longicivrata: Fauvel, 1923, p. 192, fig. 72, a, c.
Pelagobia longicivrata : Stop-Bowitz, 1948, p. 21.
Pelagobia longicivvata : Uschakov, 19574, p. 268, Chart 1.
Pelagobia longicivrata: Dales, 1957, pp. 107-108, figs. 11-13.
Pelagobia longicivrata: Tebble, 1960, pp. 202-204 ; pp. 237-242, figs. 37-44, Tables 18, 19.
DEscRIPTION. This species measures up to 12 mm. in length for fifteen to thirty
chaetigers. The prostomium is approximately cone-shaped, truncated anteriorly,
with two eyes and four small antennae. At the lateral posterior corners of the
prostomium there are two shoulders which may carry numerous pigmented spots.
The two pairs of tentacular cirri are long and subulate, between each is a pedal
ZOOL. 7. 9. 30
420 THE DISTRIBUTION OF PELAGIC POLYCHAETES
mamelon with compound chaetae. There is a ventral cirrus but no dorsal cirrus
on the second chaetiger (counting the segment carrying the tentacular cirri as the
first chaetiger). Thereafter parapodia have long cylindrical dorsal and ventral
wwO-|
Tic, 22. Pelagobia longicirrata : specimen from Stn. 42E of the
Trans-Pacific Exp.
cirri. All chaetae are compound with smooth shafts but the terminal articles are
denticulated along one edge. Anal cirri are short and blunt.
GENERAL DISTRIBUTION. P. longicivrata is known from almost all explored water
masses throughout the world (see below, pp. 460, 462).
Ne
THE DISTRIBUTION OF PELAGIC POLYCHAETES 421
Genus MAUPASIA Viguier, 1886
‘Prostomium with four antennae. Four pairs of tentacular cirri. Parapodia uni-
ramous with dorsal and ventral cirri and compound chaetae only. Proboscis smooth.
Type species. Maupasia caeca Viguier, 1886.
Type locality. Bay of Algiers.
Maupasia caeca Viguier, 1886
(Text-figs. 23, 24)
Maupasia caeca Viguier, 1886, pp. 382-385, pl. 21, figs. 14-20.
Maupasia caeca: Fauvel, 1923, pp: 190-191, fig. 171a-d.
Maupasia caeca: Uschakov, 1957a, pp. 268-269, Chart 1, fig. 1, c-e.
Maupasia caeca: Tebble, 1960, pp. 204-205; p. 242, fig. 44.
DEscriIPTION. The largest specimen collected measures 7-5 mm. in length for
twenty chaetigers and the smallest 2 mm. for twelve (in these counts the segments
carrying the tentacular cirri, which always bear chaetae, have been counted as
chaetigers). The prostomium is as wide as long and carries two dorsal and two
ventral antennae. There are four pairs of tentacular cirri arranged thus, 1/1 + 1/1,
on successive segments behind the head. The anterior pairs are pointed and as
long as the width of the prostomium ; the posterior dorsals are almost twice as long
as these and the posterior ventrals about the same length or a little smaller. Groups
of compound chaetae project from between each pair of tentacular cirri. Immedi-
ately in front of the tentacular cirri, but behind the antennae, a group of cirriform
vibratile organs may be visible. These are retractile and may not always be pro-
truding but the pit from which they emerge can always be detected. The first true
parapodia appear immediately behind the tentacular cirri. On all parapodia dorsal
cirri are cordiform with an extended tip or as Viguier (1886) described them “en
forme de coeur irregulier ” ; ventral cirri are elongate and the pedal lobes lanceolate
but all cirri may become swollen and mis-shaped in appearance in specimens carrying
eggs. All chaetae are compound with a pronounced heterogomph articulation.
Discussion. The method of counting tentacular cirri in this genus needs clarifica-
tion, for which comparison with other polychaetes is necessary. Considering the
definition of Nereis by Fauvel (1923 : 328), this genus has altogether eight tentacular.
cirri, four on each side of the peristomium, that is, four pairs. This is universally.
accepted today and the same method of counting is applied to all families of Poly-
chaeta. Fauvel (1923) in defining Maupasia, however, notes that it has three pairs
of tentacular cirri and therefore we would expect it to have six altogether, three on
each side, but, in fact, from Fauvel’s description of M. caeca, it appears to have,
twelve altogether ; that is, six pairs and not three. Fauvel (1923) takes this count
from Viguier’s (1886) original description, which was prepared before a common
method of counting tentacular cirri was adopted. I explain below, however, why.
ZOOL, 9, 7. 31
422 THE DISTRIBUTION OF PELAGIC POLYCHAETES
M. caeca has, in fact four pairs of tentacular cirri (equivalent to two pairs in Fauvel’s
description) and not six pairs (equivalent to the three pairs in Fauvel’s account).
Since Viguier’s original account of M. caeca all authorities have accepted that this
species has three pairs of tentacular cirri on each side of the body, i.e., twelve alto-
wwO:|
Fic. 23. Maupasia caeca : Specimen from Stn. 27B of the Trans-Pacific Exp.
gether. In reading Viguier’s account, however, it is clear that he counted the first
pair of parapodial cirri as a third pair of tentacular cirri on each side. Furthermore,
Viguier’s original figure (1886, pl. xxi, fig. 15) shows only two pairs on each side,
ie., eight altogether, although the presence of vibratile organs may have confused
the issue. It is singular that Fauvel does not mention these vibratile organs because
his figure, which was taken directly from Viguier’s work, shows them. Fauvel,
however, would certainly not mistake parapodial cirri for tentacular cirri and I
think he got his third pair of tentacular cirri on each side by counting a pair of the
vibratile organs. Occasionally only one of these protrudes on either side (although
THE DISTRIBUTION OF PELAGIC POLYCHAETES 423
there may be up to eight showing sometimes) and if so they answer perfectly to
Fauvel’s description of the most anterior pair of tentacular cirri in M. aupasia thus :
“une dorsal et une ventrale sur le premier segment, soude au prostomium et pourvu
d’acicules et de soies ’’.
In making this correction to the definition of M. caeca I have examined material
from the North Atlantic in the collections of the University Museum, Copenhagen,
and that reported from the southern hemisphere by Ehlers (1912), Benham (1927),
Hardy & Gunther (1935) and Tebble (1960).
Fic. 24. Maupasia caeca : parapodium from the sixth chaetiger of specimen from
Stn. 34B of the Trans-Pacific Exp.
GENERAL DISTRIBUTION. The first records of M. caeca from the North Pacific
were made recently by Uschakov (19574), at 48° 08’ N., 156° 08’ E. and Berkeley
& Berkeley (1958) from 1° 58’ N., 83° 49’ W. Elsewhere in the world it has been
recorded from scattered localities (see below, pp. 463, 466-467).
Genus PEDINOSOMA Reibisch, 1895
Prostomium with four antennae. Two pairs of tentacular cirri, without chaetae
between them. Parapodia uniramous with round to ovate dorsal cirri and cylin-
drical ventral cirri and compound chaetae only. Proboscis smooth.
Type species. Pedinosoma curtum Reibisch, 1895.
424 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Original localities. Tropical South Atlantic and Tropical and Sub-Tropical North
Atlantic Oceans.
Pedinosoma curtum Reibisch, 1895
(Text-figs. 25, 26)
Pedinosoma curtum Reibisch, 1895, p. 21; pp. 27-30, pl. 11, fig. 17; pl. 111, figs. 1-4.
Pedinosoma curtum: Fauvel, 1923, pp. 188-189, fig. 70, c-f.
DEscRIPTION. The largest specimen collected measures 3-0 mm. long for eight
chaetigers, this is a mature female, the body cavity being filled with eggs; the
Nee 7)
Fic. 25. Pedinosoma curtum : specimen from Stn. 49 of the Northern Holiday Exp.
(the dorsal cirri have fallen off some segments).
smallest is I-o mm. in length for seven chaetigers. The prostomium is a little wider
than long with two pairs of thin and pointed antennae projecting laterally from the
anterior lateral corner. There are two pairs of tentacular cirri, all a little longer
than the body width and finely pointed: no chaetae are associated with these.
Of the thirteen specimens reported here all have eight chaetigers except two, which
haveseven. Parapodia have round to ovate dorsal cirri and finely pointed cylindrical
THE DISTRIBUTION OF PELAGIC POLYCHAETES 425
ventral cirri; pedal lobes are lanceolate and carry a large number of compound
chaetae, in which the articulation is heterogomph.
‘wwg7-O
Fic. 26. Pedinosoma curtum ; parapodium from the fourth chaetiger of specimen
from Stn. 8 of the Northern Holiday Exp.
GENERAL DISTRIBUTION. This appears to be the first record of this species from
the Pacific Ocean (see below, pp. 466, 467) ; it is known only from Tropical and
Sub-Tropical waters in the Atlantic.
Subfamily IosPILINAE
Genus PHALACROPHORUS Greeff, 1879
No antennae. Two pairs of tentacular cirri, of which the posterior carries chaetae.
Parapodia uniramous, dorsal and ventral cirri small, compound chaetae with smooth
terminal articles. Proboscis with two long chitinous teeth.
Type species. Phalacrophorus pictus Greeff, 1879.
Type locality. Canary Islands, Atlantic Ocean.
426 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Phalacrophorus pictus Greeff, 1879
(Text-fig. 27c)
Phalacrophorus pictus Greeff, 1879, p. 249, pl. 14, figs. 25-30.
Phalacrophorus pictus : Reibisch, 1895, pp. 10-12, pl. 1, figs. 4-7.
Phalacrophorus borealis Reibisch, 1895, pp. 12-13, pl. 1, figs. 8-9.
Phalacrophorus pictus : Fauvel, 1923, p. 196, fig. 72f.
Phalacrophorus maculatus Treadwell, 1943, p- 34, pl. I, figs. 11-13.
Phalacrophorus pictus : Uschakov, 19574, pp. 274—-275, fig. I.
Phalacrophorus pictus : Hartman, 1956, p. 276.
DEscRIPTION. No complete specimens of this species were collected ; the largest
fragment measures 7 mm. in length for thirty chaetigers. The prostomium is
bluntly rounded with no eyes visible in any of the specimens. The proboscis carries
two chitinous unidentate teeth. The segmentation of the first three segments is
indistinct and, when the proboscis is not everted, this part of the body is swollen.
The first pair of tentacular cirri is very small and achaetous, the second longer,
with a few associated chaetae. This chaetiger and the next two are poorly de-
veloped but thereafter fully developed parapodia occur, with small bulbous dorsal
cirri, smaller ventral cirri, and with prominently projecting pedal lobes carrying
bundles of compound capillary chaetae. These chaetae have long finely pointed
terminal articles. A number of specimens have the body cavity filled with eggs.
Discussion. These specimens differ from typical P. pictus in being without
eyes and are thus close to P. borealis Reibisch, 1895 ; this is the only difference
between these species and I do not consider that it merits separating them. In
all other essentials this material is identical with two specimens of P. pictus in
the B.M. (N.H.) collections, one reported by Fauvel (1916) from the Canaries and the
other identified by Monro from Discovery collections, ‘‘ William Scoresby’, Stn. 63,
near South Georgia, but not previously reported.
GENERAL DISTRIBUTION. P. pictus is known from localities scattered thoughout
the world, but it is possible that a separate population inhabits sub-arctic and arctic
waters of the Pacific and Atlantic Oceans (see below, pp. 466, 468-9).
Phalacrophorus uniformis Reibisch, 1895
(Text-figs. 274, b)
Original localities. Tropical South Atlantic and Tropical and Sub-Tropical
North Atlantic.
Phalacrophorus uniformis Reibisch, 1895, pp. 15-17, pl. I, figs. 10-16.
Phalacrophorus uniformis : Fauvel, 1923, pp. 196-197, fig. 72, g, h.
Phalacrophorus attenuatus Treadwell, 1943, p. 34, fig. 14.
Phalacrophorus uniformis : Hartman, 1956, p. 276.
DEscRIPTION. Only fragments of this species were collected, the longest measur-
ing 4 mm. for about sixty chaetigers. The prostomium is bluntly rounded and has
THE DISTRIBUTION OF PELAGIC POLYCHAETES
427
Fic. 27. Phalacrophorus: (a) P. uniformis, extruded proboscis of specimen from Stn.
126B of the Trans-Pacific Exp., (b) the same specimen, parapodium from the 128th
chaetiger ; (c) P. pictus parapodium from the twelfth chaetiger of specimen from
Stn. 37B.
428 THE DISTRIBUTION OF PELAGIC POLYCHAETES
two small brown eye spots posteriorly. The proboscis carries two chitinous uni-
dentate teeth. The segmentation of anterior segments is distinct on the dorsal
surface but tends to be hidden ventrally. The first pair of tentacular cirri is small
and the second longer, bearing a few chaetae. Thereafter the first eight to twelve
chaetigers are poorly developed with very few, small compound chaetae and much
reduced cirri, but succeeding parapodia have very long chaetae and better de-
veloped cirri.
Discussion. Hartman (1956) has examined the type specimen of P. attenuatus
Treadwell, 1943, and considers it agrees with P. uniformis in important characters.
GENERAL DISTRIBUTION. P. uniformis is known from only a few scattered locali-
ties in the Pacific Ocean (see below, pp. 466, 468) but is well known in the Tropical
and Sub-Tropical waters of the North Atlantic.
DISTRIBUTION
The families are examined below in the order followed in the Systematic Account,
but genera and species have been arranged to meet zoogeographical considerations.
Distribution maps have been prepared for all species. These generally indicate the
presence or absence of a species at each station without an indication of the quantita-
tive distribution because most pelagic polychaetes rarely occur in large enough
numbers to make this necessary. Tomopteris elegans, T. septentrionalis and Typhlo-
scolex miilleri, however, do occur in large and varying quantities and the relative
abundance of these three species has been plotted.
TOMOPTERIDAE
Seven species of Tomopteris are reported here of which five, 7. elegans, T. plank-
tonis, T. ligulata, T. nisseni and T. apsteini, have never been collected in the Sub-
Arctic Zone and it is clear that the southern boundary of this region or the southern
boundary of the Transition Zone, indicates the limit of their northerly movement in
the Pacific Ocean ; one species, T. pacifica, was collected only in the Sub-Arctic
Zone and may be restricted to it ; and the remaining species T. septentrionalis was
found in all three hydrological zones, substantiating its known cosmopolitan dis-
tribution.
T. elegans was collected at numerous stations across the Sub-Tropical Zone and
was also found in the Transition Zone in the eastern region of the North Pacific
(Text-fig. 28). It may be concluded therefore that this species has its northerly
limit of distribution at the southern boundary of the Sub-Arctic Zone, though
further collections may show that it extends farther north in the eastern region of
the Transition Zone than in the western. There are no records in the literature
which contradict this conclusion; Izuka (1914) reported 7. elegans from Sub-
Tropical water off Japan, and Uschakoy (19574) records it from similar water
between 35 and 40°N., in the region of 150° E.; Dales (1957) notes it great abun-
dance in the California Current. Elsewhere in the world T. elegans is known only
from Tropical and Sub-Tropical waters.
429
THE DISTRIBUTION OF PELAGIC POLYCHAETES
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430 THE DISTRIBUTION OF PELAGIC POLYCHAETES
The samples examined by Dales from the California Current were collected in the
top 75 metres of water, but the Trans-Pacific Expedition explored a greater depth
range in this region and its samples show that 7. elegans occurs in abundance down
to about 350 metres. Below this depth, to 680 metres, however, there is a reduction
in numbers caught, to negligible quantities. 7. elegans is evidently also more
abundant in the California Current, and the area immediately to the west, than
elsewhere in the North Pacific. Across the breadth of the ocean it occurred regularly,
though never in great abundance, in the North Pacific Central Water Mass down
to 350 metres. Below this depth it was absent from all closing nets.
There is probably a significant relationship between the distribution of 7. elegans
and 7. septentrionalis in the eastern North Pacific, including the California Current ;
this is discussed below.
T. septentrionalis was collected in all three hydrological regions occurring in
greatest abundance in the Sub-Arctic Zone (Text-fig. 29). It was caught regularly
in the Sub-Arctic Water Mass down to about 400 metres but rarely occurred below
this depth. Across the Sub-Tropical Zone 7. septentrionalis appeared infrequently
and then only in the upper layers of water. The few records from this zone may
be due to the poor state of preservation of some of the collections.?
T. septentrionalis has been widely reported from the North Pacific, from off
Misaki, Japan (Izuka, 1914), from off British Columbia (Berkeley, 1924; Berkeley
& Berkeley, 1948), from Tropical, Sub-Tropical and Sub-Arctic waters (Treadwell,
1943), from the Bering Sea, the Sea of Okhotsk, and across the Sub-Tropical and
Sub-Arctic Zones (Uschakoy, 1955, 1957a), from Monterey Bay and the California
Current (Dales, 1955, 1957) and from the Gulf of Alaska (Berkeley & Berkeley,
1957). These records are from all explored depths, and, with the summaries of the
distribution of 7. septentrionalis from elsewhere in the world made by Step-Bowitz
(1948) and Tebble (1960), have established the species as cosmopolitan.
I give reasons below for suggesting that in the California Current, and adjacent
areas in the eastern North Pacific, 7. elegans and T. septentrionalis may be mutually
exclusive. Their relative distribution at all depths at the first thirteen stations on
the Trans-Pacific Expedition is shown in the bar-diagram Text-fig. 30. These
stations cross through the California Current to the northern edge of the Sub-
Tropical Zone. Where one of these species occurs in abundance the other appears
in only negligible quantities, if at all. Except at Stn. 1, 7. elegans is always the
more abundant. If the results obtained by Dales (1957) from samples taken entirely
in the top 75 metres of water in the California Current are analysed a somewhat
similar picture emerges. Thus Text-fig. 31 (a combination of the essentials in Dales’
figs. 53 and 54) shows only a small region where the two species occur together, at
intensities of distribution varying between <100 to 50 per 1,000 m® for T. elegans
and >100 to 25 per 1,000 m® for 7. septentrionalis. Dales does not give details of
1 In tomopterids the organs most affected by poor preservation are the parapodial pinnules. If
these are incomplete in 7. septentrionalis identification is difficult. It is very probable therefore that a
large number of the specimens listed as ‘‘ Tomopteyis not identifiable '’, in the Appendix could have
been called T. septentrionalis if in a better state of preservation. Other species of Tomopteris, within
the same size range as T. septentrionalis, clearly must also fall within this category sometimes, but on
the whole they have more readily distinguishable features and can be recognized from other parts of the
body even when the pinnules are frayed.
431
CHAETES
OF PELAGIC POLY
THE DISTRIBUTION
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THE DISTRIBUTION OF PELAGIC POLYCHAETES
— septentrionalis | elegans
|
Bar diagram showing the relative distribution of T. septentrionalis and T. elegans
at the first thirteen stations of the Trans-Pacific Exp. (semi-log scale).
THE DISTRIBUTION OF PELAGIC POLYCHAETES 433
his results so that the actual number of stations where they occur together is not
known but it must be small. Over the greater part of the region, and at the majority
of stations, however, it is clear that where one species was collected in abundance
the other was rarely present. Dales concludes from his data for T. septentrionalis
120
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Fic. 31. Occurrence of T. septentrionalis and T. elegans in the region of the California
Current (adapted from Dales (1957), figs. 53 and 54).
that it is a cold water coastal form ; in fact, as noted above it is cosmopolitan,
having been reported from all extremes of hydrological conditions. It is possible
that where T. elegans occurs in abundance T. septentrionalis does not find conditions
suitable for developing large populations. Because T. elegans is essentially a warm
water form (i.e., it is confined to Tropical and Sub-Tropical waters), T. septentrionalis
is forced into relatively colder waters whenever conditions exist where it could
exist in abundance if T. elegans were not present. This appears to be appli-
cable to distribution within the California Current and possibly westward to about
434 THE DISTRIBUTION OF PELAGIC POLYCHAETES
145° W.,1 but no results are available to suggest it applies over the main body of
North Pacific Central Water, or elsewhere in the world.
T. planktonis was collected at numerous stations, all within the Sub-Tropical and
Transition Zones (Text-fig. 32) and it is clear that in the North Pacific this species
must only rarely if ever cross the northern boundary of this latter region. It ap-
peared only in nets towed open to the surface, and in closing nets towed between
370 and 120 metres, and must be essentially an inhabitant of the upper water layers.
In only two samples were more than ten specimens collected ; at one of these, from
Northern Holiday Stn. 55, twenty-two were present, equivalent to twenty-eight per
1,000 m? of water.
Dales (1955) was the first to report 7. planktonis from the North Pacific, recording
it as T. cavallii from Monterey Bay ; under the same name he reported it from the
California Current (Dales, 1957). Berkeley & Berkeley (1957) reported 7. cavallhit
from the region of the Alaskan Gyral, about 55° N., 140° W., and although I have
not examined this material it may be 7. planktonis. Elsewhere in the world T.
planktonis has been reported from the Antarctic by Augener (1929), Monro (1930
as T. carpenteri), Stoap-Bowitz (1949, 1951) and Tebble (1960), from the Sub-Tropical
and Tropical Atlantic by Apstein (1900), Monro (1936) and Tebble (1960) whilst
Step-Bowitz (1948) called it a bipolar species. It was expected therefore that T.
planktonis would occur in some abundance in the North Pacific Sub-Arctic Zone,
but it appears to be absent from this region, except as possibly a coastal migrant if
future work shows that Berkeley & Berkeley (1957) records of T. cavallii are identical
with the material reported here.
T. pacifica was collected only in the Sub-Arctic and Transition Zones (Text-fig.
33) and is probably restricted to colder waters in the North Pacific. It was rarely
collected in abundance, normally there being only one or two specimens in a sample
but ten were present in the catch made at Stn. 19B of the Trans-Pacific Expedition,
equivalent to thirty per 1,000 m® of water. Only nets towed open to the surface
and those closing between 500 and 140 metres collected 7. pacifica, so that at the
present state of our knowledge it must be considered principally an inhabitant of
the upper waters.
T. pacifica has previously been reported from the Sub-Arctic Zone of the North
Pacific by Berkeley (1924, as T. elegans), Berkeley & Berkeley (1948, 1957 and
1960, as 7. renata) and Uschakov (1952, 1955 and 1957a as T. renata). Dales (1955)
reported it from deep water in Monterey Bay, which is probably the southern limit
of its distribution along the west coast of the U.S.A.—he did not find it in the
California Current. If there were no reports of this species from Sub-Tropical
water in the North Pacific these records would substantiate the suggestion that it
is a cold water species. There is, however, one,” the original description of 7.
1 In this region T. elegans may never inhabit waters north of about 45°N., and care must therefore
be taken to restrict examination of this relationship to waters of which both species are known to be
tolerant. In Monterey Bay, for example, Dales (1955) found T. septentrionalis in abundance but does
not report finding any specimens of T. elegans.
2 Disregarding entirely Chamberlin’s (1919) species called 7. euva, which though superficially like
T. pacifica, and reported from the Sub-Tropical Zone, is imperfectly described and cannot at the present
time be accepted as the same species (see also Dales, 1957). Consequently Treadwell’s (1943) records
of T. eura must also be disregarded because he gave no additional information.
OF PELAGIC POLYCHAETES 435
DISTRIBUTION
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THE DISTRIBUTION OF PELAGIC POLYCHAETES
436
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THE DISTRIBUTION OF PELAGIC POL:YCHAETES 437
pacifica having been made by Izuka (1914) from a sample collected off Misaka,
Japan, in which there were also present six undoubtedly sub-tropical species, in-
cluding T. elegans and T. apsteint. Undoubtedly Izuka was describing what is
accepted as the valid species, T. Pacifica, but the absence of any other undoubted
records of it since that time from the Sub-Tropical Zone suggests that his record
was anomalous, possibly the product of an aberrant coastal migration. It may be
unfortunate that the type locality of this species is outside the limits of its hydro-
logical environment but this does not effect its validity and should not be used as
grounds for accepting 7. venafa as its name.
T. ligulata was collected only in the Sub-Tropical Zone and it is probable that the
northern boundary of this region restricts its northerly movement (Text-fig. 34).
The records made here appear to be the first for the species from the North Pacific
Ocean ; Rosa (19080) reported it from 31°S., 80° W., in the South Pacific. All
catches were made in nets hauled between 370 metres and the surface, and the
largest number of specimens collected was six, at Trans-Pacific Stn. 120B, equivalent
to fifteen per 1,000 m$ of water, so that this species must only rarely become numeric-
. ally abundant. Elsewhere in the world 7. ligulata is known only from Tropical
“and Sub-Tropical waters.
’ T. apsteini was not collected at many stations but, nevertheless, these were all in
the Sub-Tropical Zone (Text-fig. 35) and it probably never occurs further north
“than this region. Very rarely was more than one specimen collected, the most
‘ being four at Stn. 56 of the Northern Holiday Expedition, equivalent to five per
- 1,000 m® of water. All collections were made in the upper 300 metres. Rosa
+ (1908d) first recorded 7. apsteini from the North Pacific, off Mexico, and Izuka
© (1914) reported it off Misaki, Japan. Elsewhere in the world it is also known only
«from Tropical and Sub-Tropical waters.
. 1. nisseni occurred at stations scattered across the Sub-Tropical Zone (Text-fig.
35), but was never collected beyond its northern boundary which suggests that this
acts as a barrier restricting its northerly movement. Dales (1955) recorded this
‘ species from deep water in Monterey Bay which was the first undoubted record
from the North Pacific. On the Trans-Pacific Expedition T. nisseni was caught
_ only in the top 370 metres of water ; all of these catches except two were within
North Pacific Central Water. At Stns. 7A and 7C it was collected in the California
Current but it appears to inhabit this water only rarely for it was not recorded in
Dales’ (1957) extensive survey of the area.
Elsewhere in the world, in the southern hemisphere, T. misseni is known only
from Tropical and Sub-Tropical waters. In the North Atlantic, however, there
are valid records from boreal waters (Wesenberg-Lund, 1950) and it was expected,
therefore, that it would occur in the Sub-Arctic waters of the North Pacific ; this
matter is discussed further, below p. 469.
ALCIOPIDAE
Twelve species within this family are reported here. All were collected at
numerous stations in the Sub-Tropical Zone ; a few appeared also in the Transition
ZOOL. 7, 9. ; 32
IC POLYCHAETES
E DISTRIBUTION OF PELAG
TH
438
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439
THE DISTRIBUTION OF PELAGIC POLYCHAETES
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440 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Zone but only one (Rhynchonerella angelini) was collected in abundance in the
Sub-Arctic.
In Tables I and II of the Appendix the presence or absence of alciopid fragments
(headless pieces) at each station has been indicated. This item is included because
of the Zoogeographical importance of the family as a whole to which the presence or
absence of these fragments lends significance. Thus many more genera and species
of Alciopidae occur in the Sub-Tropical and Tropical Zones of the South Atlantic
than in the waters of higher latitudes (Tebble, 1960), and this is shown below to
apply also to the North Pacific. The recording of the presence of the fragments is
additional proof of this. These were, for example, found at a large number of
stations in the Sub-Tropical Zone (Appendix, Table I) but at very few in the Sub-
Arctic (Table II) ; an indication that numerous species (up to twelve) can be found
in the Sub-Tropical Zone and that only one permanently inhabits the Sub-Arctic.
NAIADES
Naiades cantrainii was collected at numerous stations all in the Sub-Tropical
Zone (Text-fig. 36). It probably only rarely if ever occurs north of this region.
Collected only by nets towed open to the surface, in the top 150 metres of water,
N. cantrainii must here be considered a surface water species. The largest number
of specimens present in any tow at which the amount of water filtered was measured,
was two, at Stn. 104A, of the Trans-Pacific Expedition equivalent to five per 1,000
m® of water. The species was first reported from the North Pacific by Treadwell
(1943 as Alciopa distorta), between California and Hawaii, and subsequently Dales
(1957) found it in the California Current. Elsewhere in the world it is known only
from Tropical and Sub-Tropical waters.
VANADIS
None of the five species of Vanadis reported here was collected in the Sub-Arctic
Zone, and only V. longissima was collected in the Transition Zone (one record), so
it is probable that the southern boundary of this latter region restricts their move-
ment northwards. Elsewhere in the world all five species are known only from
tropical and sub-tropical waters, except V. longissima which has also been reported
from the sub-antarctic region of the South Atlantic (Tebble, 1960).
V. minuta was collected more often than any other alciopid, occurring regularly
at stations across the breadth of the North Pacific, south of the Transition Zone
(Text-fig. 37), and it clearly never penetrates north of the southern boundary of this
region. It is evidently a surface water species for it was present in thirty-eight
hauls towed open to the surface from 190 m., or less, but by only two nets closing
at sub-surface depths (at Trans-Pacific Expedition Stns. 132B, 345-153 m. and
135B, 290-146 m.) and never appeared in nets closed at greater depths. The
largest number collected was nine at Stn. 123A, equivalent to eighteen per 1,000 m*
of water filtered, but normally the numbers were smaller than this and it may be
presumed that V. minuta only rarely occurs in abundance. Treadwell’s (1906) type
THE DISTRIBUTION: OF
yprorereaniaisey
ne nap
PELAGIC POLYCHAETES
s
=
&
2
39
2
2
Kn,
SUB-TROPICAL ZoNS
40°
ou
441
Fic. 36. Occurrence of Naiades cantrainiz.
442 THE DISTRIBUTION OF PELAGIC POLYCHAETES
material came from the surface water off Hawaii, and Dales (1957) recorded it from
the top 75 m. of water in the California Current.
Except for one record from Trans-Pacific Expedition Stn. 51A in the Transition
Zone, all the records of V. longissima are from the Sub-Tropical Zone, where it
occurred at numerous stations across the breadth of the North Pacific (Text-fig. 38).
The largest number of specimens in any sample was eight at Trans-Pacific Expedi-
tion Stn. 104A, equivalent to twenty-one per 1,000 m’ of water. Only one specimen
was collected at Stn. 51A, and statistically such a record could be discarded, and
the northerly limit to the distribution of V. longissima taken to be the northern
boundary of the Sub-Tropical Zone, but in fact this one apparently anomalous record
may cloak a potentially significant biological relationship. Thus, in the Systematic
Account (above p. 393), it is noted that this one specimen had dark brown spots on
the head and that specimens from other stations in the Sub-Tropical Zone, but
close to the boundary with the Transition Zone, also exhibit this hitherto unreported
character. It is possible therefore that a separate population of V. longissima
inhabits the Transition Zone and immediately adjacent water to the south.
All records of V. Jongissima are from the nets towed open to the surface, and it
may therefore be considered an inhabitant of the upper layers of the North Pacific
“Central water. It has previously been reported from the Sub-Tropical Zone of the
*North Pacific by Izuka (1914 as V. grandis), Treadwell (1943, as Torrea Jase):
Uschakov (19574, as V. pacifica) and, Dales (1957).
V. crystallina was collected only in the Sub-Tropical Zone, appearing at numerous
‘stations (Text-fig, 39), and the southern boundary of the Transition Zone may. ‘be
-‘taken as the northern limit of its distribution in the North Pacific. It must penetrate
‘into deep water there only rarely for all nets collecting it fished in the upper 400m,
The largest number collected was three, at Trans-Pacific Expedition Stn. 85A,
equivalent to six per 1,000 m3 of water. Dales (1957) reported. V. crystalling fyqm
the California Current, this being the first record of the species from the Walk
Pacific.
- V. formosa did not occur at many stations, but these were scattered across; ‘the
Sub-Tropical Zone (Text-fig. 40) and it is clear that it does not penetrate north of
‘this region. Collected exclusively by nets towed open to the surface V. formosa
must at the present state of our knowledge be considered a surface water spécies,
Only rarely was there more than one specimen in a sample. The first record of
V. formosa from the North Pacific was made by Treadwell (1943) from the Sub-
Tropical Zone ; later Dales (1957) found it at sixty-seven stations in the California
Current, in marked contrast to the comparatively few records made here. Because
more than half of the latter are from east of 140° W., it may be that it is in this
area of the North Pacific that the main concentrations of this species are to be
found.
Known exclusively from the North Pacific Ocean V. tagensis was present in only
seventeen of the 416 samples examined. Twelve of these are from nets closed at
depth (between 680-130 m.) and the remainder from nets towed through a con-
siderable distance open to the surface so that the species can be considered a deeper
water form. The few records made may be explained by the smaller number of
THE DISTRIBUTION OF PELAGIC POLYCHAETES
443
UB-ARCTIC ZONE
TRANSITION ZONE *
i tn
SUB-TROPICAL ZONE
Occurrence of Vanadis minuta.
Fic. 37.
cS)
STRIBUTION OF PELAGIC POLYCHAETE
E DI
TH
‘MULISStSUO] StpHUY A JO BDUEIINDIDOQ «gE ‘DIY
VWISSIDNO7 SIGVNVA
00:
3NOZ WdidO¥L-ens
445
THE DISTRIBUTION OF PELAGIC POLYCHAETES
"pUtpjv{shs) StippuYA JO BDUELINDDQ §=“6E ‘DIY
00b=
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°
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WM yy
°
440 THE DISTRIBUTION OF PELAGIC POLYCHAETES
nets which were closed at depth (Table I). None of the catches of V. tagensis was
north of the Sub-Tropical Zone (Text-fig. 40) and it is possible that the northern
boundary of this region restricts its movement into the higher latitudes. At two
stations two specimens were caught but at the others only one was collected. The
original records of V. tagensis were made from Monterey Bay, between 500-1,000 m.
(Dales, 1955) and it is apparent that the late discovery of this species, and the
comparatively limited area from which it is known, is due to its deep water habitat,
for few expeditions can sample the deep layers as exhaustively as they do the surface
waters. A much wider range of distribution for this species may become apparent
when more deep water collections have been made.
RHYNCHONERELLA
Four species of this genus were present in the collections. R. petersii and R.
mobii in the Sub-Tropical and Transition Zones, R. gracilis mainly in these two but
also at a few stations in the Sub-Arctic and R. angelini in some abundance in all
three.
' _ R. petersii was fond at numerous stations in the Sub-Tropical Zone and occasion-
: ally penetrates into the Transition Zone (Text-fig. 41), the northern boundary of the
* latter region probably restricting its movement into higher latitudes.. At, most
. stations only one specimen was collected but four were in the sample from Stn, I1A
: of the Trans-Pacific Expedition. This is equivalent to five per 1,000 m3 pf water.
* Clearly the species must only rarely occur in abundance. Most records ‘are \from
. the top 300 m. jof water, but at Stn. 12F a net towed between 850-680 m, ' collected
: one specimen. “This record must be treated as an anomaly until extensive colléc-
« tions at depth prove otherwise. The only previous record of R. petersit; fromy the
- North Pacific was made by Uschakov (1957a, as Callizona setosa) fromt\the’ Sub-
Tropical Zone in the Western Pacific. R. petersti is not well known from pther
oceans in the world but has not been reported outside Tropical and Sub- -Tropical
waters.
R. mobii was found at comparatively few stations. These, however, were all
within the Sub-Tropical Zone (Text-fig. 42) indicating that it rarely moves further
north than this region. There was never more than one specimen of this species
in asample. It was collected in nets towed open in the top 400 m. of water and in
closing nets hauled between 370-140 m, Evidently R. mobii is principally an in-
habitant of the upper waters; Dales (1957) first recorded it in the North Pacific
from the surface waters of the California Current. Elsewhere in the world R. mobit
is known from few records but these are all from Tropical and Sub-Tropical waters.
R. gracilis was present in numerous samples most of which came from the Sub-
Tropical Zone (Text-fig. 43). It also appeared, however, in the Transition Zone
and at two stations in the Sub-Arctic Zone. If, as is probable, R. gracilis has its
northern limit of distribution at the southern boundary of the Sub-Arctic Zone the
specimens collected beyond this boundary could be explained as accidental sur-
vivors outside their hydrological limits. This may be true of the specimen from
Trans-Pacific Expedition Stn. 48D but is almost certainly not applicable to that
447
THE DISTRIBUTION OF PELAGIC POLYCHAETES
VSOWYO4 SIGVNVA ¥
‘susuasyy “4 pue vsoutsof sippuv, yo aoue1mNs09
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we awe] Mn, 3NOZ TwoIdOuL-gns
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POLYCHAETE
PELAGIC
OF
THE DISTRIBUTION
448
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449
THE DISTRIBUTION OF PELAGIC POLYCHAETES
“2190Mm vyjadauoyIUAYY JO BdUAIINDDIQ ‘zh ‘OI
IIGOW Y713Y3INOHINAHY
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450 THE DISTRIBUTION OF PELAGIC POLYCHAETES
from Northern Holiday Exp., Stn. 26, which is much further north of the boundary
line, and within the region of the Alaskan gyral. Further collections from the
North East Pacific will have to be examined before it can be established that R.
gracilis does not inhabit this region as an occasional, possibly seasonal migrant.
R. gracilis was collected mainly by nets which were towed open to the surface ;
the majority of these fished only in the top 400 m. of water within which layer the
species appears to concentrate. In most samples only one specimen was collected
but six were caught at Stn. 110A, of the Trans-Pacific Expedition equivalent to
twelve per 1,000 m of water.
R. gracilis was first reported from the North Pacific, off Misaki, Japan, by Izuka
(1914 as Callizona japonica) and subsequently by Uschakov (19574 as C. nasuta)
from between 35-40°N., about 151° E., and Berkeley & Berkeley (1960) with one
record as far north as 54° 30’ N., about 152° W., and two others in the Transition
Zone.
R. angelini was found in all three hydrological zones (Text-fig. 44). This was to
be expected if its pattern of distribution in the Atlantic Ocean, as suggested by
Tebble (1960), was to be repeated in the Pacific. Thus, although restricted in its
movements southwards, in the southern hemisphere by the Sub-Tropical Con-
vergence, there is no comparable restriction in the northern hemisphere. In the
latter there are no endemic pelagic polychaetes in higher latitudes and some of the
species there may be taken to represent Antarctic endemic elements in boreal waters,
R. angelini for instance representing the endemic antarctic R. bongrain:; the
evidence found in the present work suggests that this is now applicable to the North
Pacific in the case of these species of Rhynchonerella.
Throughout all three hydrological zones R. angelini was caught in nets towed open
in the top 200-300 m. of water and in some nets closing between 500 and 121 m.
Only on very few occasions were more than one specimen collected.
R. angelini was first recorded from the North Pacific by Moore (1908 as Callizona
angelini) in the stomachs of salmon caught off the coast of Alaska, and was subse-
quently reported under the same name by Berkeley (1930), from the east coast of
Vancouver, by Berkeley & Berkeley (1957, 1958 and 1960), from the Sub-Arctic
Zone, and the Sub-Tropical Zone ; Treadwell (1943 as Rhynchonerella pycnocera)
reported it from the Sub-Tropical Zone and Dales (1955 and 1957) from Monterey
Bay and the California Current.
PLOTOHELMIS
P. tenuis was found at numerous stations across the Sub-Tropical Zone and in a
few samples in the Transition and Sub-Arctic Zones (Text-fig. 45). Most of the
records from the latter region were near its southern boundary and probably indicate
minor intrusions of warmer water. Nevertheless, in suggesting that the southern
boundary of the Sub-Arctic Zone restricts the northerly movement of P. tenuis in
the North Pacific, I draw attention to these records, for they may indicate a seasonal
migration outside the normal hydrological limits of the species. P. tenuis was
found in open and closing nets at all depths from 850 m. to the surface, occurring
451
THE DISTRIBUTION OF PELAGIC POLYCHAETES
"St9049 vyacsuoyoudyy Jo souaImNI0Q “EF ‘o1g
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F PELAGIC POLYCHAETES
THE DISTRIBUTION O
452
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3NOZ WwoidOwL-Ens A
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453
THE DISTRIBUTION OF PELAGIC POLYCHAETES
‘sInua, SIUMIYOJO] JO BIUdLINIQ “Sh OL]
009|
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ZOOL. 7, 9.
454 THE DISTRIBUTION OF PELAGIC POLYCHAETES
more frequently in the upper layers where most nets fished. Only on few occasions
were more than one specimen collected but an exceptionally large catch was made
at Northern Holiday Station 2, sixty-nine specimens, equivalent to 110 per 1,000 m*
of water, being caught. Izuka (1914) was the first to describe this species from the
North Pacific as Riynchonerella fulgens from off Misaki, Japan, and Dales reported
it from Monterey Bay (1955) and in the California Current (1957). Elsewhere in
the world P. tenuis is known from comparatively few records and the limits to its
distribution cannot be precisely fixed, but it is probably a Sub-Tropical and Tropical
species.
KROHNIA
Krohnia lepidota was found only in the Sub-Tropical Zone (Text-fig. 46) and it is
doubtful if it ever occurs further north than this region. It was collected entirely
by nets fishing in the top 370 m. of water and at most stations only one specimen
was found, but four were present at Trans-Pacific Expedition Stn. 97A, equivalent
to five per 1,000 m of water.
Chamberlin (1919) first recorded K. /epidota from the North Pacific as Rhyncho-
nevella cincinnata off the SW. coast of Mexico and Treadwell (1943) reported it as
Callizona pigmenta from 12° 40' N., 137° 32’ W. Elsewhere in the world K. lepidota
is known only from Sub-Tropical and Tropical waters.
TYPHLOSCOLECIDAE
Six species of this family were present in the collections. Of these the cosmopolitan
* Typhloscolex miilleri was very common everywhere, and Sagitella kowalewskii and
Travisiopsis lobifera were present in abundance in the Sub-Tropical Zone ; however,
the other three species Tvavisiopsis levenseni, lanceolata and dubia were collected
only rarely and it is not possible to be conclusive about their distributional limits.
Typhloscolex miilleri was found in all three hydrological zones occurring in greatest
abundance in the Sub-Arctic (Text-fig. 47). It was collected at all explored depths,
in both open and closing nets. These records confirm the known distribution of
this species in the North Pacific where it has been reported from the Sub-Tropical
and Sub-Arctic by Treadwell (1943) and Uschakov (1957a); the Sub-Arctic by
Uschakov (1952, 1955) and Berkeley & Berkeley (1948, 1957, and 1960); the
Transition Zone by Berkeley & Berkeley (1960) and the California Current by
Dales (1957). In addition Uschakov (19576) records it from high Arctic waters in
approximately 80° N., near 180°. It has been noted inthe Systematic Account
(pp. 408-409) that in the North Pacific an ecotype of T. miilleri inhabits the Sub-
Arctic Zone.
Sagitella kowalewskii was present at a large number of the stations made in the
Sub-Tropical Zone ; indeed the persistence of its occurrence there was a feature of
the collections (Text-fig. 48). It is probable therefore that the southern boundary
of the Sub-Arctic Zone marks the northern limit of its distribution although one
specimen was found just north of this boundary. Generally no more than ten
45
ES
N OF PELAGIC POLYCHAET
TRIBUTIO
Ss
THE DI
‘myopida] viuYoAy JO adUELINIIQ “oF
“OY
VLOGId37 VINHOYN
{3NOZ NOILISNVYL
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ES
OF PELAGIC POLYCHAETE
THE DISTRIBUTION
456
“14ayj nut
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“ZY “Ol
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457
N OF PELAGIC POLYCHAETES
THE DISTRIBUTIO
“NYySMa~MoOY VIJaJLIVS JO BdUZIINIIO
“gh oly
458 THE DISTRIBUTION OF PELAGIC POLYCHAETES
specimens of.S. kowalewski were present in a sample with exceptionally fourteen at
Stn. 86A of the Trans-Pacific Expedition, equivalent to thirty per 1,000 m® of
water filtered. It was found at all explored depths in both open and closing nets,
and evidently is capable of a wide distribution in deep and surface water circulations.
Berkeley (1930) was the first to record S. kowalewskii from the North Pacific,
finding it off Vancouver Island ; subsequently Okuda (1937, 1938) reported it from
sub-tropical water off Japan and Treadwell (1943 as Plotobia paucichaeta) and
Uschakov (1957a) recorded it from the Sub-Tropical and Transition Zones, and
Dales (1957) found it in the California Current ; Uschakov (1957a), however, also
records it off Kamchatka in about 52°N., well within the Sub-Arctic Zone. I
hesitate to accept this record in the face of no supporting evidence from other
expeditions, notwithstanding Berkeley & Berkeley’s (1960) record from 50°N., in
the north-east Pacific which I consider an area to which the species could migrate
within the Alaskan gyral (Text-fig. 2).
Travisiopsis lobifera was collected at numerous stations across the Sub-Tropical
Zone and appeared also in the Transition Zone where the northern boundary probably
restricts its movement northwards (Text-fig. 49). On few occasions were more
then ten specimens collected but an exceptional catch was made at Trans-Pacific
Expedition Stn. 99A, where fifty-four specimens were caught, equivalent to forty-
two per 1,000 m® of water. Most nets collecting this species fished in the upper
330 metres but it was also caught between 680 and 130 metres suggesting that it
inhabits a considerable depth of water. Although persistent in its occurrence in
the western and eastern North Pacific 7. lobifera was only rarely found south of
40°N., between 140° W., and 180°.
The first record of T. lobifera from the North Pacific was made by Dales (1955)
from Monterey Bay, who in 1957 also reported it from the California Current.
Uschakov (19574) reported it from the northern region of the Transition Zone in the
western North Pacific and Berkeley & Berkeley (1957 and 1960) from the same
zone in the eastern North Pacific. This last record includes one from 51° 21'N.,
149° 21’ W., the farthest north the species has ever been recorded, and with that
made by Uschakov (1957@) is additional evidence for the suggestions made above
that it is the northern boundary of the Transition Zone that marks the northern
limit of its distribution.
Travisiopsis levinsent is known from the North Pacific only through the records
made by Dales (1955) from deep water in Monterey Bay and the three made here
from the Trans-Pacific Expedition (Text-fig. 50). The latter are from nets which
could have collected it in deep water but clearly little can be said about its dis-
tribution until more records are available. The few records made may be due to
lack of extensive sampling of the deeper layers. In the Atlantic Ocean T. levinsent
is known from all extremes of hydrological conditions (Step-Bowitz, 1948 ; Tebble,
1960) and is generally considered a cosmopolitan species.
Travisiopsis lanceolata was collected at only nine stations, these being mainly in
the Sub-Tropical Zone but two catches were made in the Transition Zone and one
in the Sub-Arctic (Text-fig. 50). Most of these were by nets closing at depth but
more extensive collecting in the deeper water will be required in order to define the
459
THE DISTRIBUTION OF PELAGIC POLYCHAETES
VY3IIIGOT SISCOISIAVYL
‘paafiqo] Sisqorswway, JO aUaLMIQ, “6h “Oy
a oh
ae fae ! 3NOZ WWoidO¥L-ans
.
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460 THE DISTRIBUTION OF PELAGIC POLYCHAETES
limits of its distribution. T. lanceolata was first recorded from the North Pacific by
Treadwell (1943 as Plotobia simplex), from five records in the Sub-Arctic Zone and
two in the Sub-Tropical. All these records suggest that this species inhabits both
warm and cold water regions of the North Pacific as it does in the North Atlantic
(Step-Bowitz, 1948).
Travisiopsis dubia was collected at only eight stations, all in the Sub-Tropical
Zone (Text-fig. 50) and all in nets towed open to the surface. These are the first
records of this species from the North Pacific and only Dales (1960) has previously
reported it from the South Pacific. Dales’ records were made possible through the
collections of the Trans-Pacific Expedition, which I was able to show him were
identical with material he had from the South China Sea. Otherwise known only
through its original discovery in the Atlantic Ocean by Step-Bowitz (1948) from
39° 30'N., 49° 42’ W., and 48° 24'N., 36° 53’ W., T. dubia is not known from suffi-
cient records for its distribution to be comprehensively analysed. Moreover,
because it is very like Sagitella kowalewskti (see above, p. 415), it may have been
overlooked among previous collections of this species and these will have to be re-
examined before the situation is clarified.
PHYLLODOCIDAE (LOPADORHYNCHINAE AND IOSPILINAE)
Eight species of this family are reported here, showing a diversity of generic and
specific distribution not met with in any other family of pelagic polychaetes.
LOPADORHYNCHINAE
PELAGOBIA
Pelagobia longicirrata was collected in all three hydrological zones (Text-fig. 51).
This was as expected for in the Atlantic it has been reported from all extremes of
hydrological conditions (Step-Bowitz, 1948 ; Tebble, 1960) and is generally accepted
as a cosmopolitan species. It occurred in its greatest abundance in the Sub-Arctic
Zone with sixty-five specimens at Stn. 40C of the Trans-Pacific Expedition, equivalent
to one hundred and ninety-five per 1,000 m* of water. This was the largest catch
made at any station. There were numerous stations in this zone however where
no more than one to five specimens of P. longicivrata were collected per 1,000 m%,
as was common in the Sub-Tropical Zone. In all hydrological zones it appeared
at all explored depths but had its greatest abundance in the nets closed between
700 and 300 metres. Clearly this species has a very wide depth range in the North
Pacific, similar to that found in the Sub-Antarctic and Antarctic Zones of the
South Atlantic by Tebble (1960).
The first record of P. longicirrata from the North Pacific was made by Chamberlin
(1919, as P. vigueri) from the Tropical Zone, subsequently Okuda (1937, 1938),
Treadwell (1943, as P. viguert), Dales (1955, 1957), Uschakov (19576), and Berkeley
& Berkeley (1960) reported it from the Sub-Tropical Zone and Treadwell (1943),
Uschakov (1952 as P. viguerit ; 1957a) and Berkeley & Berkeley (1960) found it in
_ the Transition and Sub-Arctic Zones. It was also reported from north of 76°N.,
by Uschakov (19576), the most northerly record for the species.
461
THE DISTRIBUTION OF PELAGIC POLYCHAETES
‘wignp \, pure tuasuiaay “[ ‘wyvjoaouv] sisdorsiawaT JO adueIINI9:Q) ‘0S ‘DI
VIGNG SISdOISIAVYL
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POLYCHAETES
LAGIC
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OF
DISTRIBUTION
THE
462
‘DIVAAIINIBUO] VIGOSYIAa JO IUIIINIICO)
“19 “Ong
oD
“3NOZ IwoidOWL-ens
THE DISTRIBUTION OF PELAGIC POLYCHAETES 463
LOPADORHYNCHUS
Three species of this genus are reported here, L. krohnii, L. uncinatus and L. brevis.
All three were collected only within the Sub-Tropical Zone, and elsewhere in the
world are known only from Tropical and Sub-Tropical waters.
Lopadorhynchus krohnit was present at numerous stations (Text-fig. 52) and
clearly never penetrates north of the Sub-Tropical Zone. It was rare for more
then one or two specimens of this species to be in any sample but six were caught
at Stn. 61 of the Northern Holiday Expedition, equivalent to eight per 1,000 m?
of water. It was collected exclusively in nets towed in the upper 370 metres, and
must be essentially a surface water species. This appears to be only the second
record of L. krohnii from the North Pacific, Dales (1957) having first recorded it
from the California Current.
L. uncinatus was collected at only eleven stations (Text-fig. 53) but these ranged
across the ocean and were also close to the northern boundary of the Sub-Tropical
Zone which almost certainly restricts its movement northwards. Although not
caught very often, on only one occasion was more than one specimen collected,
L. uncinatus was present in nets towed a little deeper than those which caught L.
krohni, and it may inhabit a greater depth range. L. uncinatus was first recorded
from the North Pacific by Treadwell (1943 as L. varius) at seven stations made by
the Carnegie in the Tropical and Sub-Tropical Zones between San Francisco and the
Marshall Is.: Dales (1955 and 1957) subsequently reported it from Monterey Bay
and the California Current and Berkeley & Berkeley (1958) found it at 20° oo’N.,
110° 35’ W. Berkeley & Berkeley (1960) also report a specimen—‘‘ 1 mm. long,
probably larval ’’, from 54° 30’ N., 152° 00’ W., which they call L. uncinatus ; this
is, I think, a most unusual record, and will have to be confirmed.
L. brevis was caught more often than L. uncinatus, though again across the breadth
of the North Pacific and on occasion close to the northern boundary of the Sub-
Tropical Zone (Text-fig. 53). This probably marks the limit of its northerly move-
ment. Never more than one specimen was collected. All catches were in nets
towed open in the top 290 metres of water, indicating that it is probably a surface
water species. The first record of L. brevis from the North Pacific was made by
Chamberlin (1919 as L. parvum) off the coast of Mexico (15° 58’N., 98° 13’ W.)
and subsequently Dales (1957) reported it from the California Current and Berkeley
& Berkeley (1958) from 3° 03’ N., 101° 35’ W., and 10° 52’ N., 88° 02’ W.
MAUPASIA
M. caeca was found in all three hydrological zones (Text-fig. 54). This was
expected because in the South Atlantic Ocean it is already known from warm and
cold water regions (Tebble, 1960). On only two occasions were more than one
specimen collected, and it appeared only in nets towed in the upper 525 metres of
water. A number of these were closed in the deeper part of the layer indicating
that M. caeca inhabits a considerable depth range.
M. caeca was first recorded from the North Pacific by Uschakov (1957a) from the
OF PELAGIC POLYCHAETES
N
THE DISTRIBUTIO
464
“MUYyoay snYyIUAYAOpYgOT JO BdUaIINIIQ “ZS “OL
oltg
°
3NOZ IWIIdO¥L-gns
St
* 3NOZ DiL¥v-ans
465
THE DISTRIBUTION OF PELAGIC POLYCHAETES
'stnadq “JT Pue snyou2IUN snYyIUAYAOpHdOT JO AdUEIINIDQ “ES “DI
o0b-
3NOZ IWIIdOwL-8ns
SIAJY@_ SNHINAHYOCdOT
466 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Transition Zone, 43° 08’N., 156° 08’E., and Berkeley & Berkeley (1958) later
reported it from the Tropical Zone, 1° 58’ N., 83° 49’ W.
PEDINOSOMA
P. curtum was collected at only twelve stations, all east of 164° W., and in the
Sub-Tropical Zone except for one record at the southern end of the Transition
Zone (Text-fig. 54). It appeared only in nets towed open in the upper 415 metres
of water: on only one occasion was more than one specimen collected. The only
previous record of P. curtum from the North Pacific was made by Berkeley &
Berkeley (1960) from 53° 32’ N., 151° 57’ W., and it is altogether too little known
to draw conclusions about its distribution. Elsewhere in the world this species is
not well known except in the North Atlantic where Reibisch (1895) found it only
in Tropical and Sub-Tropical waters.
IOSPILINAE
PHALACROPHORUS
Two species of this genus are reported here, of which P. pictus appeared at numerous
stations but P. uniformis at only one. This singular occurrence of P. uniformis at
Stn. 126B of the Trans-Pacific Expedition (Text-fig. 55) consisted of fifty-three
specimens, equivalent to sixty-two per 1,000 m® of water. This is a large number
for any polychaete species, making the record particularly remarkable. Previously
it was known from the North Pacific only through the records of Treadwell (1943
as P. attenuatus) from four stations made by the Carnegie, all south of the Transition
Zone. In the Atlantic it is known only from Sub-Tropical and Tropical waters
(Reibisch, 1895 ; Fauvel, 1916) and may be restricted to these zones in the North
Pacific but more records will have to be obtained before this can be confirmed.
P. pictus was collected at numerous stations in the Sub-Arctic Zone, but at only
one in the Sub-Tropical, Trans-Pacific Expedition Stn. 123A (Text-fig. 55). It
would appear reasonable to consider this latter record an anomaly and treat the
species as one restricted to the colder waters. There are, however, numerous litera-
ture records of P. pictus from Sub-Tropical waters which cannot be overlooked,
these include Treadwell (1943, as P. maculatus), Uschakov (1957a) and Berkeley
& Berkeley (1960), as well as others from the Sub-Arctic, Treadwell (1943), Berkeley
& Berkeley (1958). It is clear therefore that the almost complete absence of this
species from the collections reported here from the Sub-Tropical Zone was a result
of its not being caught, rather than its not being there—a major hazard of plankton
collecting.
Uschakov (1957)) has reported another species, P. borealis, from high Arctic
waters in the North Pacific, beyond 76°N. This material is identical with that
reported here as P. pictus and I consider the two species synonymous. It is possible,
however, that the material reported as P. borealis represents a geographical race
restricted to the colder water. This may also be applicable to the North Atlantic
467
OF PELAGIC POLYCHAETES
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THE DISTRIBUTIO
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THE DISTRIBUTION OF PELAGIC POLYCHAETES 469
Ocean where P. borealis was first recorded by Reibisch (1895) entirely within Sub-
Arctic waters but I would like to see material from a wider geographical range than
at present available before drawing conclusions on this point. For the present,
however, I think that P. pictus must be considered as potentially a cosmopolitan
species.
ZOOGEOGRAPHICAL REVIEW
Thirty-three species are reported here of which twenty-one appear to have the
northerly limit to their distribution in the North Pacific Ocean at either the northern
boundary of the Sub-Tropical Zone or the southern boundary of the Sub-Arctic
Zone ; they are:
Tomopteridae Alciopidae Typhloscolecidae Lopadorhynchinae
Tomopteris elegans . Naiades cantrainit . Sagitella kowalewskii . Lopadorhynchus
T. planktonis . Vanadis longissima . Tvavisiopsis lobifera . L.uncinatus —
T. ligulata . V. formosa c . Li krohnii
T. apsteini . V. crystallina : . L. brevis
T. nisseni . V.minuta
V. tagensis
Rhynchonerella gracilis
R. petersit
R. mobit
Plotohelmis tenuis
Krohnia lepidota
All of these effectively avoid the main body of the Sub-Arctic water mass in the
Sub-Arctic Zone and, in that area of the North Pacific investigated, can be con-
sidered Sub-Tropical species. Because there is no definable “line of the Sub-
Tropical Convergence’, between sub-tropical and sub-arctic water, stretching
across the North Pacific (corresponding to the Sub-Tropical Convergence in the
South Atlantic) but rather a Zone of Transition water, these species vary in the
extent to which they penetrate beyond the northern boundary of the Sub-Tropical
Zone. Vanadis minuta and V. crystallina, for example, were never found in Transition
water but Tomopteris elegans and Travisiopsis lobifera can be collected there up to
the border with the Sub-Arctic Zone. This does not warrant excluding the latter
species from the list of Sub-Tropical forms. Indeed further collections may show
that all species of this group can invade the Transition Zone, if only during certain
seasons.
It has been noted that Tomopteris planktonis, Rhynchonerella gracilis, Plotohelmis
tenuis and Sagitella kowalewskii may occasionally be found north of 45° N., princi-
pally in the North-East Pacific off the coast of British Columbia and Alaska.
These species could be carried into this region by the Alaskan gyral (Text-fig. 2)
and may be the most tolerant of the Sub-Tropical species. Boden et al. (1955)
records similar northerly extensions for the distribution of the euphausiids Nema-
toscelis difficilis, Nematobranchion flexipes and Stylocheiron longicorne. Essentially
sub-tropical and/or tropical in their distribution in the North Pacific as recorded
ZOOL. 7, 9. 34
47° THE DISTRIBUTION OF PELAGIC POLYCHAETES
by Brinton (1957) these species were found by Banner (1949) to extend to varying
degrees north of the southern boundary of the Sub-Arctic off the slope waters of
British Columbia. Bradshaw (1959) notes that a similar pattern is found in the
foraminiferan Ovbulina universa. It only remains for extensive collections from
the area of the Alaskan gyral to be investigated to establish the geographical and
seasonal extension of these and similar species. The fundamental feature of the
distribution of all of them, however, is that they avoid the main body of oceanic
water in the Sub-Arctic Zone.
It is possible that most of these twenty-one Sub-Tropical pelagic polychaetes
occur also in Tropical waters in the Pacific Ocean but investigation of the extent of
this will have to await further study. Bieri’s (1959) analysis of chaetognath dis-
tribution in the North and South Pacific Oceans and Brinton’s (1957) similar study
on euphausiids draw attention to the great variety of distributional patterns which
emerge from the study of a group over such immense areas. Involving so many
different zoogeographical regions their work motivates a sense of caution towards
any predictions whatsoever concerning distribution in the Pacific Ocean outside the
region investigated.
Of the remaining twelve species five are cosmopolitan—T omopteris septentrionalis,
Typhloscolex miilleri, Pelagobia longicirrata, Maupasia caeca and Phalacrophorus
pictus ; one is known only from Sub-Arctic and Transition Zone waters of the
North Pacific—Tomopteris pacifica; one occurs in all hydrological Zones in the
Northern Hemisphere but avoids colder water in the Southern Hemisphere—
Rhynchonerella angelini ; and five are known from comparatively few records in the
North Pacific and at the present time their distribution need not be examined
further—Travisiopsis levinsent, Tr. lanceolata, Tr. dubia, Phalacrophorus uniformis
and Pedinosoma curtum.
Of the Sub-Tropical species Vanadis minuta and V. tagensis are known only from
the Pacific Ocean. It has been noted above that the latter is a deeper-water species,
and many more collections from nets closing at depth in other oceans will have to
be examined before it can be established as an exclusively Pacific Ocean species.
V. minuta is a surface water form and one would expect it to have been reported
from other oceans if it lived outside the Pacific. In fact this species is similar to
V. crystallina, which is well known from the Atlantic, and they may have been
confused in previously reported collections. I prefer, therefore, to delay suggesting
that V. minuta is entirely restricted to the Pacific Ocean until more collections from
other oceans have been examined.
Of the remaining nineteen species in this group seventeen are known from the
North Atlantic Ocean entirely within Tropical and Sub-Tropical waters, although
the records from there for a few of them are not numerous. The two which do not
inhabit similar zoogeographical regions in the two oceans are Tomopteris planktoms
and Tomopteris nissent.
The absence of 7. planktonis from the main body of Sub-Arctic water has been
referred to above as entirely unexpected. Known from every other explored water
~ mass in the world I can offer no satisfactory explanation of why this species, hitherto
considered as cosmopolitan, should avoid this water. It may, of course, have been
THE DISTRIBUTION OF PELAGIC POLYCHAETES 471
missed. Such a possibility, though remote, cannot be overlooked, and need not be
accepted as invalidating any conclusions drawn for other species based on similar
negative records: it may indeed represent one of the major hazards of reporting
on the distribution of zooplankton.
T. nisseni inhabits Sub-Tropical and Tropical waters in the South Atlantic Ocean
and similar water in the North Atlantic. In the latter, however, it also extends
into Sub-Arctic and Arctic waters and I expected it to be present in the Pacific
Sub-Arctic, from which it was, however, entirely absent. As an explanation of the
extension of T. nisseni (and also Tomopteris Rrampi, Rhynchonerella angelint and
Travisiopsis lanceolata) into the waters of higher latitudes in the North Atlantic,
though absent from similar water in the South Atlantic, I suggested (Tebble, 1960)
that they represented endemic antarctic elements in arctic waters. There being no
endemic pelagic polychaetes in the North Atlantic, Sub-Arctic and Arctic it appeared
to me that 7. nisseni and T. krampi might represent there the endemic Antarctic
species T. carpenteri and similarly R. angelini might represent R. bongraini and
Travistopsis lanceolata the southern hemisphere Travisiopsis coniceps. (It follows
that the appearance of these four species in the Pacific Sub-Arctic was anticipated.)
Only Rhynchonerella angelini, however, occurred in sufficiently large numbers there
to lend credence to this suggestion, though Ty. lanceolata has been found there, but
not in sufficient numbers to substantiate any conclusions at present which must
await further collections. Not only was 7. nissenz not present in the Sub-Arctic,
but 7. krampi was not present in any of the samples I examined from the North
Pacific, and although Dales (1955) reported it from Monterey Bay, he did not find
it in the California Current (Dales, 1957). Disregarding then, for the present, 7.
krampt, it is necessary only to find an explanation for the absence of 7. nisseni
from the Sub-Arctic. This appears to me to be possible through the presence there,
and in the Transition Zone only, of 7. pacifica. This species may be considered as
restricted to the Pacific Sub-Arctic and Transition Zones (whether or not it extends
into high polar waters is not relevant at present) and it may have replaced T. missent
(and T. krampz) in these waters as representative of the endemic antarctic elements—
as much as we have seen Rhynchonerella angelini represents R. bongraini. It appears,
therefore, as if T. nisseni extends into waters of higher latitudes only when there
are no endemic tomopterid elements present. This is the conclusion that can be
drawn from the evidence of distribution in the North Pacific and Atlantic Oceans.
It is at the same time a reminder that animals are not necessarily the slaves of
hydrological characteristics or water masses.
Of the thirty-three species reported here from the North Pacific all except three
are also known from the Atlantic (the three exceptions Tomopteris pacifica, Vanadis
tagensis and Vanadis minuta have been examined above). It is significant that
most of the species making up such a high percentage, 91%, common to both areas,
occur in abundance rather than as scattered isolated elements. Specimens of some
species, however, in particular Tomopteris planktonis, Typhloscolex miillerr and
Vanadis longissima, have characteristics which permit immediate separation of the
Pacific from the Atlantic forms. If these particular specimens have been collected
as isolated catches they could have been described as new species; but if they are
472 THE DISTRIBUTION OF PELAGIC POLYCHAETES
examined in the light of the wide range over which they, and closely related forms,
are known to exist, and in relation to the hydrological boundaries restricting their
distribution, the problem can be viewed less empirically. Thus there is abundant
evidence that the species which vary distinctively in form, range, within their
hydrological limits, throughout the South Pacific into the Indian and Atlantic
Oceans ; in the North Pacific they either meet a hydrological barrier which restricts
their movement northwards, or enter a circulation which can be an effective isolating
mechanism.
Thus, 7. planktonis ranges throughout the southern hemisphere to the North
Pacific, where it is restricted in its distribution at the southern boundary of the
Sub-Arctic Zone. It is thus at the very edge of its range that morphological dif-
ferences occur in some members of the population. Typhloscolex miilleri is very
well known as a cosmopolitan polychaete, but it is only in the Sub-Arctic waters
of the North Pacific that a cold water ecotype has been found. Although abundant
in the Antarctic, no isolating mechanism appears to have been effective to produce
a comparable anti-boreal population. It is apparent that, within the Sub-Arctic
Zone, the necessary isolating circulation has been effective, and it would be of the
greatest interest if the hydrographers could indicate the limits of such a circulation
In the case of 7. miilleri this must be different from that applying to an endemic
sub-arctic species, for in this species the cold water ecotype is restricted but the
other members of the population are not.
The presence of a few specimens of V. longissima in and near the Transition
Zone which can be instantly separated from other members of the species by the
possession of black markings on the eyes suggests that we might be dealing here
with a separate physiological race. At the southern extremity of its distribution
in the southern hemisphere V. Jongissima meets the endemic antarctic V. antarctica.
These two are very similar morphologically and may, in fact be semi-sympatric
species. Such ecological allopatry combined with genetical contiguity probably
represents a stage towards complete separation of the species. The physiological
race (?) here reported from the North Pacific may be an earlier step in this process.
McGowan (1960) has examined the distribution of the aberrant planktonic worm
Poeobius meseves Heath, in the North Pacific Ocean. The systematic relationships
of this animal are problematical and I do not intend to comment here on whether
or not it is a polychaete ; it may be noted, however, that McGowan found P. meseres
mainly in the Sub-Arctic and Transition Zones. A few specimens he found to the
south of the latter region he considered non-endemic, having been carried in from
the north.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 473
APPENDIX I
The actual number of specimens collected at each station is recorded here. When
only a fraction of a sample was examined this is indicated and allowance made in
the column headed ‘“‘ Volume of water filtered, m*”’.
TABLE I
Stns. in the Sub-Tropical and Transition Zones
TRANS-PACIFIC EXPEDITION : . Stns. r to 18.
Stns. 51 to 60.
Stns. 70, 74 to 77, 79 to 143.
NoRTHERN HOLIDAY EXPEDITION : . Stns. 2 to 18.
Stns. 44 to 66.
CHINOOK EXPEDITION : : : . Stns. 1 to 5.
Stns. 7 to 9.
P.O.F.1. Hugh M. Smith, CruIsE No. 30 =~. ~=Stns. 26 to 32.
Stns. 44 to 79.
Stns. 87 to I02.
TABLE II
Stns. in the Sub-Arctic Zone
TRANS-PACIFIC EXPEDITION 5 F . Stns. 19 to 50.
Stns. 61 to 69, 71 to 73, 78.
NorTHERN HoLipAy EXPEDITION é . Stns. 19 to 40.
CHINOOK EXPEDITION : : : . Stn. 6.
P.O.F.I. Hugh M. Smith, CRuIsE No. 30. =‘ Stns. 37.
Stns. 80 to 86.
TABLE III
Dept. of Oceanography, University of Washington, Seattle,
Washington, Collections
CruIsE BB—199——MWT : 50 records.
CRUISE BB-202—MWT : 3 records.
PELAGIC POLYCHAETES
THE DISTRIBUTION OF
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£8 (S218 Gece
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Latitude Date Depth | filtered Se ee tm Su PS SI
(N.) Longitude (local) (m.) (m3.) Ea IGS Eg BS a Sa Ea
48° 14°2' 153° 20-1’ W. 6. vill. 53 0-129 447 I 23 12
a 5 5 164-282 332 9 10 I 16
49° 29°5' | 154° 56-5’ W. 7- Vill. 53 0-153 451 I 31 37
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ah os 5) 0-294 1,077 5 28 Il
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* Af a 0-270 1,095 | 78 2 12
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54° 00:0/ 170° 03:0’ W. 13. Vili. 53 0-132 524 45 20
” ” | ” | 149-265 175 |, 12 wa 7
| |
53° 59°5' 171° 40-0’ W. 13. Vill. 53 O-145 AS3u| awe 5 4 I
. 5 . | 0-295 852 | 86 I 9
54° 00-0 173° 15°5' W. 14. Vili. 53 | 0-180 262 | 10 3
| ny sy 165-360 166 | 5 8 I 9
| 7 | Be 305-460 277 x oh 8 14
|
535 577 ||) 275.0450 Vy 15. Vill. 53 0-125 433 | I 5
; cr | 1 0-300 472 3 10 6 I
53 sso |) Le 5a a7 Om wh 15. V1. 53 0-105 439 10
; | 130-265 555 38 ii 29 I
|
52° 2973" 176° 09-0’ W. | 15. Vill. 53 O-105 543 2 20 7 8
Pp » | » 115-265 379 4 1
x A | my 300-515 520 | 2 22 2
52° 19-9’ | 176°57°5'W. | 24. vill. 53 0-125 478 4 3 2
» 120-305 333)5)| I 8
|
53° 10-3 177° 59:0’ W. 25. Vill. 53 0-180 469 I 20 II
” » 0 0-320 780 2 a, I
54° 05'5’ | 178° 56-2’ W. 25. Vill. 53 O30 5mn eo I Tee 7
54° 00°09’ 178° 58-7" B. 26. vill. 53 0-165 381 2 14
1» + 0-290 787 | 30 x OF
53° 59-0" 176° 55:0’ E. 27. Vili. 53 0-140 400 14 30 x 167
_ x = 0-290 O14 56 10 xX 104 5
1 Half of the sample examined. :
2 Quarter of the sample examined.
3 Eighth of the sample examined.
- TABLE II.—conid.
ZOOL. 7, 9.
® 1 Plotohelmis tenuis.
<
3
5
= 8
ion Ss
&, S
aes
olume = oS
water > sy
Stn. | Latitude Date Depth: | filtered = §
No. (N.) Longitude (local) (m.) (m3.) Sit
38A2 | 53°59°1’ | 174° 49-0’ E. 28. viii. 53 0-165 107 3
B 6 p 5 145-320 212 77 (2
390A | 54° 03:1’ 172° 28:8’ E. 30. viii. 53 0-180 412
m5 = nm 160-335. 350 Sen:
40A | 53°57:0’ | 171° 10-8’ E. 30. viii. 53 0-170 422 29
B 0 a s 170-340 261 2
c » ® pi 340-510 335
D x Zn - 510-680 340
E m5 Fe 30-31. viii. 53 0-1,020| 620 58 1
4tA | 53° 32:1’ 168° 50:8’ E. 31. vill. 53 0-135 526 8
” » ” 140-290 370 260)
42A | 53° 32:4’ 176° 10:8’ E. I.ix. 53 0-175 750 4
B ” x » 175-350 695 42
Cc ” ” ” 350-525 670 I
E » 2 n 0-1,050] 587 | 21
43A | 53°35°5’ | 173° 42:0'E 1.ix.53 0-155 402 4
B ss a I-2.1x.53 0-325 1,043 LONE aL
44A | 53° 40-8’ | 161° 55-5’E 2.1K. 53 0-170 482 20
B ” Bp » 155-335 3527) 2°
c » Dp rh 320-565 462 2
45A | 52° 23-0’ 163° 15:2’ E. 3.-1X.53 0-35 277
B e Fe i 0-105 498
Cc » zs ” 40-145 259
D BS m2 3 150-300 425 | 54
46A | 51° 13-0’ | 164° 34:3’ E. 4-1X.53 0-170 I,010 19
B ” ” re 170-340 740 4
Cc ” ” » 340-510 720
, Dd » m 3-4-1. 53 0-1,015| 4,165 | 25
474A | 49° 50-1’ | 165° 49-2’E. 5.1x.53 0-20 267 2
=&B ” . 23 0-155 567 | 15
= Cc A x Sy 35-150 166 AOE
.D » no D 160-275 499
48A 48° 46-3’ | 166° 48-1’ E. 5-1x.53 0-25 163
&B 5 50 a 0-100 500 19
t e ” ” 35-115 278 5
»> ” » Z 140-320 475 | 19
J
494 47° 35°7' | 167° 44:8’ E. 6.ix.53 0-170 788 4
B . i x 170-340 60 fig 3
79-34 7
Cc ” ” my 340-510 760
D a c ry 510-680 760
ES Bs O-1,015| 359 I
50A 46° 16-5’ | 168° 52-2’ E. 6.i1x.53 0-145 478 16
: ” X ” 155-355 370 30093
6rA | 45° 15:1’ 158° 20:0’ E. 14.1X.53 0-129 527 15
Bs an 33 a 135-270 | 1,130 5
c ” D2 i 270-446 558 I
2A | 45°57°8’ | 156° 52°5/E. 14.ix.53 0-106 490 3
B ” » 7 0-258 1,086 25
4 1 Rhynchonerella gracilis.
5 One tenth sample examined. ot
Tomopteris not identifiable
1674
28
21
64
One Sagitella kowalewskii at Stn. 50B.
Rhynchonerella angelini
H
Alciopid fragments
Typhloscolex miillevi
co
as)
OO)
19
23
Pelagobia longicivrata
62
45
46
init
21
35
Phalacrophorus pictus
fon)
ied
Maupasia caeca
TABLE II.—contd.
267°
29
39°
Latitude
(N.)
46° 23-5’
2
2 Te)
g & 'S
8 gS rs
fos 3s Sy ae
= = as) $ e =
2 B= o =
Sse See
Ph eS Eh eS %
fay akan a dep
Volume| 3 3 3 8 Hedy aha
water | § $ § 3 SS
Date Depth | filtered| § § 5 2 8 &
Longitude (local) (m.) (m%.) & & = Ro Ses
155° 28:6’ E. 15.1X.53 O-129 545 3 4
” ” 135-270 408 27
” ” 270-374 685 25 ee 30
153° 55°2' E. 15.-1x.53 0-157 436 18 30
» ” 75-318 444 19 23
154° 19:7’ E. 16.1x.53 0-124 500 2 3
” ” 147-340 1,166 4 37
152° 56-8’ E. 17.ix.53 0-168 529 12 20 67
3 Fe 276-506 814 I ri
” ie 0-1,020| 3,810 a 2 red 15
rr ) 0-700 300 ZrO) & 17
151° 52:0’ E. 18.ix.53 0-97 583 9 8
» ” 0-176 1,118 14 4 20
150° 33°2’ E. 18.1x.53 0-103 490 42 8
” ” 132-276 407 28 32
149° 25'7' E. 19.1X.53 O-14t 405 24 1
146° 45:0’ E. 20.i1X.53 0-28 276
” ” 0-132 445 2 7 5
» ” 135-270 444 35 17
145° 29°3’ E. 20.1X.53 o-41 189 2
” D O-115 464 3 6 I
i. ri 153-270 370 16 24 21
143° 51°5'E. 21.ix.53 0-40 352
» O-141 435 8 I
” 0 173-390 1,128 1 I 18
146° or 1’ E. 30.1X.53 o-141 473 3 13
” ” 160-330 370 I 13 2
NORTHERN HoLipAy EXPEDITION
150° 00’ W. 14. Vili. 51 118 1,143 I 15
149° 52’ W. 15. Vili. 51 222 669 2 7
149° 52’ W. 16. vill. 51 205 715 10 9
151° 39’ W. 29. Vili. 51 206 796 9 5
151° 18’ W. 29. Vili. 51 200 847 Si Le 20) 5
150° 53°5' W. 30. vill. 51 188 834 31 2
150° 23’ W. 30. Vili. 51 222 688 29 27 el 27
149° 56’ W. 31. Vili. 51 182 759 22 I
157° 36’ W. 31. Vili. 51 203 751 I I
153° 18’ W. 1.ix. 51 227 693 5
155° 00’ W. T.1x.51 202 665 8 4
7 x Rhynchonerella gracilis.
8 1 Tyvavisiopsis lanceolata.
Pelagobia longicirrata
Ne}
10
36
Phalacrophorus pictus
He
Maupasia caeca
Latitude
(N.)
54° 00°
54° 18”
51° 00’
50° or”
49° o1’
48° 06-5’
47° 05°5'
Rogers |
P.O.F.I. Hugh M.
49° 34’
48° 07’
49° 20’
49° 42’
49° 48’
49° 35’
Longitude
156° 32’ W.
157° 58’ W.
158° 33’ W.
158° 16’ W.
157° 55° W.
157° 27’ W.
157° 16’ W.
a wn wn >
rad
on
rs)
CHINOOK EXPEDITION
178° 36’ W.
179° 58’ W.
164° 55’ W.
165° 00’ W.
162° 25’ W.
159° 40’ W.
157224 WV
29. Vii. 56
31. vii. 55
| 17. viii.55
| 17. Vili. 55
18. Vili. 55
19. Vili. 55
19. Vili. 55
Volume
water
Depth | filtered
(m.) | (m*)
219 668
188 765
182 887
160 1,004
189 788
204 794
214 793
85 565
Smith CrutsE No. 30
145
Tomopteris septentrionalis
35
46
Tomopfteris pacifica
”
Tomopteris not identifiable
10
Rhynchonerella angelini
Alciopid fragments
Typhloscolex mullevi
“
n
37
13
18
Pelagobia longicirrata
i
Phalacrophorus pictus
co
Maupasia caeca
488
THE DISTRIBUTION OF PELAGIC POLYCHAETES
TABLE III.—Collections of the University of Washington, Dept. of
Species collected
(and number of specimens)
Rhynchonerella angelini (1).
Plotohelmis tenuis (3).
Plotohelmis tenuis (1).
Tomopteris septentrionalis (1).
Tomopteris pacifica (1).
Travisiopsis lobifera (1).
Tomopteris pacifica (1).
Tomopteris septentrionalis (1).
Tomopteris elegans (1).
Tomopteris elegans (2).
Rhynchonerella angelini (1).
Rhynchonerella angelini (1).
Rhynchonerella angelini (1).
Rhynchonerella angelini (1).
Rhynchonerella angelini (1).
Rhynchonerella angelini (1).
Rhynchonerella angelini (3).
Naiades cantrainii (1).
Rhynchonerella angelini (4).
Natades cantrainii (1).
Rhynchonerella angelini (2).
Rhynchonerella angelini (1).
Rhynchonerella angelint (3).
Rhynchonerella angelini (1).
Tomopteris elegans (I).
Tomopteris elegans (1).
Travisiopsis lobifera (1).
Tvavisiopsis lobifera (1).
Tomopteris elegans (2).
Tomopteris septentrionalis (1).
Travisiopsis lobifera (1).
Tomopteris septentrionalis (1).
Tomopteris elegans (1).
Vanadis crystallina (1).
Lopadorhynchus uncinatus (1).
Tomopteris elegans (1).
Tomopteris elegans (2).
Rhynchonerella mobii (1).
Lopadorhynchus uncinatus (1).
Vanadis formosa (1).
Rhynchonerella angelini (1).
Naiades cantrainii (1).
Naitades cantrainii (1).
Rhynchonerella angelini (1).
Oceanography
Cruise BB—199—M.W.T.
Position
SSS
N. W. Date
48° 46:8’ 129° 58:8’ 2.vii.58
49° 02°6" 133” 39°5” 4. vii. 58
49° 09°3 134° 57°2 4. vii. 58
49° 23°1 140° 24:8’ 7 .vii.58
49° 36:9 = 142” 450’ 8. vii. 58
49° 48:2" 145° 27:9 9. vii. 58
49° 30-1’ 145° 52°5 9-10. vii. 58
45° 41°5/ 146° 25-4’ 12.vii.58
43° 42:0' 146° 25:0’ 13.Vii.58
PGS fad 145° 20°1’ 14.vii.58
40° 35:8’ 142° 54°5 15.vii.58
39° 35:1’ I4I° 53:0 16. vii. 58
38° 41-0’ 141° O1:0' 16. vii. 58
38° 35-7’ 140° 56:0’ 16. vii. 58
38° 24:0’ 139° 37°1 17.vii.58
38° 45:7’ 138° 08-0 17-18. vii. 58
39° 21-0’ 136° 21-2’ 18. vii. 58
30 2gnL- 136° 1371’ 18. vii. 58
39° 35°5. 135° 28-7’ 18-19. vii. 58
39° 4275’ 135, 03:9 19. vii. 58
B00 447, S45 Sat 19. vii. 58
39° 46-0’ 134° 48-0’ 19. vii. 58
40° IT-0’ 133° 26-6’ 19. vii. 58
40° I1-0’ 133° 26:6’ 19. vii. 58
40° 22’0' 131° 32:0’ . 20.vii.58
39° 58-9 130° 34:5 . 21.vii.58
39° 57:6’ 130° 28-7’ . 21.vii.58
39° 56-3 E30n022-00 21.vii.58
39° 55:0 T30; 17-4" 21.vii.58
38° 38-2’ 125, 48-6’ 23.vii.58
36° 40-0’ 123° 21-0’ 27.vii.58
34° 49:0’ 121° 03°5/ 28.vii.58
33° 44°8’ 125° 01:3’ 3. Vili. 58
33° 34:0" 126° 35°1’ 4-Vili. 58
32° 15-1’ 128° 32:9’ 4-vili. 58
35. 02:5" 130° 08-8’ 6-7 . viii. 58
35° 10-1’ 130° 11-9’ 7 Vili. 58
35 1371’ 130° 12-7’ 7 viii. 58 j
36° 44-3" 130° 51:0" 7-8 .vili.58 {
36° 47°90’ 130° 52:9 8. viii. 58 :
36° 51-8’ 130° 54:3’ 8. vili. 58
37° 03-4 130° 58:5’ 8. vill. 58
39° 19:8’ 131° 48-6’ 8-9. viii. 58
Rhynchonerella angelini (1).
THE DISTRIBUTION OF PELAGIC POLYCHAETES 489
TABLE III.—cont.
Position
HMM. Species collected
St. N. Ww. Date (and number of specimens)
, ° , 283 Rhynchonerella angelini (4).
264 . 39° 24-3 aoe aie eae Naiades Famine (Gy e
266 . 39° 32:0’ TighED SBECY 5 g. viii. 58 CREE PEALE (Cp
Vanadis longissima (2).
268 . 39° 40:0’ 131° 56:3’. g.vili. 58 . Rhynchonerella angelini (7).
5 Hane Er ey Ho nes Vanadis longissima (x).
(a Be eis) es | Rhynchonerella angelini (2).
277 . 42 41-8’ 135° 170° . 10-I1.vili.58 . Rhynchonerella angelini (1).
284 . 45° 10°5’ 139° 27:2. =-«12. viii.58 =. Tomopteris elegans (1).
Cruise BB—202—MWT
Oye 400 52:8" 130 30:0’. 23 .ix.58 . Travisiopsis lobifera (1).
50. 47° 52:1’ 134° 28-2’ . 29 .ix.58 . Tomopteris septentrionalis (1).
71. 47° 56:0’ T2Be 14°32 1.x.58 . Tomopteris septentrionalis (1).
REFERENCES
ApsTEIN, C. 1893. Die Alciopiden der Berliner Zoologischen Sammlung. Arch. Naturgesch.
59 : 141-150, pl. 5.
1900. Die Alciopiden und Tomopteriden der Plankton-Expedition. Ergebnisse Plankton-
Exped. Humboldt Stiftung. Bd. 2 H.b. Kiel and Leipzig : 1-61, pls. and maps 1-14, text-
figs. 1-6.
AUGENER, H. 1929. Beitrage zur Planktonbevélkerung der Weddellsee. Int. Revue d. ges.
Hydrob. u. Hydrogr. 22 (5-6) : 273-312.
Banner, A. H. 1949. A taxonomic study of the Mysidacea and Euphausiacea (Crustacea)
of the North Pacific (Pt. III) Euphausiacea. Trans. Roy. Soc. Canadian Inst. 28 (58) :
2-49.
BenuaAM, W. B. 1927. Polychaeta. Brit. Antarct. (“‘ Terra Nova’’) Exped., 1910. Nat.
Hist. Rep. Zool. (2) 7: 47-182, 6 pls.
BERKELEY, E. 1924. Polychaetous Annelids from the Nanaimo District. 2. Phyllodocidae
to Nereidae. Contr. Canad. Biol. Toronto, N.s. 2 : 287-294, 1 pl.
1930. Polychaetous Annelids from the Nanaimo District. Part 5. Ammocharidae to
Myzostomidae. Ibid., N.s. 6: 65-77, 8 figs.
BERKELEY, E. & BERKELEY, C. 1948. Polychaeta errantia. Canadian Pacific Fauna.
Toronto, 9, 9b (1) : 1-100, 160 figs.
== 1957. On some pelagic polychaeta from the Northeast Pacific north of latitude
40° N. and east of longitude 175° W. Can. J. Zool. 35 : 573-578, 2 figs.
& 1958. Some notes on a collection of Polychaeta from the Northeast Pacific
south of latitude 32° N. Ibid. 36 : 399-407.
& 1960. Some further records of pelagic polychaeta from the Northeast Pacific
north of latitude 40° N. and east of longitude 175° W., together with records of Siphonophora,
Mollusca, and Tunicata from the same region. Ibid. 38 : 787-799.
Bieri, RoBertT. 1959. The distribution of the Planktonic Chaetognatha in the Pacific and
their relation to the Water Masses. Limnology and Oceanography, 4 (1) : 1-28, 26 figs.
BopeEN, Brian, P., JoHnson, Martin W. AND BRINTON EDWARD, 1955. The Euphasiacea
(Crustacea) of the North Pacific. Bull Scripps, (mst. Oceanogr. Univ. Calif. 6, 8, 287-
400, 55 figs.
490 THE DISTRIBUTION OF PELAGIC POLYCHAETES
BRADSHAW, JOHN S. 1959. 196. Ecology of living Planktonic Foraminifera in the North
and Equatorial Pacific Ocean. Contributions from the Cushman Foundation for Foramini-
feral Research, 10, Part 2 : 25-64, 43 figs., 3 pls.
Brinton, EDWARD. 1957. Distribution, faunistics and evolution of Pacific euphausiids.
Ph.D. thesis, in Library of University of California, Scripps Institution of Oceanography,
La Jolla, California.
Buscu, W. 1851. Beobachtungen iiber Anatomie und Entwickelung einiger Wirbellosen
Seethiere. (Berlin, Aug. Hirschwald) : 1-143, 17 pls.
Cain, A. J. 1954. Animal Species and their Evolution. London.
CHAMBERLIN, R. V. 1919. The Annelida Polychaeta. Mem. Mus. Comp. Zool. Harvard,
48 : 1-514, pls. 1-80.
Cuun, C. 1887. Die Pelagische Thierwelt in grésseren Meerestiefer und ihre Beziehunger
zu der oberflachenfauna. Bibliotheca zoologica, Heft 1, 1-66, pl. 111.
CLAPARBDE, E. 1870. Les Annelides Chétopodes du Golfe de Naples. Seconde partie Mém.
Soc. Phys. Genéve, 20, 1 : 365-542, 14 pls.
Costa, A. 1862. Descrizione di alcuni Annellidi del Golfe di Napoli. Ann. Mus. zool. Napoli,
1 : 82-90.
Dates, R. P. 1955. The pelagic polychaetes of Monterey Bay, California. Ann. Mag. nat.
Hist. (12) 8: 434-444, 2 figs.
—— 1957. Pelagic polychaetes of the Pacific Ocean. Bull. Scripps Inst. Oceanogr. 7 : 99-
167, 64 figs.
1960. Pelagic polychaetes from the Malacca Straits and South China Sea. Ann. Mag.
nat. Hist. (13) 2: 481-487, No. 20. August, 1959.
DELLE CurajE, S. 1830. Mem. An. s. vert. Napoli. Tab. pro, 5 and 6: pl. 82.
Enucers, E. 1912. National Antarctic Expedition 1901-1904. Natural History, 6. Zoology
and Botany : 1-60, pls. 1-3.
FauveL, P. 1915. Polychétes pélagiques nouvelles des Campagnes de la Princesse-Alice.
Bull. Inst. Ocean. Monaco, 305 : 1-11, figs. 1-7.
1916. Annélides Polychétes pélagiques provenant des campagnes des yachts Hirondelle
et Princesse-Alice (1885-1910). Rés. Camp. Sci. Monaco, Fasc. 48 : 1-152, 9 pls.
1923. Polychétes errantes. Faune de France, Paris, 5: 1-488, 181 text-figs.
FriepricH, H. 1950, Vorkommen und Verbreitung der pelagischen Polychaeten im Atlan-
tischen Ozean. Auf Grund der Fange der Meteoy Exped. 6. Kieler Meeresforschungen.
Inst. Meeresk. Univ. Kiel, Bd. 7, Heft 1 : 5-23, 6 charts.
GREEFF, R. 1876. Untersuchungen iiber Alciopiden. Leopold-Carolin. d. Akad. Naturfor.
Dresden, Nova Acta, 39 : 33-132, pls. 2-7.
—— 1879. Ueber pelagische Anneliden von der Kiiste der canarischen Inseln. Zetts. Wiss.
zool. Leipzig, 32 : 237-283, pls. 13-15.
GruBE, A. E. 1855. Beschreibung neuer oder wenig bekannter Anneliden. Aych. Naturg.
Berlin, 21 : 63-158, pls. 2-5.
HarpineG, J. P. 1949. The use of probability paper for the graphical analysis of polymodal
frequency distributions. J. Mar. biol. Ass. U.K. 27: 141-153, figs. 1-6.
Harpy, A.C. & GuNTHER, E. R. 1935. The Plankton of the South Georgia Whaling Grounds
and Adjacent Waters, 1926-1927. ‘‘ Discovery ’’ Report, 11 : 1-456.
HartMAN, O. 1956. Polychaetous Annelids erected by Treadwell, 1891-1948, together with
a brief chronology. Bull. Amer. Mus. Nat. Hist. 109, art. 2 : 243-310.
Izuka, A. 1914. On the pelagic Annelids of Japan. Tokyo J. Coll. Sct. 36, Art. 5: 1-14,
1 pl.
KinBERG, J.G.H. 1866. Annulatanova. Oefv. K. Vet. Akad. Férh. Stockholm, 22 : 239-258.
Knox, GrorGeE, A. 1959. Pelagic and Benthic Polychaetes of the Central Arctic Basin.
Geophysical Research Papers No. 63, “‘ Scientific Studies at Fletcher's Ice Island, 1-3, 1952—
1955, 1.
Kroun, A. 1845. Zoologische und anatomische Bemerkungen iiber die Alciopen. Archiv
f. Natur. 11, Jahrg. 1, Bd. 171-184.
THE DISTRIBUTION OF PELAGIC POLYCHAETES 401
LANGERHANS, P. 1880. Die Wurmfauna von Madeira. Zeits. wiss. zool. Leipzig, 33, pt.
2 : 267-316, pls. 14-18.
Levinsen, G. M. R. 1885. Spolia atlantica. Om nogle pelagiske Annulata. Mem. Acad.
R. Kjob. Vidensk. Selsk. Sky. Nat. og Math. 3, No. 2 : 321-344, 1 pl.
McGowan, Joun A. 1960. The relationship of the planktonic worm Poeobius meseres Heath,
to the water masses of the North Pacific. Deep Sea Research, 6 : 125-139, 7 figs.
Monro, C. C. A. 1930. Polychaete Worms. ‘ Discovery ’’ Report, 2 : 1-222, 91 text-figs.
1936. Polychaete Worms. II. Ibid. 12: 59-198, 34 figs.
Moore, J. P. 1908. Some polychaetous annelids of the northern Pacific coast of North
America. Pyvoc. Acad. Nat. Sct. Phila. 60 : 321-364.
Oxupa, S. 1937. Note on two unrecorded pelagic polychaetes from Japan. Annot. Zool.
Japon. 16, 1, 75-76, fig. 1a-c.
—— 1938. Polychaetous Annelids from the vicinity of the Mitsui Institute of Marine
Biology. Japan J. Zool. (1) 8: 75-105, 15 figs.
QuatrREFAGEsS, M. A. 1865. Histoire Naturelle des Annelés Marins et d’eau douce. Anné-
lides et Gephyriens. Paris Libr. Encyl. de Roret. 2, pt. 1 : 1-794, 20 pls.
Reipiscu, J. G. F. 1895. Die pelagischer Phyllodociden und Typhloscoleciden der Plankton-
Expedition. Evgebn. der Plankton-Exped. der Humboldt-Stiftung, 2, He : 1-63.
Rosa, D. 19084. Nouve specie de Tomopteridi. Diagnosi preliminari. Mus. zool. anat.
comp. Torino, Boll. 23, No. 588: 1.
1g08b. Annellidi—I. Tomopteridi. Raccolte Planctoniche fatte dalla R. Nave “ Li-
guria’”’ nel viaggio di circonnavigazione del 1903-1905 sotto il comando di S.A.R. Luigi
di Savoia duca degli Abruzzi. Pubbl. R. Istit. Stud. Sup. Prat. Fische. e. Nat. Firenze,
1, fasc. 5 : 247-327, pl. 12.
SouTHERN, R. tgio. A preliminary note on the Alciopinae, Tomopteridae and Typhloscole-
cidae from the Atlantic adjacent to Ireland. Ann. Mag. Nat. Hist. Lond. 5, 8th ser. :
428-4209.
— git. Polychaeta of the coasts of Ireland. 3. The Alciopinae, Tomopteridae and
Typhloscolecidae. Fish. Iveland Sci. Invest. 3 : 1-35, 3 pls.
STEENSTRUP, J. S. 1849. Tomopteris septentrionalis. Vidensk. Medd. naturh. Foren Kjab :
iv.
St@p-Bowitz, C. 1948. Polychaeta from the ‘‘ Michael Sars’’ North Atlantic Deep-Sea
Exped. 1910. Rep. Sars. N. Atl. Deep-Sea Exped. 5 (8) : 1-01, 51 figs.
1949. Polychétes Pelagiques des expeditions Norvegiennes Antarctiques de la “‘ Nor-
vegia’’ 1927-1928, 1928-1929, et 1930-1931. Det. Norske Videnskaps-Akademi ; Oslo.
Sci. Res. Norwegian Antarctic Expd. No. 31 : 1-25, 9 figs.
1951. Polychétes Pelagiques de 1’Expédition Suédoise Antarctique 1901-1903. Swed.
Antarctic Expd. 4 (7) : 1-14.
SvERDRuP, H. U., Jounson, M. & FLremine, R. 1946. The Oceans: theiy physics, chemistry
and general biology. New York.
TEBBLE, NORMAN. 1960. The distribution of pelagic polychaetes in the South Atlantic Ocean.
“ Discovery ’’ Report, 30 : 161-300, 52 figs.
TREADWELL, A. L. 1906. Polychaetous annelids of the Hawaiian Islands collected by the
steamer ‘‘ Albatross’’ in 1902. Washington, D. C. Bull. U.S. Fish Com. 23 (1903),
3: 1145-1181, 81 figs.
1943. Scientific Results of Cruise VII of the ‘ Carnegie ’’ during 1928-1929 under Com-
mand of Captain J. P. Ault. Bzology, 4, Biol. results of the last Cruise of the ‘‘ Carnegie’’ ,
30-51, pl. 1, figs. 1-46.
Uscuakoy, P. V. 1952. Deep water form Polychaetes from the Pacific Ocean. Exploration
Far-Eastern Oceans U.S.S.R. 3 : 103-112, 7 text-figs. [In Russian.]
1955. The Polychaete Fauna of the Far-Eastern Seas of the U.S.S.R. Tabi. anal.
Faune U.S.S.R. No. 56 : 1-445, 164 figs. [In Russian.]
1957a. Pelagic Polychaeta of the North-Western part of the Pacific. Invest. Fav East
Seas U.S.S.R. 4: 267-290, 4 figs. [In Russian.)
492 THE DISTRIBUTION OF PELAGIC POLYCHAETES
Uscuakovy, P. V. 1957b. On the Polychaeta fauna of Arctic and Antarctic. Zool. Zh. 36:
1659-1672, 7 figs. [In Russian with English summary.]
Vicurer, C, 1886. Etudes sur les animaux inférieurs de la baie d’Alger. Recherches sur les
Annélides pelagiques. Arch. zool. Expéy. Gén. Paris, 4, Ser. 2 : 347-442, pls. 21-27.
WaGneErR, N. 1872. Nouveau groupe d’Annelides. Soc. Nat. St. Petersburg, Trav. (Trudy
Obsch. estest. St. Petersburg), 3 : 344-347, figs. ai. [In Russian.]
WESENBERG-LuND, E. 1939. Pelagic polychaetes of the families Aphroditidae, Phyllodocidae,
Typhloscolecidae and Alciopidae Rep. Danish Oceanographic Expd. 1908-10, to the Medi-
terranean and adjacent seas, II, Biology, 1-46, 29 text-figs, 23 charts.
— 1950. The Polychaeta of West Greenland. Medd. Grenland, 151, No. 2: 1-171, 3 tables,
37 charts.
ADDENDA.
The International Code of Zoological Nomenclature adopted by the XV _ International
Congress of Zoology (1961) was published after this paper was in page proof and it has not
therefore, been possible to incorporate the necessary alterations into the text but they are
listed below—
For Typhloscolex miilleri read
Typhloscolex muelleri—Articles 27 and 32 (c) (i).
For Rhynchonerella petersit read
Rhynchonerella petersi—Article 31.
For Lopadorhynchus krohni read
Lopadorhynchus krohni—Article 31.
25FEB 1962
PSSSENTED.
INDEX TO VOL. 7
The page numbers of the principal references and the new taxonomic names are printed in
Clarendon type.
Note. The paper by A. Myra Keen on the
Vermetidae is indexed on p. 213
acutorostrata, Balaenoptera
22-23, 34-35, 73-74, 110-111, 114; Pl. 7, 50
acutus, Lagenorhynchus 55, 98, 99-100; Pl. 39
albirostris, Lagenorhynchus
17, 28, 54, 66-67, 98, 99-100, 106; Pl. 37, 38
Alciopidae . 387-407, 437-455, 469-472
Allabenchelys ; ny 232,230)
ampullatus, Hyperoodon c ce koxp) HEIL)
angelae, Hypodontolaimus
angelini, Rhynchonerella
400-403, 450, 452, 469, 471
305-309
antarctica, Vanadis 4 5 - 472
antarcticus, Anthus 6 . F 5 Phy
anterides, Sphaerolaimus . F : 313-319
Anthus : 245-280, Pl. 56-61
158-160
385, 437, 439, 469
anurus, Thyropygus
apsteini, Tomopteris
arcticus, Trachipterus
aie 342, 347-351, Pl. 62
arnuxi, Berardius . ‘ lie 8 PME
aterrimus, Gonoamentne - . - 146-149
atribranchus, Dinotopterus 228-2209, 230, 233
bairdi, Berardius . d R , f 41
Balaena
36, 38-39, 77, us 82 ness 86, 102, 103, ITI-114
Balaenidae . 35-39, 114
Balaenoptera
22-23, 34-35, 36, 73-74, 78-79, 86, 103,
110-114, 123-126, 132-135; Pl. 7, 50-53
Balaenopteridae 34-35, 85, 102, 112-114
paluensis, Spirostreptus . . 156-158
Bathyclarias see eee
Berardius. 40-41, 79-80; Pl. 9
berthelotii, Anthus. : a ath)
bidens, Mesoplodon 19, 72- 73: Pisun, 12
blainvillei, Stenodelphis
44-45, 61-63; Pl. 19, 20
bogotensis, Anthus. F : . 286
borealis, Balaenoptera_ . 5 35, 30
borealis, Lissodelphis 60-61, 107-108
borneensis, Sousa 60, 102; Pl. 25
bowringii, Spirostreptus . 144-146
brachyurus, Anthus A 6 a 280, 281
bredanensis, Steno 59-6o, 102, 104; Pl. 24
breviceps, Kogia . : 41-43; Pl. 16
brevirostris, Orcaella - 51-52,95,96; Pl. 32
brevis, Lopadorhynchus 416—417, 463, 465, 469
brydei, Balaenoptera é A 35, 36
caeca, Maupasia
caffer, Anthus
campestris, Anthus
247, 248, 259-260, 276, Pl. 56, 60
cantrainii, Naiades 388-389, 440-441, 469
Caperea 37-38, 77-790, 85, 86, 102, 103; Pl. 5-6
catodon, Physeter . 42-43, 111, 126-130
cavirostris, Ziphius : . 40; Pl. 10
centrurus, Spirostreptus . 167-168-170
Cephalorhynchus 53-54, 97-99, 105, 108; Pl. 36
cervinus, Anthus
255, 270-271, 272, 277, Pl. 58, 61
421-423, 463, 466, 467, 470
- 280-281
chacoensis, Anthus ; 3 » 284,
Challanebes . : 5 : 2239
chavesi, Macristium : 3554 356-370
chloris, Anthus 3 é : . 282
Clariallabes . é 5 : e230)
Clarias 219, 231-239
see also Dinotopteras
Clariidae , 231-240
commersoni, Cephalorhy Fane) 53-54, 97-99
correndera, Anthus : . 284
crassidens, Pseudorca 49-51, 94-96 ; Pl. 29-30
crenatus, Anthus . e : . 282
cristatus, Zu . - 846-351
crystallina, Vanadis "390, 442, 445, 469-470
Ctenothrissidae 363-370
cunningtoni, Dinoptopterus
220-221, 229, 230, 233, 237, 238
curtum, Pedinosoma 423-425, 466, 468, 470
Delphinapteridae . 3 83
Delphinapterus 48, 88, 80, 103; = 15
Delphinidae 49-59, 81, 84, 112; Pl. 29-35
Delphinoidea : 49-61, 78, 80, 92. 102
Delphinus
17-22, 58-59, 71-72, 81, 84, 100-101, 106;
Pl. 46-47
Dinotopterus 217-219-229-241
Dolichallabes. 5 0 . 239
dubia, Travisiopsis sts, 458, 461, 470
dulitianus, Spirostreptus 157, 158
dumerili, Clarias. ¢ 5 co 24549)
498 INDEX
ehrenbaumi, Rhabditis 322, 324, 329-332
elegans, Tomopteris 380-382, 428-434, 469
erythropleurus, Thyropygus . : - 178
Eschrichtidae 5 . 39
Eschrichtius ; 39, 85- ‘86, 102, 103
euphrosyne, Stenella 57-58, too-1o1r ; Pl. 45
euryodon, Dinotopterus . 226, 230, 233, 238
everetti, Spirostreptus 152-154
feae, Spirostreptus A é 172-175
Feresa 53, ont 97, 105, 107; Pl. 35
filicibarbis, Mineroptene 226-227, 230, 233, 238
formosa, Vanadis 389-390, 442, 447, 460
foveolatus, Dinotopterus 226, 230, 233, 237, 238
furcatus, Anthus : é : 283-284
gangetica, Platanista
geoffrensis, Inia
45-47, 61, 63— aes 90-92), Plazm 22
gestri, Spirostreptus . - 174-177
gigas, Dinotopterus
43-46, 132; Pl. 17-
221, 223, 227-228, 230, 233
Globicephala
17, 27, 30, 52, 67-68, 95-97, 105-113, 118;
Pl. frontis., 33, 34, 49
godlewski, Anthus
247, 258-259, 276; Pl. 56, 60
gracilis, Rhynchonerella
396-397, 446, 450, 451, 469-470
Grampus
17, 24, 56-57, 68-70, 100, 101, 106, 108;
Pl, 41, 42
griseus, Grampus
17, 24, 56-57, 68-70; Pl. 41-42
gustavi, Anthus
250, 254, 271-272, 277; Pl. 58, 61
gutturalis, Anthus . 282-283
Gymnallabes ; : . : 5 etl
Harpagopheridae 143-179
heavisidei, Cephalorhy ait
53-54, 97-98 ; Pl. 36
hellmayri, Anthus . : : é . 286
Heterobranchus . ; 7 235, 2360, 239
Heteropneustes ¢ : : i 234
hodgsoni, Anthus . 268, 277; Fl. 58, 61
hosei, Spirostreptus 154-156
Hyperoodon . ; ; 2 = SQ Pls
Hypodontolaimus . m 3 : 305-309
ilesi, Dinotopterus .
Inia
45-47, 61, 63-64, 80, 90-92, 104; Pl. 21, 22
Iniomi ; 367
intermedia, iRogesa, 53, oe 97; Pl 35
Iospilinae 415, 425-428, 466-460, 470
jacksoni, Dinotopterus 222-223, 230, 233
jallae, Dinotopterus : : F 2008
janetae, Trissonchulus’ . 5 2 294-300
Kogia 41-43, 77-79, 88, 89, 103; Pl. 16
kowalewskii, Sagitella
410, 454, 457, 458, 469-470
Krohnia 405-407, 454, 455, 469
krohnii, Lopadorhynchus
418-410, 463, 464, 469
Lagenorhynchus
17, 28, 54-56, 58, 66-67, 98, 99-100, 106,
108; Pl. 37-40
lanceolata, Travisiopsis 413, 458, 461, 470-471
lazera, Clarias =5 2383237.
lepidota, Krohnia . "405-407, 454, 455, 469
leucas, Delphinapterus . 48, 80-89; Pl. 15
leucophrys, Anthus 262-266, 277; Pl. 57, 60
levinseni, Travisiopsis 412-413, 458, 461, 470
ligulata, Tomopteris 384, 437, ee 469
lineiventris, Anthus 280
Lipotes - 46-47, 90, 92, oe: “PL 23
Lissodelphinae < 5 - 108
Lissodelphis . 4 60-61, 104, 107-108
lobifera, Travisiopsis 411-412, 458, 459, 460
longibarbis, Dinotopterus 225, 230, 233, 237
longicirrata, Pelagobia 419-420, 460, 462, 470
longissima, Vanadis 392-394, 442, 444, 471-472
Lopadorhynchinae 415-425, 460-467, 469
Lopadorhynchus . 416-419, 463, 464, 465, 469
loweae, Dinotopterus 223-224, 231, 233, 237
lutescens, Anthus . . ‘ 9 . 284
Macristium é 355-356-370
marginata, Gane : . 87-38; Pl. 5, 6
marina, Rhabditis . : 321-320
Maupasia . 421-423, 463, 466, 467, 470
Megaptera 34-35, 36, 109-116; Pl. 48
melaena, Globicephala
17, 27, 30, 52, 67-68, 95-97, 109-113, 118 ;
Pl. frontis., 33, 34, 49
melindae, Anthus 281-252
mellandi, Clarias . é C 2 a pe5}s)
Mesonchium 4 5 C = 301-305
Mesoplodon 19, 22, 72-73, 79-80; Pl. 11, 12
microphthalmus, Dolichallabes < oe Be)
minuta, Vanadis 390-391, 440-443, 469-472
mobil, Rhynchonerella 396-398, 446, 449, 469
monoceros, Monodon
47-48, 112-113; Pl. 13, 14
Monodon 47-48, 87, 103, 112-113; Pl. 13, 14
Monodontidae : 81, 107
Monodontoidea : 47-48, 87-890
mortiauxi, Tanganikallabes : zag)
mossambicus, Clarias 232, 236, 237
miilleri, Typhloscolex gee 454, 450, 470-472
musculus, Balaenoptera 5 35, 30
Mysticeti
34-39, 73-74, 77-79, 81, 82, 85-87, 111, 123
131
mysticetus, Balaena 36, 38-39, 111-114
INDEX 499
Naiades 388, 440-441, 469
nattereri, Anthus 285
Neomeris 49, on 94, 104: ‘PL 28
nilghirensis, Anthus . - 256, 278
nini, Mesonchium . 301-305
nisseni, Tomopteris "384, 437, 439, 469, 471
novaeangliae, Megaptera
35, 36, tog-116; Pl. 48
novaeseelandiae, Anthus
247-248, 251, 253-258, 262, 275-276;
Pl. 56, 57, 60
nyasensis, Dinotopterus . 221, 230, 233
oatesii, Spirostreptus
obscurus, Lagenorhynchus
55-56, 58, 98, 99-100, 106; Pl. 40
160-163
Odontoceti
39-61, 61-73, 79-80, III, 122-123, 131
omercooperi, Polygastrophora . 309-313
orca, Orcinus. 50-51, 95, 96; Pl. 31
Orcaella 51-52, 95, 96, 105, 107; Pl. 32
Orcinae : 94-97, 107
Orcinus 50— 51, a5. 96, 105; Pl. 31
pacifica, Tomopteris 385-387, 434-437, 470, 471
pallidiventris, Anthus 262-266, 277; Pl. 57, 60
patricii, Spirostreptus 165, 166-168
Pedinosoma . 3 423-425, 466, 468, 470
Pellioditis see Rhabditis
Pelagobia - 419-420, 460, 462, 470
pelopus, Anthus, see roseatus, Anthus
petersii, Rhynchonerella 398-400, 446, 448, 460
petricola, Clariallabes —. - 239
Phalacrophorus . 425-428, 465, 468, 469, 470
Phocaena
12, 17, 49, 64-65, 92-94, 104, 112-113, 116;
Ph 0, 20, 2
Phocaenidae . : 49, 84, 92, 107
phocaenoides, Neomeris . 49, 93-94; Pl. 28
Phyllodocidae 415-428, 460-469, 470
physalus, Balaenoptera
35-36, 110-111, 123-126, 132-135; Pl.50-53
Physeter
42-43, 78, 79, 88, 89, 103, 111, 126-130
Physeteroidea 5 41-43, 79-89, 107
Physeteridae 30, 81, 83, 107, 126-127
pictus, Phalacrophorus
426, 427, 466, 468, 469, 470
planktonis, Tomopteris 383, 434, 436, 469-472
Platanista
43-46, 77-83-84, 90-92, 104, 106, 132;
Pl. 17, 18
Platanistoidea 43-47, 89-92
Plotohelmis 403— Bos, 450, 453, 454, 469-470
plumbea, Sousa 60, 102; Pl. 25
Polygastrophora_ . 2 309-313
pratensis, Anthus . 266, 277: Pl. 58, 61
proboscidens, Rhynchoproctus 169, 170-171
Pseudorca 49-51, 94-96, 105, 107; Pl. 29, 30
Rhabditis 320-333
Rhynchonerella 395-403, 440- 452, 409-471
Rhynchoproctus 169-171
richardi, Anthus 253-254
roseatus, Anthus 269-270, 277 ; Pl. 58, 61
rotundifrons, Dinotopterus
226, 230, 233, 237, 238
rubrocinctus, Thyropygus 150-152
Saccobranchus 5 . 234
Sagitella < 410, 454, 457; 458, 409-470
septentrionalis, Tomopteris
382-353, 430-434, 470
similis, Anthus
256, 258, 261-262, 276; Pl. 56, 57, 60
sokokensis, Anthus 281
Sousa . : 60, 93, 102, aye 107: ‘PL 25
Sphaerolaimus : 313-319
spinoletta, Anthus
250, 270, 272-275, 278; Pl. 59, 61
Spirostreptus. 144-148, 152-158, 160-178
spragueii, Anthus .- 5 283-284
Stenella 57-58, 100, 101, 106; Pl. 45
Stenidae p n 0 7 “ a &8
Steno . 5 59-60, 102, 104, 107; Pl. 24
Stenodelphis
44-45, 50, 61-63, 80, go, 91; Pl. 19, 20
stenorhynchus, Spirostreptus . 176-178
sylvanus, Anthus 256, 279
tagensis, Vanadis
re ae 447, 409-470
Tanganikallabes’ . o EO)
tavoiensis, Gpirostee piel 163- 164-166
tenuis, Plotohelmis
403-405, 450, 453, 454, 409-470
thioni, Gymnallabes : - 239
Thyropygus . 148-152, 158= 160, 178
Tomopteris 379-387, 428-439, 469-472
Trachipteridac : 2 : - 837-351
Trachipterus . 337-338-351; Pl. 62
trachypterus, Trachipterus
338-842-351 ; Pl. 62
pee. 458-461, 469-471
3 294-300-301
Travisiopsis
Trissonchulus
trivialis, Anthus
250, 258, 267-2608, 277; Pl. 58, 61
truncatus, Tursiops
17, 25, 57, 70-71, 100-101, 134; Pl. 43, 44
Tursiops
17, 25, 07, 10-71, 100, Lor, 106, 134; Pl. 43,
407-415, 454-460, 469-471
407-409, 454, 456, 470-472
44
Typhloscolecidae
Typhloscolex
uncinatus, Lopadorhynchus 417, 463, 465, 469
uniformis, Phalacrophorus
426-428, 466, 468, 469, 470
500 INDEX
vaalensis, Anthus . 262-206, 277; Pl. 57, 60
Vanadis 3 389-395, 440-447, 469-472
Vermetidae . a 183-213
vexillifer, Lipotes * 46- as lop evs, ney Teil #25}
vittatus, Spirostreptus . A - 171-173
weberi, Thyropygus : : » 148-150
worthingtoni, Dinotopterus 220, 227, 230, 233
Xenoclarias
Ziphiidae
Ziphioidea
Ziphius
Zu
238
22, 79, 82-83, 102
39-41, 78, 81, 87
40, ges 103; Pl. 10
345-351
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