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Full text of "Manual of conchology, structural and systematic, with illustrations of the species"

BERKELEY 

LIBRARY ' 



UNIVERSITY OF 
CALIFORNIA 









MANUAL 



OF 



ONCHOLOGY; 



STRUCTURAL AND SYSTEMATIC. 



WITTl ILLUSTRATIONS OF THE SPECIES. 



BY GEORGE W. TRYON, JR. 

CONTINUATION BY 

HENRY A. PILSBRY, 

CONSERVATOR OF THE CONCHOLOGICAL SECTION OF THE ACADEMY OF 
N<.TUHAL SCIENCES OF PHILADELPHIA. 



Vol. XI V\ 

POLYPLACOPHORA, 
(Chitons.} 

LEPIDOPLEURID^, ISCHNOCHITONID^, CHITONID^, MOPALIID^. 



PHILADELPHIA : 
Published by Concliolop-ical Section, 

ACADEMY OF NATURAL SCIENCES, 

OF PHILADELPHIA. 

1892. 





SCIENCES 
LIBRARY 



" The only possible check to the progress of Science is that the works on it are 
becoming too voluminous; it is becoming scholastic: life will be too short to learn it, 
and no time will be left for discoveries." GROVE. 

" The Truth must be told, whoever may be hurt by it. There is no doubt that some 
writers endeavor to conceal in a fog of mere words the want of clear and well-defined 
ideas, as well as of that critical knowledge which is indispensable in Natural History ; 
and it is out of this that has arisen that legion of phantoms which so effectually 
bewilder the inexperienced." Anon. Gardener's Chronicle, Dec., 1854. 



PREFACE. 



The present volume contains a monograph of the important and 
extensive Order Polyplacopliora, commonly known as Chitons. 
Although represented by many species in all seas, the Chitons have 
been much neglected by Conchologists. This may be due to the 
fact that their characters are not generally understood, or even seen 
in ordinary cabinet specimens ; and again, no illustrated work treat- 
ing the group scientifically has hitherto been produced. Certain it 
is, that if the serious study of this group be once begun, its attrac- 
tions will be found to equal or excel those of any other families. 
The numberless modifications of form, the beautiful adaptation of 
structure to life-habits and station, the marvelous parallel develop- 
ments, producing almost identical structures in totally diverse- 
phyla, all distinguish the Polyplacophora as preeminently interest- 
ing among mollusks. 

The author begs those who may use this work to begin by taking 
apart one specimen of each species to be studied ; then find the genus- 
by the Key on page xxviii. After a certain amount of practice the 
genus may be ascertained by removing valves vii and viii only ; but 
guessing it from the external features is in most cases uncertain 
and unscientific. As a rule, Chitons tell no secrets to those who 
will not take the trouble to disarticulate them. 

It is hoped that describers of new species will hereafter state the 
generic characters of their novelties. It is as rational to describe a 
bivalve without examining its hinge-teeth, as to notice the outside 
only of a Chiton. 

The synonymy is believed to be practically exhaustive, except 
that useless references to mere lists giving no new information are 
omitted. 

Attention should here be directed to the new theories of the origin 
of important structures of shell and girdle, given on pp. ix, xii ; to 
the original system of classification (p. xxiii), and the phytogenies 
(pp. xxvii, xxviii). 

The new species described herein which are credited to Carpenter 
rest upon his types when the descriptions are quoted from his Ms. (as 
in the case of Callochiton princeps, p. 50). In cases where I have 



given original descriptions of new species, whether the specific names 
be Carpenter's or my own, the types are understood to be the speci- 
mens described by me, in the collection of the Academy ; wherever 
and whatever the original Carpenteriau specimens may be. A case 
in point is Ischnochiton acrior, p. 60, and I. conspicuus, p. 63. It is 
only by this expedient that confusion can be avoided in cases of real 
or fancied wrong identification, on my part, of Carpenter's Ms. 
species. 

Many new species not illustrated in the body of the work are 
figured from the types in the Appendix. The Appendix should 
always be consulted when a species is not found elsewhere, as forms 
of unknown generic position have been included therein. 

The grateful task remains of acknowledging assistance from 
scientific friends and institutions. Through the intervention of DR. 
WM. H. DALL, Honorary Curator of the Department of Mollusks, 
U. S. National Museum, the writer has received from S. P. LANG- 
LEY, Secretary of the Smithsonian Institution, the drawings and 
MS. prepared by the lamented PHILIP P. CARPENTER upon this 
group, a work of priceless value, embodying the results of many 
years study of the subject. Throughout the text of this volume will be 
found extracts from this MS. ; such quotations in every case being 
carefully credited. For the loan of a large number of type spec- 
imens from the Smithsonian collections, the writer is indebted to the 
continued kindness of DR. DALL. To J. F. WHITEAVES of the 
Canada Geological Survey, PROF. WHITFIELD of the American 
Museum of Natural History, New York City, PROFESSOR F. W. 
HUTTON of Christchurch, New Zealand, and many other con- 
chologists, the thanks of the author are due for specimens presented 
or loaned. 

H. A. P. 



MANUAL OF CONCHOLOGY. 



MONOGRAPH OF THE POLYPLACOPHORA. 



Class AMPHINEURA. 

Bilaterally symmetrical mollusks, the nervous system consisting 
of four (two lateral and two ventral or pedal) parallel cords, meeting 
in a cerebral ganglion ; other ganglia feebly or not developed. 
Anus posterior and median ; head without tentacles or eyes. 

The Amphineura or Isopleura constitute one of the five primary 
divisions or Classes into which the Mollusk phylum divides ; and it 
is, in many respects, the most primitive of all. This class has been 
by most authors considered a sub-class or order of Gastropoda; but 
the fact should be distinctly recognized that the characters common 
to Gastropoda and Amphineura are either features possessed by the 
(hypothetical) primitive rnollusk, or are peculiarities evolved in 
response to similar habits of life. The Patellidce among Gastropoda 
have been repeatedly compared to the Amphineurous family 
Chitonidce ; but the branchial cordon of Patella is in no way homo- 
logous with the gills (or ctenidia) of Chiton, and the nervous and 
digestive systems are profoundly different. 

The class Amphineura is divisible into two Orders : 

Order I. POLYPLACOPHORA. Dorsal surface bearing eight imbri- 
cating shelly plates ; head divided from the body ; gills numerous, 
occupying a lateral groove on each side between the foot and the 
encircling mantle ; foot adapted to creeping ; genital organs and 
nephridia paired ; sexes distinct ; radula well developed. 

Order II. APLACOPHORA. Body subcylindrical or vermiform, 
without shelly plates or valves; foot rudimentary or aborted, the 
mantle cavity being reduced to a ventral groove terminating in a 
posterior cloaca containing the rudimentary gills, and the outlets of 
anus and nephridia. 

(v) 



VI 



POLYPLACOPHORA. 



Order POLYPLACOPHORA Blainville. 

The further division of this order into families and genera will 
be found on page xxiv. 

The following notes on the morphology of Chitons are mainly 
restricted to features important from a phylogenetic or taxonomic 
standpoint ; the primary object of this work being, of course, the 
establishment of a natural system of the Order. 

THE SHELL. 

The shell in Chitons consists of eight imbricating pieces or valves, 
bound together by a leathery girdle of connective tissue. The valves, 
when freed of the girdle by soaking a few hours in water, are seen to 
be of three forms: the anterior, (or "head valve") semicircular in 
outline its apex elevated ; the intermediate (sometimes called 
" central " or " median ") valves, squarish in shape, and the poste- 
rior or " tail valve," which is like the intermediate valves with the 
addition of a sloping surface behind the apex or mucro. In struct- 
ure, the valves are composed of two layers, generally quite different in 
color and texture; an outer layer, called by Middendorff the tegmen- 
tum, and an inner, the articulamentum. 

THE SURFACE OF THE VALVES (teg mentum) is divided in nearly 
all Chitons into clearly defined or indistinct areas. The interme- 

diate valves (fig. 1) are divided into 
lateral areas and a central area; the 
latter being subdivided into a dorsal or 
jugal tract, extending along the ridge 
of the valve, and two pleura or pleural 
tracts, occupying the side-slopes in 
front of the diagonal line or rib. In 
some forms (fig. 2) the diagonal line is 
obliterated, the lateral areas and the 
pleural tracts being united into a single 
uniformly sculptured expanse, the 
Fig. 1. Intermediate (fourth) latero-pleural area, on each side; the 
valve of hchnochiton mertcmii, 1, dorsal or jugal area remaining distinct. 
2, 3, central area (subdivided into ^^ modificat ion is characteristic of 
1 jugal tract, and 2, 3, pleural i-m,-,. 

tracts) ; 4, 5, lateral areas. One g reat P h 7 lum of Chitons. As a rule 

Fig. 2. Intermediate valve of tne head-valve is sculptured all over 
Acanthochites dcfilippii, showing I. like the lateral areas. The posterior 
PL, insertion plate, and S. Z., valve (fig. 4) is divided into a central 
sutural laminae. and a poster i or area ; the former being 

precisely similar to the area so named in the intermediate valves 




POLYPLACOPHORA. 



Vll 



and the latter corresponding closely in sculpture to the lateral areas* 
In some genera the mucro is near or at the posterior edge of the 
valve, and the posterior area is then reduced to a narrow tract, or 
altogether absent (see pi. 52, figs. 17, 18). In position, the mucro 
may be either anterior (pi. 30, fig. 23), or median (pi. 17, fig. 22) or 
posterior (pi. 52, figs. 22, 23) ; and it may be either elevated (pi. 36, 
fig. 94), or depressed (pi. 39, fig. 41), the last being sometimes called 
a flat or planate mucro. 

THE INNER LAYER OF THE VALVES (articulamentum) is larger 
than the tegmentum, projecting in front in two lobes called sutural 
lamince, which are separated by a median bay, ihejugal sinus. At 

the sides of the intermediate valves, 
and around the semicircle of the end 
1 valves, most Chitons have projecting 
^ plates called insertion plates, to which 
a the girdle is attached. These are 
* commonly cut into teeth by transverse 
slits. From the slits to the apex of 
each valve inside, run slight grooves 
and rows of pores, known as slit-rays; 
often they are obliterated, but in forms 
having a highly developed system of 
sense-organs in the tegmentum, the 




Figs. 3, 4. Intermediate and P 3reS f the slit ' ra y s Se rve as nerve 
posterior valves of hchnochiton foramina. The teeth are sometimes 
conspicuus. finely cut or crenulated, (technically 

" pectinated ") between the slits ; and in some forms the edges of the 
teeth are thickened outside, or " propped." Fig. 3 represents the 
interior of the fourth valve of an Ischnochiton, showing the slits, 
teeth, insertion plates, etc. 

The tegmentum is essentially cuticular in nature. It consists of 
a chitinous foundation substance, impregnated with salts of lime. 
It is perforated at the surface by a multitude of minute, definitely 
Arranged pores of two sizes, called by Moseley, the larger megalopores, 
the smaller micropores (see pi. 52, fig. 28, showing two megalopores 
and many micropores). Each megalopore leads into a cylindrical 
chamber which is continued below into a wide canal, which as it 
penetrates deeper toward the plane of junction of tegmentum and 
articulamentum, curves outward toward the girdle-margin of the 
former. On reaching the plane of junction it joins a plexus of wide 



Vlll POLYPLACOPHORA. 

main canals which ramify horizontally in this plane, and find open- 
ing from the valves at the eaves, or outer bases of the teeth and 
anterior sinus. From the sides of the megalopore chambers or from 
the deeper plexus of canals, are given off fine canals which perforate 
the tegmentum vertically and join the bases of the micropore cavities. 
All of these canals are occupied by fibrous and nerve tissues con- 
tinued in from the girdle and interior. From these ramifications are 
given off branches to each megalopore canal, in the superficial 
chamber of which they expand into obconic knobs of highly refract- 
ing tissue, sensory in function, and in all probability tactile. These 
knobs are called by Moseley, megalcesthetes ; they are capable of being 
somewhat protruded from the mouths of the pores. The micro- 
pores hold exactly similar but smaller sense-organs, the micrcesthetes. 
These structures are found in probably all Chitons ; but in certain 
genera they are subobsolete. In others some of the megalsesthetes 
have become transformed into eyes. These are connected with the 
network of soft tissues, and occupy pear-shaped cavities like the true 
megabesthetes. On one side the bulb of the pear, more or less near its 
extremity, is closely applied to the outer surface of the tegmentum, 
and here its wall is pierced by a circular aperture, the pupil-like 
opening. This opening covered by the cornea, the periphery of 
which extends to a considerable distance beyond its margin all 
round. 

The cornea is a concavo-convex, watch glass-shaped lamina, trans-' 
parent, and calcareous in structure, being continuous all around with 
the superficial calcareous layer of the tegmentum. "The pear- 
shaped cavity of the eye in the tegmentum is lined by a dark brown 
pigmented membrane of a stiff and apparently somewhat chitinous 
texture, which forms the eye capsule. This capsular membrane 
exactly follows the shape of the eye cavity, except near the surface 
of the tegmentum, where its margin curves inward beneath the 
cornea, forming a sort of iris and bounding the circular pupil, 
which is of less diameter than the cornea. The aperture of the pupil 
is occupied by the front surface of the lens. The lens is perfectly 
transparent and hyaline, arid strongly biconvex. It is filled in 
behind the iris aperture. It is composed of soft tissue and dissolves 
in strong acetic acid gradually and completely, showing a fibrous dis- 
tinct structure in the process. There is a space between the front 
surface of the lens and the cornea. 

" Within the pigmented tubular prolongation of tfce eye capsule 



POLYPLACOPHORA. IX 

the numerous fine fibres composing the optic nerve become separated 
from one another and loose. Immediately underneath the retina the 
fibres become still more widely separated, forming an expansion of 
fibres. The retina is formed on the type of that of Helix, and not, 
as might have been expected, on that of the dorsal eyes of Onchid- 
ium or the eyes of Pecten. The fibres of the optic nerve do not pass 
in front of the layer of rods to be distributed to them from in front, 
but are directed to the rods directly from behind. The retina pre- 
sents a single layer of short but extremely well defined rods, the 
extremities of which are directed toward the light. The rods when 
viewed from the surface of the layer they compose are seen to be 
hexagonal or pentagonal in .outline, and each contains a nucleus. 
They form a layer which is concave toward the lens, there being a 
space between the hind surface of the lens and the concave face of 
the layer." 

Two eyes from the shell of Enoplochiton (x 40) are shown on pi. 
52, fig. 27. On pi. 51, fig. 3 is seen an eye of Schizochiton magnified 
200 diameters, showing outside the pigmented eye-capsule, seen partly 
through the superficial layers of the tegmentum, inside of which is 
the cornea, and the lens, seen through the cornea. 

The arrangement of the eyes varies in different genera, as will be 
seen by reference to the systematic descriptions. Eyes are present 
in but one family of Chitons, the Chitonldce; and in this group they 
are found in all but two genera. In these two the megalsesthetes are 
larger and more regularly developed than in any Chitons of other 
families. This high development of sense organs is associated with 
the most complex system of insertion-plates, the completest form of 
girdle-armor and of gills to be found in the Polyplacophora. The 
family Chitonidce therefore, easily ranks as the consummation of 
Chiton development. Tonicia or Acanthopleura represent the utmost 
height yet attained by the great Amphineurous branch of mollusk 
life. 

Theory of the origin of valve-structures. Any rational theory of the 
development of a structure must rest upon a knowledge of the rela- 
tions of that structure' to the organism possessing it and to the 
external world. In discussing the genesis of the insertion-plates of 
Chitons we must therefore bear in mind (1) that the function of 
these plates is to bind the valves firmly to the girdle, and (2) that 
the entire force of all impacts on the valves is transmitted to these 
plates, which are separated from the solid surface supporting the 



X POLYPLACOPHORA. 

animal by a thin pad of girdle. It is to the direct effect of impacts 
and strains continually brought to bear upon the growing edges of 
these plates, that their development is due, in precisely the same 
manner that the enlarged joints of a laborer's hand are the result of 
the impacts and strains to which they have been subjected. All 
Chitons which live in situations exposed to the buffeting of the surf, 
possess highly-developed insertion-plates, which are, moreover, in 
nearly every cases, conspicuously corrugated for the more effective 
grasp of the girdle. Examples are the groups Enoplochiton and 
Mesotomura on the west coast of South America, Acanthopleura in 
the West Indies and elsewhere, Liolophura in Australia and Japan, 
all remarkable for the great development of strong, rough insertion 
plates, and equally for the very exposed situations in which they 
live, often subjected to the full force of the surf. It is, of course, the 
belief of the writer that characters acquired by the action of natural 
forces, acting upon many generations, become hereditary ; but in 
this case "natural selection " no doubt has had a certain consider- 
able effect, although the process has, I believe, been mainly one of 
selection from definite variations produced by the mechanical causes 
described above, not selection from indefinite variations in all direc- 
tions. 

On the other hand, forms living in less exposed stations, such as 
beneath stones at or below low water, have thin, smooth insertion 
plates (Ischnochiton, etc) ; and at great depths, where the motion of 
the water and its power of transporting pebbles or stones is reduced 
to a minimum, and where therefore the valves of the Chitons are not 
subject to impacts or strains from without, the species are found to 
be entirely without insertion plates. This excessively weak organiza- 
tion has been transmitted unchanged from the Palaeozoic Chitons, 
all of which lacked insertion-plates ; and it is a significant fact that 
this antique type has been able to exist to the present time only in 
deep water, where the forces which I believe to have moulded the 
modern Chitons do not act, and where competition in the life-struggle 
is less severe than in the shallows. 

In this connection the case of Plaxiphora (Placophoroptis) atlan- 
tica should be cited. This species was dredged off New England in 
122 to 640 fms., depths beyond the limit of the penetration of light, 
and of course far beyond the reach of appreciable water movement, 
either by currents or surface disturbances. The conditions therefore 
demand no stronger apparatus for the attachment of the valves to 



POLYPLACOPHORA. XI 

the girdle than is possessed by Lepidopleurus ; and in fact we find 
that its insertion plates are reduced to very short stumps. The 
anterior " teeth " are small, low, unevenly notched, and not nearly 
as long as the overhanging eaves. It is only necessary to point out 
that the genus Plaxiphora, the nearest ally of Placophoropsis, is 
remarkable for the length of its strong, regularly slit insertion 
plates. The same is true of the entire family Mopaliidw, to which 
these genera belong. In Plaeophoropsis atlantica we have, there- 
fore, a member of a family of littoral Chitons, which by descent into 
the abyssal region has partially lost by retrogressive development 
through disuse the characters originally evolved to fit the ancestral 
forms for existence in the littoral zone. Further deep sea researches 
will probably reveal other cases of degeneration along the lines here 
indicated ; and it is not impossible that forms as destitute of insertion 
plates as the genus Lepidopleurus have been produced from higher 
types by retrogessive evolution ; but there is at present no evidence 
of the existence of such forms. 

THE GIRDLE. 

This organ variously called ligament, zone, or girdle, is a band 
of connective and muscular tissues extending around the valves, the 
edges of which are imbedded in it. The surface of the girdle is 
variously clothed with scales, spines, haiis or spicules, or is naked. 
The armor, whether of spines, scales or hairs, consists of a chiti- 
nous foundation more or less infiltrated with lime. The girdle- 
appendages vary greatly in development among closely allied 
species ; but the general type of covering is a moderately constant 
generic character. In some forms the girdle encroaches upon or 
entirely covers the valves. In some genera having a posterior 
sinus in the tail-valve, the girdle has a corresponding sinus or slit ; 
in others it has no sinus, but in life is always curved upward into a 
posterior conduit, serving for an outlet for the anus and gills. 

In some forms having hairy or spiculose girdles, the hairs or 
spicules are gathered into tufts or groups at the sutures (i. e. lateral 
points of junction between valves), and around the anterior valve ; 
issuing from pits or pores at those places (see pi. 5, fig. 97). In 
their incipient stage, these sutural tufts are merely the gathering 
together of two or several of the ordinary surface hairs; in their 
full development they are dense clusters of long spicules ; and in 
their decadence only a small pit or pore remains. The presence of 




Xll POLYPLACOPHORA. 

pores or tufts has been considered by systematists a character of 
great value ; but not with justice. The fact is that at least three 
times in the development of Chitons has this feature appeared 
independently ; first in the genus Hemiarthrum of Lepidopleuridce, 
this form having a pore at each suture, and six around the head 
valve ; second in Callistoplatince (culminating in Mopaliidaf) where 
the pores are excessively inconstant, and the number around the 
head valve indefinite (0-6) ; and for the third time in Acantho' 
chitidce and its derivative Cryptoplacidce, where the number of 
tufts around the head valve is invariably four, in genera having 
pores. Every genus (if it has more than one or two species) con- 
taining pore-bearing species, includes also forms in which the pores 
or tufts have become subobsolete or entirely lost. In the genera of 
Mopaliidce, the pores are occasionally not of specific importance ; 
and the same is true of Amicula. 

The genesis of sutural tufts is not beyond the reach of theory. I 
believe them to be the direct result of over-nutrition of the girdle 
at the sutures, caused by its greater mobility at those points. It is 
obvious that every motion of the valves must cause a flexure of the 
girdle at the sutures; this brings a greater flow of nutriment to the 
stimulated portion, in this case a narrow strip, resulting in a more 
exuberant growth there. 

HEAD, FOOT, GILLS, ETC. 

Viewed ventrally Chiton presents a fleshy foot, similar to that 
of the Gastropoda (pi. 34, fig. 68). Separated from this by a sinus is 
the head, with the mouth in the center of the disk, which is gen- 
erally surrounded in front by a lappet called by Carpenter the 
" veil. " There are no tentacles or eyes. The inner edge of the 
ventral surface of the girdle may be regarded as the mantle. It is 
sometimes fringed or produced into finger-shaped processes in front. 
The gills consist of a row of triangular branchial plumes extending 
from near the tail forward from a fourth to the entire length of the 
foot. The anus is median and posterior, generally opening on 
a papilla. The two nephridial openings are in the gill-groove, at the 
side and in front of the anus. The two genital openings are in 
front of the nephridial orifices. 

The radula has been investigated by Lpven, Sars, and especially 
by Dall, who describes the teeth as follows : " In all Chitons exam- 
ined there is a simply cuspid rhachidian tooth, and on each side a 



POLYPLACOPHORA. Xlll 

translucent minor lateral of varying form ; a major lateral larger 
than any of the other teeth, with a conspicuous black cusp, which 
may have from one to four denticles ; two boss-like or thickened 
uncinal plates of irregular shape ; a twisted spatulate uncinal, and 
three scale-like or slightly thickened external uncini. With the 
exception of the spatulate uncinus (which is aborted in a very few 
species) none of the uncini are much raised above the plane of the 
odontophore, and none present any characters of importance." 

Dall has figured and described the dentition of species belonging 
to over half of the genera and subgenera recognized by Carpenter 
including all of the main types. He concludes that as yet no char- 
acters affording grounds for even generic distinctions can be found 
in the teeth, which exhibit a most surprising uniformity throughout 
the entire group. The dentition of a number of genera not exam- 
ined by Dr. Dall has been worked out by the writer, but without 
result as far as the discovery of structures of taxonomic value is 
concerned. It is evident that while some minor features of the 
dentition are characteristic of groups founded upon other charac- 
ters, we need expect little assistance in larger questions of group 
affinities from the further investigation of this organ. 

The gills are "posterior" or short in the lower Chitons, the 
Lepidopleuridce, and also in the lowest Ischnochitonidce, and in most 
genera of the phylum Acanthochitidce Cryptoplacidce, which arose 
from an early Ischnoid stock. All other Chitons, including the 
higher Ischnochitonidce, the Mopaliidce and the Chitonidce, have 
" ambient " or long gills. 

TERATOLOGY. 

The occurrence of six- and seven-valved Chitons has been noted 
as early as the time of Linnseus. It is likely that the six-valved 
were artificial fabrications, although a certain number may perhaps 
be traced to incorrect drawings. Most seven-valved specimens are due 
to the soldering together of two valves in consequence of some injury. 
This is not uncommon, a number of cases having come under my 
observation. Individuals actually seven-valved are known to occur, 
although they are far from common. The writer has examined many 
thousand Chitons, but has seen only two normally 7-valved examples. 
One of these is figured on pi. 64, fig. 67 ; and as may be seen, it is in 
no respect abnormal save in the want of one central valve, and the 
consequent lengthening of the others. There is absolutely no trace 



XIV POLYPLACOPHORA. 

of the missing valve. The absence of a valve produces no striking 
change in the general appearance of the animal, and it would be 
easy to pass one by among a quantity. These considerations incline 
me to think that abnormalities in the valves may be less rare than 
supposed. 

Injuries to the girdle often produce more or less irregular growth. 
In species having large girdle-scales, such as Chiton s. sir., or the 
large-scaled Isehnochitons, the loss of scales is repaired by the 
growth over the injured area of scales much smaller in size, giving 
it a singularly patched appearance. 

COLLECTION AND PRESERVATION OF CHITONS. 

Chitons may be looked for on all but sandy coasts ; on these they 
are very rare. Some species, like Nuttallina, Enoplochiton, Acantho- 
pleura, etc., are found upon the exposed rocks at or near high tide ; 
others like most Isehnochitons, live under stones between tides or at 
lowest water ; but it is only by the use of the dredge that any 
approach to a full representation of the Chiton fauna of any locality 
can be obtained. No elaborate dredging outfit is required, how- 
ever, for over nine-tenths of the species being vegetable eaters, live 
in the littoral (including the laminarian and coralline) zone, and 
may generally be taken in 25 fms. or less depth ; although num- 
bers of species extend their range to or beyond the 100 fm. line, and 
a few (the genera Lepidopleurux and Hanleya only) live in the cold 
and dark abyssal region. 

A blunt knife is useful to the collector in detaching Chitons from 
the rocks etc. ; and the specimens before they have time to curl 
themselves up, should be placed flat on a narrow strip of smooth 
wood like a ruler or lath well wetted with salt water, and bound 
down by winding with soft twine or candle-wicking. This will keep 
them in a natural position until the tissues are relaxed, when they 
may be placed in alcohol, or cleaned by cutting away the foot and 
viscera. If this precaution is not taken they are apt to curl up in a 
shape which renders them almost useless for dissection or for cab- 
inet specimens, for they will break rather than flatten out. A large 
number maybe thus set on a single stick. If they curl up before 
they can be set, it is best to put them in a pan of salt water, where 
they will eventually straighten out, if alive. 

HISTORICAL NOTES ON THE LITERATURE OF CHITONS. 
Very few species of Chitons were known to writers upon shells 



POLYPLACOPHORA. XV 

prior to 1758, the date of LINNAEUS' Tenth Edition, in which four 
species were described. By the addition of the forms of northern 
Europe, this number is increased to nine in the twelfth edition of 
the Systema. From this time on, large numbers of Chitons found 
their way into English and Continental collections, and were figured 
in the works of Chemnitz and others. Linne classed the Chitons 
with the Cirripeds and Pholads, before the bivalves ; and this sys- 
tem persisted in conservative conchological works during the first 
few decades of the present century. In 1797, SPENGLER, a Danish 
naturalist, published a good monograph upon Chiton ; but little real 
progress was made toward a right appreciation of the rank of the 
group, and the establishment of a natural classification, until 
BLAINVILLE in 1816 (Bull. Philom.) separated them from the 
other mollusks as a Class, to which he gave the name Polyplaxiphora. 
In 1825, Blainville published the article upon Chitons in the Dic- 
tionaire des Sciences Naturelles. In this work an excellent descrip- 
tion of the entire organization is given, the parts of the valves are 
definitely named, and the characters upon which the divisions of 
the genus must be based are stated. The extraordinary insight 
and genius of the French malacologist are manifest throughout 
the systematic and structural part of this paper ; but the descrip- 
tions of species, being unaccompanied by illustrations, have been 
less useful. QUOY & GAIMARD, in 1834, gave an excellent 
account of the species collected daring the voyage of the 'Astrolabe' ; 
following the general lines laid down byde Blainville. Since 1834, 
no systematic work on Chitons of more than local interest, has been 
published upon the continent of Europe. 

In England, considerable species-work upon Chitons was done 
prior to 1829, but all upon strictly Linn sean lines. In the year 
1829, Rev. LANSDOWN GUILDING, residing in St. Vincent, West 
Indies, wrote a valuable paper, in which he recognized five genera : 
Chiton, Acanthopleura, Phakellopleura, Chitonellus, Cryptoconchus ; 
defining each in an acceptable manner. Shortly after this, the discov- 
eries of Frembly, Cuming and others, threw a multitude of new 
and handsome species into the hands of the London conchologists. 
BRODERIP and SOWERBY described most of these novelities in the 
P. Z. S., 1832-1834, and in the Mag. of Nat. Hist, 1840; and Sow- 
erby illustrated them in the Conchological Illustrations, published a 
little later. These authors knew nothing of internal characters, 
confining their attention to the superficial features of the shell only. 



Xvi POLYPLACOPHORA. 

The same is true of REEVE, who in 1847, published a monograph 
containing 189 species in the Conchologia Iconica. The figures 
of Sowerby and Reeve are generally good ; but they ignore inter- 
nal characters, and their descriptions are totally inadequate. J. E. 
GRAY, in 1847, (Ann. Mag. Nat. Hist, July-August, and P. Z. S.), 
proposed a system of classification of Chitonidce, embracing many 
new genera, but largely based upon Blainville's article of 1825. 
Gray's system is as follows : 

I. Mantle simple, without any pores or tufts of spines on the sides. 

A. The plate of insertion of the anterior and posterior valves divided 
into several lobes, and of the central valves into two lobes. 

a. Containing Chiton, Tonicia, Acanthopleura, Schizochiton. 

b. Containing Corephium, Plaxiphora, Onithochiton, Enoplo- 
chiton. 

[c. Radsia, Callochiton, Ischnochiton, Leptochiton, subsequently 
added by Gray.] 

B. The plate of insertion of all the valves with only a single notch on 
each side. The valves more or less covered ; the hinder valve 
with expanded plates of insertion (as in the central valves), with 
only a single notch on each side, and a concave sinuosity below. 

a. Contains Mopalia, Katharina, Cryptochiton. 

II. Mantle with a series of pores (each furnished with a tuft of spines) 
on each side. The plates of insertion of all the valves with only a sin- 
gle notch on each side which is sometimes rudimentary. 

a. Contains Cryptoconchus, Amicula, Acanthochites, Chiton- 

ellus. 

Some inconsiderable transpositions and additions were made by 
Gray in his Guide, 1857. This classification is accepted by H. & 
A. Adams, in their Genera of Recent Mollusca, 1858 ; the two pri- 
mary divisions being regarded as subfamilies ( Chitonince and Crypto- 
placince) by them. The species of their lists in very many cases do 
not belong to the genera to which they are assigned, the lists having 
been compiled without regard to the characters of the insertion 
plates. The main defects of this system are the greatly exaggerated 
importance given to the development of girdle-pores, and the imper- 
fect apprehension of the features of the insertion plates. Some 
years before the date of Gray's last paper, J. R. SHUTTLEWORTH, 
an Englishman by birth, but resident in Switzerland, studied the 
Chitons carefully in the light of Gray's earlier paper, and published 
a well-digested synopsis of the group (Bern. Mittheil, 1853), making 
a number of decided improvements in classification. 



POLYPLACOPHORA. XV11 

At the same time that Gray published his first essay, Dr. A. TH. 
VON MIDDENDORFF proposed an elaborate scheme of classification, 
in an extensive work upon the Siberian Chitons. His divisions were 
based upon (1) the entirely internal or partly exposed condition of 
the valves, and position of the apex of each, (2) degree of immer- 
sion, indicated by the contiguity or separation of the exposed part 
of the valves, (3) comparative width of the girdle, and (4) presence 
or absence of girdle-pores. This classification although worked out 
with vast industry, is a distinct retrogression from the stand taken 
by de Blainvillein 1825. MiddendorfF however, did excellent work 
upon the anatomy of the Chitons in this publication. His arrange- 
ment is as follows : 
Genus Chiton L. 

(1) Subgenus Cryptochiton Midd. (C. stelleri). 
(1) Subgenus Phcenochiton Midd. 
(2) Section Dichachiton Midd. 

(3) Subsection Symmetr ogephyrus Midd. 

(a.) Poriferi, Ch. (Symmetr.) monticularis Q. [=Crypto- 
conchus.] 
Apori, Ch. (Symmetr.) vestitus, pallasi, amiculatus 



(3) Subsection Ametrogephyrus Midd. 

(a.) Poriferi, Ch. fasciatus Q., larvseformis Blv. [ Cryp- 

toplax.] 

(.) Apori, Ch. Isevis Lm. [=Cryptoplax.] 
(2) Section Hamachiton Midd. 
(3) Subsection Platysemus Midd. 

(a.) Poriferi, Ch. zelandicus, emersoni, biramosus, etc., [= 

Acanthochites, Plaxiphora, etc.] 

(6.) Apori, Ch. submarmoreus, tunicatus, alatus, incisus, 
wosnessenskii, [=Tonicella, Katharina, Ischnochiton, 
Mopalia, etc.] 
(3) Subsection Stenosemus Midd. 

(a.) Girdle hairy, Ch. marmoreus, lineatus, brandti, mercki, 

etc., [=Tonicella, Schizoplax, etc.] 
(6.) Girdle finely squamose, Ch. ruber, albus, cinereus, 

etc., [ Trachydermon, Lepidopleurus.] 
(c.) Girdle coarsely scaly, Ch. mertensii, etc., [ Lepido- 

zona.] 
MiddendorfFs names being published simultaneously with Gray's, 



XV111 POLYPLACOPHORA. 

cannot be given priority, save in the case of Cryptochiton ; the other 
groups are all incongrous assemblages. 

From this time, no work of importance was done on Chitons 
until 1863, when PHILIP P. CARPENTER (born in Bristol, England, 
in 1819, died at Montreal, Canada, 1877) published a catalogue of 
the West American forms (Brit. Asso. Rep). This was followed by 
many articles upon the Californian and Atlantic Chitons, and 
finally by the preparation of a monograph of the entire group. In 
his work upon this great undertaking, Dr. Carpenter examined 
critically the Cumingian and British Museum collections, contain- 
ing most of the types of Broderip, Sowerby, Gray, Reeve and H. 
Adams; and besides, nearly every collection of any size in England 
and America, including those of A. Adams, Angas, Dr. A. A. Gould, 
Newcomb, Jay, Haines, the State of California, the Smithsonian 
Institution, Museum of Comparative Zoology, etc. The information 
gained from the examination of this great amount of material was 
in process of re-arrangement at the time of his death, in 1877, that 
relating to the Leptoidea and Ischnoidea being practically com- 
pleted. A vast amount of work had been done upon the other 
groups, but his studies of them were far from finished. A large 
number of drawings had been prepared under Dr. Carpenter's 
direction, mainly by Messrs Emerton, Foord, and Smith. The 
whole of this MS. being devised to the Smithsonian Institution, 
Dr. WM. H. DALL published (Proc. U. S. Nat. Mus. 1881, p. 283- 
292) an A bstract of all the genera of Chitons, giving Carpenter's 
complete classification, and brief diagnosis of the new groups. 
Most of the Carpenterian names therefore date from this time; 
although in 1873 a large part of them were included by Carpenter 
in a table printed by the Smithsonian Institution, showing the 
characters of the " Regular Chitons. " The fact that the distribu- 
tion of this table was limited to Carpenter's personal friends and 
correspondents, that it was never advertised or offered for sale, was 
not sent to most (if any) public scientific libraries nor noticed in 
scientific journals, prevents us from dating his names from the time 
of its publication. 

The following table shows the Carpenterian classification in full. 
The group and family names given by DALL in 1889 (' Blake" 
Gastropoda) are added in parenthesis. 



POLYPLACOPHORA. XIX 

Order POLYPLACIPHOKA (Polyplacophora Dall). 

Section I. Chitones regulares (EOCHITONIA Dall). 

Head and tail plates similarly articulated. 

A. LEPTOIDEA (Leptochitonidce Dall) 
Insertion plates obsolete or, if present, unslit. 

(Extinct forms.) 

Helminthochiton Salter. Pterochiton Cpr. 

Gryphochiton Gray. f Loricites Cpr. 

Chonechiton Cpr. Probolceum Cpr. 

Priscochiton Billings. Cymatochiton Dall. 

(Recent forms.) 
Leptochiton Gray. Hemiarthrum Cpr. 

Deshayesiella Cpr. Microplax Adams and Angas. 

Hanleyia Gray. 

B. ISCHNOIDEA (Ischnochitonidse Dall). 
Insertion plates sharp, smooth, fissured ; with eaves. 

*No pores on girdle. 
Trachydermon Cpr. Ischnochiton Gray. 

Trachyradsia Cpr. Stenoplax Cpr. 

Callochiton Gray. Stenoradsia Cpr. 

Stereochiton Cpr. Ischnoplax Cpr. 

Tonicella Cpr. Heterozona Cpr. 

Schizoplax Dall. Ischnochiton s. s. Cpr. 

Leptoplax Cpr. Ischnoradsia Shuttleworth. 

Chcetopleura Shuttleworth. Lepidopleurus Cpr. 

Maugerella Cpr. Lepidoradsia Cpr. 

Spongiochiton Cpr. Callistochiton Cpr. 

**With girdlepores. 

Callistoplax Cpr. Ceratozona Dall. 

Angasia Cpr. Pallochiton Dall. 

Newcombia Cpr. 

C. LOPHYROIDEA (Lophyridce Dall). 
Insertion plates broad, pectinated, projecting backward. 
Chiton Linne. Eudoxochiton Shuttleworth. 

Eadsia Gray. Craspedochiton Shuttleworth. 

Tonicia Gray. 
Fannettia Dall. 

D. ACANTHOIDEA (Acanthopleuridce Dall). 

Insertion plates thrown forward. 
^Plates broad, pectinated (J. lophyroidea). 
Sclerochiton Cpr. 

**Plates sharp, grooved outside (<4. typica). 
Acanthopleura Guilding. Corephium Gray. 

Lucilina Dall. Francisia Cpr. 



XX POLYPLACOPHORA. 

***Plates sharp, smooth (A. ischnoidea). 
Dinoplax Cpr. Nuttallina Cpr. 

Middendorfia Cpr. Arthuria Cpr. 

Beanella Dall. Phacellopleura Guilding. 

Section II. Chitones irregulares (OPSICHITONIA Dall). 
Tail plate abnormal or with a sinus behind. 
E. SCHIZOIDEA (Schizochitonidw Dall). 

Tail valve fissured. 

Lorica H. and A. Adams. Schizochiton Gray. 

Aulacochiton (Shuttle worth) Cpr. 

F. PLACIPHOROIDEA (Placophoridce Dall). 
Tail valve unslit, internally ridged, mucro nearly terminal. 
Enoploehiton Gray. Fremblya H. Adams. 

Ornithochiton Gray. Euplaeiphora Shuttleworth. 

Placiphora Gray. Guildingia Cpr. 

G. MOPALOIDEA (Mopaliidce Dall). 
Tail valve with posterior sinus and one slit on each side. 
Mopalia Gray. Maeandrellus Cpr. 

Placiphorella Cpr. Stectoplax Cpr. 

Katherina Gray. Notoplax H. Adams. 

Acanthochiton (Leach) Herrm. 

H. CRYPTOIDEA (Amiculidce Dall). 

With double sutural laminae. 

Cryptoconclius Blainville. Chlamydochiton Dall. 

Amicula Gray. Cryptochiton Gray & Middendorf. 

Amicula s. s. Dall. 

I. CHITONELLOIDEA ( Cryptoplacidce Dall). 
Tail plate funnel-shaped. Laminae thrown forward. 
Chitonellus Blainville. Choneplax Cpr. 

Oryptoplax Gray. Chitoniscus Cpr. 

There can be no doubt that Carpenter's classification is a great 
advance upon that of Gray. It will be noticed that the primary 
division of the family is into two great groups: (1) Chitons having 
the head and tail valves similarly articulated with the girdle, and 
(2) those having them strongly dissimilar. These two great groups 
were early recognized by Carpenter, and called respectively Regu. 
lar and Irregular Chitons. 

DALL, in his Report on the Chitons of Alaska (1878), accepts the 
Carpenterian classification, correcting it in some details, notably in 
the arrangement of the Amiculoid forms. In the same year he 
published an extensive and extremely valuable paper upon the den- 



POLYPLACOPHORA. XXI 

tition of the group, giving figures and descriptions of the radulse of 
species representing a majority of the genera of Chitons. In 1889, 
Dall proposed the superfamily and family names quoted in paren- 
thesis in the above table. 

The writer proposes to show in the course of this work, that the 
primary division into Regular and Irregular forms is not funda- 
mental, the Irregular group being polyphyletic, consisting of genera 
derived from several totally distinct stocks. With the exception of 
the Leptoidea (Leptochitonidse), Ischnoidea (Ischnochitonidse) and 
Chitonelloidea (Cryptoplacidse), all of the family groups of Carpen- 
ter and Dall require dismemberment. 

DR. PAUL FISCHER, in his Manuel de Conchyliologie, 1885, adopts 
the Carpenterian arrangement, with some transpositions, but 
reduces the generic names of former authors to the rank of sub- 
genera and sections. His scheme is as follows. The Carpenterian 
equivalents being given in brackets, a glance at the above table will 
show what groups were included by Fischer. 
Family CHITONID^E. 
Genus HOLOCHITON Fischer, 1885 [=Leptoidea Cpr.] 

Subgenus Eochiton Fischer, 1885 [=rPalaeozoic Leptoidea]. 
Genus CHITON Linn. [Includes Ischnoidea, Lophyroidea, Acanthoi- 
dea of Cpr.]. 

Subgenus Tomochiton Fischer, 1885 [Includes the Ischnoidea and 
Acanthoidea ischnoidea which lack girdle pores]. 

Subgenus Porochiton Fischer, 1885 [Includes the Ischnoidea and 
Acanthoidea ischnoidea which have girdle pores]. 

Subgenus Chiton s. s. [ Lophyroidea of Cpr.]. 

Subgenus Acanthopleura Guild. [= Acanthoidea typica Cpr.]. 
Genus ANISOCHITON Fischer, 1885 [Includes Schizoidea, Placipho- 

roidea, Mopaloidea of Cpr.]. 

Genus CHITONELLUS Lam. 1819 [= Chitonelloidea Cpr.]. 
Genus DIARTHROCHITON Fischer, 1885 [Cryptoidea Cpr.]. 

It will be noticed that Fischer ignores the law of priority in the 
use of generic names. His classification is not otherwise very different 
from Carpenter's, except that he reduces the genera of Gray and 
Carpenter to the rank of sections. 

M. A. T. DE ROCHEBRUNE, in several papers upon Chitons, pub- 
lished from 1881 to 1889, has classified the group in various ways, 
the principal schemes being given below. It is necessary to give in 
brackets the equivalents of Rochebrune's genera, in order to under- 



XX11 POLYPLACOPHORA. 

stand what his family groups really mean. 

In Nouv. Archives du Museum (2) iv, 1881, Rochebrune presents 
the following arrangement : 

Family ACANTHOCHIT^ Rochebr., genus Acanthochites Risso. 

Family CH^ETOPLEUR^E Rochebr., genus Chcetopleura Shutt., spe- 
cies cjigas Chem. ; and genus Acanthopleura Guild. 

Family CHITONIDJE Gray, genus Tonicia Gray, Lepidopleurus 
" Risso " [ Ischnochiton], and genus Gymnoplax Gray [=Chiton 
s. str.~\. 

In the Zool. Cap Horn, 1889, the following scheme is given : 

Family PROCHITONID^E, genus Schizoehiton Gray. 

Family LOPHYOCHITONID^E, genus Acanthochiton Leach. 

Family CH^ETOCHITONID^:, genus Acanthopleura Guild. ; genus 
Chcetopleura Shutt. [ Plaxiphora -f- Chaetopleura]. 

Family CHITONIJD^;, genus Tonicia Gray ; genus Lepidopleurus 
" Carpenter, 1879 " [=Ischnochiton -f Trachydermon -f Callochi- 
ton !] ; genus Chiton L. [Ischnochiton + Chiton s. sir.]. 

It will be seen that the ideas of Rochebrune are so opposed to 
those of the Carpenter and the writer that any criticism of them 
would be useless. The same Parisian author has published many 
diagnoses of Chitons believed to be new ; but owing to his failure 
to mention the characters really diagnostic of genera and species, 
but little use can be made of his writings. The majority of these 
forms are still unfigured ; and of his figured forms it must be said 
that Rochebrune has been signally unfortunate in his artists. Of 
all the figures of Chitons published by him I have not yet seen a 
correct one ; most are so radically bad that no dependence whatever 
can be placed upon them. The same is true of his figures of fossil 
Chitons. 

From the above sketch it will be seen that the chief workers upon 
the classification of Chitons have been few in number, the publica- 
tions of BLAINVILLE, GRAY and CARPENTER successively mark- 
ing epochs in the taxonomic history of the group. 



POLYPLACOPHORA. XX111 

CLASSIFICATION OF CHITONS. 

The classification given in this work is based mainly upon char- 
acters furnished by the articulating surfaces of the valves. The 
hard structure in this group is comparable to the vertebrate skele- 
ton in the great variety of stresses to which it is subject. Each 
valve is not only acted upon by external forces and its body-mus- 
cles, but by the valves before and behind it, and by the girdle. 
Hard parts of great complexity have thus arisen, offering to him 
who can decipher their story clues as valuable for the construction 
of genealogical lines as have been found in the limb-bones of mam- 
mals, or the hinge-teeth of bivalve mollusks. The development of 
the gills, foot and girdle has been given due weight, and for the first 
time, systematic use has been made of the sense organs of the shell 
(tegmentum), and the system of sculpture of the latter. The non- 
differentiation of the dentition throughout the group has prevented 
the use of that character usually so important. 

The Polyplacophora known to us, form a group remarkably homo- 
geneous, when we consider the vast antiquity of the stock. The 
fossil forms are yet few in number and imperfectly known ; so that 
all attempts to trace the mutual relationships and descent of modern 
genera must still be based upon the morphology of living forms. 
The complex inter-relations of the various families and genera, the 
number of phyla, and especially the wonderful parallel develop- 
ments of different stocks, all render a linear arrangement of groups 
highly unsatisfactory. The accompanying diagrams show the main 
facts of classification and descent much more clearly. 

It is commonly known that the earlier (Palaeozoic) Chitons are 
without exception, destitute of plates of insertion, and belong, 
therefore, to the family Lepidopleuridce. This family has survived 
to the present day, but the species are now few in number and of 
small size. The higher genera of Lepidopleuridce possess insertion 
plates on some or all valves, but they are unslit; and it is to this 
branch that the genesis of the higher Chitons is to be traced. The 
lowest Ischnochitonidce known have already become well differenti- 
ated by the development of a definite system of slits. 

The Ischnoid stock must be regarded as a synthetic or unspecial- 
ized type of Chitons. In other words the common ancestors of the 
other families of the Chitons (except Lepidopleuridce') , would proba- 
bly, if known to us, be classed as Ischnochitonidce. From this general- 
ized Ischnoid stock specialization proceeded in two directions : (I) 



XXIV POLYPLACOPHORA. 

toward greater definiteness in the positions of the slits, and often 
toward the degeneration of the shell ; leading (a) through CalHsto- 
placince to the Mopaliidce, and (6) through Acanthochitidce to covered 
forms, Cryptochiton, and to worm-like forms, Cryptoplacidce ; the 
last having fewer slits than any other Chitons. In the other direc- 
tion (II) the slits became generally more numerous, the insertion- 
plates are roughened for the stronger adhesion of the girdle, the 
valves increase in general effectiveness as a protective armor, and 
their sense organs became highly developed. This phylum ( Chi- 
tonidce) culminates in Tonicia, Acanthopleura, Schizochiton, Enoplo- 
chiton, Liolophura, etc. ; and may be regarded as the highest group 
of Polyplacophora. 

NOTE. It must be understood that in cases where the classifica- 
tion below given differs from that in the descriptive part of this 
work, the former represents the mature views of the author. Page 
23 in the text, should be cancelled, as it was written when but a 
small portion of the groups there discussed had been studied. The 
synopses given on pp. 24-25, and 148-149 also require correction. 

Synopsis of Classification of the Order Polyplacophora. 
I. Superfamily EOPLACOPHORA. 
Family Lepidopleuridce Pilsbry. 
Genus Lepidopleurus Risso. p. 2. 

Section Deshayesiella Cpr., p. 16. 
Genus Hanleya Gray, p. 17. 
* 

Genus Hemiarthrum Cpr., p. 19. 
* 

Genus Microplax Ad. & Ang., p. 21. 

II. Superfamily MESOPLACOPHORA. 
Family Ischnochitonidce Pilsbry, p. 253. 
Subfamily Ischnochitoninse Pilsbry, p. 254. 
Genus Tonicella Cpr., p. 40. 
Genus Schizoplax Dall, p. 46. 
Genus Callochiton Gray, p. 48. 

Section Sterochiton Cpr., p. 52. 
Genus Trachydermon Cpr. p. 67. 



POLYPLACOPHOKA. XXV 

Subgenus Cyanoplax Pils., p. 44. 

* 

Genus Chsetopleura Shuttlw., p. 27. 
Genus Pallochiton Dall, p. 256. 
Genus Dinoplax Cpr., p. 254. 

# 

Genus Ischnochiton Gray, p. 53. 

Subgenus Stenochiton Ad. & Ang., p. 55. 
Subgenus Stenoplax Cpr., p. 56. 

Section Stenoradsia Cpr., p. 61. 
Subgenus Ischnoplax Cpr., p. 64. 
Subgenus Ischnochiton s. s. p. 87. 

Section Lepidozona Pils., p. 125. 

Section Radsiella Pils., p. 139. 

Section Ischnoradsia Shuttl., p. 144. 
Subgenus Heterozona Cpr., p. 65. 

Subfamily Callistoplacinse Pilsbry, p. 259. 

Genus Callistochiton Cpr., p. 260. 
* 

Genus Nuttallina Cpr., p. 277. 

Subgenus Middendorffia Cpr., p. 282. 
Genus Craspedochiton Shuttlew., p. 285. 
# 

Genus Angasia Cpr., p. 286. 
Genus Callistoplax Cpr., p. 288. ' 
Genus Ceratozoaa Dall, p. 290. 

Family Mopaliidce Pilsbry, p. 292. 

Genus Mopalia Gray, p. 294. 
Genus Placiphorella Cpr., p. 305. 
Genus Plaxiphora Gray, p. 311. 

Section Guildingia Cpr., p. 329. 

Section Fremblya H. Ad., p. 330. 
Subgenus Placophoropsis Pilsbry, p. 313. 

Family Acanthochitidce Pilsbry. 

Genus Spongiochiton Cpr. 
Genus Acanthochites Risso. 
Section Notoplax Ad. 



POLYPLACOPHORA. 

Section Cryptoconchus Blv. 
Section Loboplax Pils. 
Genus (?) Leptoplax Cpr. 

Genus Katharina Gray. 

* 

Genus Amicula Gray. 

* 

Genus Cryptochiton Midd. 

Family Cryptoplacidce Dall. 

Genus Cryptoplax Blainv. 
Genus Choneplax Cpr. 

III. Superfamily TELEOPLACOPHORA. 

Family Chitonidce Pilsbry. 
Subfamily Chitoninse Pilsbry. 

Genus Chiton Linn., p. 149. 

Section Radsia Gray, p. 189. 
Section Sclerochiton Cpr., p. 188. 

* 

Genus Eudoxochiton Shuttlw., p. 192. 

Subfamily Toniciinse Pilsbry. 

Genus Tonicia Gray, p. 194. 

Section Fannettia Dall, p. 212. 
Genus Acanthopleura Guild., p. 213. 

Subgenus Mesotomura Pils., p. 218. 

Subgenus Acanthopleura s. s., p. 219. 

Subgenus Maugeria Gray, p. 226. 

Subgenus Amphitomura Pils., p. 230. 

Subfamily Liolophurime Pilsbry, p. 232. 

Genus Schizochiton Gray, p. 234. 

* 

Genus Lorica Ads., p. 236. 
Section Loricella Pils., p. 238. 

* 

Genus Enoplochiton Gray, p. 252. 
Genus Onithochiton Gray, p. 244. 
Genus Liolophura Pilsbry, p. 239. 



POLYPLACOPHORA. 



XXV11 



Phylogenetic diagram of the families and subfamilies of 
Polyplacophora. 



a 
-3 



U 

1 

6 







* 



Callistoplacinae 



Lepidopleuridse 

A diagram illustrating the phylogeny of the genera of Isehnochi- 
tonince is given on page 254 ; another illustrating that of the gen- 
era of Chitonidce is given below ; and the descent of the genera of 
Acanthochitidce is shown under the head of that family. The 
mutual relations of the genera included in Callistoplacince are not 
clear to me and require much further investigation ; but the views 
expressed on pages 259, 260 may possibly suggest a clue to the 
super-generic groups. 




POLYPLACOPHORA. 

Pliylogenetic diagram of the genera of Chitonidce. 



I I 
w 6 



S o 

3 M * 

2 '" 9 

I J -a 

^ PH O 

.tn o ri 



Liolophurince 



CHITONID^E 

ANALYTICAL KEY TO GENERA OF POLYPLACOPHORA. 

a. Valves lacking insertion plates, or if present they are unslit 
(Lepidop leuridce) . 

b. Valves entirely exposed, not immersed, 
c. Insertion plates completely absent, 

LEPIDOPLEURUS, p. 2. 

cc. Head valve having an insertion plate, grooved 
outside but unslit ; valves ii-viii without plates, 
girdle spinulose HANLEYA, p. 17. 

ccc. Head and tail valves only having unslit insertion 
plates; girdle thick, sparsely downy, with sut- 
ural pores HEMIARTHRUM, p. 19. 



POLYPLACOPHORA. XXIX 

bb. Valves partly covered, the exposed portions small, sep- 
arated MICROPLAX, p. 21. 
aa. All valves possessing insertion plates ; valve i, i-vii or i-viii hav- 
ing slits ; teeth smooth or but slightly roughened between the slits, 
never closely, finely pectinated ; valves lacking eyes. 

b. Surface of intermediate valves divided into lateral and 
central areas by a diagonal (often indistinct), extend- 
ing from beak to outer front angle of tegmentum ; or if 
this is not clearly the case, the posterior valve has an 
even, crescentic series of well developed teeth; all 
valves having slits. 

c. Posterior valve having a crescentic series of well 
developed teeth (Ischnochitonidce). 

d. Anterior and side slits not corresponding in 
position to external ribs (Ischnochitonince.) 
e. Valves porous at the eaves, appar- 
ently smooth outside or nearly so; 
teeth sharp, smooth; girdle naked, 
sparsely hairy or densely covered with 
elongated corneous bodies, the visible 
ends of which appear like diamond- 
shaped scales (Tonicelloid group). 
/*. Sutural plates not connected 
across the sinus ; girdle naked ; 
side-slits single ; gills shorter than 
the foot. 

g. Median valves having a me- 
dian slit filled with carti- 
lage, SCHIZOPLAX, p. 46. 
gg. Median valves normally cal- 
cified, TONICELLA, p. 40. 
//. Sutural plates connected across 
the sinus, or side-slits several, or 
both ; girdle either sparsely hairy, 
naked, or with compact diamond- 
patterned covering ; gills as long 
as the foot, CALLOCHITON, p. 48. 
(This includes the typical forms 
of Trachyradsia, p. 83.) 
fff. Girdle with chaffy scales or pap- 



XXX POLYPLACOPHORA. 



illose ; gill-row short or long, 

TRACHYDERMON, p. 67* 
ee. Valves solid at eaves, generally with 
beaded sculpture ; teeth sharp, often 
rugose outside; girdle leathery with 
few or many hairs or spiculse, never 
scaly ; gills as long as the foot (Chatee- 
pleuroid group). 

/. Sinus squared, the sutural plates 
not connected across it; girdle 
hairy or naked. 

g. Mucro in front of the mid- 
dle, CH^TOPLUERA, p. 27, 
[and appendix. 

gg. Mucro decidedly posterior, 

PALLOCHITON, p. 256. 

ff. Sutural plates connected across 

the sinus ; girdle thick, bearing 

minute clumps of short spicules, 

DINOPLAX, p. 254. 

eee. Valves solid at eaves ; girdle densely 
covered with imbricating scales, rare- 
ly elongated like fluted pillars (Isch- 
noid group) ISCHNOCHITON. 

/. Shell much elongated, narrow 
(gills short at both ends ; foot no- 
tably dilated and produced in 
front, at least in some of these 
sections). 

g. Girdle scales uniform ; mu- 
cro near the middle 

h. Valves longer than 
wide, roundly arched, 
with several side slits ; 
animal Julus-like, 

Stenochiton p. 55. 
hh. Less elongated ; Amer- 
ican forms 

Stenoplax, p. 56. 
gg. Girdle scales very unequal ; 



POLYPLACOPHORA. XXXI 

mucro elevated, posterior, 

Ischnoplax, p. 64. 
ff. Shell not greatly elongated. 

g. Girdle clothed with large 
and small intermingled 
scales, Heterozona, p. 65. 
gg. Girdle scales regular, uni- 
form. 

h. 1 slit on each side of 
median valves 
i. Girdle scales flat, 
Ischnochiton, p. 86. 
ii. Girdle scales very 
convex, 

Lepidozona, p. 125. 
hh. 2 or more slits on 
each side, 

i. Girdle scales flat, 
Radsiella, p. 139. 
ii. Girdle scales con- 
vex, 

Ischnoradsia, p. 144. 

dd. Anterior and side slits corresponding in 
position with external ribs (Callistoplacinse). 
e. Surface of valves having strong radial 
ribs ; girdle densely clothed with im- 
bricating scales, 

CALLISTOCHITON, p. 260. 
ee. Surface of valves granulated or peb- 
bly ; girdle not densely imbricated 
with scales. 

f. Anterior valve with more than 
7 slits ; sinus very spongy ; mu- 
cro posterior, 

NUTTALLINA, p. 277. 

ff. Anterior valve with 5 slits ; mu- 
cro subcentral, not posterior, 
g. No sutural pore tufts. 

CRASPEDOCHITON, p. 285. 

gg. Sutural pore tufts present, 

ANGASIA, p. 286. 



XXX11 POLYPLACOPHORA. 

eee. Surface of valves wrinkled or ribbed ; 
girdle naked except for hairs or cor- 
neous spines. 

/. Valves having very strong radial 
ribs ; girdle naked, with sutural 
tufts, CALLISTOPLAX, p. 288. 
ff. Valves not very strongly sculp- 
tured ; girdle tough, with corne- 
ous curved spine-like processes, 
CERATOZONA, p. 290. 

cc. Posterior valve having a sinus behind, with one slit 
or none on each side ; girdle hairy or nude, never 
scaly (Mopaliidoe'). See key to genera on page 293. 
bb. Surface of intermediate valves divided into a narrow 
dorsal area, and latero-pleural areas, the latter formed 
by the union of the lateral and the pleural (or sides of 
the central) areas ; valves more or less covered by the 
naked, spiculose or hairy (never scaly) girdle ; gills gen- 
erally short (Acanthochitoid phylum). 

c. Posterior valve either having well developed slits, 
or a posterior sinus, or both ; not funnel-shaped, 
anterior valve with 5 or more slits (Acanthochiti- 
dce, see next volume for species). 

d. Valves not completely covered by the girdle, 
the first 7 having their apices posterior and 
marginal. 

e. Anterior valve having 5 regularly 
placed slits ; exposed portion of each 
median valve much longer than wide. 
/. Girdle provided with pores bear- 
ing tufts of bristles ; posterior 
teeth wanting or irregular 

ACANTHOCHITES. 

ff. Girdle naked ; posterior valve 
with 6 slits, the teeth even, spread- 
ing LEPTOPLAX. 
fff. Girdle spongy, produced forward 
as in Placiphorella 

SPONGIOCHITON. 



POLYPLACOPHORA. XXX111 

ee. Anterior valve having the slits irregu- 
larly spaced, more than 5 ; posterior 
valve with a median angular tail sinus ? 
its edge with several unequal notches 
or slits ; exposed part of valves flask- 
shaped KATHERINA. 
eee. Anterior valve having 6-8 unequal 
slits; posterior valve 2 slits and a 
median wave ; exposed part of each 
valve far shorter than the ridge of the 
valve, heart-shaped AMICULA. 
dd. Valves completely covered by the girdle, 
their apices not marginal, CRYPTOCHITON. 
b. Median valves partly lacking side slits ; tail valve with 
2 or no slits 

cc. Posterior valves without distinct slits, and having 
no posterior sinus ; more or less hollowed out and 
funnel-shaped ; anterior valve with 3-5 slits ; body 
rather vermiform ; gills short, posterior ( Cryptopla- 
cidce ; see next volume for species). 

d. Valves small, narrow and sagittate, gener- 
ally partly disjointed ; not covering the 
body to any considerable extent 

CRYPTOPLAX. 

dd. Valves transverse,'all strongly imbricating ; 
covering a considerable portion of the upper 
surface CHONEPLAX. 

aaa. All valves, or valves i-vii, possessing insertion plates cut into 
teeth by slits ; the teeth sharply sculptured or "pectinated " out- 
side by fine vertical grooves (Chitonidce). 
b. Valves lacking eyes (Chitonince). 

c. Girdle scaly CHITON, p. 149. 

cc. Girdle leathery, with short bristles 

EUDOXOCHITON, p. 192. 

bb. Valves having eyes ; posterior valve not deeply sinused 
behind, its insertion plate developed (Toniciince) 

c. Girdle leathery, nude or nearly so, TONICIA, p. 194. 
cc. Girdle covered with calcareous spines or spinelets, 

ACANTHOPLEURA, p. 213. 

bbb. Valves having eyes (rarely subobsolete) ; posterior 



XXXIV POLYPLACOPHORA. 

valve either having a deep sinus behind, or lacking the 
insertion plate altogether (Liolophurince). 

c. Median valves having eyes developed only on the 
diagonal ribs. Sinus notably narrow and small. 
Insertion plates of tail valve a low, rounded, 
rugose ridge more or less notched, slit or waved 
upward in the middle behind, or sharp, long and 
pectinated. 

d. Eyes developed on radiating ribs of all 
valves ; the ribs of head valve correspond- 
ing to internal slits ; girdle having minute 
spines ; shell elongated, posterior valve and 
girdle slit behind SCHIZOCHITON, p. 234. 
dd. No eyes on head valve, its riblets not corre- 
sponding to slits ; girdle densely scaly 

LORICA, p. 236. 

cc. Eyes developed upon the lateral areas. Sinus 
wide and large. Insertion plate of the tail valve 
reduced to a smooth ledge or ridge, having no 
posterior sinus or wave. 

d. Valves polished or eroded, dark brown out- 
side and within, having excessively minute 
eyes scattered over lateral areas and head 
valve (when not eroded) ; interior very 
densely, minutely and peculiarly grooved 
and punctured. Girdle fleshy, bearing sep- 
arated rude scales, ENOPLOCHITON, p. 252. 
dd. Valves polished, colored outside, porcella- 
nous and smooth within, having the eyes 
disposed in radial bands on each lateral 
area and the head valve. Girdle leathery, 
microscopically velvety, 

ONITHOCHITON, p. 244. 

ddd. Valves lusterless, granulated, having minute 
eyes scattered over the lateral areas, sides 
of the central areas, and head valve. Gir- 
dle densely covered with stout calcareous 
spines LIOLOPHURA, p. 239. 



\ 




Family LEPIDOPLEURID.E. 

Leptoidea CARPENTER. LeptochitonidceDALL, 'Blake' Gastrop. 
p. 414, 1889. Genus Holochiton FISCHER, Manuel de Conchy], p. 
877, 1885. 

Chitons in which the head and tail valves are similarly articu- 
lated, and having the insertion plates either obsolete, or if present, 
without slits. Girdle finely scaly or bristly ; gills short, posterior. 

This family is readily known by the entire absence of insertion- 
plates, or the simple, unslit character of them when present. The 
living species are few in number, and mainly either northern in dis- 
tribution, or living at considerable depths. All of the Palaeozoic 
Chitons yet known belong to this family, and this fact, together with 
the weak, imperfect articulation of the valves, causes us to regard 
the Leptoids as the most primitive of the existing groups. 

Synopsis of Genera. 

A. Valves entirely exposed, not concealed by the girdle. 
B. Girdle without pores. 

Genus I. LEPIDOPLE17RUS Risso, 1826. 

Insertion plates absent. Girdle with minute, gravelly, smooth or 
striated scales, usually with a marginal fringe of longer scales. 
Type, L. cajetanus Poli. 

Section Deshayesiella Carpenter, 1878. Girdle having delicate 
spines and chaffy scales. Valves curved and beaked; sutural 
plates and sinus as in Leptochiton. Type, L. curvatus Cpr. 

Genus II. HANLEYA Gray, 1857. 

Front valve having an insertion plate which is grooved outside 
but without slits. Intermediate and posterior valves without inser- 
tion plates. Girdle finely spiculose, without pores. Type, H. han- 
leyi Bean. 

BB. Girdle with pores at the sutures. 

Genus III. HEMIARTHRUM Carpenter, 1876. 

Head and tail valves having smooth, unslit insertion plates, the 
intermediate valves without insertion plates. Sinus broad and 



2 LEPIDOPLEURUS. 

spongy. Girdle downy, having small, tufted pores. Type, H. set- 
ulosum Cpr. 

A A. Valves partly covered, the exposed portions small and sepa- 
rated. 

Genus IV. MtCROPLAX Adams & Angas, 1804. 

Insertion plates smootfi and thin, well developed in all the valves. 
Sutural plates and sinus obsolete. Girdle thin, most minutely gran- 
ular, not poriferous. Type, M. grayi Ad. & Ang. 



Genus I. LEPIDOPLEURUS Risso, 1826. 

Lepidopleurus Risso, Hist. Nat. 1'Eur. Merid., iv, p. 267, 1826, 
(in part ; first species L. cajetanus Poli). SARS., Moll. Reg. Arct. 
Norv., 1878, p. 110. Not Lepidopleurus of H. & A. Adams, Car- 
penter, Dall, et al. Leptochiton GRAY, Proc. Zool. Soc. Lond. 1847 y 
p. 127 ; Guide Moll.B.M., p. 182, 1857. CARPENTER, MS. p. I 
DALL, Proc. U. S. Nat. Mus. 18*78, p. 314. Leptochiton, in part, of 
H. & A. ADAMS, Gen. Rec. Moll, i, p. 473, and of CHENU, 
Manuel, i, p. 381. 

In Lepidopleurus the insertion plates are completely absent; the 
girdle is narrow, with minute striated or smooth scales, and some 
longer scales at the edge. 

The present genus has hitherto been known as Leptochiton, but 
the rejection of that name seems to be inevitable as will be seen 
from the following : 

History of the name Lepidopleurus. The first publication of 
Lepidopleurus was in Risso's Histoire Naturelle des principales pro- 
ductions de PEurope Meridionale, vol. iv, p. 267, 1826, where it is 
quoted as of Leach's ms. It is characterized as having the triangular 
lateral areas elevated and the girdle covered with small scales, and 
in it are included (711) L. cayetanus Poli, (712) L. corallinus n. sp. 
and (713) L. sulcatus n. sp. Of these, the first species belongs to 
the group which Gray subsequently named Leptochiton, and the 
two latter belong to the genus Chiton as restricted to Linnaeus' 
type. It is therefore evident that if used at all, the name Lepido- 
pleurus can properly be used for Leptochiton only. It is greatly to 
be regretted that it was not so used by Gray, as much subsequent 
confusion would have been avoided. The republication of the 



LEPIDOPLEURUS. 6 

genus in Gray's edition of Leach's Synopsis Moll. Gt. Brit., in 
1852, need not be considered here as it has no bearing upon nomen- . 
clature. In 1858, Messrs. H. and A. Adams, in the Genera of 
Recent Mollusca, adopted Risso's name for a large list of species 
composed mainly of Ischnochitom, but including also species of 
Callochiton, Leptochiton , etc.. among them L. cajetanus Poli. Car- 
penter in his later writings used Lepidopleurus tu cover that group 
of Ischnochitons having the girdle clothed with large, smooth con- 
vex scales, like those of the typical Chitons. Nothing can be said 
in favor of this use of the name, for Carpenter expressly states that 
the species cited by Risso are excluded from the group as rehabili- 
tated ! It is, therefore, obvious that Lepidopleurus Cpr. is a totally 
distinct group from Lepidopleurus Risso. No argument is needed 
to show the imtenability of Carpenter's position. In 1889, Carus, 
in his Prodromus Faunce Mediterranean, has used Lepidopleurus as a 
subgenus under Chiton (which he places in the Ischnoidea !), and 
has included in it species of Trachydermon and Ischnochilon, as 
well as Leptochiton cajetanus. In 1878 G. O. Sars correctly 
restricted Lepidopleurus to the genuine Leptochitons. 



L. CANCELLATUS Sowerby. PI. 3, figs. 54, 55, 56, 57, 58. 

Shell small, elongated, much elevated, regularly arched, not 
angled. Orange-ashen or whitish. 

Anterior valve radiately, evenly, very finely, granose-lirate. 

Central areas of the intermediate valves having distinct longitu- 
dinal, fine, close granulous lirse, the granules being sometimes 
arranged in transverse lines also, giving a latticed appearance ; lat- 
eral areas distinct, decidedly raised, convex, having radiating but 
rather irregular rows of granules. 

Posterior valve with central elevated apex ; posterior slope con- 
cave. 

Interior white, the sutural plates small, triangular; jugal sinus 
very broad. 

Girdle narrow, densely beset with delicate, scarcely imbricating 
or striated, scales (figs. 55, 57). 

Length 51, breadth 2 mill.; divergence 80. 

Northern Atlantic and Arctic Seas. Britain; Norwegian Coast 
in 50-100 fms. ; Lofoten Is. 300 fms. ; Greenland; South to Gulf 
of Lyons, Vigo, Spain (jund Dalmatia /). Northern Pacific. Alaska, 
at Unalashka, Shumagins, Port Etches and Sitka Harbor, 6-100 fms. 



4 LEPIDOPLEURUS. 

Chitons cancellatus Sows (as ? of Leach ms.~), Conch. 111. f. 104- 
5, 1839. REEVE, Conch. Icon. t. 59, f. 152. FORBES & HANLEY, 
Hist. Brit. Moll, ii, p. 410, t. 59, f. 3. JEFFREYS, Brit. Conch, iii, 
p. 217; v, p. 198, t. 56, f. 1. Lepidopleurus cancellatus SARS, 
Moll. Reg. Arct. Norv. p. Ill, t. 7, f. 6 ; t, i, f. 8. Leptochiton 
cancellatus CPR. MS., p. 3. BALL, Proc. U. S. Nat. Mas. 1878, p. 
315. Chiton albus PULT. not ~Linn.,fide Hanley. Chiton asellus 
MiDD.,not of Lowe. Ch. rissoi AUCT., not Payr. / Ch. islandicus 
GMEL., Syst., p. 3206. 

This species without careful inspection will usually be confounded 
with small specimens of Trachydermon albus, but a glance at the 
sculpture is sufficient to separate it. From several other species of 
Leptochiton it is less readily distinguished, and a magnifier is indis- 
pensable. The differential characters are as follows : 

The pustules which constitute most of the sculpture are arranged 
like overlapping coins or a solid-linked chain in lines which in the 
dorsal area are nearly parallel with the longitudinal axis of the 
animal. The lateral areas are distinct, and the pustules upon them 
are arranged in rather indistinct lines radiating toward the lateral 
ends of the valves, at nearly right angles to the lines on the dorsal 
area. The sculpture on the mucro is more delicate than elsewhere. 
The apex of the posterior valve is not sunken and is not so sharp 
as in other species compared with it here ; the girdle is scaly, with 
also some small, spinose, transparent scales near the margin. There 
are five gill plumes on each side, prominent and near the vent. 
There appear to be two fenestra on each side. The lateral areas 
and other portions of the valves are nearly always colored with 
blackish or ferruginous patches, but these, as with Trachydermon 
albus seem to be really composed of extraneous matter. In L.fuli- 
ginatus Ad. & Rve., the pustules are much smaller, and while hav- 
ing a general longitudinal arrangement on the dorsum, do not form 
regularly defined rows or chains. The areas are not raised above 
the dorsum. The shell is much larger and more elevated, with a 
somewhat sunken and quite sharp posterior mucro. The other 
mucrones are not raised but about them the sculpture is more regu- 
larly aligned than elsewhere. I have compared the valves of a 
typical specimen from Korea, collected by Belcher. Reeve's figure 
of the sculpture is very bad, as are most of his details. L. alveolus 
Sars is a very distinct species, though it has been confounded with 
this. Its sculpture is composed of larger and rather more sparse, 



LEPIDOPLEURUS. 5 

isolated pustules, absolutely irregular in distribution and of the 
same size on the mucro and elsewhere. Nowhere do they form 
lines. The arch of the back is peculiarly round, the lateral areas 
not raised and barely distinguishable. The girdle seems similar. 
I have compared typical examples. 

L. concinnus Gould, from the types, is of a different color, and 
has a much stronger and different sculpture like lines of rope. 

L. internexus Carpenter and var. rugatus Cpr., are more like con- 
cinnus, but distinguished from either by the peculiar girdle covered 
with subequal scales. 

L. nexus Carpenter more nearly resembles cancellatus but the 
sculpture is of separate, not lapping, rounded rhomboidal pustules; 
the mucrones are much more pronounced, and the white ground is 
prettily marbled with black and gray inherent coloration. The 
name cancellatus is a misnomer, since it is only in certain lights that 
any trace of reticulation can be observed faintly. The young are 
flatter than the adults. It bears no resemblance to L. asellus, with 
which Middendorff united it, probably without a comparison. 

L. arcticus of Sars seems to be a finely grown variety of this spe- 
cies, if one may judge from the figures; at least, no differential 
characters are given which seem to be of a permanent character, 
and not subject to variation within the limits of a species. 

The gills occupy a space corresponding to the posterior quarter 
of the foot ; there are about eight or ten on each side. The 
mantle edge is plain and thick. The veil is plain. The muzzle is 
rounded, with a little papilla at the posterior corner on each side 
(Dall.) 

L. ARCTICUS Sars. PI. 3, figs. 59-63. 

Shell subdepressed, dorsal keel obsolete, lateral areas little con- 
spicuous. Posterior valve smaller than the anterior, subrhom- 
boidal, roundly produced in front. Median plates three times as 
long as broad, the front margin truncate in the middle. Surface of 
the valves nearly smooth, indistinctly granulose. (Sars.) 

Length 12 mill. 

Spitzbergen, Greenland, Vadso and Finmark, 20-100 fms. 

Lepidopleurus arcticus SARS, Moll. Keg. Arct. Norv. p. 112, t. 7, 
f. 7. Chiton arcticus JEFFREYS, P. Z. S. 1882, p. 668. 

Dall, judging from the description and figures, considered this a 
form of L. cancellatus. Jeffreys, who found the species in the 



b LEPIDOPLEURUS. 

' Lightning ' dredgings, says that it differs from the white variety of 
cinereus [=asellus] in its comparatively greater length and more 
raised or arched form, in the less distinct or regular catenation of 
the granules which cover the surface, and in the prominence of the 
lateral areas. 

L. ALVEOLUS Sars. PI. 2, figs. 23-31. 

Shell quite convex, back equally arched, without trace of a keel 
or defined lateral areas; valves rather elongate, the posterior larger 
than the anterior valve, half-round, truncated by a straight line in 
front; median valves subequal, their posterior margins straight, 
anterior margins lightly emarginate in the middle. Entire surface 
sculptured with minute ovate tubercles, regularly disposed. (Sars.) 

Length 16 mill. 

North Atlantic at Bergen, Lofoten, Finmark, 150-300 fms. ; Bay 
of Biscay, 120-664 fms. ; Gulf of St. Lawrence between Cape Rosier 
and the S. W. point of Anticosti Id., 220 fms. ; St. George's Bank, 
Gulf of Maine, 150 fms. 

Chiton alveolus (SARS ms.~) LOVEN, Ind. Moll. Lit. Scand. p. 27, 
159, 1846. JEFFREYS, P. Z. S. 1882, p. QGB.Lepidopleunu alve- 
olus G. O. SARS, Moll. Reg. Arct. Norv. p. 110, t. 7, f. 3 ; t. i, p. 7, 
1878,Leptochiton alveolus DALL, Proc. U. S. Nat. Mus. 1878, p. 
317. HADDON, Challenger Rep. vol. xv, p. 12. 

L. PERGRANATUS Dall. Unfigured. 

Shell elongated, moderately elevated, regularly arcuate, without 
jugum. Pale waxen, sometimes white. Valves wide, without 
apices. Front and back valves more or less concave ; posterior 
valve without elevated apex. Sculpture as in L. cancellatus, but 
the granules larger, lateral areas less defined. Sutural plates elon- 
gated. Girdle wide, densely beset with delicate scales. (Dall.*) 

Length 12, breadth 6* mill. 

Near Dominica, West Indies, in 138 fms. 

Leptochiton pergranatus DALL, 'Blake' Rep. p. 414, 1889. 

This fine species is nearest the Atlantic L. cancellatus Sowerby, 
and the Japanese L. fuliginatus Ad. & Reeve. It differs from both 
in its concave or excavated, instead of convex, terminal valves, in 
the absence or obsolete condition of the posterior mucro, in its 
much larger and more regular granules, and in the subdepressed 
appearance also of the part of the median valves near the girdle 
on each side. It is larger than cancellatus and smaller than full- 



LEPIDOPLEURUS. 7 

ginatus, and without the dingy blackish painting of either. L. can- 
cellatus is narrower, higher, and with a sharper median angle. In 
L.faliginatus the middle valves are shorter from front to back, the 
sutural laminae smaller and much more triangular. There is no 
sign of a mucro on these valves, but in L. pergranatus there is a 
beginning of one, quite perceptible. The latter is a proportionally 
wider and flatter species, with a stronger and more prominent girdle 
densely set with elongated silvery scales like short stiff gray hairs; 
these form a pretty fringe at the periphery. The sculpture follows 
the pattern of L. cancellatus, but the lateral areas are less clearly 
defined, the granules are more clearly cut, more regularly arranged 
and larger than in any of the species hitherto known. There are 
twelve gills on each side, reaching forward to about the middle of 
the sixth valve. (Dall.) 

L. BELKNAPI Ball. PI. 1, figs. 18-22. 

Shell elongated, much elevated, dorsally angled ; whitish, more 
or less tinged with ashen or black. Valves elevated, with distinct 
apices ; mucro central, conspicuous. Sculpture as in L. alveolus, 
but the granules of the dorsal areas sparse, and disposed in quin- 
cunx. Posterior valve concave below the apex, sinuated behind. 
Girdle narrow, having delicate spicules toward the margin. (DalL} 

Length 10, breadth 3 mill. ; divergence 90. 

North Pacific Ocean in lat. 53 08' N., Ion. 17 19' W., at a depth 
of 1006 fras. ; off Cape Bolinas, Luzon, Philippines, 1050 fins. 

Leptochiton belknapi DALL, Proc. IT. S. Nat. Mus. 1878, p. 1, 
Jan., 1878 ; L c. p. 317. HADDON, Challenger Rep. xv, p. 10, t. 1, 
f. 2 ; t. 2, f. 2. 

This specimen much resembles L. alveolus, to which I at first 
referred it. A careful microscopical examination, however, shows 
differences which I am disposed to consider specific ; but I have 
but one specimen, and others might show modifications in these 
particulars. The differential characters are as follows : In alveolus 
the pustules are distributed evenly, closely and in no pattern what- 
ever, all over the surface. In belknapi, they are more widely 
separated and arranged in quincunx on the dorsum, the spaces 
seeming to radiate from the median dorsal line. In alveolus the lat- 
eral areas are barely perceptible. In belknapi they are raised, con- 
centrically rugose, and the pattern of the pustular arrangement is 
different and more irregular than that on the dorsum. In belknapi 



8 LEPIDOPLEURUS. 

also the girdle is very thin, narrow, and sparsely set with small pel- 
lucid spicules near the margin. The posterior mucro or apex of 
the posterior plate, in belknapi, is prominent, overhangs a shallow 
concavity and from its point there diverge anteriorly four depressed 
lines, the outer two to the anterior lateral angles of the plate, the 
inner two equidistant from each other and the outer lines. Between 
these lines the plate is swelled, forming three rounded ridges, 
extending forward like the leaflets of a trefoil or clover. Nothing 
resembling this has been observed on any of the other species which 
have come under my notice. The soft parts in spirits appear to 
resemble the other species compared with it. It is evidently adult. 
(DalL) 

The figures represent the form dredged by the 'Challenger' off 
Luzon, Philippines. Haddon describes these specimens as follows : 

Shell. Brittle, closely covered with large, round, smooth tuber- 
cles. The sides meet at an angle of about 110. Sutural laminse 
small. 

Anterior valve. With a few irregular lines of growth, thickly 
covered with irregularly disposed tubercles. 

Intermediate valves. Central areas : with a shallow depression 
on each side of the median ridge, which gives the latter a pinched 
appearance ; this depression is most apparent at the hinder border 
of each valve. The tubercles have a general arrangement in 
oblique lines radiating forwards from the keel and at the same time 
in lines concentric to the umbo, but these two series of lines are not 
always regular, and the tubercles often appear to be irregularly dis- 
posed. A series of short concentric rows usually demarcate the 
anterior border of the lateral areas. Lateral areas : scarcely ap- 
parent ; a groove indicating a line of growth occurs at a short dis- 
tance from the girdle ; tubercles irregularly disposed, with a ten- 
dency, however, to concentric lines. 

Posterior valve. With a small subcentral umbo, behind which 
is a slight depression. Anterior area: the lateral longitudi- 
nal depression causes the jugum to be slightly prominent and thus 
gives the anterior area a somewhat trilobed appearance; the tuber- 
cles radiate from the rounded keel. Posterior area; with concen- 
tric lines of growth and closely set tubercles. 

Girdle. Narrow, thickly covered with delicate small oval scales ; 
longer, narrower and more pointed scales occur along the border 
and in the angles between the valves. 



LEPIDOPLEURUS. 9 

Color. Grayish-white. 

Size. Length about 12 ram.; breadth 5 mm.; height about 2*5 
mm. 

Gills. Forming a short posterior row, six or seven in number. 

This species is considerably larger and coarser than the preceding 
(L. benthus). The tubercles are twice the size and closer together. 
The shell is also comparatively sharply keeled, instead of having a 
gently rounded appearance. 

L. BENTHUS Haddon. PI. 1, figs. 1-13. 

Shell. Delicate, brittle, surface with minute inconspicuous short 
ridges more or less radially disposed, and studded with small tuber- 
cles. The sides meet at a rounded angle of about 100. Sutural 
laminae small. 

Anterior valve. With minute scattered tubercles, which pass 
towards the apex into low tubercular ridges, having a concentric 
arrangement. 

Intermediate valves. Central areas : The minute surface ridges, 
when visible, are longitudinally disposed on the jugum, but become 
radial or oblique on the pleura. The tubercles are round on the 
jugum, but become somewhat oval on the pleura, and there appear 
to be concentrically arranged, although in some valves they seem 
to more or less regularly diverge from the apex. Lateral areas : 
The surface ridges are radial and more pronounced than elsewhere. 
On the upper portion of the areas there are transverse low ridges 
placed further apart than the former ; these ridges by being inter- 
rupted gradually pass into tubercles. The tubercles are round, 
distinctly smaller than in the central areas, and more scattered. 

Posterior valve. With a small central umbo. Anterior area : 
With concentric tubercles, as in the lateral areas. Posterior area : 
Similar to the anterior valve. 

Girdle. Narrow, with delicate scales, which form a minute fringe 
at the edge. 

Color. Greenish-white with one or two irregular reddish-brown 
flecks. 

Size. Length, 8 mm. ; breadth, 3.5 mm. 

Northern Pacific, Lat. 35 41' N., long. 157 42' E., in 2300 fms. 

L. benthus HAD., Chall. Hep. xv, p. 10, t. 1, f. 1, t. 2, f. 1. 

Gills. Seven in number, extending between the prominent anus 
and postero-lateral angle of the foot. The gill row is one-seventh 



10 LEPIDOPLEURUS. 

of the total length of the body, the proportion with regard to the 
length of the foot is 1 : 4.5. They are of moderate size, the middle 
being the largest, slightly decreasing behind but much more so in 
front. (Haddon.) 

L. FULIGINATUS Adams & Reeve. PI. 4, fig. 88. 

Shell elongate, elevated, whitish, tawny-ashen sometimes soiled ; 
apices eroded ; jugum rounded. Mucro moderately elevated, posterior 
slope very concave; jugal area hardly defined ; central area hardly 
sculptured ; lateral areas quite elevated, frequently sculptured with 
irregular concentric incremental wrinkles; jugal sinus wide and 
straight. Girdle narrow, very thin, thickly covered with very deli- 
cate small and fugacious scales, which are somewhat elongated and 
purplish. (Qor.) Length 20, breadth 9J mill. ; divergence 90. 

Korea. 

Chiton fiiliginatus AD. & RVE., Conch. Icon. t. 26, f. 174, 1847. 
Leptochiton fullginatus A. & R., CPR. ms. p. 4, 5. DALL, Proc. U. 
S. Nat. Mus. 1878, p. 318, 316. 

This specimen is an approach to Stenoplax in its outward form 
and the character of its girdle covering. The scales appear smooth, 
and have the shape of those of Stenoplax. It has a curious general 
resemblance to Trachydermon albus, but the absence of insertion 
plates at once distinguishes it. , The concentric furbelowing at the 
sides is variable. (Qpr..from B. M. specimens.) 

See remarks under L. cancellatus for further distinguishing char- 
acters of this species. 

L. CATILLUS Reeve. PI. 4, fig. 87. 

Shell ovate, attenuated anteriorly ; terminal valves and lateral 
areas of the rest concentrically ridged, radiated with minute gran- 
ules, central areas very finely grooved and cancellated, whitish, liga- 
ment horny, arenaceous (Reeved) 

Habitat unknown. 

C. catillus Rv. Conch. Icon. t. 23, f. 159, 1847. Leptochiton 
catillus Rv., CPR. MS. p. 6. 

Might easily be taken for stramineus Sby. outside. Coarsely 
granose-lirate, like the Mogador specimen [Z/. granoliratus] ; girdle 
gravelly. The sculpture consists of longitudinal granose lira? upon 
the central areas, and radiating granose Iira3 upon the lateral areas. 
No insertion plates, but the line of them is rugose. Length 9, 
breadth 6-] mill.; divergence 110. Jugum rounded. (Cpr.) 



LEPIDOPLEURUS. 11 

L. CONCINNUS Gould. Unfigured. 

Shell minute, reddish, elliptical, vaulted, all over punctate [granu- 
lose], the points arranged in radiating, curving series ; lateral areas 
hardly elevated, longitudinally waved. Front valve crescentic ; 
posterior valve with an acute umbo. concentrically waved. Girdle 
narrow, buff. (Gld.~) Length 8, breadth 5 mill. 

Sutural plates small, subtriangular ; jugal sinus very wide, flat ; 
scales of the girdle delicate. ( Cpr.} 

HaJcodadi, Japan, laminarian zone, on shells and stones. 

C. (Leptochiton) concinnus GLD., Otia Conch, p. 117. Lepto- 
chiton concinnus CPR. MS., p. 3. DALL, Proc. U. S. Nat. Mus. p. 
318, 316, 1878. 

L. NEXUS Carpenter. Unfigured. 

Shell small, whitish-ashen, valves gothic-arched ; lateral areas 
scarcely defined ; entire surface ornamented with series of subquad- 
rate granules, the series longitudinal upon the central, radiating 
upon the lateral areas and end valves, very close, scarcely inter- 
rupted. Jugum elevated, subacute; umbones inconspicuous. Mucro 
conspicuous, median. Inside with strong sutural lobes and a wide 
plane sinus to the middle valves ; insertion plates obsolete. Girdle 
having narrow, close, striated scales and needle-shaped, crystalline 
bristles here and there and around the margin. (Cpr.~) 

Length 7i, breadth 4 mill.; div. 90. 

Catalina Island, California, 20-80 frns. 

Leptochiton nexus CPR., Rep. Brit. Asso. Adv. Sci. for 1863, p. 
650,1864; Proc. Cal. Acad. iii, p. 212, 1866; ms. p. 2. DALL, 
Proc. U. S. Nat. Mus. 1878, p. 316, 319. 

A variety is prettily variegated with olive, has stronger sculpt- 
ure, and the valves slightly beaked. The spicules which appear on 
the girdle among the striated, elongated scales, are very numerous. 
It is curiously like the young of Ischnochiton radians. ( Cpr.} 

See notes under L. cancellatus for comparison with that species. 

L. RUGATUS Carpenter, n. sp. PL 3, figs. 67-70. 

Oval, rather convex, the lateral slopes nearly straight, dorsal 
ridge broadly arched. Front and back valves and lateral areas of 
the intermediate valves sculptured with excessively fine radiating 
strise which are feebly granose, and having well-marked, coarse, con- 
centric wrinkles ; central areas having an equally minute sculpture 



12 LEPIDOPLEURUS. 

of longitudinal subgranose stride. Mucro subcentral and prominent. 
The lateral areas are slightly raised. 

Length 13-14, breadth 7 mill.; divergence 100. 

Monterey, CaL, to Todos Santos Say, L. California. 

L. (? internexus var.~) rugatus CPU. MS., p. 3. 

This form resembles somewhat the L. granoliratus, but it is much 
more finely sculptured, the arch of the valves is narrower and the 
lateral areas are less strongly marked by concentric wrinkles. It 
is likely that the following is merely the young of this, but I have 
not been able to compare typical specimens of internexus. 

L. INTERNEXUS Carpenter. 

Shell similar to L. nexus, but much smaller, orange colored. 
Valves regularly arcuate, without jugum. Sutural plates small, 
triangular; sinus larger. Girdle with more solid scales, scarcely 
pilose. (Cpr.) Length 4i, breadth 3i mill.; div. 90. 

Santa Barbara, California. 

L. internexus CPR. MS., p. 3. 

L. KERGUELENSIS Haddon. PI. 1, figs. 14-17. 

Shell. Minute, smooth, or with scattered minute tubercles ; the 
sides meet at an angle of about 100 ; sutural laminae small, tri- 
angular. 

Anterior valve. Small, smooth, with scattered aborted tubercles. 

Intermediate valves. Central area smooth, with very faint longi- 
tudinal striae; lateral areas scarcely discernible, with faint radial 
striae and minute concentric interrupted ridges towards the apex, 
which pass into inconspicuous small scattered tubercles. 

Posterior valve. With full rounded umbo, behind which is a 
shallow depression. Anterior area : similar to the central areas of 
the intermediate valves. Posterior area similar to the anterior 
valve. 

Girdle. Narrow, with delicate scales. 

Color. Uniform whitish. 

Size. Length 3, breadth T5 mill. 

Gills. Posterior, eight or nine in number (Haddon.^) 

Balfou.r Bay, Royal Sound, Kerguelen, 60 fms. 

L. Jcerguelensis HAD., Challenger Rep. xv, p. 12, t. 1, f. 3 ; t. 2, f. 
3a-3e. 

L. PAGENSTECHERI Pfeffer. PL 2, figs. 39-40. 

Shell elevated, roof-shaped, with the dorsal angle rounded; 
covered with a fine, indistinct, irregular granulation, without dif- 



LEPIDOPLEURUS. 13 

entiated areas. Middle valves with short but high sutural plates ; 
no insertion plates ; sinus large and deep ; the division of the central 
and lateral areas is marked inside by a slight groove. The front 
margin of the anterior valve is semicircular, the posterior margins 
meeting at an angle of 150. The posterior margin of the posterior 
valve is about the third of a circle, its front margin is seen from 
above as a straight line. The mucro is subcentral, somewhat more 
forward than behind. 

The color of the valves is a pale gray-brown, irregularly covered 
with brown dots which are lacking at the margins, leaving there 
a paler, unicolored zone. The girdle is brownish, the scales White. 
The length cannot be given exactly, as all the specimens were 
strongly rolled up ; but the maximum length seemed to be 4*7, 
breadth of the shell 2'5 of the girdle 0'8 mill. (P/r.~). 

South Georgia. 

Leptochiton pagenstecheri PFFR., Jahrb. Hamburg. Wissen- 
schaftlichen Anstalten, iii Jahrgang, p. 107, t. 3, f. 3, 1886. 

L. AHELLUS Spengler. PI. 3, figs. 64, 65, 66. 

Shell small, rather elevated, the dorsal ridge bluntly angular. 
Very minutely and evenly, but rather indistinctly, lirate-granulate; 
olive-ashen, often having longitudinal delicate pencilings of olive- 
green. 

Anterior valve very densely, minutely and evenly granulated, 
the granules being irregularly, but usually visibly, arranged in radi- 
ating rows ; the peripheral third of the valve having coarse concen- 
tric wrinkles. 

Intermediate valves have the central areas finely densely longi- 
tudinally granose-lirate. Lateral areas closely granose, the granules 
arranged in radiating rows on the lower portions, which are also 
wrinkled like the anterior and posterior valves. The lateral areas 
are separated from the central area by an inconspicuous low ridge. 

Posterior valve with subcentral, rather low umbo, the posterior 
slope concave. Interior of valves white ; sutural plates small. 

Lojoten Is., Norway, Iceland and Greenland, south to Gulf of 
Gascony. 

Chiton asellus SPENGLER, Skriv. Nat. Selsk. 1797, vol. iv, p. 99. 
LOWE, Zool. Journ. ii, p. 101, t. 5, f. 3, 4, 1825. BROWN; 
DESHAYES in LAMARCK An. s. Vert. ; MIDDENDORFF ; FORBES & 
HANLEY, Brit. Moll. vol. ii, p. 407, t. 59, f. 1, 2. Chiton minimus 
CHEMNITZ; WOOD; DILLWYN. Chiton cinereus MONTAGU; 



14 LEPIDOPLEURUS. 

SOWERBY ; REEVE ; LOVEN ; JEFFREYS, Brit. Conch, vol. iii, p. 
218, v, p. 198, t. 56, f. 2 ; P. Z. S. 1882, p. 668., non LINNE, teste 
HANLEY, Ips. Lin. Conch, p. 17. Lepiochiton cinereus GRAY, P. 
Z. S. 1847, p. 127, 168 (var. white, C. " albus " exclus.) as type of 
genus. Leptochiton asellus H. & A. ADAMS, Gen. i, p. 473. GRAY, 
Guide, p. 182. CPR. ms., p. 2. BALL, Proc. U. S. Nat. Mus. 1878, 
p. 318. / Lepidopleurus cinereus L., SARS., Moll. Reg. Arct.Norv. 
p. 112, t. 7, f. 8. Chiton islandicus GMEL., Syst. p. 3206. C.fus- 
catus LEACH, not Brown. C. scoticus LEACH, teste JefFr. C. onyx 
SPENGLER, Skrivter af Naturhistorie-Selskabet (Udforlig Be Skri- 
velse over det mangeskallede Conchylie Slaegt af Linne kaldet 
Chiton med endeel nye Arter og Varietat) Oplaest, 28 Febr., 1794. 
iv, 1 Heft. p. 62, 1797 cf. Mai. Bl. xvii, p. 113. 

This species is allied to L. granoliratus Cpr., but that is more 
elevated, the central and lateral areas are more diverse in sculpture, 
and the concentric wrinkles are much stronger. In L. cancellatus 
the lateral areas are raised, which is not the case with the asellus. 

" Under the microscope this species can easily be separated from 
T. cinereus I^n.(=marginatus JefFr.) by external characters. In the 
Tracliydermon the scales are very minute, smooth, granular, reddish 
and closely appressed to the girdle ; in the Leptochiton they are 
gravel-like, irregularly crowded, larger, lengthened and striated. In 
T. marginatus, also, the valves are more beaked, especially in young 
shells." (Cpr.') 

L. GRANOLIRATUS Carpenter, n. sp. PI. 2, figs. 47-53. 

Shell oval, rather low and regularly convex, not angulated dor- 
sally. Very finely and closely granose-lirate, the anterior and pos- 
terior valves, and the lateral areas of the median valves strongly 
corrugated concentrically. Color "ashen-orange" or fleshy-ashen, 
with an ill-defined darker dorsal stripe. 

The anterior valve, and the lateral areas of the intermediate valves 
are finely radially granose, and have a number of strong concentric 
wrinkles. The central areas have close fine subgranose longitud- 
inal lirse. The lateral areas are slightly raised. 

Umbo of the posterior valve somewhat in front of the middle, 
rather prominent ; posterior slope concave, radiately granose-lirate 
and strongly, irregularly, concentrically wrinkled. 



LEPIDOPLEURUS. 15 

Girdle narrow, closely beset with delicate elongated, striated 
scales. 

Length 10, breadth 7 mill. ; divergence 130. 

Mogador. 

Leptochiton granoliratus CPR. MS. p. 3. 

This species may easily be distinguished from L. asellas by its 
strong concentric wrinkles and the low, rounded arching of the 
back. 

L. CAJETANUS Poli. PL 2, figs. 41-46. 

Shell oblong, elevated, solid. Valves regularly arched, the lateral 
areas very strongly raised, coarsely sculptured. 

The median areas of the valves are sculptured with longitudinal 
lirse, which are granulous and anastomose or branch irregularly. 
The head valve has strong concentric ridges, 7 to 10 in number in 
adults, the intervals being finely pitted or granose. The lateral 
areas of the intermediate valves are very much raised, and sculp- 
tured with concentric ridges like the head valve. The posterior 
valve is very solid and thick, its apex posterior but recurved for- 
ward and much elevated ; its posterior slope is subvertical, convex, 
terraced. 

The sutural plates are triangular and stout; the jugal sinus 
rather narrow. Insertion plates are completely lacking. It is 
lusterless, and light buff in color. 

Girdle very narrow and thin, bearing most minute, close delicate 
deciduous scales. 

Length 23, breadth 12 mill. 

Length 11, breadth 6 mill. 

Mediterranean and Adriatic Seas; Atlantic Ocean from Cape 
Breton to the Gulf of Gascony ; Canaries ; Pliocene of Biot {Mar- 
itime Alps^), of Calabria and Modenais; Pleistocene of Monte 
Pellegrino. 

Ch. cajetanus POLI, Test. utr. Sicil., i, t. 4, f. 1, 2, 1791. PHIL. 
Enum. Moll. Sicil. i, p. 108, ii, p. 83. WEINKAUFF, Conch, des 
Mittelm, ii, p. 412. REEVE, Conch, Icon. f. 171. Lepidopleurus 
cayetanus Poli, Risso, Hist. Eur. Merid. iv, p. 267. Ch. caietanus 
Poli, JEFFR., P. Z. S. 1882, p. 667. Leptochiton cajetanus Poli, 
CPR. mss. p. 7. Holochiton cajetanus Poli, BUQUOY, DAUTZENBERG 
and DOLLFUS, Moll. Mar. Roussillou, i, p. 500, t. 61, f. 1-3 ; t. 62, 
f. 5. 



16 LEPIDOPLEURUS. 

In sculpture this species is strikingly different from the other 
Leptochitons, and in fact from all other Chitons. The lateral areas 
and front valve are strongly terraced, the latter being compared by 
Carpenter to a circular flight of rounded steps. 

The Atlantic specimens are always larger than those from the 
Mediterranean, the measurements first given above being taken from 
an Ocean example, the second measurements from an Italian speci- 
men. 

It is the type of Risso's genus Lepidopleurus. 

Section Deshayesiella Carpenter, 1878. 

Deskayesiella CARPENTER mss., p. 10. DALL, Proc. IT. S. Nat. 
Mus., 1878, p. 314; I.e. 1882, p. 286. HADDON, 'Challenger' 
Polyplacophora, p. 9. 

Shell elongated; valves curved, somewhat beaked; umbo flat- 
tened ; no insertion plates ; sutural plates triangular ; girdle spicu- 
lose. 

Differs from Leptochiton not only in its hairy girdle but also in 
its flattened umbo and its valves, which are somewhat thrown for- 
ward, forming a decided transition toward some of the palaeozoic 
forms. ( Cpr.) 

L. CURVATUS Carpenter, n. sp. PI. 4, figs. 78, 79, 80, 81. 

Shell rather elongated, whitish-ashen, planate ; dorsal ridge 
rounded ; umbo central, flat ; valves with pointed apices, all curved ; 
the interior of the posterior part of each valve much scooped out. 
Jugal area broadly V-shaped, quasi reticulated, the lines of pus- 
tules parallel in the middle, diverging at the sides, interstices punc- 
tate. Central areas with longitudinal distant, beaded lines, 8 to 10 
on each side, tending toward the jugum forward, interstices decus- 
sated. Lateral areas somewhat swollen, expanded, but scarcely 
denned by a line from the central areas ; coarsely, irregularly gran- 
ose, and concentrically waved. 

Inside: insertion plates absent, the position of them flat; sinus 
broad, following the curvature of the valve. 

Girdle delicate, clothed with small scattered spines, occasionally 
larger, and chaffy scales. (Qor.) 

Length 14, breadth 6 mill.; div. 120. 

Okosiri, Japan (A. Adams). 



HANLEYA. 17 

Leptochiton (Deshayesiella) curvatus Cpr., DALL, Proc. U. S. 
Nat. Mus., 1878, p. 314 (name and generic characters only). 
Deshayesiella curvata Cpr. MS. p. 10. 

This shell externally looks very much like an Acanthochiton 
without the pore bunches, of which there is no trace. The planed 
off parts inside the apices are unusually large. (Q?r.) 

Genus II. HANLEYA Gray, 1857. 

Hanleya GRAY, Guide Syst. Disk Moll. B. M., p. 186, type " H. 
debitis Gray= Chiton hanleyi Thorpe." Hanleyia DALL, and Han- 
leia of CARPENTER, MS. 

Anterior valve having an insertion plate without slits, but rough- 
ened ; intermediate and posterior valves having no insertion plates ; 
eaves small ; girdle with fine spines ; no girdle pores. 

This genus differs from Leptochiton and Deshayesiella in possess- 
ing an insertion plate upon the anterior valve. It differs from 
Hemiarthrum and Microplax in having no insertion plates upon the 
intermediate and posterior valves, and in lacking girdle pores. 

In Dr. Gray's original generic diagnosis, the girdle is said to 
have pores furnished with tufts of bristles. This has proved to be 
an error, the statement evidently having been based upon a speci- 
men in which the girdle was transversely wrinkled, throwing the 
bristles into close groups. 

H. HANLEYI Bean. PI. 3, figs. 71-79. 

Shell oblong, convex, the lateral slopes nearly straight, the dorsal 
ridge rather angular. Sculpture consisting of numerous rounded 
tubercles, arranged in longitudinal rows on the central areas, the 
series of tubercles finer and closer upon the jugum; head plate and 
lateral areas having coarser rather irregular tubercles. The lateral 
areas are not raised. The mucro is median, rather elevated. 

The plates of insertion of posterior and intermediate valves are 
obsolete, edges roughened ; anterior valve having a short, acute 
insertion plate, outwardly rugose-sulcate, the sulci indenting, but 
scarcely slitting the margin. Sutural plates moderate ; sinus very 
wide, denticulated by the sculpture of the outside. Eaves very 
small. 

Girdle narrow, beset with numerous short and longer horn-col- 
ored spicules. Length 10, breadth 5 mill., sometimes larger. 
2 



UNIVERSITY 
V ^.. c 



18 HANLEYA. 

British seas northward ; Scandinavia ; Mageroe, near North Cape, 
in 25-300 fms. ; Stelhvagen Bank, Massachusetts Bay, in 38 fms. 

Chiton hanleyi BEAN, suppl. to Thorpe's Brit. Mar. Conch, p. 263, 
f. 57, 1844. FORBES and HANLEY, Hist. Brit. Moll, ii, p. 398, t. 
62, f. 2. JEFFR., Brit. Conch, iii, p. 215 ; v, p. 198, t. 55, f. s. 
SARS, Moll. Reg. Arct. Norv. p. 109, t. 7, f. 5. Hanleia hanleyi 
Bean, CPR. mss. p. 8. Hanleya debilis GRAY, Guide, p. 186, 1857. 
Hanleyia debilis Gray, DALL, Proc. U. S. Nat. Mus. 1878, p. 319. 
f Chiton nagelfar LOVEN, Ind. Moll., p. 26. 

This species has been reported from Palermo by Monterosato 
(Jour, de Conch. 1878, p. 147). 

Var. ABYSSORUM M. Sars. PI. 4, figs. 74, 75, 76, 77. 

Closely allied to H. hanleyi, but more than double the size, hav- 
ing the girdle wider and thicker, spicules shorter; shell narrower, 
with less distinct sculpture. Pale brown, the girdle flesh-brown. 
Length 34 mill. (Sars.~) 

Bergen, Norway, 1 50-200 fms. 

Ch. abyssorum M. Sars, G. O. SARS, Moll. Reg. Arct. Norv. p. 
109, t. 7, f. 4 ; t. 34, f. 3. 

H. MENDICARIA Mighels & Adams. PI. 4, figs. 82, 83, 84, 85. 

Shell oblong-oval, not much elevated, dorsal ridge obtuse, lateral 
slopes flattened ; ashen-white, the entire surface granulated, gran- 
ules closely crowded, forming longitudinal series, about 20 on each 
side ; lateral areas hardly defined, irregularly granulated, the granules 
larger. Jugum scarcely defined, broadly vaulted. Mucro low or 
flat, central. 

Interior having a solid, rather acute, but scarcely fissured inser- 
tion plate to the anterior valve ; none upon the central and posterior 
valves. Sutural plates large, subtriangular ; sinus simple, wide, 
scarcely laminate. Eaves wide. Girdle wide, solid, leathery, 
very finely spiculate, the spicules glassy, here and there crowded ; 
no pores. 

Gills posterior, about 15 on each side. 

Length 15, breadth 8| mill. ; divergence 123. 

Length 27, breadth 15 mill. ; divergence 108. (Qor.) 

Casco Bay, Portland Harbor and Grand Manan, Maine. 

Chiton mendicarius M. & A., Bost. Journ. N. H. iv, p. 42, t. 4, f. 
8, 1842. GOULD, Invert, of Mass., Binney's Edit., p. 263, f. 526. 
Chiton (Acanthopleura) mendicarius Migh., JEFFR., P. Z. S. 1882^ 



HEMIARTHRUM. 19 

p. 667. Hanleyia mendicaria CPR., N. Eng. Chitons, Ann. Mag. 
N. H. (4) xiii, p. 121 ; MS., p. 9, 10. BALL, Proc. U. S. Nat. Mus. 
1878, p. 319. 

H. TROPICALIS Ball. PL 6, figs. 12-18. 

Chiton about lO'O mm. in length and 5'0 mm. in width, with the 
usual characters of the genus, i. e., anterior valve with an unslit 
insertion plate, other valves without even the plates ; back with an 
angle of about 90. Girdle (fig. 13) in the dried specimens, thin, 
narrow, covered with close-set, white, glassy, slender spines (TO-1'5 
mm. in length) above, and below with similar but much shorter 
ones. Anterior valve with a well-marked mucro, from which 
proceed concentric striae of growth, and in front of which the valve 
is a little concave ; sculpture of little less tesselated flattened nodules 
radiating from the mucro, above which are irregularly distributed 
small, opaque, white pustular bubbles of shelly matter looking like 
attached grains of coral sand ; posterior valve smaller, flatter, with 
similar sculpture, but the pustules take on a decidedly cylindrical 
shape and are elongated, looking like the stalks of decapitated 
mushrooms; this arrangement is still more marked on the posterior 
lateral areas of the intermediate valves, the anterior lateral areas 
also exhibit (less prominently), but with an obliquely anteropos- 
terior radiation, while the former have it more entirely lateral from 
the mucrones; dorsal areas with the tesselated sculpture alone, 
arranged longitudinally. Color entirely white. 

Sand Key, Florida, in 128 fms. 

Hanleyia tropicalis DALL, Bull. Mus. Comp. Zool. ix, p. 53, 1881 ; 
'Blake' Gastrop. p. 415, t. 26, f. 8c, 8d ; Bull. U. S. Nat. Mus. No. 
37, p. 172, t. 26, f. 8c, 8d. 

Genus III. HEMIARTHRUM Carpenter, 1876. 

Hemiarthrum CPR., in Ball's Moll, of Kerguelen I., Bull. U. S. 
Nat. Mus. ii, 1876, p. 44. 

Head and tail valves having smooth, unslit insertion plates, the 
intermediate plates lacking them. Eaves minute. Sinus broad and 
spongy. Girdle solid, downy, poriferous, the lateral tufts small. 
Gills short. 

Differs from all the preceding genera in having both head and 
tail valves provided with insertion plates, and in the poriferous 
girdle. 



20 HEMIARTHRUM. 

H. SETULOSUM Carpenter. PI. 5, figs. 89-100 ; 1-8. 

The color of the shell is a uniform warm dark brown, and the 
girdle is chestnut brown, with a pale crenulated border round the 
margin of the valves. In each of the dark triangular bays between 
the valves is a small tuft of short white spicular scales, and there are 
six similar tufts round the anterior border of the first valve. The 
anterior and posterior valves and the lateral areas of the inter- 
mediate valves are marked by concentric lines of growth, otherwise 
the latter are scarcely discernible. The jugurn is very gently 
rounded, so that the pleura are slightly depressed. The unslit in- 
sertion plate of the anterior and posterior valves is shown in figs. 
90, 94, and 4, 5, 6. The girdle (fig. 98) is thick and soft, with a 
few minute scattered scales. There is a distinct fringe of reddish 
brown elongated striated scales round the margin. The scales 
forming the tufts are stout, and white in color. Carpenter describes 
the anterior tufts as about four in number ; in my specimen there 
are six anterior tufts. Evidently Carpenter was not quite satisfied 
on this point, as in all other Chitons which possess tufts, only four 
are present; and, consequently, that number might be expected to 
occur in this species also. The head lappets are rather large, and 
the anus is on a large rounded papilla. The longitudinal band on 
the under side of the girdle (veil of Carpenter) is produced into flaps 
at the posterior extremity. 

The gills (pi. 5, figs. 1, 99, 100, 7), form a short posterior row, 
and appear to be about six in number ; they decrease in size anter- 
iorly. 

Length 9 mm. ; breadth 4 mm. ; side of valves meet at an angle 
of about 115. (Haddon.) 

Length 13, width 7 mill. (Q>r.) 

Kerguelen Island, on stones at low water (Kidder); and Royal 
Sound on shore (' Challenger ') ; South Georgia (Pfir). 

Hemiarthrum setulosum CARPENTER MS., p. 13. DALL, Bull. U. 
S. Nat. Mus. ii, 1876, p. 44. HADDON, ' Challenger ' Polyplacophora, 
p. 14, t. 1, f. 4; t. 2, f. 4a-l. MARTENS and PFEFFER, Jahrb. der 
Hamburgischen Wissenschaftlichen Austalten iii, p. 108, t. 3, f. 4, 
1886. 

The specimens from S. Georgia were much eroded ; they meas- 
ured about 8-11 mill., and were when alive, "brown-black almost 
black. " One of these is figured on pi. 5, figs. 1, 2, 3. 



MTCROPLAX. 21 

This shell, externally, resembles some of the coarse, ill-defined 
Acanthochitons. The girdle, however, is narrower and smoother 
than in that genus, and the pores so extremely minute that in a dry 
specimen they would escape attention. Within, however, the 
features are entirely new though not unexpected. It forms a tran- 
sition between Hanleya (mendicaria) and the articulate chitons. A 
single unslit lamina surrounds both the terminal valves, projecting 
far beyond the external layer. In the posterior plate this is con- 
tinued forward to form part of the sutural laminae. These in all 
the valves slope off both toward the middle and toward the sides, so 
as to take the place of the ordinary side-laminae, which here do not 
exist. 

Genus IV. MICKOPLAX Adams & Angas, 1864. 

Microplax H. AD. & ANG., Proc. Zool. Soc. 1864, p. 194, type M. 
grayi Ad. & Ang. CARPENTER MS., p. 12. 

Insertion plates smooth and thin, present in all the valves. Sut- 
ural plates obsolete, the sinus extremely shallow. Girdle thin, 
horny, most minutely granulous. Valves largely concealed in the 
girdle, the exposed portions small and separated. 

In the present genus a small portion only of each valve is exposed ; 
and the sutural plates and sinus are obsolete. No other Chiton 
having unslit insertion plates approaches this remarkable group. 

M. GRAYI Adams and Angas. PI. 6, figs. 9, 10, 11. 

Shell elongated, convex, brown ; exposed portion of the valves 
minute, wide heart-shaped, carinated, strongly granulated, the inter- 
vals between the exposed parts of the valves about as long as the 
latter. Lateral areas defined by a distinct rib. Girdle moderate, 
corneous, smooth (A. and A~). Length 13, width 5 mill. 

Sydney Harbor, Australia, under stones at low water. 

Microplax grayi H. AD. and ANG., P. Z. S. 1864, p. 194, /. c. 
1865, p. 58, t. 11, f. 16. ANGAS, P. Z. S. 1867, p. 224. CARPEN- 
TER MS., p. 12. 

The figures given were drawn by Mr. E. A. Smith from the type 
specimen. 

Carpenter's notes upon the unique specimen in coll. H. Adams 
are as follows: It is quite transparent, looking like thin horn. 
There are very slight overlappings of the valves, corresponding to 



22 MICROPLAX. 

the sutural lamina?, but no slits at all are to be seen. The laminse 
are very square, not wavy as in the other covered species. There 
is a very slight indication of riblets or striae continuing from the 
diagonal rib down to the edge of the lamina, but I cannot see the 
least indication of nicks or lobes at the edge. The sutural laminse 
are extremely slight, projecting over each other about to the line 
of the mucro, with the very slightest sinus in the middle between 
them. 

The front valve is horse-shoe shaped, with flat base, mucro a 
little removed from the margin. It is nearly smooth at the mucro, 
becoming gradually more granulose. The whole color is a greenish 
pink. 

The intermediate valves all point forward ; their mucrones in no 
case touch the posterior edges ; two smooth, diagonal ribs, curved 
forwards, separate the lateral and central areas, both of which are 
granulose. 

The posterior valve has the mucro a little anterior, the two 
oblique ribs curving backwards. 

It will be noted that the umbo or mucro in the posterior valve is 
directed forward, whilst in the other valves it is, as usual, directed 
backwards. 

The divergence is 76, very elevated. The exposed part of the 
valves measure about 1? X If mill. The girdle is everywhere 
minutely granular too minutely to be shown in the illustration. 



Family CHITONID^E. 

=Ischnoidea -f- Lophyroidea -f- Acanthoidea of CARPENTER. Isch- 
nochitonidce, Lophyridce and Acanthopleuridce DALL, Blake Gastro- 
poda, p. 415, 416. Lophyochitonidce, Chcetochitonidce (part), and 
Chitonidce ROCHEBRUNE, Miss. Sci. du Cap Horn, vi, Zool., p.{?131- 
143, 1889. Chiton L., FISCHER, Manual, p. 879. 

Chitons in which all of the valves possess insertion-plates slit 
into teeth ; the insertion-plate of the tail valve similar to that of 
the head valve. Eaves developed. 

The conclusion has been forced upon me that the three divisions 
B, Ischnoidea, C, Lophyroidea, D, Acanthoidea of Carpenter's 
arrangement cannot be separated by sufficiently definite characters 
to give them the rank of families. The Ischnoidea blend with the 
Lophyroidea through certain species of Chcetopleura, Tonicella and 
Tonicia; and the connection with those Acanthoidea having Isch- 
noid insertion plates is even closer. It is by no means certain that 
the Acanthoidea constitute a natural group ; the portion having 
pectinated insertion plates may prove more closely allied to the 
true Chitons (Lophyroidea), whilst those with sharp, smooth inser- 
tion plates would hold a like relation to the Ischnoidea. It is, in 
fact, not an easy matter to decide whether such genera as Callisto- 
chiton and Pallochiton belong to the Ischnoid or the Acanthoid 
series, Carpenter referring them to the former, whilst my own stud- 
ies cause me to place them in the last named group. 

In the present work I have concluded to recognize Carpenter's 
three divisions as subfamilies, believing it better to retain a classifi- 
cation admitted to be faulty than to institute radical changes which 
I am at present unable to place upon an indisputable basis. The 
regular Chitons having slit insertion plates may therefore be divided 
into the following three 

Subfamilies : 

Subfamily ISCHNOCHITONIN.E. Insertion plates smooth or nearly 
so, sharp, slit into teeth, which project outward on all of the valves. 

Subfamily CHITONIN^E. Insertion plates finely pectinated, blunt- 
edged, the teeth all projecting outward. 

Subfamily ACANTHOPLEURIN^:. Insertion plates smooth and 
acute, or pectinated and obtuse ; teeth of the posterior valve dis- 
tinctly directed forward, not outward. 

(23) 



24 CHITOXID^E. 

Subfamily ISCHNOCHITONIN^E. 

Ischnoidea CPR., Table of Regular Chitons, and DALL, Proc. U. 
S.Nat. Mus. 1882, p. 283, (in part; Genera 19-24 excluded). 
IschnochitonidcB DALL, ' Blake ' Gastrop. p. 415, 1889. 

I have above given some of the reasons which induce me to con- 
sider this group as a subfamily rather than a family. I am wholly 
disposed to believe that the subfamily as here constituted, is rather 
artificial ; and some of the genera may require consolidation. The 
relation existing between Chcetopleura and Tonicia especially calls 
for investigation ; and there are some forms (section Cyanoplax) which 
seem to bridge the gap between Chcetopleura and Tonicella. 

Synopsis of Genera of Ischnochitonince. 
Genus V. LEPTOPLAX Cpr. 

Valves thin, partly immersed in the thin smooth girdle ; insertion 
plates acute, having few slits. Umbo of posterior valve median. 

Genus VI. SPONGIOCHITON Cpr. 

Valves partly immersed. Insertion plates acute; umbo of pos- 
terior valve median. Girdle spongy, having chaffy scales and hair- 
lets, and produced forward. 

Genus VII. CH^TOPLEURA Shuttlw. 

Valves exposed ; insertion plates smooth or obsoletely grooved 
outside; eaves solid; umbo of posterior valve central or anterior. 
Girdle leathery, more or less hairy. 

Genus VIII. TONICELLA Cpr. 

Valves exposed ; insertion plates smooth or slightly grooved out- 
side ; eaves spongy ; umbo of posterior valve anterior. Girdle 
leathery and smooth, without scales or hairs. 

Genus IX. SCHIZOPLAX Dall. 

Valves exposed, and similar to those of Tonicella except that the 
intermediate valves have & median' longitudinal slit filled with cartil- 
age. Eaves very spongy. Girdle leathery, as in Tonicella. 



LEPTOPLAX. 25 

Genus X. CALLOCHITON Gray. 

Valves exposed ; insertion plates cut into numerous teeth rising 
from very spongy eaves, the teeth more or less buttressed at the out- 
side edges. Sutural-plates continuous across the very shallow median 
sinus. Girdle typically covered with fine compact diamond-shaped 
scales ; but in the subgenus Stereochiton sparsely downy, frequently 
naked by erosion. 

Genus XI. ISCHNOCHITON Gray. 

Valves exposed ; insertion plates sharp, smooth ; eaves not 
spongy, or rarely so. Umbo of posterior valve varying from pos- 
terior to anterior. Girdle covered with imbricating scales. 



Genus V. LEPTOPLAX Carpenter, 1882. 

Leptoplax CPR. MS., and Table of Kegular Chitons, 1871. DALL, 
Proc. U. S. Nat. Mus. 1882, p. 286. Type C. eoarctdtus Sby. 

Valves thin, partly immersed in the thin, smooth girdle. Inser- 
tion plates acute, with few slits, but regular. Sinus scarcely toothed ; 
mucro median. (Qjr.) 

The prominent characters of this genus are, (1) valves partly 
covered by a thin extension of the girdle, (2) girdle smooth, as in 
Tonicella, (3) insertion plates long, with few slits. The gills are 
unknown. 

L. COARCTATUS Sowerby. PL 11, figs. 38, 39. 

Shell elongated, very delicate, little elevated, the dorsal ridge 
acute ; greenish-ashen or reddish-olive. Valves of the normal form, 
but two-thirds covered by a thin cuticle continued from the girdle. 
Exposed portion of the valves flask-shaped, the jugular area smooth, 
subelevated, having longitudinal rows of points; central areas and 
end valves having large pustules, close and somewhat radiately 
placed, about 20 on each side in a young specimen, 100 in an adult ; 
lateral areas scarcely defined ; mucro slightly behind the center, 
rather elevated. Interior : Plates of insertion very long, rose- 
tinted, here and there delicately striated outside. Slits small, in the 
posterior valve 6, posteriorly situated ; central valves 1, anterior 
valves 4, having shallow grooves running up to the eaves. Sinus 



26 



SPONGIOCHITON. 



moderate, indented by the sculpture of the outside. Girdle very 
thin, rather expanded, smooth. (Cpr.) 

Length 131, breadth 7] mill. ; divergence 120. 

Island of Bohol, Philippines- 
Chiton coarctatus SOWERBY, P. Z. S. 1841, p. 62. REEVE, Conch. 
Icon., t. 20, f. 127. Leptoplax coarctatus CPR. MS., and Lept. 
rubrotincta CPR. MS. olim. 

This might be regarded as an extremely delicate Katherina, but that 
the valves are thrown forward and the tail-plate is Ischnochitonoid 
rather than Mopaloid. It differs from Fannia as Ischnochiton does 
from Chiton, in the extreme thinness and general smoothness of the 
sharp teeth and in the non-dentition of the sinus. I have seen no 
other regular Chiton in which the insertion plates are tinted, the 
head valve having only four slits, and the tail valve with so long a 
lamina, unfissured, at the anterior sides. ( Cpr.) 

Carpenter at first described this form under the name rubrotincta 
but he discovered its identity with C. coarctatus by an examination 
of the type of the latter. The sculpture varies much ; sometimes 
there are a few large grains, sometimes many smaller ones. 

Genus VI. SPONGIOCHITON Carpenter. 

Spongiochiton CPR., Table of Regular Chitons, 1873. DALL, 
Proc. U. S. Nat. Mus. 1882, p. 272, 283, 286, 289, 290. 

Valves partly immersed ; insertion plates acute, Ischnoid ; sinus 
large, smooth ; mucro median, flat ; girdle spongy, produced forward. 
(Qpr.) 

S. PRODUCTUS Carpenter, n. sp. 

Shell oval, the valves immersed two-fifths of their width ; exposed 
portion rubicund, flat, the jugum arcuate, paler. Lateral areas 
scarcely defined. Entire surface sculptured with prominent pebbles, 
worn at the jugum. Mucro submedian, flat. 

Interior : posterior valve with 6, central valve 1, anterior valve 
5 slits; teeth long, acute, scarcely serrate; sinus wide, smooth, 
extremely deep. Eaves narrow, scarcely grooved. 

Girdle produced in front, spongy, sparsely covered with chaffy 
scales and translucent hairlets. 

Length 25, breadth 161 mill. ; divergence 130. (Q>r.) 

New Zealand (Mus. Cum. no. 50). 



CHJETOPLEURA. 27 

This very peculiar shell resembles Mopalia blainvillei in mantle 
and mucro ; and Nuttallina in the long, smooth plates, separated by 
a deep, not laminated sinus. The side slits, however, are single and 
deep instead of duplicate and! angular, as in that genus ; the poste- 
rior plates are not thrown forward nor waved as in Mopalia. Leav- 
ing out of view the anterior prolongation of the mantle, which is a 
variable character even among Mopalia, it may be regarded as a 
partially covered Tonicella. The slits are abnormally few, as in 
Leptoplax. But for the characters of the tail plate I should have 
considered it intermediate between Mopalia and Katherina. (Cpr.~) 

Genus VII. CH^ETOPLEURA Shuttleworth, 1853. 

Chcetopleura SHUTTLW., Diagn. neuer Moll. no. 4, iiber den Bau 
der Chitoniden, etc., in Bern. Mittheil. p. 66, June, 1853 (=Acan- 
thopleura Gray, ex parte). Chcetopleura CPR. MS. and DALL, Proc. 
U. 8. Nat. Mus. 1878, p. 329, type C. peruviana Lam. Acantho- 
pleura, GRAY, Guide Moll. B. M. p. 183. 

Valves as in Ischnochiton ; eaves solid ; girdle leathery, more or 
less hairy ; gills extending almost or entirely to the front end of the 
foot. 

The present group seems to me to stand naturally on the confines 
of the Ischnochitonoid series, having decided relations to the true 
Chitons and especially to Tonicia. 

Carpenter made a subgenus, Maugerella, under Chcetopleura, for 
a Radsioid Californian form, which I have excluded from the genus, 
as its affinities are with the Radsioid Ischnochiton s. The following 
able discussion of this genus is from Carpenter's MS. : 

Shuttleworth, in distinguishing this genus from Acanthopleura by 
the mantle characters only, does not seem to have observed the co- 
ordinate differences in the hind valve and the insertion plates. 
Messrs Adams united to this genus Eudoxochiton and Craspedo- 
chiton which do not belong to the same section. Gray, in his 
" Guide," p. 183, ignores the genera of Shuttleworth, but preserves 
the distinction between Chaetopleura and Acanthopleura. Most 
unfortunately, however, he chooses to keep the name Acanthopleura 
for Chsetopleura of Shuttleworth and Add., and makes a fresh name 
Maugeria for the restricted Acanthopleura of Shuttleworth and 
Add. Even if Shuttleworth had been unwise in his mode of 
division, he would have been entitled to precedence ; but fortunately 
he kept Acanthopleura for the first section of Guilding's group, 



28 CHyETOPLEURA. 

Zool. Journ. v, p. 28, represented by Chiton spinosiis Sby. The 
West Indian species belonging to this section (A. picea) must have 
been familiar to him and given rise to the " zona crassa carnosa " 
of his diagnosis, with which Chsetopleura does not accord. The 
latter as represented by C. peruvianus, forms only the sixth among 
seven subgeneric sections into which Guilding divided his genus. 
Shuttle worth and Adams place the hairy Chitons in Chsetopleura 
and those with shelly bristles in Acanthopleura. 

The distinction is obvious as between peruviana and picea, but 
not so in the case of many species when the bristles are corneous but 
with more or less of shelly matter in their substance. There are 
also many species in which the hairs are shortened and flattened 
into chaffy scales and others in which hairs grow irregularly in the 
midst of a spongy or chaffy mass. Gray, moreover, assigns " shelly 
bristles" to the peruviana group and " shelly spines or bristles " to 
the picea group. To the first, however, are assigned thin, to the 
second thick valves. Both are described as having the insertion 
plates pectinated ; but as being " regular well developed " in peru- 
viana, but " narrow, rather irregular " in picea. This last results 
from what seems to me the essential difference. Acanthopleura is 
hunch-backed on the tail plate, with the insertion plates thrown for- 
ward and grooved outside; while Chsetopleura has the normal tail 
plate of Chiton and Ischnochiton and agrees with the latter genus 
in having the insertion plates not pectinated and nearly smooth. 
The transition forms from the densely pilose peruviana to the 
smooth mantle of Tonicella are so gradual that the latter might 
rank as a subgenus under Chsetopleura were it not that the gills in 
this genus are represented as elongate. (CJpr.) 

Chsetopleura should be compared with the Lophyroid genus Ton- 
icia, which has similar ambient gills and solid eaves, and frequently 
has the teeth scarcely more pectinated than in the larger Chseto- 
pleuras. 

The genus consists of several groups of species. (1) Typical 
forms, rather large, and having very delicate sculpture ; and (2) 
Group of C. gemmea, having the lateral areas strongly raised and 
coarsely sculptured, the central areas also sculptured. 

(1). Group of C. peruviana. 

C. PERUVIANA Lamarck. PI. 12, figs. 42-46. 

Shell oval, depressed, dull ash colored, the girdle clothed with 
long, stiff, crisp black hair, a fringe of which also projects from each 



CH^TOPLEURA. 29 

suture. The valves are minutely sculptured with very minute 
granules in lines which diverge slightly at the jugum, more upon 
the sides of the central areas, divaricate on the border between 
central and lateral areas, and are radiating upon the lateral areas 
and terminal valves. The umbo of the tail valve is low, somewhat 
anterior. 

Interior white with a brown stain at the back edge of each valve. 
Anterior valve having long insertion plates which are distinctly 
crenulated outside, and have 9-10 slits, central valves with 1 slit, 
post, valve with 7-9 slits. Sutural plates very broad, connected 
across the sinus by a narrow plate ; eaves narrow, short, not spongy. 

Length 38, breadth 26 mill. 

Lima, Peru ; Chili ; to Cape Horn. 

Chiton peruvianus LMK., An. s. Vert, vi, p. 321 ; ed. Dh., vii, p. 
491. Barnes, Amer. Jour. Sci. vii, p. 10, t. 3, f. 2. SOWB., Conch. 
Illustr. f. 44. REEVE Conch. Icon. f. 50. Ckaetopleura peruviana 
Lm., SHUTTLW., Diagn. n. Moll. nr. 4, p. 67. ROCHEBR., Moll. 
Cap Horn, p. 135. Acanthopleura peruviana Lm., TAP. CAN., 
Viag. Magenta, p. 77. 

This form is readily known by its girdle covering and sutural 
fringes of long black hairs. The sutural plates are strongly devel- 
oped, slightly recalling Leptoplax. The hair is. crisp and coarse, 
like that of a horse's tail. The gills extend forward to the head. 

C. HENNAHI Gray. PL 12, figs. 47, 48, 49 ; pi. 17, fig. 39. 

Shell oval, rather depressed, dorsal ridge obtuse, side slopes 
nearly straight. Color variable, but generally either reddish-brown 
marked with red, or greenish-w'hite marked with brown ; surface 
smooth to the naked eye. Girdle leathery, covered with short hairs, 
which may readily be rubbed off. 

The median valves are about four times as wide as long; the 
lateral areas are only weakly indicated ; the tail valve is depressed, 
with the slightly prominent umbo in front of the middle, the pos- 
terior slope concave. 'The sculpture consists of closely beaded fine 
separated threads, which are longitudinal on the central, radiating 
on the lateral areas and end valves ; under this may be seen an 
excessively fine, close shagreening of the whole surface. 

Inside white, each valve marked with brown under the beaks. 
Sutural plates of equal width from the outer angle of the valve to the 
rather shallow sinus. Ant. valve having 13, central valves 1, post. 



30 CHJETOPLEURA. 

valve 13 slits, (Carpenter gives: ant. v. 10, centr. 1, post. 9-12 
slits). Teeth sharp, those of the head valve prominently grooved 
outside. Eaves narrow and short, grooved just above the teeth, not 
spongy. 

Girdle (pi. 17, fig. 39) granulated, sparsely clothed with stiff 
white spinelets. 

Gills continuous to the head, as in C. peruviana. 

Length 43, breadth 28 mill. 

Callao Peru, on Pectens, in 5-7 fins- 

Ch. hennahi GKAY Spicil. Zool. p. 6, July, 1828. SOWB., Conch. 
Illustr. f. 1, 33. REEVE, Conch. Icon. t. 7, f. 37, and pi. 23, lower 
central figure. 

This species is closely allied to C. peruviana in form of the 
valves and sculpture. The girdle hairs are short, deciduous, and 
when retained they are disposed to lie in bunches. The front 
teeth are decidedly grooved outside, in old specimens resembling 
those of Tonieia fulva. 

C. NOBILIS Reeve. PI. 14, fig. 80. 

Shell ovate, smooth or very closely marked throughout with 
minute raised dots ; lateral areas faintly radiately grooved. Red- 
dish chocolate-brown, unspotted ; ligament horny, beset with very 
short, hard bristles (.Rve.) 

Habitat unknown. 

Chiton nobilis " Gray," REEVE, Conch. Icon. t. 21, f. 139, May, 
1847. Not Chiton nobilis Gray. Chcetopleura nobilis Rv., CPU. 
MS. 

Carpenter further describes the type specimen : mucro median 
little elevated ; valves rounded at the sides. Interior. : post, valve 
with 9, ant. 11, centr. 1 slit. Teeth acute; eaves small; sinus 
small, deep, planate, smooth. Girdle leathery, pale brown, sparsely 
and irregularly beset with very short, solid, black, somewhat scale- 
like bristles. 

The above is written from the type specimen which Rve. described 
as the C. nobilis of Gray, and which Mr. Adams most kindly sub- 
mitted to my examination. This shell proves to be a normal Chseto- 
pleura : while Eudoxochiton nobilis Gray, belongs to the Lophy- 
roid section. Lest the confusion should be repeated, the following 
notes on the sculpture of C. nobilis Rve. may be useful. 



CH^ETOPLEURA. 31 

Central areas having subparallel or slightly radiating lines of 
granules, about 20 on each side. Lateral areas scarcely defined, 
having about 10 irregular radiating lines, the ant. valve having 50, 
post, valve 40 such lines. Entire surface most minutely punctate. 

This species must not be mistaken for the externally very similar 
Eudoxochiton. 

(2) Group of C. gemmea. 

C. GEMMEA Carpenter, n. sp. PI. 13, figs. 69-74. 

Shell oblong, elevated, red, olive-ashen or yellow ; umbo of tail 
valve depressed, situated behind the middle. Lateral areas decidedly 
raised, coarsely radiately tuberculate ; central areas having longi- 
tudinal beaded lirse. Girdle narrow, leathery, sparsely clothed with 
short hyaline hairs, which are readily rubbed off. 

The valves are elevated. The central areas are sculptured with 
elevated, distinctly beaded longitudinal cords, about 15 in number 
on each side ; they became very small or subobsolete upon the 
jugum. The lateral areas are strongly differentiated ; they have 5 
to 7 radiating rows of distinct, clear-cut tubercles. The mucro does 
not rise above the general level of the posterior valve. 

Inside often tinted with red, often having a red or black spot at 
the jugal sinus. Sutural plates well-rounded, the sinus rather deep 
and angular. Anterior valve having 9-12, median 1, posterior 
valve 7-8 slits. Teeth rather blunt and stout ; eaves not spongy, 
rather wide. 

Length 16J, breadth 8 mill. 

Monterey, California. 

Chwtopleura gemmea CPR. MS. 

This beautiful little species is excessively similar to Ischnochiton 
mertemii in sculpture, but the smaller size, narrower form, and 
especially the short, transparent hairs of the girdle, distinguish it. 

C. BULLATA Carpenter. 

Shell subovate, elevated, olivaceous; intermediate valves ornamented 
with strong rows of pustules ; lateral areas very narrow, tubercu- 
late, sometimes pustulate. Central areas having lines of tubercles, 
about 7 on each side, and perpendicular lines, interstices granulated. 
End valves having about 11 radiating rows of pustules; mucro 
somewhat conspicuous. Girdle wide, having small hairlets. Sutural 



32 CEUETOPLEURA. 

plates triangulate ; sinus deep ; margins of the valves simple, the 
median having 1, the terminal valves about 7 slits. (Qyr.) 

Length 4J, breadth 3, alt. t mill; divergence 110. 

Muzatlan, on Spondylus calcifer. 

Lepidopleurus bulletins CPU., Mazat. Catal. p. 195. Chcetopleura 
bullata CPR. MS. L. bulletins var. calciferus CPR., 1. c. p. 196. 

One fresh specimen (somewhat crushed in extraction) and a few 
perfect valves were found of this species, which is characterized by 
the very strong row of tubercles, (like pebbles) which lie on the 
diagonal line ; by the rows of somewhat strong tubercles on the 
central area, running perpendicularly from the diagonal towards the 
jugum and the granules over the whole surface, somewhat corru- 
gated on the jugum. The internal plates of all the valves have an 
external projection from the outer surface, as in L. sanguineus. 

Carpenter describes a larger specimen in ms. as follows : Mucro 
median, scarcely elevated. Vermilion and olive, very irregularly, 
vividly maculated. Interior: posterior valve with 9, central valves 
1, anterior valve 11 slits. Teeth acute. Eaves projecting, pectin- 
ated by the sculpture. Sinus moderate, high, laminate. Girdle 
smooth, ornamented with sparse hairlets. Gills subambient, scarcely 
reaching the head. Abedhas Keefs. (Mus. Yale College). This 
specimen is about 15 mill, long, GT broad, divergence 125. It 
agrees in most respects with the very young shell described in Maz. 
Catal., but is much longer in proportion. 

Var. CALCIFERA Cpr. 

Lateral areas tuberculate, without pustules ; diagonal line peb- 
bled ; central areas with lines of tubercles irregular, tubercles smal- 
ler. Hairs of the girdle larger, very close. 

Mazatlan* 
C. BEANII Carpenter. 

Shell ovate, elevated, brown-olive or maculated with whitish and 
bluish. Intermediate valves strongly mucronate, interstices curved, 
margins somewhat rounded. Posterior valve depressed, excavated, 
the mucro small, superior; jugal and lateral areas indistinct; sur- 
face covered with granules and ornamented with small close points. 
Sutural plates large, curved; sinus flat; insertion plates acute, the 
intermediate valves with lj terminal valves 10 slits. Girdle hairy, 
spines small, erect, flat. 

Length 5:|, breadth 3i, alt. 1 mill.; divergence 110. 

Mazatlan* 



CHJETOPLEURA. 33 

f Lepidopleur us beanii CPR., Maz. Catal. p. 197. Chcetopleura 
beanii CPR. MS. 

Differs from L. Macandrei in being longer, with the valves 
mucronated and rounded at the extremities, the posterior being hol- 
lowed out and the rest much elevated, without conspicuous middle 
portion or lateral areas. The only perfect specimen found (on 
Acma3a fascicularis) displays no trace of solid scales. The account 
of the interior is taken from a large central and small anterior 
valve supposed to belong to this species from their agreement in 
other respects. 

C. FLAVESCENS Carpenter. Unfigured. 

Shell ovate, much depressed, yellow, spotted with orange. Valves 
wide, somewhat rounded at the margins, the interstices curved, 
strongly mucronate. Lateral areas and jugum indistinct ; mucro 
small, superior. Entire surface furnished with close granules, 
scarcely punctulate ; girdle thick, nearly smooth, furnished at the 
margin with delicate erect flattened spines. Sutural plates large, 
arcuate; sinus large. End valves with about 10, intermediate 
valves 1 slit. Length 4, breadth 2f, alt. f mill.; divergence 150. 

Mazatlan, on shells. 

Chiton flavescens CARPENTER, Maz. Cat. p. 198. 

This is the least uncommon of the small Chitons, six specimens 
having been found of it. It is distinguished by its yellow color, 
great depression and imall strong mantle margin, without covering, 
except at the margin where a fine row of transparent flattened hairs 
may be seen. The smaller lobe on the margins of the inner valves 
is bounded by two rows of holes which proceed to the jugum. (Cpr.) 

C. LURIDA Sowerby. PI. 12, figs. 53, 54. 

Shell oblong, rather elevated, ashen ; front valve, lateral areas of 
intermediate valves and posterior valve coarsely granulose; central 
areas longitudinally sulcate, threads between the grooves granulose. 
Length 30, breadth 15 mill. (Sby.*) 

Sta. Elena, W. Colombia, on stones in 5 fms. 

Chiton luridus SOWB., P. Z. S. 1832, p. 26 ; Conch. Illustr. f. 20. 
REEVE, Conch. Icon. f. 85. Chiton scabriculus SOWB., P. Z. S. 
1832, p. 28 ; Conch. Illustr. f. 21. REEVE, 1. 15, f. 81.Ischnochiton 
parallelus CPR., Ann. and Mag. N. Hist. (3), xiii, p. 314. Ischno- 
chiton (? var.~) prasinatus CPR., I. c., p. 314. 
3 




34 CH^TOPLEURA. 

To this species Carpenter unites C. scabriculus Sowb. (pi. 12, figs. 
55, 56) and Ischnockiton parallelus Cpr., a figure of which, drawn from 
a Carpenterian specimen from Cape St. Lucas, is given on pi. 12, 
fig. 50. It is likely that C. columbiensis should be added to the 
synonymy, as it presents no differential characters of much value. 

Var. PARALLELA Cpr. PI. 12, fig. 50. 

The specimen before me of the form parallelus, measures 17 by 
11 mill. It is rather acutely carinated, the sides slopes nearly 
straight. There are 17 beaded longitudinal threads on each side 
of the central areas, and from 6 to 7 rows of separated, rounded^ 
erect tubercles on each lateral area. The lateral areas are decid- 
dly elevated; the mucro is slightly prominent. The girdle has 
sparsely scattered hyaline short hairs. The gills continue as far as 
the front end of the foot. The outside is reddish, marbled with 
darker and white, the girdle dark ashen. The interior is bluish- 
white. 

Cape St. Lucas. 

The style of sculpture is the same as in C. gemmea, but the shell 
is much broader than in that species. 

Var. PRASINATA Cpr. 

Similar to parallela, but vivid green ; lateral areas irregularly 
ornamented with series of tubercles. Cape St. Lucas. 

Var. COLUMBIENSIS Sowerby. PL 12, figs. 51, 52. 

Shell ovate, a little depressed, ashen ; end valves and lateral 
areas sparsely granulose ; central areas longitudinally granose-lin- 
eate. (Sby.) Length 31, breadth 18J mill. 

Bay of Panama, under stones at low water. 

C. columbiensis SOWB., P. Z. S. 1832, p. 58 ; Conch. Illustr. f. 15. 
REEVE, Conch. Icon. f. 82. Cficetopleura columbiensis Sby. CPR., 
ms. 

Carpenter says: Mucro slightly in front of the middle, sub- 
planate, the posterior part excurved. Interior: posterior valve 
with 8, anterior valve 9, central 1 slit. Teeth obtuse, scarcely 
roughened; eaves large; sinus narrow, moderately deep. Girdle 
leathery, with a few corneous hairlets. . . . One of Colonel 
Jewett's specimens is of a uniform dark chocolate color, but parts 
of some of the valves are of a variegated olive. 

Of another specimen Cpr. writes : One specimen of the scabri- 
culus type. Girdle finely hairy. Red, with dark girdle. On each 



CH7ETOPLEURA. 35 

side of the central areas there are 16 fine rows of beads, not very 
much developed ; jugular areas not defined ; side areas with irregu- 
larly scattered grains. Mucro central, depressed. 

Length 28, breadth 17 mill. 

Carpenter seems disposed to unite to columbiensis the species 
described as scabriculus and luridus, the former of these two being 
less, the latter more beaded than the typical columbiensis. In case 
this view is correct, columbiensis will fall into the synonymy of 
luridus. 

C. ISABELLEI d'Orbigny. PL 13, figs. 57, 58. 

Shell oblong, brown ; back carinated ; front valve and lateral 
areas of the intermediate valves radiately granulate ; central areas 
longitudinally granulose-striate. Length 22 mill. (Or&.) 

Bay of San Bias, Patagonia. 

Chiton isabellei ORB., Voy. dans I'Ame'r. Merid. p. 488, t. 65, f. 
14-19. Tonicia isabellei ROCHEBR., Cap Horn, p. 138. Chceto- 
pleura isabellei CPR. MS. 

Allied, by its granulated stride, to C. peruvianus, but narrower, 
more carinated, the girdle smooth. ( Orb.) 

The gills are figured as continuing almost to the front end of the 
foot. Tn the absence of any information regarding the insertion 
plates it is impossible to say whether this species is a Tonicia or a 
Chcetopleura ; if the latter, the girdle is probably not truly smooth. 
In sculpture it seems near to columbiensis and its allies. 

C. DIEFFENBACHII Reeve. PI. 13, figs. 65, 66. 

Shell somewhat elongately ovate ; valves covered with very min- 
ute raised dots ; lateral areas scarcely raised ; posterior valve umbo- 
nated ; variegated with red, green and yellow ; ligament horny, 
arenaceous. (Rve.~) 

Newcastle) Australia. 

Chiton dieffenbachii RVE., Conch. Icon. t. 22, f. 149 ; species no. 
148. 

The locality must be regarded with doubt until confirmed. It 
may prove to be from Peru, and a synonym or variety of C. lurida 
Sowb. The figure is enlarged. 

C. APICULATA Say. PI. 13, figs. 75-79. 

Shell oval, elevated, light buff or ashen, unicolored or having 
black patches at the sides or on the ridge (sometimes red or purple 



36 CH^TOPLEURA. 

in Southern specimens) ; carinated, the side-slopes nearly straight ; 
central areas having beaded threads, lateral areas and end valves 
having numerous scattered pustules. 

The lateral areas are distinctly defined, raised, and bear numer- 
ous erect rounded pustules, irregularly scattered, not arranged in 
rows. The end valves have the same sculpture, but the pustules 
are more crowded. The central areas have minutely beaded longi- 
tudinal threads, from 15 to 20 on each side. The umbo of the pos- 
terior valve is in front of the middle, and rendered slightly pro- 
jecting by the concavity of the slope back of it. 

The interior is white or stained with leaden in places. The 
sutural plates are rounded ; sinus moderate but angular. Slits of 
anterior valve 11, central valves 1, posterior valve 9-11. Teeth 
slightly crenulated ; eaves short, solid. 

Girdle narrow, bearing sparsely scattered, transparent, short 
hairs. 

Gills extending almost to the forward end of the foot, 24 branchiae 
on each side. 

Length 17, breadth 10 mill. 

Length 16, breadth 12 mill. 

Cape Cod, Massachusetts, to Florida. 

Chiton apiculatus SAY, Amer. Conch., edit. Binney, p. 231. 
SOWB., Conch. Illustr. f. 140. DEKAY, Moll. N. Y. p. 164, t. 10, f. 
201, 202. GOULD, Invert, of Mass. (edit. Binney), p. 258, f. 522. 
Chcetopleura apiculata Say, CPR. Ann. Mag. N. H. (4), xiii, p. 
120. DALL, Proc. U. S. Nat. Mus. 1882, p. 410 ; Bull. 37, U. S. 
Nat. Mus., p. 172, t. 51, f. 10. Chiton labeculatus REEVE, Conch. 
Icon. t. 18, f. 108. 

The tubercles of the lateral areas and end valves of this species 
show a lack of arrangement into radiating rows, which will readily 
distinguish this from other species. 

It is quite commonly distributed along the Atlantic coast of the 
United States from Naritucket to Florida, and has also been 
reported from Haiti. 

The Northern examples are generally buff or ash colored, some- 
times with patches of black ; but in a suite before me from Marco, 
Florida, one specimen is scarlet and another purplish-pink. These 
southern examples, whilst agreeing with the typical form in sculp- 
ture, are smaller and comparatively narrower. (Figs. 78, 79.) 
A specimen from Anglesea, New Jersey, has the lateral areas and 



CH^ETOPLEURA. 37 

end valves pink, the central areas buff, and each valve has a trian- 
gular black patch at the dorsal ridge. The girdle is alternately 
buff and pink. 

C. CANDISATUS Shuttle worth. Unfigured. 

Shell elliptical, convex, dull waxen, the back sometimes banded 
with white ; terminal valves having large white granules, which are 
much elevated, sparsely and somewhat concentrically arranged. 
Median valves subcarinated, the central areas having smaller whit- 
ish granules, arranged in straight necklace-like series, crowding at 
the umbones; lateral areas conspicuously elevated, having large, 
remote, irregularly placed granules. Entire surface covered with a 
very minute, chaffy puncticulation. Girdle narrow, waxen, marbled 
with pale brown; chaffy-pustulose, and having pellucid, corneous 
white setae here and there, especially at the insertions of the valves. 

Length 8-9, breadth 4*-5 mill. 

Guadeloupe, on dead valve of Cardium serratum. 

Chiton (Chwtopleura) candisatus SHUTTL., Jour, de Conch. 1856, 
p. 168. 

Apparently closely resembling C. apiculata Say, in pattern of 
sculpture. 

C. JANEIRENSIS Gray. PI. 13, figs. 59, 60. 

Shell oblong, elevated, rather narrow ; dorsal ridge somewhat 
angular, olive-ashen or brownish ; strongly sculptured, the mucro 
in front of the middle, rather prominent. 

Lateral areas strongly elevated, sculptured with four coarse, 
granoseribs; anterior valve having 11 to 18 such ribs, usually 
having a tendency to be in pairs or to split. Central areas having 
about 12 granose acute threads on each side of the jugum, parallel 
with it. 

Interior white, sutural plates rounded ; sinus shallow ; anterior 
valve with 10, median valves 1, posterior valve 9 slits. Teeth solid, 
eaves wide, solid. 

Girdle having a few delicate short hairs. 

Length 18, breadth 9 mill. 

Gills reaching the neck. 

Key West, Florida, to Rio Janeiro, Brazil. 

Chiton janeirensis GRAY, Spicil. Zool. p. 6, t. iii, f. 8, 1828. 
SOWB., in Zool. Beechey's Voy., t. 40, f. 2. REEVE, Conch. Icon, 



38 CH^ETOPLEURA. 

t. 19, f. 116 (not t. 15, f. 81). SOWB. Conch. Illustr. f. 56. Chce- 
topleura janeirensis CPR. MS. ; C. apparata and Callistochiton rufi- 
costalus CPR., olim. Chcetopleura janeirensis DALL, Bull. 37, U, S. 
Nat. Mus. p. 172. Chiton segmentatus REEVE, Conch. Icon. t. 23, 
f. 155. Chiton (Chcetopleura) asper SHUTTLW., Jour, de Conchyl. 
1856, p. 169. 

This species is much elongated, about twice as long as broad- 
The sculpture of the end valves and lateral areas consists of coarse, 
nodulous ribs, which are quite unlike the clear-cut pustules of C. 
apiculata, gemmea, etc. 

Young specimens have only two or three nodulous ribs on the 
lateral areas. 

The C. segmentatus of Reeve (pi. 13, figs. 61, 62) differs in no 
way from the type. 

C. SPINULOSA Gray. PL 13, figs. 63, 64. 

Shell ashen, partially tessellated with dark and light at the 
sutures, and stained with brown on some of the jugular areas. 
Jugum very acute, elevated. Mucro median, not much raised, the 
posterior slope very concave. Jugal area not distinct ; central 
areas having about 22 rows of very fine granules on each side of 
the otherwise smooth areas ; lateral areas much raised, having 
about 10 rows of radiating grains, separate, sparse; grains very 
irregular and sparse on terminal valves. 

Interior: Anterior valve with 10, central valves 1, posterior 
valve 9 slits. Teeth not very sharp but Ischnoid, the posterior 
slightly rugulose. Sinus smooth, channelled, broad, deep, the 
projecting jugular sculpture of the outside giving a faint appear- 
ance of denticulation. Eaves moderate, not spongy. Interior 
whitish, with two rays of chestnut. 

Length 31, breadth 15 mill. 

Rio Janeiro. 

Chiton spinulosus GRAY, Spicil. Zool. p. 6, t. 6, f. 7, 7a. Sowb., 
Conch. 111. f. 84, 84a. REEVE, Conch. Icon. t. 27, f. 90. Chceto- 
pleura spinulosa CPR., MS. 

It is doubtful whether the C. spinulosa of Sowerby, Reeve and 
Carpenter is the same as the form originally so named by Gray. 
Carpenter's description/ given above, is drawn from a single speci- 
men, which apparently served Reeve for his illustration. This 
specimen is much injured, having lost its girdle, and some of the 



CH^TOPLEURA. 39 

valves and teeth are broken. The figures here given are from 

Reeve. 

C. SOWERBIANA Reeve. PL 13, figs. 67, 68. 

Shell oblong-ovate, valves having the lateral areas conspicuously 
elevated, granosely ridged throughout, ridges of the central areas 
much finer. Dull yellowish-brown, with a triangular whitish spot 
along the umbonial summit of each valve. Ligament horny. 
(Eve.} 

Rio Janeiro. 

Chiton janeir ens is Gray, REEVE, Conch. Icon. t. 15, f. 80. C. 
sowerbianus REEVE, L c., in note under species No. 116, May, 1847. 
Sowerbyi REEVE, 1. c., expl. of pi., detail of sculpture, sp. 80. 
Sowerbyanus REEVE, /. c., index to Chiton. 

Carpenter says : Seems to me a coarse var. of spinulosa Gray. 
Rio Janeiro. Very like apiculata, but with more swelling side areas. 
The sinus represented in the sculptured figure of Reeve is only the 
part left after the swelling of the sides. With this impression, I 
did not think it necessary to examine the single specimen in Cum- 
ing's collection ; but on further examination I thought it might be a 
distinct species and described it thus : Valves arched ; jugum rather 
rounded ; jugular area finely striate. Central areas having about 
18 nearly parallel ribs on each side, the interstices decussated 
between the ribs, which are sharp (not in necklaces). Lateral 
areas swelling, with 6 to 8 very close rows of coarse granules, inter- 
calating, and no spaces between. In the end valves they go into 
close radiating rows. Mucro in front of the middle, depressed, the 
slope behind it very concave. Girdle with very few scattered hairs. 
Interior: Anterior valve with 9, central 1, posterior 8 slits; teeth 
sharp, normal ; eaves conspicuous, rugulose, but not spongy. Sinus 
moderate, sharp, deep, channelled. 

Length 26J, breadth 13 mill. 

C. ARMILLATA Carpenter, n. sp. Unfigured. 

Shell subelongate, elevated, the jugum acute; mucro a little in 
front of the middle; reddish-brown, maculated with darker. 
Valves quadrate, scarcely apicate ; jugal area scarcely defined; 
central areas having 14 to 20 lines of small granules on each side, 
the interstices flat. Lateral areas scarcely elevated, having sub- 
radiating, distant, sparse granules ; entire surface nearly smooth, 
very minutely punctulate and striatulate under a lens. Interior : 



40 TONICELLA. 

Posterior valve with 9, anterior 9, central 1 slit. Teeth acute ; 
eaves conspicuous ; sinus narrow, deep, smooth. Girdle leathery, 
very minutely downy-scaled and having occasional delicate, corneous 
hairs. (Qor.) Length 25, breadth 11} mill.; divergence 100. 

Is. Gorriti (Mus. Cum. No. 34). 

One of the specimens is light colored on the jugum of each valve, 
encircled with a triangular spot. (Q>r.) 

Genus VIII. TONICELLA Carpenter, 1873. 

Tonicella CPR., Bull. Essex Inst. v, p. 154, 1873, type C. marmo- 
reus Fabr. DALL, Proc. U. S. Nat. Mus. 1878, p. 324. Tonicia, 
in part. of GRAY, ADAMS, et al. Boreochiton (part) SARS, Moll. 
Reg. Arct. Norv. p. 116, 1878. 

Valves, sutural plates sinus and teeth as in Ischnochiton, but the 
eaves are spongy ; girdle as in Tonicia, leathery, smooth or nearly 
so. Gills extending forward from two-thirds to three-fourths the 
length of the foot. 

Distribution, Northern Atlantic and Northern Pacific shores. 

This group differs from Trachydermon, Callochiton, Ischnochiton, 
Chcetopleura, etc., in its naked, scale-less girdle ; from Stereocliiton 
in having a single slit in the median insertion plates. It differs from 
Tonicia, to which genus the species of Tonicella were formerly referred, 
in the non-pectinated insertion plates, spongy eaves and shorter gills. 

The surface of the valves is smooth, or evenly microscopically 
granulated. 

The essential differences between Tonicella and Chcetopleura seem 
to be bridged by several species which are intermediate in charac- 
ters .of gills, girdle or both. The former should perhaps rank as a 
subgenus rather than a genus, as the pattern of sculpturing of the 
valves, shorter gills and spongy eaves are about all there is to sep- 
arate the two groups. 

Under Tonicella, as a subgenus, I include the peculiar type Cyano- 
plax, proposed for the reception of the C. hartwegii Cpr. The genus 
will therefore be divided thus : 

Subgenus TONICELLA s. s. 

Teeth rather long; valves nearly smooth ; gills shorter than the 
foot. 

Subgenus CYANOPLAX Pils. 
Teeth stumpy, bi- or tri-lobed ; valves granulated ; gills ambient. 



TONICELLA. 41 

Subgenus TONICELLA Cpr. 
T. MARMOREA Fabricius. PI. 10, figs. 8-15. 

Shell oblong or oval, elevated, rather acutely angular ; buff, 
closely speckled and maculated with dark red, as in Trachydermon 
ruber. Surface densely, microscopically granulated, but apparently 
smooth. Lateral areas not distinct. Valves beaked, umbo of pos? 
terior valve slightly prominent, central. 

Interior rose tinted; anterior valve with 8-10, median valves 1, 
posterior valve 8-9 slits. Sutural plates broad, rounded ; sinus 
deep, angular. 

Girdle leathery, nude. 

The gill rows extend forward three-quarters the length of the foot, 
each containing 20-25 branchiae. 

Length 40, breadth 24 mill. 

Length 27, breadth 16 mill. 

North Atlantic : Massachusetts Bay to Greenland ; ^Holland to 
Ireland and northward. North Pacific: Aleutian Islands and 
Japan. 

Chiton marmoreus FABR., Faun. Gronl. p. 420, 1780. FORBES 
<fc HANLEY, Hist. Brit. Moll, ii, p. 414, t. 58, f . 2 ; t. 59, f. 4. 
JEFFREYS, Brit. Conch, iii, p. 227; v, p. 199, t. 56, f. 7. Chiton, 
(Tonicia) marmoreus Fabr. Smith, Ann. and Mag. N. H. (4) xx, p. 
139 (Franklyn Pierce Bay, Greenland). Tonicella marmorea Fabr. 
CPR., Bull. Essex Inst. v, p. 154, 1873 ; Ann. Mag. N. Hist. (4) 
xiii, p. 121. BALL, 1. c., vi, p. 124 (anat.) ; Proc. U. S. Nat. Mus. 
1878, p. 324. Chiton ruber SPENGLER, Skrift. Nat. Selsk. iv, p. 92, 
not of Linne. Chiton Icevigatus FLEMING, Edinb. Encyc. p. 113, t. 
vii; Brit. Anim. p. 290. KEEVE, Conch. Icon. t. 27, f. 179.; 
Chiton punctatus STROM, (teste JEFFR.) Acta Nidr. iii, p. 433, t. 6, 
f. 14. Chiton latus LOWE, Zool. Journ. ii, p. 103, t. 5, f. 6, 7. 
SOWB., Conchol. Illustr. f. 113. Chiton fulminatus COUTH., Bost. 
Journ. Nat. Hist, ii, p. 80, t. 3, f. 19. GOULD, Invert. Mass, i, p. 
148, f. 3. Chiton pictus BEAN, in Thorpe's Brit. Mar. Conch, p. 
264. Chiton flemingius LEACH, Moll. Gt. Brit. p. 230. Boreo- 
chiton marmoreus Fabr. SARS, Moll. Reg. Arct. Norv. p. 116, t. 8, 
f. 3. 

This species has very much the color pattern of C. ruber, but 
may readily be distinguished by its nude, leathery girdle. Sars 
was evidently led by this superficial resemblance to create his genus 



42 TONICELLA. 

Boreocliiton for the two forms. The Greenland and East American 
specimens are more elevated and generally larger than the British 
form, which might retain the varietal name latus Lowe. 

Middendorff found the number of slits variable in his specimens 
from the White Sea and the Arctic coast of Russian Lapland, the 
anterior valve having 5 to 7, posterior valve 6 to 9 slits. 

T. SUBM ARMOREA Middendorff. PI. 10, figs. 16-24. 

Shell oval, rather depressed, rather smooth and shining, the entire 
surface seen under a lens to be very minutely, regularly and closely 
granulose. Lateral areas scarcely distinct, slightly swollen. Color 
rosy or yellowish-white, closely painted with spots and flames of red. 
Interior rose colored ; terminal valves each with five slits. 

Girdle smooth, shining, yellow or brown. 

Branchiaa median, consisting of about 24 plumes. 

Length 38, breadth 24, alt. 12-13 mill. 

Japan, Okhotsk Sea ; Aleutian Is. to Sitka and Fuea Strait. 

C. submarmoreus MIDD., Bull. Acad. Sci. St. Petersb. iv, 1846 ; 
Mai. Ross, i, p. 98 ; Sib. Reise. p. 178, t. 14, f. 7-10 ; t. 15, f. 7, 8. 
Tonicella submarmorea Midd., DALL, Proc. U. S. Nat. Mus. 1878, 
p. 296, t. I, f. 7 ; p. 327 ; 1. c. 1886, p. 210. Chiton insignis REEVE, 
Conch. Icon. t. 22 ; f. 148, 1847. 

This species is readily distinguished from T. lineata by its micro- 
scopic granulation ; from T. marmorea by its more depressed shell, 
different color-pattern, etc. 

T. LINEATA Wood. PL 11, figs. 25-28. 

Shell oblong, rather low, roundly arched or subcarinated. Sur- 
face smooth, shining, ground color light reddish. End valves con- 
centrically marked with black-brown lines bordered above with 
white, intermediate valves having similarly colored longitudi- 
nal lines, sloping obliquely backward, the ridge or jugum of each 
valve having a light triangle with a narrower dark one in the mid- 
dle on some valves. Occasionally some valves are wholly dark 
brown, unmarked. 

Lateral areas scarcely raised ; umbo of posterior valve in front 
of the middle. 

Interior white, more or less tinged with rose color. Sutural 
plates broad, rounded ; sinus deep and angular. Anterior valve 
with 8-10, median 1, posterior valve 8-10 slits. Teeth short, espe- 



TONICELLA. 43 

cially in the posterior valve, and blunt, in adults decidedly crenu- 
lated at the tips and obsoletely fissured outside. Eaves small. 

Girdle leathery, apparently smooth and nude, brown in dried 
specimens. 

Gills extending forward two-thirds the length of the foot, com- 
posed of 27 branchiae each. 

Length 37, breadth 20 mill. 

Length 30, breadth 15 mill. ; divergence 120. 

From Bering Strait southivestward to the Okhotsk Sea and Japan, 
southeastward to the Bay of Monterey, California. Aleutian Is. 

Chiton lineatus WOOD, General Conchology p. 15, t. 2, f. 4, 5, 
1815 MIDD., Mai. Koss. i, p. 109, t. 12, f. 8, 9. Sows., Conch. 111. 
f. 77. REEVE, Conch. Icon. t. 7, f. 33. Tonicia lineata Wood, H. 
& A. AD., Genera Rec. Moll, i, p. 474. Tonicella lineata CPR. MS., 
p. 38. BALL, Proc. U. S. Nat. Mus. 1878, p. 326. 

In many old specimens of this species the teeth are distinctly, 
though obsoletely crenulated and striated outside, presenting an 
approach to Tonicia. The slit in the median valves frequently has 
its edges thickened, and there is a distinct notch on each side of it. 

This is one of the handsomest north Pacific Chitons. It is read- 
ily distinguished from T. marmorea and T. submarmorea by the 
absence of microscopic granulation of the surface, as well as by the 
pattern of coloring. Dall writes : 

The painting of this very characteristic species is very variable, 
even on different valves of the same individual. Nothing can 
appear more distinct than the coloration of typical specimens of 
some varieties, but in a large series the differences do not hold 
equally good. The number of slits is also somewhat variable, occa- 
sional abnormal or injured specimens having only six or seven slits 
in the tail valve. But fine and normal specimens of both varieties 
show no more than individual variations. 

Middendorff, while pointing out the distinctions between the fol- 
lowing species and T. marmorea, appears to have overlooked the 
connection between the former and T. lineata and his description 
does not always agree with his figures. 

From Tonicia lineolata Sowerby, from South America, besides the 
internal generic characters, the exterior differs by the absence of 
punctures and raised granules at the sides. j 



44 TONICELLA. 

T. SACCHARINA Dall. Unfyured. 

Shell small, oblong, the entire surface painted with lustrous red 
and whitish. Urabo subcentral, inconspicuous. Lateral areas 
indistinctly raised ; dorsal area blood colored, reticulated in quin- 
cunx. Anterior valve having 10-11, posterior 8-10, median 1 
slit. Teeth small, spongy ; sinus small ; eaves spongy, moderate. 
Girdle leathery. Gills median. Length 6J, breadth 4 mill. 

Aleutian and Shumagin Is. ; Kyskn, Unalashka, and Koniuzhi, 
3-13 fms., on stones; St. Paul, Pribiloff Is., 15 fms. 

Tonicella saccharina DALL, Proc. U. S. Nat. Mus. 1878, pp. 2, 
327. 

This interesting little species has the luster of rock-candy, through 
which the microscopic reticulation is barely perceptible. It is 
marked in all the specimens obtained, by the red wine colored dor- 
sal areas contrasted with a waxy white color of the lateral areas, 
rendering its recognition easy. The girdle is dark, leathery, nar- 
row, slightly pubescent, and furnished at its extreme margin with a 
fringe of fine spiny hairs or spicules, as in T. marmorea. 

T. SITKENSIS Middendorff. PI. 11, figs. 29, 30, 31. 

Shell depressed, smooth, the lateral areas indistinct, under a lens 
seen to be sparsely granulose ; reddish. Anterior valve having 8, 
posterior 10, central 1 slit. Gills posterior. 

Length 10, width 6 mill. ; divergence 130. 

Sitka. 

C. sitkensis MIDD., Bull. Acad. Sci. St. Petersb. vi, p. 121, 1846 ; 
Mai. Ross, i, p. 112, t. 13, f. 1, 2. Not C. sitkensis Reeve, 1847. 

Described from a single specimen, and not found by later collec- 
tors. Middendorff 's figures and description do not agree upon sev- 
eral points. The anterior teeth are figured as grooved outside, a 
character also seen in T. lineata. 

Subgenus CYANOPLAX Pilsbry, 1892. 

Valves resembling those of Ischnochiton, but having the teeth 
stout, obtuse, crenulated or bi- or trilobed at their tips; and the 
eaves spongy. Girdle leathery, minutely papillose. Gills extend- 
ing to the anterior end of the foot. 

Differs from Chcetopleura in the spongy eaves and papillose, not 
hairy girdle ; from Tonicella in the long gills, different girdle, 
stumpy, bilobed anterior teeth, etc. It might be considered a 



TONICELLA. 45 

Tr achy Sermon were it not for the peculiar blunt teeth, ambient 
gills and almost scaleless girdle. 

The girdle seems to be dusted with a few small, smooth white 
scales in places. 

On account of the spongy eaves and hairless girdle, I include 
this subgenus in Tonicella rather than in Chcetopleura ; but its 
close affinities with both of these groups renders the question of 
its position peculiarly difficult. 

T. HARTWEGII Carpenter. PI. 14, figs. 81. 82, 83, 84, 85. 

Shell oval, rather low, the dorsal ridge obtusely rounded ; dull 
olive green, generally having a pair of lighter stripes on the ridge 
of each valve with a black blotch outside of the light dashes. 
Girdle (fig. 82) rather narrow, dense, microscopically closely 
granulated. 

The tail valve is convex as a whole, but the subcentral umbo is 
not conspicuous. The entire surface is very closely microscopically 
granulated, and bears larger wart-like granules irregularly scattered 
over the minute sculpture, these warts being much more numerous 
upon the lateral areas (which are otherwise rather ill-defined) and 
the terminal valves. 

The interior is of an intense blue-green color. Sutural plates 
rounded, leaving a wide, angular sinus. Insertion plates shorter 
than the eaves, blunt, the anterior valve having the teeth bi- or tri- 
lobed, the posterior valve having them crenulated. Slits of ante- 
rior valve 10-11 ; median valves 1 ; posterior valves 9-12. Eaves 
spongy. 

Gills extending forward to the front end of the foot. 

Length 30, breadth 17 mill. 

Length 27, breadth 18 mill. 

Vancouver Island to Magdalena Bay, Lower California. 

Chiton hartwegii CPU. P. Z. S. 1855, p. 231 ; Trachydermon hart- 
wegii CPR. B. A. Rep. 1863, p. 649. Chcetopleura hartwegii CPU. 
MS. p. 45. D ALL, Proc. U. S. Nat. Mus. 1878, p. 329. 

The prominent differential characters of this species are its sys- 
tem of sculpture, vivid blue-green interior, slightly spongy eaves, 
stumpy, bilobed teeth of the front valve, etc. 



46 SCHIZOPLAX. 

Var. NUTTALLII Cpr. 

Umbo flatter ; valves broad, non-swelling, squared at the sides, 
and not beaked or waved. Posterior valve having 11, central 1, 
anterior 8 slits. 

Habitat same as hartwegii. 

Chiton nuttallii CPR. P. Z. S. 1855, p. 231 ; Trachydermon n., 
CPR. Suppl. Rep. B. Asso. 1863, p. 649 ; Chcetopleura n., CPR. MS., 
in Dall, Proc. U. S. Nat. Mus. 1878, p. 330. 

I am unable to separate this form from hartwegii, as transition 
specimens are numerous. 

T. BIPUNCTATA Sowerby. PL 14, fig. 90. 

Shell ovate, smooth ; green, variegated with black and white ; 
margin concolored, generally having a white spot on each side 
between the first and second valves, marginal ligament smooth. 
Length 12, breadth 61 mill. (Sowb.) 

Inner Lobos Island, Pern, under stones at low water. 

C. bipunctatus SOWB. P. Z. S. 1832, p. 104 ; Couch, lllustr. f. 27. 

This species varies much in coloring, some specimens being nearly 
black, others light green, and some much and prettily varied. In 
almost all a white mark may be observed on the margin just 
behind the anterior valve. (Sowb.} 

Carpenter's notes on the types are as follows : Posterior valve 
having 9, central 1, anterior valve 9 slits ; teeth smooth, stumpy ; 
eaves very short, spongy. Girdle smooth with extremely short, 
scattered hairs, and two white spots at the sutures of anterior valve. 
Valves beaked, but they seem to have no pattern of sculpture, only 
a very close quincunx (arrangement of granules). Looks like 
a Trachydermon without scales. The mucro is in front of the 
middle, the slope behind it concave. Color greenish, generally 
with a white blotch behind. 

Length 12, breadth 7 mill. 

Congeneric with and very like a small nuttallii. 

Genus IX. SCHIZOPLAX Dall, 1878. 

Schizoplax DALL, Proc. U. S. Hat. Mus. p. 2, Jan., 1878 ; 1. c. p. 
328. CPR. MS. Type Chiton brandtii Midd. 

Shell and girdle as in Tonicella, except that the median valves 
have a central jugal slit filled with cartilage, narrower in front; 



SCHIZOPLAX. 47 

tegmentum very spongy ; gills extending three-fourths the length 
of the foot. 

This form, whilst allied to Tonicella, differs from all other known 
Chitons in the curious slit along the jugum of each of the median 
valves. This slit is wedge-shaped, narrowing to a point in front, 
where it is lost in the spongy jugal sinus. The slit is filled with a 
cartilaginous substance resembling the ligament of a bivalve. Out- 
side there is a corresponding furrow not extending to the terminal 
valves. 

The tegmentum, or external layer of shell substance, is remark- 
ably porous where exposed at jugal sinus and eaves. 

S. BRANDTII Middendorff. PI. 11, figs. 32-37. 

Shell oval, rather elevated, the jugum rounded; olive-brown, 
streaked, maculated or clouded with blue, sometimes chestnut. 
Umbo central, irregularly planate. Lateral areas scarcely defined. 
Entire surface smooth, seen under a lens to be finely granulated in 
quincunx. Girdle narrow, olive-ashen, maculated, closely beset with 
minute spines, but appearing almost smooth to the naked eye. The 
median valves have a sharply cut longitudinal median sulcus. The 
jugal sinus is moderate, deep, scarcely laminate, conspicuously 
spongy. Eaves small, very spongy. Anterior valve with 11, pos- 
terior 11 and median valves with 1 slit. Gills about 22, subambient. 

Length 16, width 5 mill.; divergence 140. 

Shantar Bay, Okhotsk Sea; Aleutian Is. eastward to Sitka Har- 
bor, low water to 12 fms., on stones and shells. 

C. brandtii MIDD., Bull. Acad. Sci. St. Petersb., vi, p. 117, 1846 ; 
Mai. Ross, i, p. 128 : Siber. Reis. p. 174, t. 15, f. l-Q.Schizoplax 
brandti CPU. MS. DALL, Proc. U. S. Nat. Mus. 1878, pp. 2, 328. 

This very remarkable species is very prettily marbled with olive, 
chestnut and blue ; the girdle generally dark olive, dashed with 
ashy spots and in fine specimens having a pubescent appearance. 
The slit is occupied by a cartilaginous substance of a dark brown 
color, most visible from within. It is quite possible that it may 
reach as far south as Puget Sound. 

The soft parts are yellowish-white. The gill rows extend three- 
fourths of the length of the foot 'forward from their posterior termina- 
tion, and each contains about twenty-two branchiae. Mantle-edge 
thick, plain ; veil small, plain. Muzzle small, plain, with two large 
squarish lappets at the posterior corners. The supposed oviducts 



48 CALLOCHITON. 

open on each side through a small rounded papilla in the vicinity 
of the third or fourth branchia, counting forward, and between the 
line of the gill row and the side of the foot. (DalL~) 

Genus X. CALLOCHITON Gray, 1847. 

Callochiton GRAY, P. Z. 6. 1847, pp. 126, 168; type Ch. Icevis. 
SHUTTLEW Bern. Mittheil., Juni, 1853, p. 65. Callochiton GRAY, 
Guide Syst. Dist. Moll. B. M. p. 181, 1856. Callochiton CARPEN- 
TER MS. 1871, and of BALL, Proc. U. S. Nat. Mus. 1882, p. 286, 
not Callochiton of Carpenter's earlier writings (P. Z. S. 1865, p. 
276, etc.), = Callistochiton. 

Valves exposed ; insertion plates rising out of porous or spongy 
eaves and cut into numerous teeth ; sutural plates connected or 
continuous across the shallow jugal sinus. 

Two subgenera are recognized by Carpenter: 

Subgenus CALLOCHITON (restricted). 

Girdle covered with a smooth, compact layer of very small dia- 
mond-shaped scales. 

Subgenus STEREOCHITON Cpr. 

Girdle leathery, more or less downy, frequently naked when the 
delicate scales are rubbed off. 



Subgenus CALLOCHITON s. sir. 

The essential characters of the restricted genus Callochiton are 
correctly stated by Carpenter as follows: (1) The insertion plates 
are broken up into very numerous teeth rising out of spongy eaves; 
(2) that these have a tendency to become propped outside; (3) that 
the sinus is a mere wave in the otherwise united branches of the 
sutural laminae ; (4) that the mantle is reticulated with what look 
like diamond-shaped scales, which are only the points of long, flat- 
tened, closely appressed corneous bodies, not found on any other 
Chiton. For Gray's second group, in which the peculiar covering 
is not seen, a subgenus should be created, unless indeed the species 
may rank under Trachyradsia. For two species with a mantle 
intermediate between Choetopleura and Tonicella I have established 
a subgenus Stereochiton. Of the whole series there are very few 
species known. All of them are rare and display very little sculp- 
ture on the valves. 



CALLOCHITON. 49 

C. LJEVIS Montagu. PL 9 figs. 95-99. 

Shell oblong, rather elevated and rather acutely carinated, the 
sides straight or convex. Color very variable, but mainly yellow- 
ish-olive, spotted and marbled more or less with dark red or reddish, 
but green often predominating. Girdle olive with creamy spots, 
and often red patches. 

The valves are slightly beaked and apparently smooth, but under 
a lens a fine but half-effaced granulation is seen. The lateral areas 
are distinctly raised. The umbo is low and in front of the center. 

Interior pink-tinted. Anterior insertion plate having 14 to 17 
slits, median valves with about 3 slits, posterior valve with 14-16 
slits. The teeth rise from very spongy eaves, and are more or less 
thickened at the sides or " propped." Sutural plates continuous, 
the jugal sinus indicated by a shallow depression. 

Girdle firm, smooth and wide, composed of excessively fine dia- 
mond-shaped scales. 

Length 21, breadth 11 mill., sometimes larger. 

British Seas; Mediterranean. 

Chiton Icevis MONTAGU, Test. Brit. p. 2. REEVE, Conch. Icon, 
f. 125. FORBES & HANLEY, Hist. Brit. Moll. p. 411, t. 58, f. 3. 
JEFFREYS, Brit. Conch, iii, 226, t. 56, f. 6. Chiton marginatus of 
some authors. C.achatinus BROWN, Illustr. Conch. Gt. Brit. p. 65, 
t. 21, f. 4, 12, 13, 15. C. septemvalvis MONT., Test. Brit. p. 3 and 
C. discors MATON & RACKETT, Trans. Linn. Soc. viii, p. 20. Chi- 
on cranchianus LEACH, Moll. G. B. p. 230. Lepidopleurus punctu- 
latus LEACH, I. c. p. 228. Chiton dorice CAPELLINI, Journ. de 
Conchyl. (2), iii, p. 325, t. 12, f. 2, a", b", c", 1859. 

This is a rather high and sharply keeled species although 
depressed specimens occur. It may be known from other Euro- 
pean Chitons by the comparative smoothness of both valves and 
girdle, the latter wide and covered with very fine diamond-shaped 
scales ; by the propped teeth and spongy eaves, the number of 
slits in the median valves, etc. 

The Mediterranean form has been called (?. dorice, but I am 
unable to see that it has distinctive characters. 

C. PLATESSA Gould. PL 10, figs. 1-5. 

Shell smooth, entire surface delicately shagreened, terminal valves 
and lateral areas only with indistinct concentric lines of growth ; 
4 




50 CALLOCHITON. 

lateral areas not prominent, with no radial markings ; umbones 
small, pointed. 

Girdle. With delicate flat elongated scales. 

Gills. Extend along whole length of foot, about thirty in num- 
ber on each side. 

Color. Central areas yellowish, obscurely mottled with orange ; 
on some valves there are a central and a lateral pair of pale lines. 
Lateral areas and terminal valves of a uniform dull orange color, 
and uniformly spotted with minute black dots, which are absent 
from the central areas, the posterior border of the valves is orna- 
mented with alternate lighter and darker spots. Ligament brown- 
ish, with a few irregular small white flecks and five large white 
spots, four very large spots extending from the points of junction 
of the first and second and seventh and eighth valves respectively 
to the edge of the girdle ; the fifth spot being in the median line 
posteriorly. (Haddon.) 

Interior. Posterior valve with 14, anterior 16 and median valves 
with 3 slits. Teeth solid, separated, propped outside, bifid or 
3-shaped. Eaves very spongy, simple, short. Sinus small, wide ; 
sutural plates united ; girdle normal. (Cpr.) 

Sydney; Port Jackson; Botany Bay ; Australia; (and New Zea- 
land?}. 

C. platessa GLD., Proc. Bost. Soc. N. H. ii, 1846, p. 143; U. S. 
Expl. Exped. p. 320 ; atlas, f. 434, 434a, left hand, under Ch. fru- 
ticosus. Lepidopleura platessa GLD., Otia Conch, p. 242. Callo- 
chiton platessa Old., CPR., mss. HADDON, Challenger Rep. p. 1 5. 
Chiton crodnus Eve., Conch. Icon. t. 22, f. 146, 1847. Chiton ver- 
sicolor A. AD., P. Z. S. 1852, p. 92, t. 16, f. 5. Leptocldton versico- 
lor, ANGAS, P. Z. S. 1867, p. 223. 

There is an error in the lettering of Gould's plate, the figures 
being numbered 434 instead of 431. There is considerable varia- 
tion in coloring. C. versicolor, which Carpenter considered a syn- 
onym, is represented in pi. 10, fig. 6. C. crocinus (pi. 10, fig. 7) is 
a larger form, length 35 mill., said to be from New Zealand. 

C. PRINCEPS Carpenter, n. sp. 

Shell large, very flat, oval; jugum angulate ; red, streaked with 
paler and deeper. Posterior valve large, very flat, the median 
umbo inconspicuous. Lateral areas hardly defined ; central valves 



CALLOCHITON. 51 

rounded at the margins, sometimes (abnormally?) pectinated. 
Entire surface conspicuously but minutely granulated. 

Interior : Posterior valve having 17, anterior 18, median valves 
3 slits. Teeth elegantly radiately propped, curved outward, two or 
three lobed, sometimes striated. Eaves short, reddish, spongy. 
Inside light flesh colored. Sutural plates joined, broadly but 
slightly sinuated in the middle. Girdle normal. (Cpr.) Length 
32 J, breadth 20 mill. ; divergence 135. 

Habitat unknown. (Mus. Cum. No. 95.) 

The complicated external structure of the insertion plates is more 
beautiful in this than in any other known species, resembling the 
fret-work of a Gothic pinnacle. It is specially displayed where the 
eaves have been broken off through accident, and the grooving is 
displayed under the colored part of the valves, which are there pec- 
tinated at the edges. It is unfortunate that the locality of this 
typical species is unknown. (Qor.) 

C. ILLUMINATUS Reeve. PL 9, figs. 92, 93, 94. 

Shell oval, red, rather elevated, the jugum acute ; umbo a little 
in front of the middle, slightly elevated. Entire surface very min- 
utely wrinkle-striate and granulose under a lens, the central areas 
longitudinally, the rest radially. Central areas with slender ele- 
vated separated threads, parallel to the jugum, 6 to 14 on each 
side. Lateral areas rather elevated. 

Interior roseate. Anterior valve with 15-16, posterior with 11-14 
slits, median valves with 1 slit. Teeth acute, quite distant, scarcely 
propped. Eaves spongy, sinus small, the sutural plates connected 
across it. Girdle normal, the scales rather large, solid ; sometimes 
spotted with paler at the sutures. (CJpr.) 

Length 16, breadth 10 mill. ; divergence 120. 

Straits of Magellan. 

Chiton illuminatus REEVE, Conch. Icon. t. 22, f. 147,1847.-- 
C. (Callochiton) illuminatus Rve., SMITH, P. Z. S. 1881, p. 35. 
Lepidopleurus illuminatus ROCHEBRUNE, Miss. Cap Horn, p. 141. 

There are about 16 gill plumes on each side, reaching three-fifths 
of the distance forward, according to Carpenter. In having but 
one slit in the median insertion plates and in the want of props on 
the teeth this species is abnormal ; in other respects it agrees with 
Callochiton. 



52 CALLOCHITON. 

Subgenus STEREOCHITON Carpenter. 

Stereochiton CARPENTER MS., 1871. DALL, Proc. U. S. Nat. 
Mus. 1882, p. 286 (type C. castaneus Wood). 

Valves like Callochiton, but the girdle leathery and downy, the 
scales very delicate and deciduous. In this group the teeth are 
numerous, the median valves having 5 or more; but on account of 
their narrowness they do not always have the lateral buttresses or 
props outside, so characteristic of the teeth of the true Callochi- 
tons. The eaves are very narrow, but distinctly porous or spongy, 
as in Callochiton, and the bottoms of the slits are also coarsely 
spongy. The sutural plates are continuous from side to side, the 
median sinus being a mere wave, also a characteristic of Callochiton. 
It is therefore obvious that the characters of the girdle alone sepa- 
rate Stereochiton from Callochiton. In C. castaneus the girdle of 
moderate sized specimens is always, so far as I know, denuded of 
most of the covering of downy scales, but under a strong lens the 
close, fine markings where they were inserted in the girdle may be 
seen, as well as occasional scattered scales. 

Stereochiton externally resembles Tonicella, but it may be at once 
distinguished from that group by its numerous side slits. 

C. CASTANEUS Wood. PL 9, figs. 86-91. 

Shell oval, depressed, dark chestnut brown or variegated with 
lighter brown. Jugum obtusely keeled ; lateral areas rather distinctly 
defined, slightly raised. Entire surface very minutely, densely 
granulated, when seen under a lens ; the granules low, not arranged 
in distinct lines, but an obscure oblique radiation is more or less 
visible. Growth striae light. Umbo of the posterior valve some- 
what in front of the middle, somewhat elevated. 

Interior rose colored ; Anterior valve with 20, posterior with 18, 
median valves with 5 deep slits. Teeth rather high and narrow* 
blunt, not propped, those of the terminal valves frequently bilobed 
or trilobed inside, and obtusely crenulated at their apices. Inter- 
stices spongy. Eaves very narrow, short, spongy. Sutural plates 
connected, the jugal sinus shallow. Girdle leathery, bearing (when 
not rubbed off) delicate elongated scales. 

Length 42, breadth 28 mill. 

Cape of Good Hope. 

Chiton castaneus WOOD, General Conchology, p. 13, t. 2, f. 2, 3 ; 
t. 3, f. 2, 3, 1815. SOWEBBY, Conchol. Illustr. f. 114, 115. REEVE, 



ISCHNOCHITON. 53 

Conch. Icon., t. 5, f. 25. NOT C. castaneus Quoy nor C. castaneus 
Conth. O.cerasinus Chemn., REEVE, Conch. Icon. f. 63. 

This species is variable in coloring, being either uniform chestnut 
brown or having spots and patches of brown on a lighter ground. 
The interior is always roseate. The numerous narrow teeth, short 
spongy eaves, spongy slits, etc., readily separate it from other forms. 

C. LOBATUS Carpenter, n. sp. PL 8, figs. 83-85. 

Shell large, flattened, with acute jugum ; intense olive colored; 
umbo median, the posterior slope concave. Valves scarcely beaked, 
rounded at the margins. Lateral areas not well defined. Entire 
surface minutely granulated in quincunx. 

Interior : Posterior valve with 20, median valves 5 to 7 (usually 
6, the posterior minute), anterior valve 24 slits. Teeth small, 
deeply separated, and outside very strongly propped, as if bilobed ; 
interstices deeply spongy. Eaves small, spongy, grooved inside ; 
sinus subobsolete ; sutural plates connected. Girdle leathery, 
smooth, under a lens seen to bear short, minute, sparsely placed 
hairlets. Length 41, breadth 27 mill.; divergence 130. 

Tasmania. (Mus. Cum. No 19.) 

This fine and curious species has the general aspect of Mopalia 
vespertina (from which it is known at once by the lophyroid 
mucro) ; the insertion plates, props, spongy eaves and minute sinus 
of Callochitou ; and a mantle resembling an aberrant Tonicia. 

Genus XL ISCHNOCHITON Gray, 1847. 

=Ischnochiton -f Trachydermon + Maugerella Cpr. 

Valves external, having sharp, slit, insertion plates, the teeth not 
buttressed. Eaves solid (rarely somewhat porous in s. g. Trachy- 
dermon} ; girdle covered with imbricating scales, either flat or con- 
vex, smooth or striated. Gills typically extending the entire length 
of the foot, but in some species they are short in front or at both 
ends. 

Ischnochiton is the typical or central point in development of the 
sharp-toothed division of Chitons, around which the other genera 
naturally group themselves. 

The great diversity in the girdle covering permits us .to use that 
character for the foundation of a number of subgeneric and sec- 
tional divisions, as follows: 



54 ISCHNOCHITON. 

Synopsis of Subgenera and Sections. 
Subgenus I. STENOCHITON Ad. and Ang. 

Very much elongated, valves longer than wide, roundly arched, 
the median valves having several slits ; unibo subcentral ; girdle 
covered with minute, smooth imbricating scales. 

Subgenus II. STENOPLAX Cpr. 

Elongated, narrow, the posterior valve large, depressed, with sub- 
central or posterior umbo. Girdle covered with small crowded 
striated scales. 

Section Stenoplax s. s. Median valves 1 slit. 

Section Stenoradsia Cpr. Median valves with several slits. 

Subgenus III. ISCHNOPLAX Cpr. 

Elongated, narrow ; posterior valve elevated, the umbo posterior; 
girdle covered with very minute scales, having conspicuously larger, 
striated scales mingled among them. 

Subgenus IV. HETEROZONA Cpr. 

Shell like normal Ischnochiton. Girdle bearing small scales 
with large striated scales intermingled. 

Subgenus V. TRACHYDERMON Cpr. 

Oval ; valves having the sharp teeth of normal Ischnochiton ; 
eaves narrow, rarely spongy. Girdle having very small smooth 
scales. 

Section Trachydermon s. s. Median valves having one side slit. 

Section Trachyradsia Cpr. Median valves having more than one 
side slit. 

Subgenus VI. ISCHNOCHITON (Gray) Cpr. 

Oval or oblong ; valves having sharp smooth teeth and solid 
eaves. Girdle covered with short flat, generally striated imbricating 
scales of moderate size. 

Section Ischnochiton s. s. Central valves having one slit. 

Section Radsiella Pils. Central valves having two or several 
slits. 



ISCHNOCHITON. 55 

Subgenus VII. ISCHNORADSIA Shuttlew. 

Shell oval, as in Ischnochiton ; girdle covered with solid, convex, 
smooth scales, like those of Chiton s. s. 

Section Ischnoradsia s. s. Median valves having several side 
slits. Type J. australis Sowb. 

Section Lepidozona Pils. Median valves having one side slit. 
Type I. mertensii Midd. 



Subgenus I. STENOCHITON Adams and Angas, 1864. 

Stenochiton AD. AND ANG., P. Z. S. 1864, p. 193. 

Shell very much elongated, roundly arched ; valves Ischnoid, 
the central valves having several slits ; girdle having minute smooth 
imbricating scales. 

This section was discarded by Carpenter, who referred its only 
species to his own later group Stenoradsia with doubt ; Stenochiton, 
however, seems to have as much individuality as most of the divis- 
ions of Ischnochiton, and may be allowed to stand as a subgenus. 

I. JULOIDES Adams and Angas. PL 16, figs. 6, 7, 8. 

Shell much elongated, narrow, narrower in front; rufous brown, 
minutely spotted with white. Valves narrow, longer than wide, 
very convex, not carinated; lateral margins scarcely rounded, pol- 
ished. Lateral areas elevated and at the margins concentrically 
sulcate. Girdle narrow, pale-brown, spotted with black-brown, 
covered with very minute, polished, imbricating scales. (Ad. and 
Ang.) Length 25, breadth 6 mill. 

Holdfast Bay, South Australia. 

Stenochiton juloides AD. AND ANG., P. Z. S. 1864, p. ?93; 1. c. 
1865, p. 58, t. 11, f. 15. ANGAS, P. Z. S. 1865, p. 188. "J Stenor- 
adsia " juloides Ad. and Ang., CPU. MS. 

This species, from its narrow, convex form and polished surface 
has much the general appearance of a Myriapod. (Ad. and Ang.) 

This species is the type of the genus Stenochiton Adams and 
Angas, which is thus characterized by them : " Shell elongated, 
narrow, convex ; valves longer than wide, not carinated ; apex of 
the posterior valve subcentral ; plates of insertion small, multi- 
fissate in the end valves, the intermediate valves having 5 fissures 
on each side ; girdle covered with very minute, polished, imbrica- 
ting scales." 



56 ISCHNOCHITON. 

Carpenter gives the following notes on the type specimen : Length 
22 , breadth 4? mill. ; shell very narrow, elongate, elevated, cylin- 
drical, the jugum rounded ; red-brown, narrowly streaked with 
paler. Posterior valve elongated, mucro median, scarcely conspic- 
uous, the slope behind it straight. Anterior valve forming more 
than a semicircle, its posterior margin (suture) emarginate. Entire 
surface delicately granulated in quincunx; jugal area scarcely 
defined ; lateral areas conspicuously elevated. Girdle inconspic- 
uous, covered with minute imbricating scales. Scales almost all 
destroyed, but looking like those of /. sanguineus, etc. Sinus 
large, very deep, flat, wide ; sutural plates much elongated, narrow. 
Central valves regularly 3-slit ; posterior valves about 16, anterior 
valves about 13 slits. The slits are irregular, sometimes bifurcating 
but typically rather distant. Teeth very acute, moderately long. 
Eaves moderate. 

Subgenus II. STENOPLAX Carpenter, 1878. 

= Stenoplax Cpr. + Stenoradsia Cpr. -f- Manger ella Cpr. 

Elongated, narrow Ischnoids, having the girdle covered with 
minute, crowded, imbricating striated scales. Median valves having 
the lateral areas much raised; posterior valve large, depressed, the 
mucro subcentral or slightly posterior. 

The subgenus Stenoplax (-}- Stenoradsia and Maugerella) has a 
very characteristic peculiarity. The sides and front end of the foot 
are so much dilated that the head of the animal is nearly or entirely 
concealed from below, the thin, produced, anterior end of the foot 
extending quite over it. The gill row is shortened at both ends, 
reaching nearly to the head, but shortened at the tail about one- 
fourth the entire length of the foot. The branchiae are largest at 
the middle. 

STENOPLAX divides naturally into two sections: (1) Section 
Stenoplax (restricted), in which the median valves have a single 
slit on each side, and (2) Section Stenoradsia, the species of which 
have two or several side slits in the median valves. 

Section Stenoplax Cpr. (restricted). 

Stenoplax CPR., MS. and table of Regular Chitons, 1873. DALL, 
Proc. U. S. Nat. Mus. 1878, p. 330, type J. limaciformis Sby. 

This section is closely allied to Stenoradsia, the latter differing 
only in having several slits in the plates of the intermediate valves. 



ISCHNOCHITON. 57 

I. LIMACIFORMIS Sowerby. PL 16, figs. 9-16. 

Shell elongated and narrow, elevated, well arched ; buff, gray or 
greenish, indistinctly marbled with darker, and occasionally blotched 
with red; longitudinally costulate, not granose ; girdle scales very 
minute. 

The sculpture upon the central areas consists of fine, close, smooth 
longitudinal riblets ; these continue upon the lateral areas, becom- 
ing broader and flat there, and being decidedly waved or irregular 
on the slope between central and lateral areas. The end valves are 
sculptured with close, flattened concentric ridges, which are more 
or less wavy or irregular. The lateral areas are well raised, and 
are separated by a considerable space at the jugum. The mucro is 
subcentral and low. 

Interior stained with bright pink and blue-green ; sutural plates 
well developed; sinus flat, angular, wide; anterior valves with 11, 
central valves 1, posterior valves 9 slits. Teeth sharp, smooth ; 
eaves grayish, solid. 

Girdle covered with extremely minute subequal scales. 

Length 35, breadth 12 mill. 

Length 25, breadth 10 mill. 

Florida Keys ; St. Thomas, St. Vincent and West Indies gener- 
ally ; Central America and Peru; under stones at low water. 

Chiton limaciformis SOWERBY, P. Z. S. 1832, p. 26 ; Conchol. 
Illustr. f. 38. REEVE, Conch. Icon. t. 8, f. 42. Ischnochiton lima- 
ciformis SHUTTLEW, Bern. Mittheil. 1853, p. 190. Ischnochiton 
(Stenoplax) limaciformis Sowb., CPR. MS., and DALL, Blake Gas- 
trop. p. 415. Ischnochiton multicostatus Ad., DALL, Proc. U. S. 
Nat. Mus. vi, p. 337, 1883, not of C. B. Adams. Chiton productus 
REEVE, Conch. Icon. t. 17, f. 97, 1847. Chiton sanguineus REEVE, 
1. c. f. 98. f Lepidopleurus sanguineus CPR., Maz. Catal. p. 194. 

The West Indian specimens collected by Robert Swift at St. 
Thomas, and the Peruvian specimens which I have examined are 
absolutely identical in character except that the former are finely 
mottled with pink, and one specimen is heavily blotched with crim- 
son on the second and tail valves (fig. 9). Another tray from the 
Swift collection contains pale buff examples with faint darker 
markings. Carpenter has reported the same species, or one very 
closely allied, from Mazatlan and from Japan. The last certainly 
requires confirmation. 



58 ISCHNOCHITON. 

The characteristic mark of this species is the sculpture of the 
lateral areas and end valves, which are non-granulated but have 
slightly serrated concentric flat riblets. The girdle scales are flat, 
solid, not striated or very obsoletely so, and far more minute than 
in /. alatus. 

I. FLORIDANUS Pilsbry, n. sp. PI. 17, figs. 19-22. 

Shell elongated, narrow, elevated, the valves roundly arched, not 
carinated. Color whitish or delicate green, variously marked and 
mottled with olive, blackish-olive or gray. 

The lateral areas are raised, longitudinally costulate, the riblets 
cut into granules by radiating impressed or incised lines devel- 
oped over the whole area or over the forward half of it. End valves 
similarly cut into granules by radiating and concentric lines. Cen- 
tral areas covered with longitudinal riblets which are finer and 
closer upon the jugum, usually showing a tendency to be a little 
irregular on either side of it, and are granulous toward the outer 
angles of the areas. Posterior valve large, rather depressed, the 
mucro slightly posterior. 

Interior pink, blue and white, in various proportions, rarely all 
roseate or all white. Sutural plates strongly developed, rounded ; 
sinus wide, deep, square. Anterior valve having 9, central valves 
1, posterior 9 slits; teeth sharp, smooth or very obsoletely lobed. 
Eaves narrow, solid. 

Girdle delicately marbled with bluish and gray, densely clothed 
with rounded, solid, delicately striated scales. 

Length 41, breadth 15 mill. 

Length 35, breadth 11J mill. 

Key West, Florida. (Hemphill.) 

This species is allied to /. limaciformis, differing in the differently 
sculptured lateral areas. It is also related to C. purpurascens C. 
B. Ad., but differs in several respects, notably in the flatter poste- 
rior valve and longer central valves. 

I. PURPURASCENS C. B. Adams. PI. 17, figs. 23, 24. 

Shell elongated, narrow, much elevated, the lateral slopes of the 
valves nearly straight, dorsal ridge roundly subangular. Generally 
pale buff, marbled with olive or mottled with black, and having red 
patches along the dorsal ridge. The lateral areas are raised and 
longitudinally ribbed, the riblets cut into granules by radiating 
impressed lines ; end valves cut into coarse granules by radiating 



ISCHNOCHITON. 59 

and concentric lines. Central areas having the dorsal ridge smooth 
or only minutely punctured ; the longitudinal riblets of the lateral 
areas extend forward upon the "pleura" or sides of the central 
areas. Posterior valve elevated, the mucro slightly posterior, 
elevated. 

Interior white or stained ; sutural plates short ; sinus wide, flat. 
Anterior valve having 10, central valves 1, posterior valve 10 slits. 
Teeth sharp, smooth. Eaves narrow. 

Girdle rather wide, alternately bluish and buff, densely clothed 
with minute, solid, striated scales. Length 16, breadth 7 mill. 

Jamaica (Adams) ; Key West, Florida (Hemphill ; Rush.) 

Chiton purpurascens C. B. ADAMS, Proc. Bost. Soc. N. H. ii, p. 
9,1845. Ischnochiton purpurascens Ad., DALL, Bull. U. S. Nat. 
Mus. No. 37, p. 172. 

Adams' description is as follows : Shell much elongated, purplish- 
ruddy, concentrically striated ; margin wide, very minutely scaly, 
bluish, alternately paler. Length 1-1, breadth '5 inch. 

This species differs from I. floridanus in having all of the valves 
decidedly shorter and broader ; the posterior valve much more 
elevated, the jugum almost smooth. It differs from /. limaciformis 
in having the lateral areas and end valves conspicuously granulose, 
etc. 

In this species the valves are almost as short as in the typical 
Ischnochitons, but the sculpture is quite that of Stenoplax. The 
mucro is more raised than in any other described Stenoplax. The 
species is abundant at Key West. 

The color-pattern is excessively variable. 

I. FALLAX Carpenter, n. sp. PI. 16, figs. 17, 18. 

Almost exactly like Ischnochiton magdalenensis in form and sculp- 
ture, but more roseate ; the central areas pitted ; lateral areas 
having close radiating wrinkles interrupted by lines of growth. 
Interior : Posterior valves having 9, central 1, anterior 10 slits ; 
teeth acute ; eaves conspicuous ; sinus moderate, scarcely laminate, 
but the jugal part of the valves produced forward. Girdle having 
very minute granules. 

Length 271, breadth 12J mill. ; divergence 120. 

Monterey, California. 

The color is either entirely reddish-fleshy or clouded and dotted 
with olive and whitish. The main distinction between this form 



60 ISCHNOCHITON. 

and /. magdalenensis is that the latter has radsioid valves and coarser 
girdle scales. Carpenter's description is given above, and the fig- 
ures represent the type specimen. 

The foot is produced forward, and the gill row is short at both 
ends. 

I. ALATUS Sowerby. PI. 16, figs. 1-5. 

Shell much elongated, narrow, elevated, rather thin. On a light 
fleshy buff or greenish ground it is delicately marbled and mottled 
with olive or olive-green. The sculpture consists of longitudinal 
close, narrow ridges, which are finer on the dorsal ridge, and change 
to an irregular granulation on the lateral areas and terminal valves. 
The lateral areas are decidedly raised; the jugal area is divided 
from the pleura by a change in sculpture, which becomes coarser 
and more or less divaricating, sometimes forming a cellular pattern 
at the edges of the jugal area and on the slopes of the lateral areas. 

Interior rose-pink, rarely almost white ; anterior valve having 9, 
central 1, posterior valve 9 slits. Teeth sharp, eaves moderate, 
solid. Sutural plates large, rounded ; sinus very deep, narrow. 

Girdle wide, thin, covered with fine, even, short, striated solid 
scales. 

Length 57, breadth 16 mill. 

Length 40, breadth 16 mill. 

Islands of Siquijor and Zebu, Philippines, under stones at low 
water. 

Chiton alatus SOWERBY, P. Z. S. 1841, p. 61. RVE, Conch. Icon, 
t. 8, f. 45. Ischnochiton alatus GRAY, P. Z. S. 1847, p. 127, and 
/. altus Gray, Guide, p. ] 82. Stenoplax alata CPR. MS. 

The solid, deeply striated scales of the girdle are very character- 
istic, as is also the sculpture. The pattern of color is an indefinite 
and variable mottling. Figures 3, 4, 5 are drawn from a typical 
specimen received from Sowerby. Figures 1, 2 are from draw- 
ings made for Carpenter, and represent the scales as much more 
elongated, and the head valve as less ernarginate. I am disposed 
to believe that this last peculiarity is a mistake. 

The sole is produced forward as far as the mouth; head fleshy; 
veil copious, neck lappets long. Gills about one valve's breadth 
removed from neck and the same at tail. Vent inconspicuous. 
Foot fleshy, projecting. 



ISCHNOCHITON. 61 

Section Stenoradsia Carpenter, 1878. 

Stenoradsia CPE. (MS., and table of Reg. Chitons, 1873), DALL, 
Proc. U. S. Nat. Mus. 1878, p. 330, type C. magdalenensis Hinds. 
Maugerella CPR. MS. and table of Reg. Chitons, type M. conspicua 
Cpr. MS. Ischnoradsia (in part), SHUTTLEW., Bern. Mittheil. 1853, 
p. 66. 

Like Stenoplax, but intermediate valves having several side slits. 

The Radsioid valves alone distinguish this from Stenoplax. Its 
relations with the Australian Stenochiton juloides are probably not 
especially close. 

In one species, I. conspicuus, the mantle scales have been trans- 
formed into short, round, striated bristles, and on account of this 
modification Carpenter established for it a subgenus under Chceto- 
pleura which he called Maugerella. We are compelled to suppress this 
group because of the excessively close relationship existing between 
I. conspicuus and the two species of genuine Stenoradsia, L acrior 
and I. magdalenensis. 

I. ACRIOR Carpenter, n. sp. PL 14, figs. 86-89. 

Shell much like I. magdalenensis, but broader and flatter, with 
much sharper sculpture. Olive-green, pink where worn, or some- 
times light flesh-colored, with the jugum or central areas often 
green. Girdle dark ashen or olive. 

The anterior valve is notably concave, as in J. conspicuus. The 
lateral areas are much raised, and sculptured with acute radiating 
riblets, sometimes splitting ; central areas having acute longitudinal 
riblets. 

Interior pink, with a blue spot at the jugal sinus. Sutural plates 
wide, pink ; sinus broad, deep, angular. Anterior valves having 
13-15, central valves 2-4, posterior valves 10-13 slits. Teeth long, 
sharp, smooth. Eaves wide, dark-blue. 

Girdle wide, tough, covered with very small, solid, short scales. 

Length 110, breadth 55 mill. 

Length 75, breadth 40 mill. 

Cerros (Cedros*) Island to Cape St. Lucas, Lower California. 

Stenoradsia acrior CPR. MS. Chiton magdalenensis (part) REEVE, 
Conch. Icon. t. 4, f. 20a, not of Hinds. 

This species represents one extreme of variation of the 1. 
magdalenensis type, the other extreme being 7. conspicuus. I have 



62 ISCHNOCHITON. 

still to see specimens truly connecting the three forms, although 
they are doubtless closely allied. The present form differs from 
magdalenensis in having a concave head valve, strong, distinct, 
acute riblets upon the central areas, and a generally more robust 
growth. 

J. conspicuus also has a concave head valve, but the sides of the 
central areas show no sculpture except microscopic granulation, 
and the scales of the girdle are pulled out into true spines or bris- 
tles. 

There is a light form of acrior which is fleshy-white, the girdle 
gray-white or dark ; and some of these have the jugum or the cen- 
tral areas of the normal green-olive color (fig. 89.) 

I. MAGDALENENSIS Hinds. PI. 15, figs. 98, 99, 100. 

Shell elongated, rather narrow, generally faintly mottled with 
delicate olive on a light greenish, blue or pinkish ground. Interior 
bluish, white or pink. Lateral areas and end valves having radia- 
ting riblets, central areas finely pitted. 

The lateral areas are distinctly raised, radiately delicately ribbed. 
Front slope of the anterior valve straight. Central areas having a 
more or less developed system of branching reticulating wrinkles pro- 
ducing oblong or diamond-shaped pits. Umbo of posterior valve 
central, but little projecting. 

Interior : Sutural plates well developed, the sinus deep, angular. 
Anterior valve having 10-13, central valve 2-4, posterior valve 
10-12 slits. 

Girdle having fine, close, solid imbricating scales. 

Length 75, breadth 30 mill. ; divergence about 130. 

Length 55, breadth 27 mill. 

Monterey, California, south to Magdalena Bay ; Catalina and. 
Sta. Barbara Is. 

Chiton magdalenehsis HINDS, Zool. Voy. 'Sulphur' ii, p. 54, t. 
19, f. 1. REEVE, Conch. Icon. t. 5, f. 20b. Stenoradsia magdalen- 
ensis CPR. S. " magdalensis " KEEP, West Coast Shells, p. 107, f. 
94, and of collectors generally. 

This species differs from I. conspicuus in its pitted instead of finely 
granulose central areas and in the mantle-covering of minute, solid 
scales, unlike the short spines of the other form. It differs from /. 
acrior in the much finer sculpture and more delicate coloring. 



ISCHNOCHITON. 63 

The foot projects forward, concealing the head from beneath. 

I. CONSPICUUS Carpenter, n. sp. PL 15, .figs. 91-96. 

Shell large, elongated, moderately elevated ; green (or rarely 
earthy-brown), but where eroded at the beaks it is pink. Interior 
pink, with a blue spot at the jugal sinus. Lateral areas much 
raised, having acute radiating riblets or striae ; central areas appar- 
ently smooth, but microscopically granulated, sometimes having some 
faint longitudinal striae at thejugum. Front slope of the anterior 
valve concave ; girdle densely beset with short bristles, giving it a vel- 
vety aspect. 

The entire surface is very densely microscopically granulated, 
where not eroded. The lateral areas have fine acute radii and 
often the back edge of each valve is crenulated by oblique, sharp, 
little folds. The color is often varied by darker little flames on the 
central areas. The posterior valve is large and depressed. 

The sutural plates are large, the sinus deep and angular. Inser- 
tion plates having in anterior valve 9, central valves 2 or 3, poste- 
rior valve 10 slits. Teeth sharp and thin in posterior and central 
valves, but blunt and bi- or trilobed in anterior valve. Eaves wide, 
solid, light blue-green colored. 

Length 82, breadth 36 mill. 

Length 89, breadth 41 mill. 

Santa Barbara, California, to Magdalena Bay. 

Maugerella conspicua CPR. MS. OROUTT, Proc. U. S. Nat. Mus. 
1885, p. 544. 

This species may be separated from /. acrior by its unsculptured 
central areas and velvety rather than scaly girdle. It is more 
closely allied to I. magdalenensis and may, indeed, prove tointergrade 
with that species ; but in magdalenensis the front valve is scarcely 
concave in front, the sides of the central areas have a honeycomb 
sculpture, and the girdle is very finely scaly, not velvety. 

A specimen before me from Magdalena Bay is ferruginous 
brown, the central areas are more rugose, and the size is smaller, 
length 45, breadth 20 mill. Another specimen has the central 
areas sculptured like /. acrior, but less strongly ; the girdle being 
bristly, however, as in typical conspicuus. San Diego may be 
regarded as the center of distribution of this species. 



64 ISCHNOCHITON. 

Carpenter has given a varietal name to a broad, worn specimen, 
which he thus describes : 

Var. solidus (pi. 15, fig. 97). Very solid, wide, ashen; inside 
whitish, the posterior valve with 10, central valve 2-3, anterior 
valve 12 slits. Length 72, breadth 40, divergence 130. 

Carpenteria, near Sta. Barbara, California. 

This is scarcely more than an individual variation. The figure 
represents the valves only of the type specimen. The mantle is 
normal. The sculpture is worn away except at the edge. It has 
evidently lived in a very exposed situation. 

Subgenus III. ISCHNOPLAX Carpenter. 

Ischnoplax CPU. (Table of Keg. Chit. 1873), DALL, Proc. U. S. 
Nat. Mus. 1878, p. 330, type C. pectinatus Sowb. 

Body elongated, elevated, the valves having high suturpl plates 
and strongly elevated lateral areas ; mucro posterior, elevated ; 
girdle clothed with very minute imbricating scales and having larger 
conspicuous striated scales scattered among them. 

The girdle is like that of Heterozona, but the valves and general 
shape are similar to Stenoplax, except that the mucro is posterior 
and elevated, a character recalling Callistochiton. 

I. PECTINATUS Sowerby. PI. 17, figs. 25-30. 

Shell elongated, narrow, elevated ; gray, mottled and dotted all 
over with black, more or less stained in places with pink. 

The valves are strongly convex ; end valves radiately coarsely 
granose-ribbed ; umbo of posterior valve elevated, situated behind 
the center. Lateral area much raised, having radiating granose 
riblets ; central areas having smaller cords, which are close and lon- 
gitudinal on the jugum, but become more spaced, coarser, and 
diverging on the pleura or sides of the central areas. 

Interior bright pink. Anterior valve with 10-12, intermediate 
valve 1, posterior valve 8-11 slits. Teeth sharp, frequently bifid 
eaves unusually wide, solid, scalloped by the sculpture of the out- 
side. Sutural plates high, rounded. Sinus deep, square. 

Girdle (pi. 1 7, figs. 28, 29) covered with extremely fine scales among 
which larger, long flat scales are irregularly scattered. 

Length 36, breadth 16 mill. 

Length 40, breadth 17 mill. 

Cuba (Cuming) ; Guadeloupe (Swift) ; Barbados (Rush). 



ISCHNOCHITON. 65 

Chiton pectinatus SOAVB., Mag. of Nat. Hist., June, 1840, p. 288, 
t. 10, f. 3; Conch. Illustr. f. 146. REEVE, Conch. Icon. t. 26, f. . 
133. C. (Ischno chiton) pectinatus SHUTTLEW., Bern. Mittheil. 1853, 
p. 77. Ischnoplax pectinatus CPR., MS. Chiton acutiliratus 
REEVE, Conch. Icon. t. 8, f. 46. Chiton multico status C. B.- AD., 
Proc. Bost. Soc. N. H. ii, p. 8, 1845. 

Readily known from other West India Chitons by its elongated 
form, speckled and mottled coloring, and especially by the very 
peculiar girdle. The large scales are distinctly but finely striated. 
The ground-color of the girdle is pale buff, with patches of olive- 
green. The large scales are mingled white and buff on the light 
tracts, and are a dark blue-green on the dark patches. 

Reeve's C. acutiliratus (fig. 30) is a typical pectinatus. I have 
not seen the Ch. multico status of C. B. Ad., described from Jamaica, 
and the description is too meager to permit certainty in referring it 
here. 

Subgenus IV. HETEROZONA Carpenter, 1878. 

Heterozona CPR. (Table of Regular Chitons, 1873), DALL, Proc. 
U. S. Nat. Mus. 1878, p. 331. Type H. cariosa Cpr. MS. 

Shell like normal Ischnochiton ; girdle bearing small scales with 
large striated scales intermingled. 

The girdle is that of Ischnoplax, but the shell is not elongated, 
and the umbo of the posterior valve is median, not posterior. The 
arrangement of scales normal in this section is the same as a patho- 
logic condition sometimes met with in individuals of species 
normally having regular and equal scales, but in which the girdle 
has been injured; the injury being repaired with scales much 
smaller than those upon the healthy portions of the girdle. 

I. CARIOSUS Carpenter, n. sp. PI. 24, figs. 20, 21, 22. 

Shell oblong, rather elevated, the valves broadly arched and 
rounded dorsally. Color, soiled yellowish, unicolored or with 
indistinct brown spots. 

The lateral areas are raised, and sculptured with a varying num- 
ber (about 7) of radial ribs, which are irregular, often splitting, 
and very unevenly granose. Central areas finely granulated upon 
the dorsal ridge, the granulation giving place on the side-slopes to 
a rather strong but fine corrugation ; the wrinkles longitudinal, 
but converging forward toward the middle; and minutely irregular 




66 ISCHNOCHITOX. 

or undulating. Toward the outer edges the wrinkles become 
coarser and more separated. End valves sculptured with radiating 
riblets ; posterior valve having the mucro central. Interior white, 
the end valves usually marked with a brown crescent ; sutural lobes 
rounded ; sinus wide and flat. Anterior valve having 12, median 
valves 1, posterior valve 12 slits ; teeth smooth, rather sharp. 
Eaves solid. 

Girdle covered with flattened striated scales, which are very 
unequal in size, but become larger toward the valves (fig. 21). 

Length 32, breadth 16 mill. 

Australia. 

The texture of the shell is peculiar, the outer layer being thin 
and easily broken through, exposing an extremely spongy layer. 
Carpenter's specimens seem to have been worn so as to expose this 
layer in places, hence the name cariosus. In the normal and un- 
worn specimens before me the outer surfare is scarcely carious 
though dull and uneven, nor are the eaves spongy. Carpenter's 
original description is as follows : 

Heterozona cariosa (pi. 24, fig. 23). Shell subelongate, rather 
elevated, the jugum rounded. Mucro median, moderately elevated ; 
whitish-ashen, slightly variegated at the sutures occasionally. 
Central areas very granose in a young specimen, the granules 
minute and close toward the jugum, then becoming rugose lines, 
undulating anteriorly, and widely separated on the sides; the adult 
shell is carious. Lateral areas having 3-8 deeply but irregularly 
granose radii, the grains at the sutures large ; end valves having 
30-40 graniferous radii. Interior : posterior valve with 11, central 
1, anterior valve 11 slits. Teeth acute; eaves wide, spongy; sinus 
large, flat, smooth. Girdle (pi. 24, fig. 23), clothed with noriial 
striated imbricating scales and having long, large striated solid 
scales scattered here and there. (Cpr.~) 

Length 30, breadth 16J mill., divergence 100. 

Australia (Mus. Cuming No. 46). 

This shell forms an exact transition between Ischnoplax and the 
true Ischnochiton. The mantle resembles Ischnoplax in its double 
series of scales ; although if the large ones were plucked out, the 
latter would be nearly of a normal arrangement, except that they 
are rather narrow as in /. castus. It differs from Ischnoplax, not 
only in not being narrow and elongated, but in having a normal 
mucro. The species is curiously like Stenoradsia magdalenensis, 



ISCHNOCHITON. 67 

young, in shape and plan of sculpture, but the scales are not chaffy 
and the central valves have only one slit. (Cpr.~) 

Carpenter's description and figure differ somewhat from the 
specimens before me, described above. If the latter proves specifi- 
cally distinct it may be called 1. subcariosus. 

Subgenus V. TRACHYDERMON Carpenter, 1863. 

Trachydermon CPR., Rep. Brit. Asso. Adv. Sci. 1863, p. 649. 
Crasvedochilus G. O. .SARS, Moll. Reg. Arct. Norv. p. 1 14 (for C. 
marginatus Penn. = cinereus L.). Boreochiton SARS (in part), L c., 
p. 116 (proposed for C. ruber Lowe and C. marmoreus Fabr.). 
Chiton, Lepidopleurus, Leptochiton, Isehnochiton and Lophyrus sp., 
of various authors. 

Valves exactly like those of Isehnochiton , both outside and 
within ; girdle having the scales very small, close and smooth, 
Gills from one-half to over three-fourths the length of the foot. 

This group was originally proposed as a subgenus of Isehnochiton, 
and the following species referred to it : retiporosus Cpr., inter- 
stinctus Gld., trifidus Cpr., dentiens Gld., gothicus Cpr., hartwegii 
Cpr., nuttallii Cpr., flectens Cpr. Carpenter subsequently stated 
that Trachydermon was equivalent to Gray's second section of 
Isehnochiton, " ** scales of mantle minute, granule-like." (P. Z. 
S. 1847, p. 127), this section containing only the species P. margin- 
atus= C. cinereus L. and Lowe. Still later, Carpenter raised the group 
to the rank of a genus, adding to his diagnosis the words " gills short." 
It is evident that a type species for the group should be selected 
from Carpenter's original list ; not from among the species subse- 
quently referred to the group by him. The shortness of the gills 
influenced Carpenter and Dall to place this group next to the 
Leptochitons, but there is probably no affinity indicated by this 
character, Trachydermon being phylo genetically as far from Lepto- 
chiton as Isehnochiton is. 

The length of the gill-row is so variable that genera cannot be 
founded upon that character in the present family. In the species 
albus and ruber I have ascertained the gills to be median, 
as they are said to be also in the scrobiculatus and lividus 
of Midd. In the other species which I have examined, or upon 
which data are available, inter stinctus, cinereus, dentiens, the gills 
extend from two-thirds to over three-fourths the length of the foot. 



68 ISCHNOCHITON. 

It is therefore obvious that no separation can be made from other 
subgenera of Ischnochiton on this character. 

Several species of Trachydermon have distinctly spongy eaves, 
like those of Tonicella. This structure is exceptional in Ischno- 
chiton where the eaves as a rule, are solid, as in the genus Chceto- 
pleura. The fact seems to be that certain forms of Trachydermon, 
such as T. ruber, form a partial transition from Ischnochiton to 
Tonicella. 

From Trachydermon, Carpenter has sundered a few species hav- 
ing Radsioid central valves, to which he has given the sectional 
name TRACHYRADSIA. 

Section Trachydermon, s. sir. 

I. CINEREUS Linne. PI. 6, figs. 25-31. 

Shell oblong, elevated, the dorsal ridge subarigular. Anterior 
valve half-circular, the posterior margin decidedly emarginate. 
Very evenly and finely sculptured with diamond-shaped granules, 
which, although somewhat irregular, seem to be formed by the 
oblique intersection of curved incised lines radiating in two direc- 
tions from the apex. Intermediate valves having precisely the 
same sculpture upon both central and lateral areas, the latter 
slightly raised, but not distinctly separated from the central areas. 
The posterior margin of the intermediate valves is rather produced 
or beaked in the middle. Posterior valve decidedly smaller than 
the anterior, having the umbo low, inconspicuous, and somewhat 
anterior. 

Interior whitish or brown-tinged ; sutural plates wide ; sinus 
narrow. 

Insertion plates nearly smooth, slightly roughened outside. 
Number of slits in the anterior valve 9 or 10; in the posterior 
valve 10 or 12. The teeth of the posterior valve are rugose. The 
intermediate valves have a single slit on each side. 

Color varying greatly, the most common pattern being ashen 
thickly mottled and blotched with olive ; others are a light fleshy- 
orange, and frequently the light and dark patterns are combined on 
the various valves of one individual. 

The girdle has usually alternating light and dark bars. It 
is covered with minute scales, the edge having a fringe of delicate 
glassy spines. 



ISCHNOCHITON. 69 

Length 12*, breadth 7* mill. 
Length 18, breadth 10* mill. 

British and Scandinavian .Seas, north to Lofoten, south to Bay of 
Kiel and Vigo Bay. 

Chiton cinereus LINNE, Syst. Nat. xii, teste Hanley, Ipsa Linnsei 
Conch, p. 17. LOWE, Zool. Journ. ii, p. 99, 1825. FORBES & 
HANLEY, Hist. Brit. Moll, ii, p. 402, t. 58, f. 1, ((7. marginatus on 
plate). C. marginatus PENNANT, Brit. Zool. iv, p. 71, t. 36, f. 2, 
and of MONT., Sows., RYE. and JEFFREYS, Brit. Conch, iii, p. 221, 
t. 56, f. 5; P. Z. S. 1882, p. 669. C. marginatus MEYER & 
MOBIUS, Fauna der Kieler Bucht, ii, t. 1, f. 1-5. Craspedochilus 
marginatus BARS, Moll. Arct. Norv. p. 115, t. 20, f. 16 ; t. 2, f. 2. 
Trachydermon marginatus CPR., New Eng. Chitons, p. 153. 
Trachydermon cinereus CPR. MS. p. 15. DALL, Proc. U. S. Nat. 
Mus. 1878, p. 323. NOT Lepidopleurus cinereus SARS, /. c., t. 7, f. 
8. Chiton circumvallatus REEVE, Conch. Icon. t. 27, f. 168. 

This species may be known by the evenly shagreened surface, 
which is quite different from other North Atlantic Trachydermons. 
Tr. dentiens Old., which Jeffreys considers the same as cinereus, 
differs in sculpture, color, and the shorter form. There are a num- 
ber of old and more or less doubtful synonyms, such as Ch. 
fuscatus Brown, 111. Conch. G. B. p. 66, t. 21, f. 17 ; and Jeffreys 
quotes also cimex Chemn. and cimicinus Landt. 

Carpenter seems to have supposed that the gills of this species 
did not extend forward beyond the middle of the foot, but I have 
determined by the examination of alcoholic specimens, one of which 
is drawn on pi. 7, fig. 57, that they extend nearly to the head, 
being composed of 16 or 17 plumes on each side. They are also so 
figured by Meyer & Mobius. In this character, cinereus differs 
from albus and ruber, in which species the gills are median. 

Carpenter, having examined the type of C. circumvallatus Rve., 
writes that he is satisfied that it is merely a cinereus. The locality 
given by Reeve is no doubt wrong. 

Var. variegatus Phil. PI. 7, figs. 58, 59, 60. 

Smaller, with triangular sutural laminse. Anterior valve having 
8 or 9, posterior valve having 7 or 8 slits in the insertion plates. 
Length 8, breadth 5, alt. 3 mill. 

Mediterranean and A driatic Seas. 



70 ISCHNOCHITON. 

Chiton variegatus PHIL., Enum. Moll. Sicil. i, p. 107, 1836; ii, p. 
83, t. 19, f. 13. WEINKAUFF, Conchyl. des Mittelm. ii, p. 412. 
ISSEL, Chit, del mare di Geneva, Bull. Mai. Ital. iii, p. 7, t. 1, f. 1, 
1870. Chiton marginatus Perm., TIBERI, Bull. Soc. Mai. Ital. iii, 
p. 139, 154. MONTEROSATO, Enum. e Synon. p. 16, 1878. BUQ,, 
DAUTZ. & DOLLF., Moll. Mar. Rouss. i, p. 497, t. 61, f. 13-16; t. 
62, f. 3. 

I have preferred to retain the Mediterranean form distinct, at 
least as a geographic variety, for it differs from Tr. cinereus of the 
north in being constantly smaller, having fewer slits in the end 
valves, and having the sutural plates of a decidedly different shape. 

I. ALBUS Linne. PI. 7, figs. 35-38. 

Shell oblong, elevated, the back keeled, lateral slopes nearly 
straight. Anterior valve half-circular, its posterior margin slightly 
concave ; sculpture consisting of some scarcely perceptible, low 
radiating ridges, often wholly obsolete, and an excessively minute 
shagreening or granulation of the whole surface, the granules 
showing a disposition to be arranged in oblique curved lines. 
Intermediate valves slightly beaked, produced forward in the mid- 
dle, having the same sculpture, and showing low, irregular growth 
wrinkles. Lateral areas scarcely raised, sculptured like the front 
valve. Posterior valve having the umbo slightly elevated, central, 
inclined backward. 

Interior white. Sutural plates large and wide, extending from 
the insertion plates nearly to the jugum. Sinus rounded. 

The anterior valve has 13 slits in the smooth and rather sharp 
insertion plate ; the intermediate valves have one slit ; the posterior 
valve has 10 slits, and the edge of the plate is decidedly roughened 
and irregular. Another specimen has 14 slits in the anterior valve, 
12 in posterior valve; and in still another individual, some of the 
intermediate valves have two slits on one side. 

The girdle is covered with small gravelly scales, and has no 
marginal fringe of long scales or spines. 

The gills consist of thirteen leaflets on each side, extending for- 
ward two-thirds the entire length of the foot. 

The color is a very delicate buff tint, sometimes almost white, 
often shading into a light orange on the posterior part and lateral 
areas of each valve. Most specimens have more or less of a black 
deposit on the back part of the valves. 

Length 15, breadth 7 mill. 

Length 10, breadth 5-6 mill. 



ISCHNOCHITON. 71 

Arctic and North Atlantic Seas; Greenland; Iceland; Spitz- 
bergen; Scandinavia; British Seas, south to Isle of Man; Gulf q 
St. Lawrence, Maine, and south to Massachusetts Bay (Cape Cod). 
In the Pacific from Arctic Ocean, south to the Shumagin Is., west to 
Kyska. Low water to 337 fins. 

Chiton albus LINNE, Syst. Nat. xii, p. 1107. LOWE, Zool. Journ. 
iii, p. 80. SOWB., Conch. 111. f. 99, 100. GOULD, Inv. Mass. p. 
150, f. 21. MIDD., Mai. Ross, i, p. 120. FORBES & HANLEY, 
Brit. Moll, ii, p. 405, t. 62, f. 2. STIMPSON, Sh. of N. Engl. p. 28; 
Inv. of Grand Manan p. 22. JEFF., Brit. Conch, iii, p. 220 ; v. p. 
199, t. 56, f. 3. BINNEY, in Gould's Invert. Mass. p. 265, f. 525. 
? Chiton oryza SPENGLER, Skrift. Nat. Selsk. iv, hft. 1, 1797, teste 
Jeffr. Ch. aselloides LOWE, Zool. Journ. ii, p. 103, t. 5, f. 3. 
WOOD, Index Test., Suppl., t. 1, f. 9. Ch. sagrinatus COUTHOUY, 
Amer. Journ. Sci. xxxiv, p. 217, 1838; Bost. Journ. ii, p. 82. 
Leptochiton albus H. & A. AD., Gen. Rec. Moll, i, p. 473. Chiton 
(Lepidopleurus) albus JEFFREYS Brit. Conch, iii, p. 210. Ch. 
(Lophyrus*) albus JEFFR. P. Z. S. 1882, p. 669. Lophyrus albus 
SARS, Moll. Reg. Arct. Norv. p. 114, t. 8, f. 2 (? not t. I, f. 9). 
? Ch. minimus GMEL., Syst. Nat. xiii, p. 3205. Trachydermon 
albus CARPENTER, New Engl. Chitons, Bull. Essex Inst. v. p. 153 ; 
MS. p. 15. BALL, Proc. U. S. Nat. Mus. 1878, p. 322. 

This well known Arctic and subarctic species is intermediate 
between Tr. cinereus and Tr. ruber in sculpture. The granulation 
is much finer than in the former of these, but is on the same general 
plan. 

On pi. 6, figs. 32-34, is copied a Carpenterian drawing of the 
interior of Tr. albus. It is, however, incorrect, the form of head 
and tail valves being unusual, and the slits of the latter entirely 
incorrect. The central valve is well represented however. The 
tail valve of a specimen from Grand Manan, drawn by the writer, 
is shown in fig. 38 of plate 7, correctly delineating the slits. 

I. EXARATUS Sars. PI. 7, figs. 39-49. 

Elongated, oblong-elliptical, strongly convex ; valves distinctly 
obtusely carinated medially. Anterior valve nearly semicircular 
in front ; the posterior edge forming an obtuse reentrant angle r 
with a rounded notch in the middle ; surface distinctly, radially 
grooved with single rows of rounded granules between the grooves, 
becoming larger toward the margin. 



72 ISCHNOCHITON. 

Median valves are moderately wide, nearly straight posteriorly, 
the hinder ones with a slight median beak with distinct diagonal 
furrows and ridges, dividing them into median and lateral areas ; 
the median areas are covered, on the sides, with fine but very 
distinct longitudinal grooves, with the intervening ridges narrow 
and rounded, more or less confluent and broken up into granules, 
near the diagonal lines towards the median ridge becoming finer and 
irregular, and finely granulous anteriorly and along the carina. 
The lateral areas are more elevated and covered with stronger 
radiating ridges, broken up into oblong and rounded, flattened 
granules, and separated by narrow radial furrows. The lateral 
insertion-plates of the median valves project but little beyond the 
upper lamina ; they are sub-truncate, with a thin notch or slit cor- 
responding to the diagonal line above. The posterior valve is 
transversely elliptical, with the posterior edge evenly rounded ; the 
front area is as in the preceding ones ; the posterior area is covered 
with fine radial and concentric grooves, dividing it into radiating 
rows of small rounded granules; the articulating plates of its front 
edge are rather wide, broadly rounded or sub-truncate, and separated 
by a broad, rounded median sinus ; posteriorly the inner surface is 
marked by about sixteen radiating lines, terminating in thin 
notches of the inserted edge, which is very narrow and simple. 

The marginal membrane is rather narrow and covered with 
rather stout, prominent, oblong and obtuse spinules, regularly 
arranged in quincunx, their ends looking like granules, at the 
edge and on the lower side these are replaced by small slender 
spinules. 

Head rounded ; hood large, the sides produced backward into 
rounded lobes. Foot long and rather narrow. Gills about twenty- 
four on each side, extending from the posterior end of the foot to 
about its anterior third. 

Length, 17 mm.; breadth, 8 mm.; height, 5.5 mm.; length of shell, 
15.5 mm.; breadth, 7 mm.; length 1st valve, 3 mm.; breadth, 6 mm.; 
length 3rd valve, exposed part, 2 mm.; breadth, 7 mm., length of 
posterior valve, 3.5 mm.; breadth, 6 mm. (Verrill.') 

Norway; Off Martha's Vineyard, 101-194 fms.; off Fernandina, 
Fla. 

Lophyrus exaratus SARS, Moll. Keg. Arct. Norv. p. 113, t, 8, f. 
1 ; t. II, f. 1, 1878. Trachydermon exaratus Sars, VERRTLL, Amer. 
Journ. Sci. xxiv, p. 365, 1882 ; Trans. Conn. Acad. Sci. vi, p. 208, 



ISCHNOCHITON. 73 

t. 30, f. 2, 2a, 2b. DALL, Bull. U. S. Nat. Mus. 37, p. 172, t. 45, 
f. 2. 

This species is readily distinguished from T. albus by the 
very distinct differentiation of the valves into median and lateral 
areas, having lines of sculpture running in different directions, and 
by the much coarser granulation of their surfaces. In T. albus 
there are no distinct lateral areas ; the radiating grooves and ridges 
are absent; and the granulation is so fine and obscure as to be 
scarcely visible without a lens. The spinulation of the marginal 
membrane is similar in the two species. ( Verrill.) 

I^DENTIENS Gould. PI. 8, figs. 61-65. 

Shell oval, rather elevated, dorsally angled, ash colored, closely 
and finely mottled with olive, and having a series of alternating 
olive and light spots upon the back edges of the valves along the 
sutures. These spots are often obscure or wanting, and in some 
specimens the ground color is a pale orange-flesh tint. 

The valves are covered with a very minute sharp granulation, 
the granules small but well raised, and on the central areas of some 
specimens they are somewhat disposed to be arranged in longitud- 
inal lines converging toward the dorsal ridge, this disposition usu- 
ally stronger toward the lateral extremities of the valves. The 
lateral areas are a little raised, the diagonal lines separating them 
from the central areas rather distinct. The umbo of the posterior 
valve is median, somewhat raised, the slope behind it being 
depressed and concave. 

The interior is either whitish stained with gray-green, or quite 
green. The sutural plates do not project as far as usual, and on 
some valves they are emarginate in front. The jugal sinus is wide, 
angular, flat or encroached upon by the jugum. The anterior 
valve has 11 slits in the insertion plate, the intermediate valves 1, 
the posterior valve has 10 or 12, and some of the median teeth are 
bifid at the tip. 

The girdle is narrow, gravelly, covered with minute scales. 

The gills extend to the front end of the foot. 

Length 15, breadth 10 mill. 

Puget Sound (Gld.) ; San Diego, California (Hemphill, in A. N. 
S. P. coll.). 

Chiton dentiens GOULD, Proc. Bost. Soc. N. H. ii, p. 145 ; Otia 
p. 6. (7/i. (Omthochiton) dentiens GLD., I. c., 242; U. S. Expl. 




UNIVERSITY 



74 ISCHNOCHITOX. 

Exped. p. 321, t. 433 (bad). Trachydermon dentiens DALL, Proc. 
U. S. Nat. Mas. 1878, p. 323. Tracfiydermon pse'udodentiens CAR- 
PENTER, Brit. Asso. Adv. Sci. Rep. 1863, p. 649 ; Proc. Acad. Nat. 
6ci. Phila. 1865, p. 60. 

This species is closely allied to cinereus L., but differs in the 
sharper granulation, the granules being less regularly arranged, in 
the form of the sutural plates and the color both externally and 
within. The girdle of dentiens differs from that of cinereus in 
lacking the marginal spicules characteristic of that species. The 
gills are long, as in cinereus. 

Gould's diagnosis and figures are extremely incorrect, the light 
spots along the sutures having been mistaken by him for projections, 
or "teeth," whence the name dentiens. Carpenter ascertained the 
identity of dentiens with the present form by an examination of 
Gould's type specimen. 

A series from San Ignacio Lagoon, Lower California, differs from 
the San Diego shells in being narrower, chiefly dark green (occa- 
sionally with some lighter valves), and in being more subtly granu- 
lated. The interior is vivid dark green. One of these is shown in 
fig. 65. These specimens show a short, slightly acute and beaked 
umbo on the central valves. In the larger northern specimens this 
is lost by erosion. 

I. GOTHICUS Carpenter. Unfigured. 

Shell small, much elevated, green, elegantly tinted with rose and 
olive ; valves gothic-arched, the dorsal ridge acute ; lateral areas 
small, arcuately distinctly defined, granulose; umbones prominent; 
umbonal margin having a tessellated color pattern and incurved. 
Central areas longitudinally ribbed, ribs rounded, close, not much 
elevated, the interstices small, sometimes slightly decussated. End 
valves sculptured like the lateral areas, the tail valve having the 
umbo median and somewhat elevate:!. 

Interior having the sutural plates scarcely separated, the jugal 
sinus very broad and shallow ; insertion plates of median valves 
having a single slit, terminal plates with 8-10 slits ; the plates are 
obtuse; eaves hardly elevated. 

Girdle most minutely scaly, the granules very close, rounded 
smooth ; edge with small suberect hairs. (Cpr.) 

Length 5, breadth 2* mill. ; div. 80. 

Catalina Island, California. 



ISCHNOCHITON. i 

Trachydermon gothicus CARPENTER, Kep. Brit. Asso. Adv. Sci. 
1863, p. 649 ; Proc. Cal. Acad. Sci. iii, p. 212, 1866 ; MS. p. 18. 

An unusual character in this very 'small, prettily sculptured spe- 
cies is that the sutural laminae are slightly connected [across the 
jugal sinus] by a layer lining the very broad, shallow sinus. As in 
pseudodentiens \_=dentiem Gld.] a false appearance of dentation is 
given to the sutures by the spots of darker painting. (Cpr., MS.) 

ISCHNOCHITON. 

I. RETIPOROSUS Carpenter. Unfigured. 

Shell small, subelongate, a % shen colored ; much elevated, the jugum 
arcuate. Valves subquadrate, apices concealed, lateral areas little 
defined, having 3 to 6 rounded, obsolete riblets, here and there with 
acute projecting granules. Central areas pitted all over, interstices 
small, punctate. Terminal valves with more acute close narrow 
riblets. Mucro little raised, anterior. Inside with broad sutural 
sinus. Insertion plates of intermediate valves with one slit on each 
side, terminal valves with about 12 slits. Girdle bearing close, 
minute scales, which are little elongated. 

Length 11, breadth 7 mill.; div. 90. 

Puget Sound- 

Trachydermon retiporosus CPR., Brit. Asso. Rep. 1863, p. 649. 
Ischnochiton (Trachydermon) retiporosus CPR., Proc. Acad. -Nat. 
Sci. Phila. 1865, p. 59. 

A species like scrobiculatus Midd., the central pattern in net- 
work, lateral areas with 3 to 6 ribs. 

Known to me only by Carpenter's description. 

I. FLECTENS Carpenter. Unfigured. 

Shell small, subelongate, roseate; jugum acute; lateral areas 
scarcely defined. Valve margins excurved, suture incurved, apices 
very prominent ; valves having minute, not very close granules 
sparsely subradiating, all over very minutely punctulate. Mucro 
conspicuous, anterior. Inside : sutural sinus wide, flat ; eaves 
scarcely projecting. Terminal valves with 11, median 1 slit. 
Girdle very minutely granulate. 

Length 8f, breadth 6 mill. ; div. 110. (Cpr.) 

Puget Sound. 



76 ISCHNOCHITON. 

Trachydermon fledens CPR., Rep. Brit. Asso. Adv. Sci. 1863, p. 
649. Ischnochiton (Trachydermoii) flectens CPR., Proc. Acad. Nat. 
Sci. Phila. 1865, p. 60. 

A variety from Catalina Is. has the posterior valve with 7, inter- 
mediate 1, anterior 8 slits, the mucro less anterior ; divergence 90. 



I. LIVIDUS Middendorff. PL 6, figs. 22, 23, 24. 

Shell elevated, tegrnentum smooth, shining, livid. Anterior 
valve, lateral areas and posterior valve obsoletely radiately rib- 
striate. Central areas longitudinally costulate, the riblets sepa- 
rated, sharply cut, whitish, 18-20 in number. Lateral areas 
depressed. Gills median. 

Length 23 mill. ; divergence 120. 

Sitka. 

Chiton (Stenosemus) lividus MIDD., Beitr. zu einer Malac. Ros- 
sica, i, p. 124, t. 13, f. 3, 4. 

This species and the next have not been found by later observers. 

I. SCROBICULATUS MiddendorfF. PL 8, figs. 66, 67, 68. 

Shell depressed, tegmentum rough, opaque, ashen or yellow- 
brown. Central areas regularly pitted in longitudinal series; lat- 
eral areas swollen, divided by a radiating groove which widens 
below. Girdle having narrow scales. Gills median, 16 in number. 

Length 9 mill.; divergence about 130. 

California. 

Chiton (Stenosemus') scrobiculatns MIDD., Mai. Ross, i, p. 127, t. 
14, f. 4-7. 

I. SOLIDIOR Carpenter, n. sp. Unfigured. 

Shell small, oval, somewhat elevated, rather flesh-colored; jugum 
obtuse ; mucro elevated, in front of the middle. Valves pointed, a 
little rounded at the margins; lateral areas scarcely defined. 
Entire surface smooth, under a lens minutely roughened and very 
minutely punctate ; wrinkles of growth conspicuous. 

Inside : posterior valve with 9, anterior with 8, median with 1 
slit; the teeth obtuse, solid, much separated, at times somewhat 
roughened. Sinus wide, flat ; eaves short. 

Girdle normal for Trachydermon, the granules solid. 

Philippines. 



ISCHNOCHITON. 77 

This is the only tropical species that I have met with, and it is 
very abnormal in its stumpy projecting teeth, resembling those of 
Tonicella. The girdle is, however, normal, the extremely minute 
crowded granules presenting a somewhat bristly appearance under 
the microscope. 

The above is taken from Carpenter's MS. The type specimen is 
Mus. Cuming, No. 106. 

I. ASPERIOR Carpenter, n. sp. Unfigured. 

Shell small, oval, depressed, the jugum acute. Valves apicu- 
late ; ashen, maculated with darker. Mucro rather raised, the 
posterior slope concave. Entire surface under a lens seen to be 
conspicuously pustulose ; central areas having about 7 subparallel 
lines of small but projecting granules, bending toward the jugum, 
closer on the jugal area. Lateral areas hardly elevated, having 
about 3 very distant and a little larger lines of granules ; anterior 
valve with about 18 such lines. 

Interior: anterior valve with 8, central valves 1, posterior valve 
with 9 slits ; teeth acute, long ; eaves conspicuous, short ; sinus nar- 
row, deep, laminated but scarcely dentate. Girdle thickly beset 
with most minute purple smooth scales (and occasionally corneous 
hairs, perhaps foreign to it). 

Length 11}, breadth 71 mill. ; div. 140. 

East Asia. 

f Trachydermon asperior CPE., MS. p. 19. 

The solitary specimen was found in a mixed group of species, 
named C. pulcherrimus Sby., and Lept. craticulatus by Dr. Gould, 
and coming from either Hong Kong or Hakodadi. It will be 
easily recognized by its sculpture and minutely chaffy scales. 
Whether it belongs to this genus or to Chcetopleura will probably 
be decided by the gills. (Q?r.) 

I. PERORNATUS Carpenter, n. sp. Unfigured. 

Shell, small, subelongate, elevated; jugum acute; ashen or olive 
maculated ; mucro slightly before the middle, planate. Central 
areas with subparallel strong tuberculate bars, about 10 on each 
side, interstices decussated ; jugal area granulate, sculptured in 
front ; lateral areas strongly denned, having rounded irregularly 
radiating tubercles, of which there are around the margin of the 
posterior valve about 20, the median valves 5, anterior valve 24. 



78 ISCHNOCHITON. 

Interior: anterior and posterior valves having 7 slits, median 
valves 1 slit ; teeth a little acute, eaves large, pectinated by the 
tubercles or little bubbles of the outer surface ; sinus moderate, 
deep, flat, smooth. 

Girdle closely beset with rather flat, subpilose, minute scales. 

Length 15, breadth 7* mill. ; div. 95. 

Habitat unknown. 

f Trachydermon perornatus CPU., MS. p. 19. 

Congeneric with asperior, but easily distinguished by the very 
strong sculpture, flattened mucro, yet sharp elevation of the shell. 



I. VIRGATUS Reeve. PL 8, figs. 72, 73 (enlarged). 

Shell oblong-ovate, minute ; valves smooth, or under a lens very 
finely reticulated ; beautifully mottled and striped with bluish- 
green and yellow. Ligament very minutely scaly, marbled. (Rye.*) 

Port Lincoln, Australia. 

Ch. virgatus Rv., Conch. Icon. t. 28, f. 192, 1848. Trachydermon 
virgatus Rv., CARPENTER, MS. p. 22. Ischnochiton virgatus Rv., 
CPR., MS. p. 106. 

Carpenter writes as follows of the type specimens : Two speci- 
mens, Mus. Cuming ; minute, length 5, breadth 2 mill. ; div. 85. 
Shell very arched, the jugum rather obtuse but not very. Mucro 
elevated, the posterior slope slightly concave. It looks externally 
like the young of lentiginosus, being painted in the same way- 
olivaceous with bluish-green spots. Girdle tessellated with very 
small scales, not striated; granular. The three areas are scarcely 
to be distinguished. Very conspicuously quasi-granulate all over. 
The jugular part is partially streaked with brown in one specimen, 
blotched with ashen in the other. The anterior valve has 9, central 
valves 1, posterior valve 9 slits. Teeth sharp, few, long. Eaves 
moderate. Sinus broad, moderate, flat, not channelled. 

I. VIRESCENS Reeve. PL 8, figs. 74, 75. 

Shell ovate, valves smooth, crenulated along the posterior edge ; 
bright pale green ; ligament horny. (Ev.) 

Habitat unknown. 

Chiton virescens REEVE, Conch. Icon. t. 20, f. 126, May, 1847. 
"/ f Trachydermon virescens " CPR., MS. p. 21. 



ISCHNOCHITON. 79 

Carpenter's notes are as follows : Five specimens, no localities, 
Mus. Cuming. A very remarkable species, with a very singular 
combination of characters. Perhaps it belongs rather with gemmea, 
etc. Valves rather pointed in front, and broader behind ; shell 
oval, somewhat elevated, jugum rather sharp. Green, with one or 
more valves always variegated with darker ; fine tessellations at 
sutures, causing it to appear toothed. Mucro rather raised at 
anterior third ; posterior slope very concave. Valves rather curved, 
with conspicuous, rather obtuse apices. Side areas scarcely distinct. 
The whole surface is rather glossy, but under the microscope with 
extremely fine granulation, which runs into fine lines along and 
near the jugum. Girdle Trachydermoid, covered with extremely 
minute scales and occasional hairlets, but at the sutures and in a 
row around the margin are a series of brown dots which turn out 
to be semi-pores, quite regular but without hairs, only larger grains 
making a kind of knob. They are very conspicuous as pore-lumps 
when the shell has been soaked. The anterior valve has 11, central 
1, posterior 9 slits. Teeth stumpy, like nuttallii, but not striated. 
Sinus shallow and rounded, with about 16 teeth, formed by the 
lirations of the anterior part within. Eaves short and very spongy. 

Length 12, breadth 7 mill.; divergence 113. 

I. STRAMINEUS Sowerby. PI. 8, fig. 71. 

Shell ovate, smooth, pale straw-colored ; back rounded ; marginal 
scales sparse. (Sowb.~) Length 10, breadth 6 mill. 

Island of Chiloe, under stones at low water. 

Chiton stramineus SOWB., P. Z. S. 1832, p. 104 ; Conchol. Illustr. 
f. 28; Zool. Beechey's Voyage, p. 150, t. 41, f. 13. Trachydermon 
stramineus Sowb., CARPENTER, MS. p. 21. 

Carpenter remarks : A distinct species. Five specimens in Mus. 
Cuming, much worn and smashed. They scarcely show the sculpt- 
ure ; in the best there is an attempt at granulation. Rather broad, 
flat, rounded jugum. Girdle gravelly; mucro median, a trifle 
raised ; posterior slope nearly straight. The anterior valve has 15, 
median 1, posterior 10 slits; teeth sharp, Ischnoid ; eaves moderate. 
Length 11 J, breadth 7 mill.; divergence about 114, the valves 
rounded. 



80 ISCHNOCHITON. 

I. PUSILLUS Sowerby. PI. 8, figs. 69, 70. 

Shell small, obovate, whitish ; back elevated ; intermediate valves 
narrow, very minutely punctulate ; lateral areas somewhat distinct ; 
posterior valve larger, the apex central, inclined backward. (Botch.) 

Length 61, breadth 2 mill. 

Pacasmayo, Peru, on a coral reef in 17 fms., 9 miles from shore. 

C. pusillus Sows., P. Z. S. 1832, p. 57; Conch. Illustr. f. 31. 
REEVE, Conch. Icon. f. 189. 

Carpenter's notes on the two specimens in the Cumingian collec- 
tion are as follows: Length 5*, breadth 2* mill.; divergence 90, 
nearly semicircular. Small, whitish-ashen, long, arched. No 
jugum or jugal area. Lateral areas slightly swollen ; granulated, 
but no other pattern. Mucro rather elevated, posterior slope very 
concave. Posterior valve with 11, median 1, anterior 10 slits. 
Teeth sharp, long and very thin; eaves conspicuous, not spongy. 
Sinus deep, broad, flat, not channelled. The shell might pass in 
sculpture for a young punctulatissimus ; in shape and size for Lep- 
tochiton cancellatus; but as far as I can see the girdle scales, they 
are very minute and like Trachydermon, but they have mostly per- 
ished, and the specimens have been rather smashed and are in bad 
condition. 

I. RUBER Linne. PI. 7, figs, 50-56. 

Shell oblong, elevated, solid, the back roundly subangular, lat- 
eral slopes somewhat convex ; surface apparently smooth except 
for well-marked grooves or wrinkles, indicating growth-periods. 
Under the microscope, however, an excessively fine reticulation is 
visible. The color is light buff, marbled all over with orange-red 
in various patterns, or entirely suffused with reddish ; usually hav- 
ing a red dorsal stripe bordered on each side with buff. 

The anterior valve is twice as wide as long, crescentic rather 
than half-round. The intermediate valves are slightly beaked, 
their lateral areas slightly raised and having stronger concentric 
wrinkles than the central areas. Posterior valve having a rather 
elevated but obtuse median umbo. 

The interior is bright pink. The sutural plates are wide, large ; 
the jugal sinus is deep, narrow and angular. The insertion plate of 
the anterior valve has 8 to 11 slits; intermediate valves normally 1 
slit; posterior valve 7 to 11 slits. The insertion plates are sharp 
and smooth. 



ISCHNOCHITON. 81 

The girdle is reddish-brown, covered with minute elongated 
scales. 

The gills extend forward to the middle of the body. 

Length 20, breadth 12 mill. Alaskan specimens grow to the 
length of an inch. 

Arctic and northern seas of Europe; south to Massachusetts Bay ; 
N. Pacific and Bering's Sea from Pribiloff Is. west to Attu, south to 
Sitka ; Kamchatka. Low water to 80 fms. 

Chiton ruber L., Syst. Nat. xii, p. 1107. LOWE, Zool. Journ. ii. 
p. 101, t. 5, f. 2. GOULD, Invert. Mass. p. 149, f. 24 ; edit. Binney 
p. 260, f. 523. FORBES & HANLEY, Hist. Moll. G. B. ii, p. 399, t. 
59, f. 6 ; t. A A, f. 6. HANLEY, Sh. of Linn. p. 17. SOWERBY, 
Conch. Illustr. f. 103, 104. REEVE, Conch. Icon. f. 175. JEF- 
FREYS, Brit. Conch, iii, p. 224; v, p. 199, t. 56, f. 4. Ch. dnereus 
O. FABR., Faun. Gronl. p. 423, not of authors nor of Linne. Ch. 
minimus SPENGL., not of Gmel. Ch. Icevis LOVEN, Ind. Moll. lit. 
Scand. p. 28, 1846, not of Mont., Forbes & Hanley, et al. Ch. 
Icevis PENNANT (probably), Brit. Zool. (iv), iv, p. 72, t. 36, f. 3. 
Ch. latus LEACH, Moll. Brit. p. 231. Chiton (Lepidopleur us*) ruber 
JEFFREYS, Brit. Moll, iii, p. 210. Trachydermon ruber CARPENTER, 
Bull. Essex Inst. v, p. 153, 1873. Boreochiton ruber SARS, Moll. 
Reg. Arct. Norv., p. 116, t. 8, f. 4. Tr. ruber BALL, Proc. U. S. 
Nat. Mus. 1878, p. 320 (1879). Chiton incarnatus REEVE, Conch. 
Icon. f. 194, 1848. 

The shell is apparently smooth, as described by Forbes and Han- 
ley, but under a high power appears finely reticulated as observed 
by Jeffreys. Its color is very variable, being usually marbled red 
and whitish like Tonicella marmorea, but the valves may be uni- 
form dark red or nearly pure white. I have one specimen with 
the four central valves dark red and the rest white ; one valve in a 
specimen is often dark red, while all the others are marbled. It is 
most likely to be confounded with Tonicella marmorea and some 
varieties of T. litieata, both of which have leathery girdles, while 
this species can almost always be determined by its farinaceous 
girdle, dusted with alternate red and whitish patches, the latter 
nearly opposite the sutures. (Dall.) 

I. PUNICEUS Couthouy. PL 8, figs. 76, 77. 

Shell small, thin, elongated, elliptical, elevated and sharply car- 
inated along the back, of a dull rose, or bright brick-red color, and 
6 



82 ISCHNOCHITON. 

everywhere minutely punctured. The lateral areas are very 
abruptly and distinctly elevated, regularly ridged by the obtusely 
rounded stages of growth and bearing a few scattered granules. 
Central areas with the lines of increase well marked, and remark- 
ably barred with about six elevated, longitudinal, parallel ridges, 
which are generally dislocated about the middle by some of the 
lines of increase. The posterior valve has a very minute, and 
acute, nearly central umbo, with an abrupt depression passing 
transversely through it ; the margin is very minutely imbri- 
cated by prismatic scales, colored like the shell, and with yellowish 
bands crossing it, opposite to the junctures of the valves. (Old.) 
Length 12, breadth 7* mill. 

Orange Harbor, Terra del Fuego. 

Ch.puniceus (COUTHOUY MS.) GOULD, Proc. Bost. Soc. N. H. ii, 
1846, p. 143 ; Exped. Sh. p. 5 ; U. S. Expl. Exped. Moll. p. 324, t. 
27, f. 412; Otia Conch, p. 5. Trachydermon ruber var., CARPEN- 
TER MS. Lepidopleurus puniceus ROCHEBR., Miss. Sci. Cap Horn, 
Moll. p. 140. 

The gills extend forward to the middle of the foot. They are 
erroneously represented upon Gould's plate. Carpenter considered 
this a synonym of T. ruber, but it is probably distinct. 

I. STEINENII Pfeffer. PI. 6, figs. 19, 20, 21. 

The form of the animal is a somewhat elongated oval, bluntly 
rounded before and behind, the middle keel-like and elevated. 
Girdle covered with granules which are somewhat elongated in a 
radial direction. Eighteen gills on each side, reaching from the 
middle of the foot nearly to the posterior end. 

Shell rather elevated, very finely granulated. Median valves 
comparatively narrow, their length not much over i of their 
breadth, the posterior angles not produced backward ; younger 
examples having strong, acute apices, older having less projecting 
blunt apices. Lateral areas separated from central areas by a dis- 
tinct ridge. Central areas having transverse lines of fine grains, 
which turn at right angles and become longitudinal on the lateral 
areas; there are also more or less terrace-like marks of growth- 
arrest. There is a system of weak radial wrinkle-striae, converging 
toward the umbo, upon the central areas, more developed in young 
specimens, and totally absent in the larger ones. Anterior valve 
half-round, concentrically finely granulated, and having coarse con- 



ISCHNOCHITON. 83 

centric growth-marks. Tail valve half-circular, its latter part 
sculptured like the head valve ; its central area from i to more 
than i the length of the posterior slope. Umbo acute in young" 
examples. 

The insertion plates are all overhung by the eaves, the latter pro- 
jecting beyond them. The anterior valve has 17, posterior valve 
12 teeth. 

The ground color of the shell has a light reddish-white or bril- 
liant red tone, with more or less distinct radiating flamed streaks of 
lighter and darker ; girdle yellowish-brown, lighter toward the 
edge, with few or numerous transverse tracts of lighter. (Pffr.") 

Length 26, breadth 14 mill. 

South Georgia. 

Trachydermon steinenii PFFR., Moll, von Siid-Georgien, in Jahrb. 
Hamb. Wiss. Anstalten, iii, p. 103, t. 3, f. 1, 1886. 

Closely allied to T. puniceus, but different in having the central 
and lateral areas equally granulated, and the central area entirely 
without longitudinal sculpture. 

Section Trachyradsia Carpenter. 

Trachyradsia CPU., MS. DALL, Proc. U. S. Nat. Mus., Jan., 
1878, p. 1, 323. Type, Ch. fulgetrum Reeve. 

Chitons like Trachydermon except that the insertion plates of the 
median valves have two or several slits. 

The species of this group should be carefully compared with 
Callochiton and Stereochiton, with which groups they agree in the 
multiple slits of the central valves and the markedly spongy eaves. 

I am not disposed to group these forms with Trachydermon but 
leave them here in deference to the views of Carpenter. It should 
be noted that Carpenter did not consider Ch. fulgetrum the type of 
his group, that species having been selected by Dall. 

I. FULGETRUM Reeve. PI. 8, figs. 80, 81, 82. 

Shell ovate, a little attenuated in front, very minutely and closely 
decussately punctured under the lens, throughout. Terminal 
valves and lateral areas of the rest somewhat obscurely radiately 
grooved. Reddish-brown, peculiarly painted with longitudinal yel- 
low and black zigzag waves. Girdle horny. (Eve.) 

Habitat unknown. 



84 ISCHNOCHITON. 

Chiton fulgetrum REEVE, Conch. Icon. t. xiii, f. 71, March, 1847. 
f Trachyradsia fulgetrum CPU., MS. p. 24. ? Chiton dentatus, 
SPENGLER, Skrivter af Naturhistorie-Selskabet, iv, p. 88, t. 6, f. 16, 
Kiobenhavn, 1797. 

Carpenter writes as follows of the type specimen, unique in the 
Cuming Collection : The mucro is prominent and median, the slope 
behind it very concave. The interior is vivid rose color. 

The insertion plate of the front valve has 20 slits, median valves 
4 to 5, and posterior valve 18 slits. Sinus small, imperfect in each 
valve, but probably as shown in fig. 81. Eaves small. 

Girdle thin, wide, ornamented with small, scarcely imbricating, 
slightly elongated, very close, deciduous scales. 

Length 63, breadth 38 mill.; divergence 103. 

The scales are extremely minute deciduous, crowded into an 
irregular spongy mass, and when seen separately are not like a flat 
spine as in Callochiton, but somewhat rectangular and scarcely 
elongate. They have perished over most of the specimen, although 
that is in fine condition. It appears to have been tessellated with 
white over the chestnut surface but most of the specimen is now of 
a light horn color. The radsioid character of the valves and the 
brilliant rose interior makes this specimen very like castaneus but it 
is known outside by the obsolete riblets formed by slight depressions 
co-ordinate with the slits inside. Even these do not appear in the 
younger part of the shell. The color markings are probably vari- 
able. It is probably from S. Africa. ( C-pr.) 

I. ALEUTICUS Dall. Unfigured. 

Shell small, rufous-ashen, oblong, vaulted, the jugum very acute ; 
mucro submedian ; apices prominent ; lateral areas inconspicuous, 
entire surface minutely reticulated in quincuncial pattern. 

Interior: anterior valve with 16, central with 2, posterior with 
11 slits; teeth small, very spongy, widely separated ; eaves spongy, 
sinus small. Girdle beset with minute scales. (Dall.} 

Length 6, width 3 mill. 

Kyska Harbor, Kyska Id. ; Constantine and Kiriloff Harbors, 
Amchitka Id., and Nazan Bay, Atka, in the ivestern Aleutians, at 
low-water mark, under stones on the beach. 

Trachyradsia aleutica DALL, Proc. U. S. Nat. Mus. p. 1 , Jan., 
1878 and t, c., p. 323. 



ISCHNOCHITON. 85 

This modest little species is of a dull livid purplish red, with an 
ashy tinge, especially on the narrow girdle. Except for the well- 
marked ridges of growth, it appears smooth, but possesses (like all 
Chitons) a fine reticulation, only visible under a magnifier. The 
lateral areas are not distinct, the back is very much rounded and 
the valves well hooked in the median line. The substance of the 
valves from within appears remarkably spongy as if rotten, or 
even like vesicular pumice, especially under the eaves. The ante- 
rior slits are marked by radiating lines of holes, though the teeth 
between them can hardly be made out. The posterior valve, how- 
ever, has not this aid to counting, and in the general sponginess it 
is almost impossible to say how many teeth or denticles exist. It 
bears no marked resemblance to any other species of the region. 
(Da//.) 

I. MULTIDENTATUS Carpenter, n. sp. TJnfigured. 

Shell small, reddish-ashen, oblong, vaulted, the jugum very 
obtuse ; umbo of the last valve submedian ; apices prominent. 
Entire surface having the appearance of being minutely scaled in 
quincunx ; lateral areas scarcely distinguishable. 

Interior having 20 slits in the posterior valve, 2 or three in the 
intermediate valves ; teeth small, solid, obtuse, deeply and broadly 
separated ; eaves short, spongy ; sinus small, very wide, scarcely 
laminate. Girdle beset with minute scales. ( Cpr.) 

Bonin Islands (Stiinpson). 

Trachyradsia multidentata CARPENTER, MS. p. 24. 

The type is in the Smithsonian collection. 

The only specimen known^has lost its head valve, and most of the 
mantle scales; what remain of these, however, are of the Trachy- 
dermon rather than the Callochiton type. The shell was named 
Lepidopleurus lepidus by Dr. Gould, but has little in common with 
that species. There is no character to distinguish it by outside ; 
but within the incisors are represented by a series of roundish, 
stumpy, peg-shaped denticles, set rather widely apart in the short 
spongy gums that are characteristic of Callochiton. The three or 
four lobes in the side valves are rather longer. (Cpr.') 

I. LINDHOLMI Schrenck. PI. 27, figs. 35, 36, 37, 38, 39. 

Shell ovate, about twice as long as wide, depressed ; olive-green, 
the eroded umbones rosy-white. Lateral areas and end valves 



86 ISCHNOCHITON. 

radiately costulate, decussated by concentric growth sulci, the rib- 
lets more or less scaly-gran ose, the interstices very delicately punc- 
tate. Central areas longitudinally wrinkled, the interstices deli- 
cately punctate. Mucro subcentral. Anterior valve having 16, 
median valves 4, posterior valve 12 slits. Sutural plates yellowish- 
rose color. Girdle half as broad as the lateral slope of the valves, 
very delicately granulose, blackish-green maculated with white. 
Gills ambient, composed of 44 branchiae. 
Length 44 mill. ; divergence 130. 

Bay of Hakodadi, Japan. 

Chiton lindholmi SCHRENCK, Bull. 1'Akad. Imp. Sci. de St. 
Petersb. v, p. 511 ; Melanges Biolog. iv, p. 253; Reisen u. Forsch. 
iin Amurlande ii, Zool. p. 288, t. 12, f. 9-16. 

This large radsioid species may prove to be a Stenoradsia (see p. 
61) ; but the meagre description of the girdle given by Schrenck, 
causes me to place it, for the present, in the decidedly heterogeuous 
group Trachyradsia. 

Subgenus VI. ISCHNOCHITON Gray (restricted). 

Ischnochiton GRAY, P. Z. S. 1847, p. 126. SHUTTLEWORTH, 
Bern. Mittheil. 1853, p. 66. Lepidopleurus (part) H. & A. ADAMS, 
and CARPENTER, olim., not Lepidopleurus Risso. Ichsnochiton 
FISCHER, Manuel p. 880. 

Valves having sharp, non-pectinated insertion plates ; mucro 
median or anterior ; girdle covered with imbricating scales. 
Within this subgenus three subdivisions may be recognized : 

Section Ischnochiton s. s., in which the valves and insertion plates 
are thin and smooth, one side-slit in each median valve ; the 
scales of the girdle flat and striated. 

Section Lepidozona, differing in the convex, solid girdle scales, 
which are usually almost smooth. 

Section Radsiella, like typical Ischnochiton except that there are 
two or several side-si its in each median valve. 

The subgenus Heterozona should properly be included here also, 
and Ischnoradsia is not far removed from Lepidozona in characters. 



ISCHNOCHITON. 87 

Section Ischnochiton s. str. 
(1.) Group of I. longicymba. 

Oblong species, with fine, not conspicuous, sculpture, the central 
areas granulated in quincunx or in zigzag pattern, lateral areas 
radially ribbed. 

The species are from Australo-Zelandic seas. 

I. LONGICYMBA Quoy & Gaimard. PI. 22, figs. 58-66. 

Shell oblong, rather highly and broadly arched, not in the least 
carinated. Surface to the naked eye appearing smooth on the cen- 
tral, radiately lirulate on the lateral areas and end valves. Color 
extremely variable, usually pale olive mottled with dark olive or 
purple-black, or having a broad light band along the back. 

Lateral areas distinctly raised, sculptured with 8-12 radiating 
riblets, often bifurcating, the intervals densely granulated ; the rib- 
lets are interrupted by irregular impressed concentric growth-lines. 
Central areas very closely and finely granulated in quincuncial 
pattern ; the granulation is nearly even on the jugum, although the 
anteriorly divergent rows of granules are sometimes slightly more 
prominent ; on the slope between central and lateral areas, and on 
the extreme sides of the latter the granules are arranged to form 
more or less distinct longitudinal rows. The end valves are very 
minutely granulated and radially lirulate. Umbo of posterior 
valve rather low, obtuse ; posterior slope visibly concave. 

Interior green or blue sometimes varied with red or corneous. 
Anterior valve with 9-12, central 1, posterior valve 11 slits; teeth 
thin, sharp and smooth ; posterior tooth of the side insertion plates 
short, and terminating abruptly before attaining the posterior mar- 
gin of the valve (figs. 61, 64) ; eaves solid. 

Girdle closely covered with solid, convex but somewhat flattened 
imbricating scales, most of which are rather weakly striated, but 
among which non-striated scales are mingled (pi. 22, figs. 63, 66). 

Length 33, breadth 16 mill, (often smaller). 

New Zealand : Auckland to Dunedin ; Pitts' Island; Auckland 
Is. ; Campbell Id. 

C. longicymba (? Dufresne, Mus. Paris; Blainville, Diet, des Sci. 
Nat. xxxvi, p. 542), QUOY & GAIMARD, Voy. de PAstrol. Zool. iii, 
p. 390, t. 75, f. 1-18 (1834). REEVE, Conch. Icon. t. 19, f. 125, t. 
24, f. 163d. Lepidopleurus longicymbus HUTTON, Man. N. Z. 
Moll. p. 113 (1880). 



88 . ISCHNOCHITON. 

There is no certainty in the identification of de Blainville's loiigi- 
cymba but I have accepted the form recognized under that name by 
Quoy, as he was the first to figure the species. This identification 
compels us to regard the New Zealand shell as the type form. Figures 
58, 60-66 represent New Zealand specimens furnished me by Prof. 
Hutton and Mr. G. W. Wright. These differ from the Australian 
form, which I have named Haddoni, in the much less distinct, less 
regular striation of the girdle scales, the broadly rounded arch of 
the back, and the short, abruptly terminating posterior tooth of the 
side insertion plates. 

I. HADDONI Pilsbry, n. sp. PI. 22, figs. 67-73. 

Shell distinctly keeled on the back ; scales of the girdle beauti- 
fully regular in size and arrangement, and evenly and deeply grooved 
(fig. 67). Sculpture and color patterns like I. longicymba. 

Interior white, greenish or bluish ; anterior valve with 10, cen- 
tral 1, posterior valve 12 slits; teeth thin, sharp. Posterior tooth 
of the intermediate valves long, extending almost to the posterior-lat- 
eral angle of the valve, and not terminating abruptly (fig. 72). 

Length 27, breadth 12 mill. 

The coloring is even more variable than in the New Zealandic 
J. longicymba; some specimens are clear, light greenish-buff (fig. 
71) ; some are brown, speckled all over with olive-black ; some are 
mainly red, or black, having a wide white dorsal stripe. 

Port Jackson, Australia. 

Chiton longicymba SOWERBY, Conchol. Illustr. f. 67. REEVE, 
Conch. Icon. t. 24, f. 163a-c. Ischnochiton longicymba CPE., MS., 
and of HADDON, Challenger Rep. Polyplac. p. 17 (not Ch. 
longicymba Quoy). 

Having examined extensive suites of specimens of the longi- 
cymba type of Ischnochitons from New Zealand and Australia, I 
find myself compelled to separate specifically those from the latter 
locality, although in general appearance, color and sculpture they 
certainly resemble the true longicymba. The differences indicated 
above, and shown in the figures, seem to be remarkably constant, 
and readily recognized if one takes the trouble to look for them. 
It must be admitted, however, that to thoroughly examine a small 
Chiton involves some little trouble ; and therefore we must feel no 
surprise if the superficial collector and the often no less superficial 
author, continue to confound species which are really distinct. It 



ISCHNOCHITON. 89 

must be said, however, that the confusion of these two species has 
probably been due to the lack of specimens from the two localities 
for comparison ; else the differences would hardly have escaped 
writers so careful and observant as Carpenter and Haddon. 

I. CRISPUS Reeve. PI. 24, figs. 98, 99 (enlarged). 

Shell rather elongately ovate; terminal valves and lateral areas 
of the rest finely decussately granulately crisped, central areas 
smooth, or under the lens very minutely reticulated. Olive-green, 
thickly painted with dots of a darker color. Ligament minutely 
granulously coriaceous, obscurely tessellated. (Reeve.} 

Australia. 

C. crispus RVE., Conch. Icon. t. 19, f. 120, May, 1847. 

Allied to C. longicymba, but distinguished from that by the min- 
ute decussated character of the sculpture of the lateral areas. 
(Eve.) 

Carpenter seems to think this simply a pale variety of C. longi- 
cymba, saying that he cannot see the decussation spoken of by 
Reeve, unless it is from the concentric ribs of growth seen in some 
of the specimens. 

In view of the inadequate description and figure, the species had 
better be dropped. 

I. PALLIDUS Reeve. PI. 23, fig. 91 (enlarged'). 

Shell oblong-ovate, valves smooth throughout ; dead white ; lig- 
ament horny, arenaceous, brown. (Reeve?) 

A ustralia. 

C. pallidus REEVE, Conch. Icon. t. 16, f. 92, March, 1847. Isch. 
pallidm CPR., MS. 

Carpenter's notes on the specimens in the British Museum are as 
follows, but I am not sure that these are Reeve's species : Shell 
almost exactly like I. longicymba, gothic-arched ; whitish, ashen, or 
variously tinged or streaked with roseate, blue and olivaceous ; 
jugal area scarcely defined, jugum obtuse ; central areas wrinkle- 
striated, the wrinkles irregularly tending forward toward the jugum, 
sometimes v-shaped; lateral areas well-defined, having 12-30 gran- 
ulate-wrinkled striae, sometimes the wrinkles, sometimes the gran- 
ules predominating, sometimes having concentric growth wrinkles. 
Mucro median, rather elevated, the slope behind it little concave. 
Interior : front valve with 11, central 1, posterior valve 13 slits ; teeth 




90 ISCHNOCHITON. 

acute ; sinus very broad, flat ; eaves large, scarcely spongy. Girdle 
thin, irregularly imbricated with very small, very close, solid, sub- 
elevated, conspicuously sulcated scales. Australia. Five speci- 
mens, B. M., the tablet including two specimens of longicymba and 
one of Heterozona cariosa f. 

In the first specimen the radiating sculpture is almost lost in the 
granules in the side areas. The painting is sometimes with delicate 
broken lines of brown longitudinally. Sometimes one jugular 
patch more or less broken into streaks, side areas rarely if ever 
painted, but often tinged with bluish green. The specimen opened 
B. M. has 2 central teeth on posterior valve changed into an irreg- 
ular series of pectinations evidently consequent on an injury. 
(Qn-.) 

I. INQUINATUS Reeve. PL 18, figs. 49, 50 (enlarged). 

Shell oblong-ovate ; terminal valves and lateral areas concen- 
trically, somewhat obscurely ribbed, finely radiately grooved; cen- 
tral areas longitudinally finely ridged. Ligament horny, arena- 
ceous. Whitish, stained with a light brown spot along the summit 
of each valve. (Rve.*) 

Tasmania. 

C. inquinatus RVE., Conch. Icon. t. 23, f. 154, May, 1847. Isch- 
nochiton inquinatus CPU., MS. 

The shell is sometimes partially stained throughout with the 
faint brown color which appears on the umbonal summit. (five.*) 

Compare /. diver gens Rve. 

I. DIVERGENS Reeve. PI. 22, figs. 74-77. 

Shell oblong, moderately elevated, varying from obsoletely to 
distinctly angled at the dorsal line. Lateral areas raised and 
rugose. Color very variable, but usually a light green tint, spotted 
with dark olive-brown, or cream-white, variegated with olive, olive- 
brown or dull scarlet. 

The raised lateral areas are sculptured with a varying number of bi- 
furcating or irregular riblets, the surface between them being granular. 
Central areas sculptured in the middle with very fine subgranose striae 
diverging forward /\-likefrom the dorsal ridge; pleura or sides of the 
central areas having stronger longitudinal rugce at the sides and on 
the diagonal slope; a region of fine zigzag striation sometimes inter- 
vening between the side corrugation and the /\-like striation of the 
jugal tract. End valves sculptured like the lateral areas. Umbo 



ISCHNOCHITON. 91 

of the posterior valve rather acute, in front of the middle ; posterior 
slope concave. 

Interior whitish or bluish, marked at the sinus with blue-green, 
and posteriorly with rose ; the tail valve having a conspicuous black 
crescent in the middle. Anterior valve having 10-12, central 1, 
posterior valve 10-13 slits ; teeth sharp ; eaves narrow, solid. 

Girdle indistinctly tessellated with purplish on a paler ground, 
covered with large, convex, closely and deeply striated solid scales 
(fig. 74). Length 28, breadth 14 mill. 

Port Jackson, Australia. 

Chiton divergevs REEVE, Conch. Icon. t. 8, f. 44. Ch. proteus 
REEVE, I. c., t. 18, f. 111. Lepidopleurus proteus ANGAS, P. Z. S. 
1867, p. 222. litchnochiton diver gens and Isch. proteus CPU., MS., 
Iscli. intricatus and Isch. intricandus CPU., MS., olim. 

This species differs from I. longicymba, haddoni and fruticosus in 
the very much larger convex scales of its girdle. It has the lateral 
areas much as in I. fruticosus, but the median portion of the cen- 
tral area is more distinctly patterned, and the jugum is subcar- 
inated. It varies greatly in coloring, and usually has some rose- 
pink inside. 

I. divergens has been erroneously united to fruticosus by Angas 
and by Haddon. It should be understood that all of the detail 
drawings of the girdles are drawn to exactly the same scale; if this 
be considered, the student need not hesitate in identifying the pres- 
ent species. 

I. FRUTICOSUS Gould. PL 23, figs. 78, 79, 80. 

Shell oblong, moderately highly arched, the back rounded, not 
carinated. Surface lusterless and showing distinct, irregularly 
radiately roughened lateral areas. Color usually grayish or light 
green, becoming olive-green or brown toward the sides, and more 
or less spotted with blackish. 

The lateral areas are raised and irregularly sculptured 
with a varying number (3-6) of bifurcating subnodose 
radiating riblets, the posterior one of which is transformed 
into a series of nodes ; the other riblets often much interrupted 
(fig. 80), but sometimes nearly continuous; intervals between 
the riblets are finely granulated. The central areas are either 
minutely and evenly shagreened in the middle, much as in I. longi- 
cymba, except that the granules are more distinctly arranged into 



92 ISCHNOCHITON. 

oblique zigzag rows ; but toward the sides of the central areas, 
along the diagonal slope, a coarse sculpture of longitudinal wrinkles 
is developed. End valves sculptured like the lateral areas; umbo 
of posterior valve rather obtuse, the posterior slope concave. 

Interior white and blue or blue-green ; posterior valve having a 
black crescent. Anterior valve having 10, central valves 1, poste- 
rior valve 9 slits. Teeth sharp, thin, smooth outside, but slightly 
roughened inside; posterior tooth of the side plates terminating 
abruptly near the posterior edge of the valve. Eaves narrow, solid. 

Girdle indistinctly marbled with ashy-purple on a paler ground ; 
very closely covered with microscopic, deeply imbricating striated 
scales (fig. 79). Length 33, breadth 15 mill. 

New South Wales. 

Chiton fruticosus GOULD, Proc. Bost. Soc. Nat. Hist, ii, p. 142 
(July, 1846) ; U. S. Expl. Exped. p. 319, f. 428 ; Otia, p. 4, 242. 
Ischnochiton fruticosus CARPENTER, MS. and of HADDON ? Chal- 
lenger Polyplac. p. 17. Iscli. sowerbyi n. s. f, CPR., MS. 

This species has the lateral areas more roughly and irregularly 
sculptured than L longicymba or I. haddoni, and the girdle is some- 
what more compactly, flatly scaled than either. The external 
sculpture of the valves is extremely similar to I. diver gens Rve. ; 
but the latter differs totally in its very coarsely pebble-scaled girdle. 

I. SCULPTUS Sowerby. PI. 23, figs. 89, 90. 

Shell subelongate, depressed, subattenuated in front, back 
rounded. Central areas smooth, striated at the sides ; lateral areas 
ornamented with radiating exfoliating ribs ; margin smooth. 
Length 20, breadth 10 mill. (Sowb.) 

Habitat unknown. 

C. sculptus SOWERBY, Mag. of Nat. Hist, iv, p. 292, June, 1840 ; 
Conch. Illustr. No. 44, f. 66. REEVE, Conch. Icon, no, 177, t. 26, 
f. 121. 

A beautiful little shell, remarkable for the exfoliated sculpture of 
the lateral areas, on each side of which there are three radiating 
series of strongly relieved laminae. The central areas are nearly 
smooth except at the sides, where they are slightly striated. The 
margin is nearly smooth, light brown irregularly striped with gray ; 
and the general color is creamy-white. (Sowb.^) 



ISCHNOCHITON. 93 

I. CONTRACTUS Reeve. PI. 23, figs. 81, 82. 

Shell oblong, peculiarly contracted at the extremities 
especially the anterior; terminal valves and lateral areas of 
the rest concentrically granulated, granules solitary, central 
areas very minutely and closely ridged, ridges curved and con- 
spicuous towards the sides, finer towards the middle and decussated 
with oblique striae ; light bay, flamed in the middle with brown ; 
ligament grauosely coriaceous, dark brown. (Eve.) 

Tasmania (Mus. Cuming) 

Chiton contractus REEVE, Conch. Icon. 1. 15, fig. 78, March, 1847. 

Chiton decussatus REEVE, Conch. Icon. t. 18, f. 107, April, 1847. 

Chiton castus RVE., t. 22, f. 145, May, 1847. Ischnochiton 
castus CPR., MS., and 1. intergranosus CPR., MS. Lepidopleurus 
speciosus H. AD. & AN GAS, P. Z. S. 1864, p. 192 ; 1. c., 1865, p. 187. 

This species has been several times described, but the range of 
variation seems to be less than in some other allied forms, although 
the coloring varies considerable. The acute dorsal ridge, divergent or 
zigzag sculpture of the dorsal areas, the granulation of the lateral 
areas and serration of the sutures are characteristic. The descrip- 
tions of the several forms included under contractus follow below. 

Carpenter's notes are as follows: shell oval, subelevated, ashy, 
irregularly streaked with brown-olive. Otherwise like /. castus, 
but the central areas are everywhere zigzagly wrinkled, the lines 
which in castus are conspicuously at right angles to the diagonal 
line are not seen in contractus. Lateral areas and end valves hav- 
ing close radiating wrinkles, more or less broken into granules con- 
centrically, sometimes scarcely at all, sometimes entirely so. Inte- 
rior: anterior valve having 14, central valve 1, posterior valve 13 
slits; teeth acute; eaves conspicuous, hardly spongy; sinus wide, 
flat, smooth ; it appears broader and the sutural laminse not so high 
as in castus. Girdle pale black-brown ; scales as in /. castus. 
Length 37, width 17i mill.; divergence 110. 

There are 3 specimens in the Cuming collection, from Tasmania, 
and two on the same tablet which are really an intermediate varietv 
of I. castus. I cannot see the contracted shape figured by Reeve, 
in either of the specimens, which are shaped just like /. longicymba. 
The streaked coloring is quite exaggerated ; it is very irregular, not 
in even lines as in Reeve's figure. The divergence is the same as in 
I. castus. Side by side they exactly correspond. The difference 



94 ISCHNOCHITON. 

in the sinus is perhaps accidental, from their being older specimens. 
(Cpr.) 

C. deeussatus Keeve. (PL 23, figs. 83, 84.) Shell oblong-ovate, 
a little attenuated posteriorly. Terminal valves and lateral areas 
grained, the grains rather obtuse, numerous, irregular, -interstices 
rough. Central areas decussated with very close slightly wrinkled 
striae. Pale yellowish-green, flamed along the summit with brown. 
(Rve.) 

Australia (Mus. Cuming, 1 specimen). 

C. castus Reeve. (PI. 23, figs. 87, 88.) Shell oval, subelongate, 
rather elevated, orange tinted with red ; jugum acute ; mucro rather 
raised, median, the slope behind it concave. Central areas closely 
wrinkled, the wrinkles at the jugum diverging laterally, sometimes 
interrupting one another and forming zigzags. Lateral areas and 
end valves with concentric nodular wrinkles, sometimes the wrinkles, 
sometimes the nodules predominating; nodose at the sutures. 

Interior orange-flesh tinged ; front valve with 9, central 1, poste- 
rior 13 slits; teeth acute, scarcely pectinated ; sinus wide, flat, deep, 
slightly and very minutely denticulated by the external sculpture ; 
eaves large, hardly spongy. 

Girdle olivaceous, slightly tessellated, imbricated with large, 
wide and solid, deeply striated scales. Length 21, breadth 12 mill. ; 
divergence 103. (Cpr.,from type specimen.') 

Australia. 

The general characters of this species are the same as in textilis 
and cariosus, but it differs sufficiently in sculpture. Both of the 
two specimens in the Brit. Mus. are curved up so that they cannot 
be measured accurately. 

Another form which Carpenter described in MS. as " I. castus n. 
sp.," but which he afterward decided to be synonymous with castus 
Rve., is white with a black girdle. The shell is much elevated with 
acute jugum ; the central areas have delicate but much raised lira}, 
about 30 on each side, and subparallel except toward the ridge 
where they bend outward, and upon the jugum they are elegantly 
undulating. The lateral areas and end valves have rather large, 
separated grains, scarcely radiating, serrating the sutures. The 
anterior valve has 13, central 1, posterior valve 11 slits. The 
girdle is clothed with narrow, stout, deeply grooved scales. Length 
30, breadth 16 mill.; divergence 110. It is from Swan River 
(Mus. Cuming, No. 100). 



ISCHNOCHITON. 95 

Lepidopleurus speciosus. Shell lengthened, tawny, back orna- 
mented longitudinally with red-brown, the margin with a wide con- 
centric green zone. End valves and lateral areas concentrically 
ribbed, the ribs pustulose, interstices minutely granulated. Lateral 
areas somewhat elevated. Median valves carinated. Dorsal areas 
divaricately wrinkle-striated. Girdle pale brown, covered with 
closely imbricating scales. Length 35, breadth 20 mill. (Ad. & 
Aug.) 

Port Lincoln. 

This is an excellent description of the exterior of this species. 
I. COLUBRIFER Reeve. PI. 21, figs. 51, 52. 

Shell oblong-ovate, somewhat elevated in the middle. Terminal 
valves and lateral areas peculiarly flat-grained, central areas very 
finely reticulated with circular and oblique striae. Whitish blotched 
with black ; ligament scaly. (Reeve.} 

Habitat unknown. 

C. colubrifer REEVE, Conch. Icon. t. 28, f. 188, Jan., 1848. Isch- 
nochiton colubrifer CPR., MS. 

Carpenter writes : Three specimens, Mus. Cuming. Very like a 
young variety of the castus group. Shell arched, not keeled, ele- 
vated ; ashy, spotted with dark here and there, tinged with orange 
about the umbos, which are not beaked. Central areas, and the 
undifferentiated jugal areas, covered with a minute granulation, 
running perpendicular to the diagonal line and then branching off 
into wrinkles. Lateral areas and end valves having granulations 
running into coarse concentric wrinkles. Posterior valve having 
10, central valves 1, anterior valve 9 slits ; teeth extremely sharp 
and fine ; sinus broad, deep, smooth, deeply channelled at the sides ; 
eaves long, solid. Girdle having typical Isclmoid scales, rather 
large, flat, broad, thin, regularly imbricated, very finely striated. 

Length 16, breadth 7 mill.; divergence about 83. 

I. PALLIDULUS Reeve. PI. 23, figs. 96, 97. 

Shell elongated ; terminal valves and lateral areas concentrically 
undulately wrinkled ; central areas minutely rough ; whitish 
throughout ; ligament horny, arenaceous, whitish. (Eve.) 

Habitat unknown. 

C. pallidulus REEVE, Conch. Icon. t. 20, f. 131, May, 1847. 
Ischnochiton pallidulus CPR., MS. 



96 ISCHNOCHITON. 

Carpenter gives the following notes: Anterior valve with 9, 
central valves 1, posterior valve 9 slits; teeth typically Ischnoid ; 
sinus deep, broad, channelled, flat ; eaves moderate. Jugum obtuse, 
elevated; central areas very conspicuously granulated in quincunx, 
passing somewhat into the V-sculpture ; lateral areas conspicuously 
raised, concentrically wrinkled, " thuinby." Mucro central. Gir- 
dle with pretty large, broad, thin, distinctly striated regularly 
imbricated scales. Length 22, breadth lOi mill, ; divergence 106. 

The peculiarity of the shell is the elongation. It is probably 
Australian and belongs to the I. contractus group. 

I. USTULATUS Keeve. PL 24, figs. 11, 12 (enlarged}. 

Shell elongately ovate ; terminal valves and lateral areas radi- 
ately ridged ; ridges wrinkled, here and there grained and bifur- 
cated ; central areas very minutely reticulated. Burnt brown. 
Ligament granosely coriaceous. (Reeve?) 

Australia. 

C. ustulatus REEVE, Conch. Icon. t. 17, f. 102, March, 1847. 
Ischnochiton ustulatus CPR., MS. Lepidopleurus ustulatus ANGAS, P. 
Z. S. 1867, p. 222. 

Carpenter briefly notes that the scales of the type specimens are 
rather gravelly and irregular, very small, but apparently a little 
striated. The drawings of scales and valves given on my plate 
were prepared for Carpenter, presumably from specimens in the 
collection of Mr. Wm. A. Haiiies, of New York City. 

I. CARINULATUS Reeve. PL 23, figs. 94, 95. 

The finely keeled Chiton. Shell oblong : ovate, terminal valves 
and lateral areas of the rest concentrically and radiately somewhat 
obscurely ridged and sculptured with obtuse granules arranged in 
wrinkles, central areas also granulated, smooth in the middle, 
peculiarly keeled at the summit; ruddy rose; ligament finely 
squamately coriaceous. (/2-yg.) 

Tasmania. 

Ch. carinulatus REEVE, Conch. Icon. t. 23, f. 158, May, 1847. 
Ischnochiton carinulatus CPR., MS. 

Carpenter's notes on the single type specimen in the British 
Museum are as follows : A long, narrow, rather pollicaroid shell, 
the shape of longicymba. Girdle with very small, distinctly but 
finely striated scales. Mucro at the anterior fourth. Jugum rather 



ISCHNOCHITON. 97 

sharp, curiously marked by a long, narrow white line which may 
be accidental. Central areas having very strongly marked rugose - 
granulations ; falling irregularly into corrugations, but made up of 
grains. Lateral areas moderately raised, with the same grain- 
wrinkling passing over about four very blunt obsolete ribs ; end 
valves obsoletely radiated. Interior: posterior valve having 11, 
central valves 1, anterior valve 10 slits; teeth sharp, short, thin ; 
sinus broad but shallow, very straight, smooth, not channelled ; 
eaves moderate, rather close to the teeth. Length 111, breadth 4i 
mill. ; divergence 103. 

I. CURTISIANUS E. A. Smith. PL 24, fig. 6 (enlarged). 

Shell oval, flattish, of a dirty dark grayish color, having a con- 
spicuous black broadish line from end to end down the middle of 
the back, with a pale one on each side of it, and with the mantle 
patched alternately light and dark, irregularly granulated through- 
out. Valves arched, not carinate at the vertex, with very indistinct 
lateral areas, exhibiting strong concentric lines of growth, especially 
conspicuous at the sides and anterior margins. Front plate well 
curved anteriorly, the posterior margin being broadly sinuated. 
Second plate longer than the other intermediate valves, slightly 
incurved on each side, the central outcurved point in front, rather 
peaked in the middle of the hinder edge. The third, fourth, fifth, 
sixth and seventh valves are very short in comparison with their 
width in proportion as 1 is to 3. The jugal sinus is large and arcu- 
ate. Last valve of a narrow acutely elliptic form, with the mucro 
probably near the center. Interior of the plates greenish-blue, 
stained dark brown in the middle. Laminse of insertion in the 
front plate with about ten notches at unequal distances, leaving 
different sized teeth between them, which are striated on both sides, 
but more strongly externally, their edges being sharp, but not 
smooth. The central plates have a single minute notch on each 
side, the insertion lamina being comparatively smooth on the upper 
surface and marked with a small brown spot on each side against 
the edge of the valve. Tail plate much thickened within along the 
posterior edge, which is roughened by fine cross stria?, there being 
no prominent teeth, and of course no notches. Mantle margin cov- 
ered with small subi rubricating oval granules. Length without 
margin 16 mill. ; width of fourth plate 9. 



98 ISCHNOCHITON. 

The granules of the surface have an irregular concentric disposi- 
tion, following to some extent the lines of growth. (Smith.') 

Port Curtis. 

Chiton (Ischnochiton) curtisianus SMITH, Rep. on Zool. Coll. H. 
M. S. 'Alert,' p. 78, t. 6, f. D. 1884. 

This is certainly not a typical Ischnochiton. It is difficult, with- 
out an examination of a specimen, to refer it to its proper genus. 

I. EXIGUUS Sowerby. PI. 23, figs. 85, 86. 

Shell oblong, small, rufescent, narrow. Intermediate valves hav- 
ing a very wide trigonal dorsal carina, the margins grooved; lateral 
areas distinctly defined. Length 4*1, breadth 1*3 mill. (Sowb.~) 

This is the smallest species Mr. Sowerby has seen ; the dorsal 
keel of the intermediate valves is very broad, and distinguished by 
a groove on each side. (Sowb.*) 

Lord Hood's Island, Polynesia, on Pearl Oysters. 

Chiton exiguus SOWB., P. Z. S. 1832, p. 104; Conchol. Illustr. f. 
36. REEVE, Conch. Icon. t. 28, f. 186. Ischnochiton exiguus CPU., 
MS. 

Carpenter writes: Interior: end valves having 14-16 slits, cen- 
tral valves 1 slit; sinus wide, curved; girdle irregularly clothed 
with large, slightly striatulate scales. Habitat, Central Pacific 
(Pease). Mr. Pease's solitary specimen seems conspecific with Mr. 
Cuming's hitherto unique specimen from Lord Hood's Island. It 
is in better condition than the type, but extremely minute and evi- 
dently very young. 

2. Group of I. textilis. 

Central areas granulated, becoming striolate at the sides; lateral 
areas radially wrinkled. South African species. 

I. TEXTILIS Gray. Un figured. 

Shell oblong, elongate, white, pellucid when young, green with a 
uhite central band; convex above; end valves and lateral areas of 
the middle valves finely radiately striated and concentrically 
wrinkled; central area closely and minutely punctated, and behind 
finely longitudinally striated ; margin [girdle] white, minutely scaly. 
Length one inch and a half. (Gray.) 

Cape of Good Hope (Capt. Carmichael, Mus. Brit.). 

Chiton textilis GRAY, Spicilegia Zoologica, pt. 1, p. 5, pi. 6, f. 20 
(July 1, 1828). KRAUSS, Die Siidafric. Moll., p. 38. (?) Ch. solea 



ISCHNOCHITON. 99 

SOWB., Conch. Illustr. f. 61 (not described, and referred by Sowerby 
to textilis). Not Ch. text His of Reeve, Conch. Icon. f. 91. 

The above description is from Gray's Spieilegia, the more impor- 
tant passages being italicised by me. Gray's figure is absolutely 
worthless. Reeve's figure and description do not pertain to this 
species, but to /. (Radsiella) zebra Krauss. The true 1. textilis is 
in all respects a typical Ischnochiton. I refer the undescribed (7. 
solea of Sowerby to textilis because it is said to be that species by 
Sowerby himself; but the figure is very poor. The details herein 
given will enable students to identify Gray's species with compara- 
ative ease and certainty, without a figure ; for it seems to be closely 
allied to the /. oniscus only among South African Chitons. The 
details of sculpture of the central areas and the coloring seem to be 
especially characteristic. Krauss describes specimens collected by 
him, and which he at one time considered a new species which he 
intended naming C. ludwigi. His description is as follows : 

Shell ovate-elongate, semipellucid, subctirinated ; white in the 
middle, the sides ashen green, often spotted with brown ; interior 
white. Front valve lunate, tail valve rather depressed, submucro- 
nate in the middle; intermediate valves having the central areas 
finely punctate on the ridge, longitudinally striolate at the sides ; 
lateral areas and end valves radiately rugulose-striated. Girdle 
ashen, submaculated, scaly, the scales small and oblong, excessively 
finely multicarinated. Length 22, breadth 11 mill. Table Bay. 

The anterior valve and the posterior part of the posterior valve 
are radially wrinkle-striated and have 12 slits in the insertion 
plates, which are smooth and shorter than the eaves. The median 
valves are rather narrow (8*6 x 3 mill.) and have distinct lateral 
areas with 5 to 6 strong wrinkle-like and interrupted striae. The cen- 
tral areas are seen under a lens to be covered with fine raised points, 
which toward the margins become more and more distinct, and 
near the lateral margins as well as in front of the lateral areas they 
unite into distinct longitudinal rows. The sutural plates are 
rounded ; insertion plates short, smooth, and having a single slit. 
The girdle is covered with extremely small, thin longitudinal scales, 
not disceruable to the naked eye, and prettily marked with 8-9 
stria. The color is Avhitish in the middle of the shell, grayish- 
green on the sides, and dotted and flecked throughout with brown. 

Krauss also describes the following : 



100 ISCHNOCHITON. 

Var. punctulata. Shell carinated, ashen-whitish, unicolored or 
spotted and dotted with brown ; very finely punctate. Lateral 
areas and end valves radially striated. Length 22, breadth 10 
mill. The valves are keeled and covered with regularly arranged 
elevated points only to be seen under a lens. 

As an illustration of this variety Krauss refers to Sowerby's 
Conchol. Illustr. fig. 55, but in my opinion this is not correct. 

I. ONISCUS Krauss. PI. 20, figs. 12, 3, 14, 15. 

Shell small, ovate-oblong, thin, semipellucid, subcarinated ; white, 
rarely with a reddish dorsal band, or yellowish with green dots. 

Intermediate valves having the central areas very finely punctu- 
late in the middle and longitudinally striolate at the sides; lateral 
areas and end valves finely undulately striolate. Girdle yellowish, 
maculated with green, scaly, the scales very minute, oblong, smooth. 
(Krauss.) Length 10, width 5'6 mill. 

Natal, on the shore. 

Chiton oniscus KR., Die Siidafric. Moll. p. 39, t. 3, f. 4. IscJino- 
chiton oniscus CPU., MS. 

This species, whilst it has a superficial resemblance to I. textilis 
Gray, is readily distinguished under the lens by the smaller and 
smooth scales and by the smaller number of slits. The valves as 
well as the girdle appear smooth to the naked eye, but the lateral 
areas are visible. Under the lens the central areas are very finely 
punctate on the dorsum, and on the pleura they are longitudinally 
striated ; these stria? continue upon the lateral areas becoming wavy 
stria? there. The end valves have feeble wavy stride toward the 
margins, and have 10 slits in their insertion plates. The interme- 
diate valves are strongly convex, 5 mill, wide, 4 long, rounded at 
both sides, and having a single slit in each insertion plate. One 
specimen is white with greenish-brown girdle ; another is whitish 
with a red-brown band along the back ; a third specimen is dirty 
yellow with green dots, the girdle also green dotted. (Krauss.") 

Carpenter gives this note on specimens received by him from 
Stimpson : Terminal valves having 10-12, central 1 slit: teeth 
acute ; eaves short, spongy ; sinus broad, flat. In one of the speci- 
mens examined the hind valve has the central teeth very small and 
close, while the side teeth are long and distant. 



ISCHNOCHTTON. 101 

I. YERBURYI E. A. Smith. PL 20, fig. 11. 

Shell small, depressed, slightly carinated in the middle ; pale 
gray maculated with dull green. 'Lateral and central areas and 
anterior valve subequally reticulated all over ; apex of the poste- 
rior valve subcentral, moderately acute ; girdle covered with very 
minute scales, rosy-gray maculated with dull green. (Smith.) 

Length 15, breadth 8 mill. 

Aden. 

Chiton (Ischnochiton) yerburyi SMITH, P. Z. S. 1891, p. 420, pi. 
33, f. 6. 

Only a single specimen of this species was found by Major Yer- 
bury. The sculpture recalls that of a thimble. It is a trifle coarser 
on the lateral, especially along their posterior margins, than on 
the central areas. The dirty green spotting is also more noticeable 
on the hinder edges of the valves than elsewhere. (Smith.') 

I. MACGILLIVRAYI Carpenter, n. sp. Unfigured. 

Shell elongated, small, elevated, the jugum slightly acute, valves 
beaked ; ashen-brown or pale ashen, often elegantly painted with 
lines or angular flames. Entire surface minutely granulose ; lateral 
areas scarcely denned, having radiating wrinkles, not very distinct. 
Mucro median, little elevated. Interior : posterior valve having 
12-13, anterior valve 12-11, median valves 1 slit. Teeth subacute ; 
eaves very conspicuous ; sinus wide, flat, smooth. Girdle closely 
covered with delicate, subelongated, strongly lirate scales. 

Length 14, breadth 7 mill.; divergence 110. 

Tristan d'Acunha (Macgillivray, Mus. Cuming, No. 74, 92) ; St. 
Paul's (Mus. Curning, No. 7). 

The specimens from the last locality have the teeth acute. 

This shell has the general aspect of Trachydermon albus but is 
longer, not so sharp at the ridge, more highly sculptured, and the 
scales strongly lirate. The pattern varies greatly in the specimens. 
It is nearly related to I. oniscus, and a larger series of individuals 
may prove them identical (Cpr., MS.) 

I. RETICULATUS Reeve. PI. 20, figs. 16, 17. 

Shell oblong-ovate ; terminal valves and lateral areas of the rest 
radiately ridged ; central areas rudely and closely reticulated ; 
dull brown ; ligament horny, rough. (Reeve.) 

West Indies (Reeve). 



102 ISCHNOCIHTOX. 

Chiton textiiis var. SOWB., Conch. Illustr. f. 61, according to 
Reeve. Chiton reticulatus Rv., Conch. Icon. pi. 15, fig. 83 (1847). 
Ischnochiton reticulatus CPR., MS. 

Reeve states that this is the textiiis of Sowerby but not of Gray, 
and he is probably right, although his own identification of textiiis 
Gray is erroneous. Carpenter gives these notes upon Reeve's type 
specimen : One specimen, which is over-colored and over-drawn in 
Reeve's illustration. It looks to me like a fine textiiis, as Sowerby 
seems to have taken that species, but I have no textiiis by me for 
comparison. It is very light brown, with little black irregular dots 
which appear to be adventitious. Girdle typically Ischnoid, with 
moderate-sized striated imbricating scales. Fine radiating ribs on 
the lateral areas, very numerous on the terminal valves ; honey- 
combed in the middle ; jugum very much rounded. Anterior valve 
with 14, central valve 1, posterior valve 12 slits; teeth sharp ; sinus 
very broad and flat, not toothed. Length 303, breadth 16 mill. 



Compare textiiis Gray, from which this differs in coloration and 
apparently in sculpture. 

3. Group of I. rissoi. 

Small species having longitudinal riblets upon the central areas, 
and continuing backward over the lateral areas. These are closely 
allied to the group of /. atriol-atii*. 

Distribution : Mediterranean, African and West Indian. 

I. RISSOI Payraudeau. PI. 20, figs. 1-7. 

Shell oblong, elevated, the back regularly arched or subcarinated, 
side slopes convex. Surface longitudinally lirate on the intermedi- 
ate, concentrically on the end valves. Color pale brown -olive, the 
lateral areas and end valves more or less maculated with snow-white 
and brown. 

The lateral areas are moderately raised and sculptured with 
coarse, flat, uneven-edged longitudinal riblets, which are separated 
by narrow punctate intervals and are frequently irregular ; under 
a higher power of the microscope the surface appears to be min- 
utely punctate, the dots whitish. The central areas have close, fine 
riblets in the same direction, somewhat finer .on the dorsal ridge, 
and giving way to a minute punctation in the region of the beak of 



ISCHNOCHITON. 103 

each valve. The umbo of the posterior valve is central and mod- 
erately elevated. 

Interior white ; sutural plates small, separated by a very wtdep- 
flat sinus. Anterior valve having 13, posterior valve 10 slits, cen- 
tral valves 1 slit ; teeth sharp ; eaves narrow, short, solid. 

Girdle covered with close, very small, striatulate, imbricating 
scales. Length 15, breadth 8 mill. 

Mediterranean and Adriatic Seas. 

Chiton rissoi PAYR., Moll. Corse, p. 87, t. 3, f. 4, 5 (1826). 
PHILIPPI, Enum. Moll. Sicil. i. p. 107. CAPELLINI, Journ. de 
Conchyl. (2) iii, p. 322 (1859). ISSEL, Intorno ai Chiton del mare 
di Geneva, in Bullettino Malacologico Italiano, iii, p. 5, t. 1, f. 2, 3 
(1870). MONTEROSATO, Journ. de Conchyl. 1878, p. 147. BUQ., 
DAUTZ. & DOLLF., Moll. Mar. Kouss. p. 495, t. 61, f. 10, 11, 12 ; t. 
62, f. 2. Ch. meneghinii CAPELLINI, Journ. de Conchyl. (2) iii, p. 
325, t. 12, f. l. Ch. mediterraneus "Gray MS." REEVE, Conch. 
Icon. t. 23, f. 157 (1847). 

This species is well characterized by its flat close concentric rib- 
lets and the sparsely scattered snowy spots on the end valves and 
lateral areas. The sculpture of the lateral areas is irregular and 
variable, the riblets being ragged-edged and occasionally subobso- 
lete, leaving the raised areas almost smooth. The C. polii Phil, is 
readily distinguished from this species by its differently formed 
posterior insertion teeth ; in rissoi the posterior teeth are normally 
Ischnoid. 

The Ch. mediterraneus of Reeve is simply a synonym of the typi- 
cal form of this species. The form which Reeve calls rissoi (C. 
Icon. t. 19, fig. 122) is a synonym of the variety meneghinii. 

Var. meneghinii Capellini (pi. 20, figs. 8-10). Sculpture stronger, 
the end valves and lateral areas exhibiting distinct radiating striae. 

Var. fragilix Monts. (Enum. e Sinon.). Smaller in size, the 
sculpture obsolete, without trace of radiating strise. 

I. PERTUSUS Reeve. PI. 20, figs. 18, 1 9. 

Shell oblong-ovate, valves elevated in the middle, verv closely 
grooved throughout, ridges of the central areas thin, converging 
towards the umbones, interstitial grooves pricked, posterior edge of 
the valve serrated ; dark red, sprinkled with a few minute white 
dots ; ligament horny, very sparingly beset with short bristles. 
(Jfoe.) 



104 ISCHNOCHITON. 

The pricked interstices between the close-set ridges which consti- 
tute one of the distinguishing features of this species are scarcely 
discernible without the lens. (Rve.) 

Simon's Bay, Cape of Good Hope. 

C. pertuxu* RVE., Conch. Icon. pi. xvi, f. 88 (1847). Iwhnoclii- 
ton pertiwt* CPU., MS. 

Carpenter's notes from two specimens in the Cuming collection 
are as follows : The figure in Reeve does not represent it well. It 
is one of the rissoi group. Shell much arched, elevated, but the 
jugum rather blunt. Umbo of posterior valve raised, situated at 
the anterior third ; the slope behind it very slightly concave, nearly 
straight. Girdle with Ischnoid scales, but small, long, somewhat 
imbricating and striated. Color olivaceous, variegated. Jugal 
area not defined from the central areas, which are sculptured with 
very numerous and fine rather blunt lirulse with extremely small 
interstices ; or the surface might be described as finely grooved. 
These small riblets are longitudinal, very slightly granose, and at 
the diagonal border of the lateral areas become rugulose, passing 
on to join with the riblets of the latter. The lateral areas have 
about 9 to 12 very fine radiating riblets which are made granose by 
the longitudinal riblets from the central areas crossing them. The 
end valves have very close and regular radiating rows of grains, the 
sculpture being very like that of catenulatus, but in that species the 
concentric wrinkles predominate. The head valve has 12 slits, 
median 1, posterior valve 9 slits. Teeth quite sharp, with long pro- 
jecting eaves, which are not spongy. Sinus broad, rather deep, flat, 
smooth, but deeply channelled on each side at the inner bases of the 
sutural plates. Terminal valves stained with brownish-purple inside. 

Length 32, breadth 163 mill. ; divergence 113. 

I. ERYTHRONOTUS C. B. Adams. Un figured. 

Shell small, subelongate, [convex, not carinated] ; yellow-white, 
[the back] irregularly maculated with red ; lateral areas ribbed, the 
ribs nodulous ; dorsal areas [sulcate-] striated; girdle scaly [yel- 
lowish-white, maculated with ashen]. Length 13f, width 73, mill. 
(Ad.-) 

Jamaica (Adams) ; St. Thomas and Porto Rico (Blauner). 

Chiton erythronotu* C. B. AD., Proc. Bost. Soc. N. H. 1845, p. 9. 
C. (lechnochitori) ergthronotus SIIUTTJ,W., Bern. Mittheil. 1853, 
p. 76. 



ISCHNOCHITON. 105 

The passages in brackets of the above diagnosis are Shuttle- 
worth's interpolations. 

I. LATERITIUS Shuttleworth. Unfigiired. 

Shell elliptical-oblong, convex ; brick colored, sparsely maculated 
with whitish ; end valves subconcentrically lineate and punctate. 
Median valves not carinated ; central areas irregularly foveolate- 
irapressed, becoming transversely costulate-subsulcate at the sides ; 
lateral areas subelevated, radiately subsulcate and minutely punc- 
tate-foveolate. Girdle unicolored red, densely beset with minute 
flattened scales. Length 12, breadth 6 mill. (Shuttlw.*) 

St. Thomas, West Indies. 

Chiton (Ischnochiton) lateritius SHUTTLW., Diagn. n. Moll, in 
Bern. Mittheil. 1853, p. 75. 

I have not identified this species, of which Shuttleworth writes : 
I have two specimens. The color is an intense brick- red, both 
inside and out. It is allied to C. erythronotus C. B. Ad., but differs 
abundantly in the sculpture and color, and in the less elongated 
shell. 

4. Group of I. xtriolatn*. 

Small species, apparently smooth, but under a lens showing a 
sculpture of longitudinal riblets or lines of granules on the central 
areas, interrupted on the lateral areas, which are roughened by 
peculiar irregular impressions (pi. 18, figs. 54,55). It is difficult to 
describe the sculpture of the lateral areas of these species ; it is 
what Carpenter called "thuniby " or " pollicaroid." 

Distribution : Antillean and Pananiic provinces. 

Species with striated scales. 

I. STRIOLATUS Gray. PI. 20, figs. 20-24. 

Shell oblong, moderately arched, the back sometimes distinctly, 
sometimes scarcely visibly keeled ; side slopes convex. Surface 
showing no sculpture to the naked eye, but having the lateral areas 
moderately distinct. Color excessively variable but generally 
either olive-green or olive-slate colored with white or creamy flecks; 
or cream-colored, minutely mottled with light brown. The poste- 
rior edge of each valve is dotted withjight and dark, forming a 
sutural articulation. 




106 ISCHNOCHITON. 

Lateral areas slightly raised, sculptured longitudinally with nar- 
row zigzag groove*, the elevations between them flat, and een under a 
powerful lens to be most minutely pustulate, the pustules whitish. 
Central areas covered with an excessively fine, close quincuncial 
granulation which becomes slightly coarser toward the sides, where the 
granules gradually become merged into longitudinal rows giving a 
lirate appearance to the pleura, especially to the part lying at and 
immediately in front of the diagonal line. End valves having con- 
centric zigzag grooves and a minute granulation, like the lateral 
areas ; posterior valve having a moderately elevated, central umbo, 
posterior slope concave. Interior light gray-blue or white ; anterior 
valve with 9, central valve 1, posterior valve 9 slits. Teeth smooth, 
sharp. Eaves narrow, solid ; sutural plates whitish, rather wide 
and low ; sinus flat, angular. 

Girdle whitish clouded with blue, or blue marbled with white, 
generally having some small yellow or orange flecks. It is densely 
covered with imbricating, deeply striated scales. (PI. 20, fig. 24.) 

Length 14 to 15, breadth 8 mill. 

St. Thomas; Barbados. 

Chiton xtriolatus GRAY, Specil. Zool. p. 6 (1828). REEVE, 
Conch. Icon. t. 22, f. 144. 

The coloring of this species is extremely variable, and the sculpt- 
ure, while it is unmistakable when seen under a sufficiently high 
power, still varies considerably. The side areas and end valves 
are generally sculptured with the concentric zigzag grooves 
described above (fig. 23) ; but occasionally these become so irregular 
and broken that the surface appears coarsely granulous or scaly. 
The West Coast species dispar Sowb. and adamsii Cpr., as 
well t as the roseus of Sowerby, all belong to the striolatus group, 
and are closely allied in sculpture. There are also a number of 
described West Indian Ischnochitons which seem to be either mere 
synonyms of /. ttriolatn*, or closely allied forms, the exact status 
of which it is quite impossible to fix with certainty until the origi- 
nal types can be examined by a competent person, thoroughly 
acquainted with the subject. The original descriptions of these 
forms here follow. 

C. *qnamnlo*n* C. B. Adams. Shell olivaceous, ornamented with 
a pale green dorsal line; lateral areas covered with prostrate 



ISCHNOCHITON. 107 

unequal scales ; central areas nearly smooth in the middle, puncto- 
striate ; girdle finely scaly, alternately ashy-greenish and green. 
Length 171 breadth 10 mill. (Ad.) 

Jamaica. 

Chiton $quamiilo#tt# AD., Proc. Bost. Soc. Nat. Hist, ii, p. 8 (1845). 
C. (Isch.) squamulosus SHUTTLW. Bern. Mittheil. 1853, p. 76. 

This is unquestionably the same form I have described above as 
striolatm. The name squamulosus will therefore become a synonym. 

C. lidulatn* Shuttlw. Shell small, elliptical-ovate, somewhat 
narrower in front; dull olivaceous spotted with white; terminal 
valves impressed-punctate, toward the margins irregularly concen- 
trically subcostulate ; jugum not keeled; dorsal areas finely and 
regularly impressed-punctate, and toward the margins flexuously 
and irregularly transversely plicatulate. Girdle olivaceous and 
spotted with white, the scales small, flattened, imbricated. Length 
12, width 5 mill. (Shutthv.) 

Porto Rico. 

Chiton (Ixchnochiton) lutulatm SHUTTLW., /. c. p. 76, 1853. 

This was described from a single specimen, and said to differ 
from C. 8qvamulo#i8 in being narrower with more regular sculpture. 
I have no hesitation in considering it an absolute synonym of /. 
striolatus. 

C. carrib&orum (Cpr.) Smith. (PL 20, figs. 25, 26). Shell 
lengthened-oval, scarcely carinated, variedly painted, grayish-olive, 
white, reddish and olivaceous, or purple, sometimes blackish with 
white markings ; end valves concentrically and roughly granose 
striate or scaly, central areas ornamented with delicate, curved, 
flexuous, granose Iira3; lateral areas roughly granose or scaly. 
Posterior valve slightly concave behind the central apex. Girdle 
minutely scaly, covered with ^elongate oval scales pa^e rosy-gray, 
tessellated with diluted black. Length 27, diam. 9 mill. (Smith.) 

St. Thomas; Fernando Noronlia. 

The above appears to be a manuscript name attached to speci- 
mens in Cuming's collection which are identical with few shells 
from Fernando Noronha. The color is very variable, some speci- 
mens, when viewed from a distance of twelve inches, appearing 
olive-gray, speckled with white ; others are of a pinkish cream 
color speckled with red or blotched along the sides in front of the 



108 ISCHNOCHITON. 

lateral areas with black, as in some of the specimens from Fernando 
Noronha. The granules or scales of the lateral area and on the 
front and posterior valves are peculiarly flat and are somewhat 
transversely arranged on the former and concentrically on the lat- 
ter. The central areas are finely punctured along the center, and 
become more and more coarsely granosely lirate as the sides are 
approached. One example is almost entirely reddish purple, and 
others are blackish with a broad pallid stripe down the middle from 
end to end. (Smith.) 

Chiton (Itchnochiton) caribbceorum CPR., MS., SMITH, Journ. 
Linn. Soc. Lond., xx, p. 496, t. 30, f. 5, 5a. 

The dimensions given by Smith may possibly be a mistake, for the 
size mark on his plate is only 13 mill. long. In other respects the 
description and figures indicate no tangible points of difference 
from the /. striolatus. 

Carpenter's original description of carribceorum is before me, 
and it is an excellent word picture of some of the St. Thomas spec- 
imens of xtriolatux. It is worthy of note that Carpenter recognized 
the specific identity of etriolatus, caribbceorum, jamaicensis and 
squumulosis, in one of his later notes. 

L(f caribbceorum var.) jamaicensis Cpr. Smaller than caribbce- 
oi-inn, the lateral areas scarcely denned. 

Length 7?, breadth 4, alt. IT mill. Habitat, Jamaica. 

I. (f jamaicensis) viridior Cpr. Larger than 1. jamaicensis, 
green, variously maculated with olive; interior: posterior valve 
having 8, anterior 9, central valves 1 slit. Length 11], breadth 7 
mill.; divergence 100. There is no character but size and color 
by which this solitary specimen can be distinguished from the 
Jamaican shells. (Cpr.) 

The specific identity of these two MS. forms with /. xtriolahi* was 
conceded by Carpenter. 

I. funiculatus Carpenter. Shell small, strongly oval, subelevated, 
the jugum little acute ; pale ashen, ochraceous or olivaceous varie- 
gated; mucro central, moderately prominent. Entire surface 
wrinkled and minutely pitted ; wrinkles subregular, nearly paral- 
lel with the dorsal ridge on the central areas, about 18 on each side, 
obsolete toward the jugum ; the moderately distinctly defined lat- 
eral areas and the end valves undulated and having subobsolete 
radiating lirulse. Interior: posterior valve with 7-9, anterior valve 



ISCHNOCHITON. 109 

7-1 0, central valves 1 slit. Teeth acute ; eaves moderate ; sinus 
wide, flat. Girdle furnished with very close, deeply striated, flat- 
tened scales. Length 10, width 5 mill. ; divergence 95. 

Guadaloupe (Mus. Cuming, No. 44). 

One specimen is of a pale yellowish tint slightly variegated with a 
brighter color ; another is more ashy and with the variegations of 
pale olive. It has stronger sculpture than I. cdribbceorum, the 
rugulse rising up like close rungs in a rope-ladder, and dentating 
the sutures. (Cpr.) 

The above description, from Carpenter's MS. defines a form 
which will probably prove to be a variety of /. caribbceorum, with 
which species Carpenter, at a later date, united it. 

I. PRUINOSUS Gould. PI. 21, figs. 27, 28. 

Shell small, elongated, nearly elliptical, convexly elevated, sub- 
carinate, or rather somewhat doubly carinate along the back ; sur- 
face generally covered with microscopic punctures, arranged in 
lozenge. Lateral areas very slightly raised, and longitudinally 
imbricate-sulcate ; central areas with faint lines of growth and 
punctures in quincunx ; anterior valve concentrically striate, not 
punctate ; posterior valve slightly umbonate, and crossed by a 
transverse ridge, behind which it is concentrically striate. It is 
frosted or mottled with dark brown, ash, purple, green, &c. Mar- 
gin minutely granulated, so as to look hoary. (Old.*) 

"Some specimens are of a uniform pale green. Margin clouded 
with dark green ; some had two or three distinct, white blotches on 
the sixth valve, the rest of the shell being olive-green, with a line 
of faint green along middle of back ; another had the ground-colour 
a clear olive, three dark brown spots bordered with white on each 
side of posterior margin of valves, a row of similar spots surround- 
ing the terminal valves just above insertion, and the whole surface 
sparsely and irregularly spotted in the same way, so as to present a 
delicately mottled aspect. A fourth variety was of a uniform dark 
rose-color, and the margin clouded with dark red bands. Inter- 
nally it was dark red or rosy along the middle, and dull yellow 
towards the sides. All the other varieties were of a pale greenish 
hue internally." (Couth, in Old.') 

Length 17-1, breadth 8| mill. 

Off Fort Santa Cruz, Rio Janeiro, on stones in 2 or 3 fms. 



110 ISCHNOCHITON. 

C.j'i'iiinosm OLD. Proc. Bost. Soc. N. H. ii, p. 144, July 1846; 
Otia Conch, p. 5, 242; U. S. Expl. Exped. p. 316, f. 419. 
ROCHEBRUNE, Polyplax. Cap Horn, p. 141. lachnochiton j>rn!n<>- 
8W CPE. MS. p. 77* 103. 

Carpenter seems to consider this the same as caribbceorum and 
xti'iolatus; but the specimen before me is too worn to enable me to 
decide. 

I. REGULATUS Sowerby. PL 21, figs. 53-57. 

Shell oblong, rather smooth, olivaceous varied with white ; front 
valve, lateral areas and posterior valve concentrically undulately 
wrinkled ; central areas smooth, wrinkled at the margins. Length 
20, breadth 10 mill. Girdle granose. (Sowb.} 

Puerto Portrero and Inner Lobos Id., Central America, under 
stones at low water. 

Chiton rugulatus SOWB., P. Z. S. 1832, p. 58 ; Conchol. Illustr. f. 
42, 78, 143, 144 ; Beechey's Voyage, Zool. p. 150, pi. 41, fig. 18. 
REEVE, Conch. Icon. t. 19, f. I 1 8 ; t. 20, f. 128, l33.Ic/uH>rIuton 
rugulatus CPR., MS. 

Carpenter describes the interior and girdle from the type speci- 
men, thus: Posterior and anterior valves having 9, central valves 
1 slit; teeth solid ; eaves moderate; sinus wide, flat. Girdle closely 
imbricated with moderate sized solid scales, scarcely striated. 

It is very like striotatus but having stronger sculpture. It goes 
through all the color variations of longicymba. The scales seem to 
be smooth, but here and there are slight striolations from the dried 
skin. 

I. CATENULATUS Sowerby. PI. 21, figs. 47, 48. 

Shell long and narrow, elevated, arched, the jugum rounded. 
Girdle smooth, broad, thin, with imbricating striated scales. Mucro 
central, elevated, the posterior slope somewhat concave. Central 
areas sculptured with very close parallel lirulas, which pass into 
wrinkles on the lateral areas, which are swollen. End valves con- 
centrically wrinkled. Interior : posterior valve having 10, central 
1, anterior valve 9 slits; teeth long, sharp, thin ; eaves moderate, 
not long, but well developed ; not spongy. Sinus broad, deep, 
smooth, channelled. Length 17, breadth 7 mill. ; divergence about 
102. (<>-.) 

Inner Lobos Island, Peru. 



ISCHNOCHITON. 1 1 1 

Ch. catetnilatux SOWB., P. Z. S. 1832, p. 104; Conch. Illustr. f. 
145. REEVE, Conch. Icon. t. 20, f. 130. Ischnochiton cateuulatu* 
CPR., MS. 

The single specimen before me is whitish, sparsely variegated with 
brown, the girdle ashen-bluish. The sculpture of the valves is 
more like that of I. striolatus Gray and adamsii Cpr., than any- 
thing else, having exactly the same pattern, but not quite so distinct. 
The girdle has conspicuously striated scales. 

* * Species with convex, smooth scales. 

The following species were referred by Carpenter to " Lepido- 
pleurus," but they are closely allied to the present group. 

I. DISPAR Sowerby. PL 18, figs. 47, 48. 

Shell oval, smooth, ashen varied with whitish and black. Cen- 
tral areas smooth, posteriorly longitudinally subsulcate ; anterior 
valve, lateral areas, and posterior area of the posterior valve granu- 
lous. Girdle granose. Length 25, breadth 124 mill. (Sowb.) 

Inland Saboga, Bay of Panama, under stones on the shore. 

Chiton dispar SBY., P. Z. S. 1832, p. 58 ; Conchol. Illustr. f. 25. 
REEVE, Conch. Icon. t. 18, f. 96. Not Ischnoradsia dispar 
Carpenter MS. Chiton proprius REEVE, Conch. Icon. f. 161. 0. 
picus REEVE, Conch. Icon. t. 25, f. 121. 

The name has been suggested by the circumstance of the central 
areas being quite smooth, while the lateral areas are covered with 
granules. (G. B. Sowerby.) 

The description given by Sowerby differs entirely from the spe- 
cies which I take to be the Ischnoradsia dispar of Carpenter's MS., 
and indicates a form very similar to Carpenter's L. adamsii. 

Carpenter writes of the type of C. proprius Rv. as follows : One 
specimen, smashed ; " West Coast of America," Dr. A. Sinclair, R. 
N. This is exactly like the Lepidopleurus dispar, having very 
large, smooth scales. Reeve's C. picus is also said by Cpr. to be a 
synonym for /. dispar. 

I. ADAMSII Carpenter. PL 18, figs. 51, 52, 53, 54, 55. 

Shell resembling L. dispar ; pale red-brown, irregularly streaked 
and maculated with darker, sometimes ornamented with white spots 
at the diagonal region. Jugum scarcely acute ; central areas and 
terminal valves conspicuously granulous ; lateral areas irregularly 



112 ISCHNOCHITON. 

waited, the warts lobed. Mucro anterior, slightly conspicuous. 
Interior having the central valve with 1 slit, end valves 8-10 slits. 
Eaves small ; teeth acute ; sinus flat, very wide. Girdle imbricately 
scaled. Length 15, breadth 7i mill.; divergence 110. (C/>r.) 

Panama. 

Lophyrus adamsii CPU., P. Z. S. 1863, p. 24. Lejndopleurus 
ailamsii CPR., P. Z. S. 1865, p. 274. 

The shells which I have drawn in figs. 51-55 of pi. 18, seem to 
me to belong to this species rather than to I. dispar. They are 
described below. It must be understood that the more minute 
sculpture can be seen only under a compound microscope or a very 
powerful lens. 

The shell is oval, rather low, the jugum rounded, side-slopes 
nearly straight. Color dark olive mottled with lighter, or having 
large whitish tracts on some valves; the interior light blue, sutural 
plates white. The central areas are closely sculptured with very 
minute pointed whitish granules, arranged in oblique lines at the 
jugum (fig. 52) but toward the sides or pleura a system of shallow 
grooves with granulous inter-ridges curve forward from the diagonal 
line, as shown in fig. 54, and at the left side of fig. 55. The lateral 
areas and terminal valves have a coarsely reticulated pattern, 
formed by impressed zigzag or irregularly lobed impressions, over 
which a fine granulation extends (fig. 55.) 

The interior has 8-10 slits in the posterior valve, 1 in the inter- 
mediate valves (fig. 53). Teeth sharp, smooth ; eaves very narrow. 
The girdle was denuded of nearly all of its scales in both of the 
specimens before me, but such as remain are large, solid. 

Length 14, breadth 8J mill. 

I. TENUISCULPTUS Carpenter. Unfigured. 

Shell similar to L. adamsii; olivaceous, minutely variegated with 
paler and darker color. Entire surface minutely granulose ; lateral 
areas scarcely defined ; sutures spotted with white ; mucro anterior, 
rather conspicuous, the slope behind it concave. Interior as in L. 
adamsii. (Cpr.~) 

Panama. 



Chiton ilitpar C. B. AD., Cat. Panam.Sh.no. 373 (part). Lcpido- 
jtleurus tenaisculptus CPR., P. Z. S. 1865, p. 275. 

A variety is paler, tinged with rufous at the jugum. 



ISCHNOCHITON. 113 

The outside of this shell so much resembles the young of Chiton 
stokesii that specimens may have been distributed under that name. 
Very few individuals were found. A few striated scales lie loose 
on the type specimen, probably from one of the other species. In 
the only place in which they lie in situ, they are quite smooth. 
(Qpr.) 

I. ROSEUS Sowerby. PI. 21, figs. 49, 50. 

Shell ovate-oblong, smooth, roseate ; back rounded ; front valve 
and lateral areas of the intermediate valves longitudinally, central 
areas transversely sulcate ; posterior valve with central apex, con- 
centrically sulcate. Length 17$, breadth 7 2 mill. (Sowb.) 

I. of Plata (Cum ing) ; Fernando Noronha (Challenger Exped.), 
Peru (Bradley, in Mus. Yale College.) 

Ch. roseus SOWB., P. Z. S. 1832, p. 58; Conch. Illustr., f. 14. 
REEVE, Conch. Icon., t. 25, f. 119. DESK, in Lam., An. s. Vert., 
vii, p. 498 (not Chiton roseus Blainville, Diet. Sc. Nat. xxxvi, p. 
553, 1825, a species of Acanthochiton). Ischnochiton roseus CPU., 
MS. Ischnochiton boogii HADDON, Chall. Rep., Polyplac., p. 15, 
(1886.) 

There is not the shadow of an excuse for the change of name made 
by Haddon, as Blainville's prior G. roseus belongs to a genus uni- 
versally admitted to be distinct. The west coast locality is doubted 
by Haddon, but it is supported by specimens in the Yale College 
collection. 

Carpenter gives the following notes on this species : Valves and 
plates very thin, subdiaphanous; mucro median, little elevated. 
Interior: post. v. with 8, central v. 1, ant. v. 11 slits; teeth very 
acute ; eaves very slender, moderately projecting ; sinus large, flat, 
high, scarcely laminate ; sutural plates small, subtriangular. Girdle 
imbricated with minute solid, smooth scales, with bristles intercalated 
at the margin. The sutural laminae are as small as in Leptochiton, 
and look like a mere prolongation of the insertion plates round the 
corner. The scales though normally shaped and arranged, are so 
minute that Deshayes placed the species in the Tonicioid group. 

Haddon writes of /. roseus (under the name J. boogii), as follows : 

The locality attributed, on the authority of Cuming, to this species, 

made the identification with it of a Chiton from Fernando Noronha 

very doubtful ; a shallow-water species was not likely to live in both 

the Atlantic off Brazil and in the Pacific off' West Columbia, with 

8 



114 ISCHNOCHITON. 

the whole breadth of South America between. That the Challenger 
specimen is identical with the British Museum specimens is beyond 
doubt. May not the difficulty find solution in the fact that the " I. 
of Plata," as it stands on Cuming's tablet in the British Museum, 
and to which Sowerby (loc. cit.) added "W. Columbia" is really some 
island in the estuary of La Plata ? 

The above criticism was first suggested to me by the Rev. R. 
Boog Watson, to whom it gives me great pleasure to dedicate this 
species. 

The single specimen in the collection is of a pink color mottled 
with creamy yellow, with an obscure yellow line along the jugmu, 
and with a pale spot on each side of the line on several valves ; 
there are also several irregular dark patches; the posterior valve is 
deep-rose below the umbo. The girdle is mottled brown and white, 
there being a white patch at the junction of each valve. 

The shell is long, narrow, and arched, anterior and posterior 
valves with fine concentric ridges ; the umbo of the latter is prom- 
inent. The intermediate valves are apparently smooth, but really 
with extremely delicate longitudinal striae; the lateral areas are 
characterized by wide ridges. The ligament has stout, tall, 
imbricate scales. 

The three specimens of this species in the British Museum are 
pink and only slightly flecked with white, no black or brown spots, 
and in two of them the central areas have concentric lines like 
those of the lateral areas. 

5. Group of I. pundulatissimus. 

Small species, having the central and lateral areas closely and 
minutely granulated. No riblets. West Indies and South Ameri- 
can coasts. 

I. PAPILLOSUS C. B. Adams. PL 21, figs. 40, 41. 

Shell small, oval, carinated on the back, the side slopes slightly 
convex; surface not divided into distinct areas, apparently smooth, 
but under a strong lens seen to be closely and evenly granulated 
throughout; color whitish, closely mottled with olive-green; or 
olive-green or olive-brown, with or without snow-white spots. 

The lateral areas are not raised, and are sculptured precisely like 
the central areas, from which they are denned simply, by an incon- 
spicuous diagonal ridge. The posterior valve is moderately eleva- 
ted, the umbo central, rather acute, posterior slope concave. 



ISCHNOCHITON. 115 

Interior whitish ; anterior valve having 10, central 1, posterior 
valve 9 slits; teeth sharp, thin and smooth ; eaves narrow. 

Girdle narrow, alternately olive-brown and whitish, clothed with 
very minute, imbricating striated scales. 

Length 8'<, breadth 5 mill. 

Length 5-}, breadth 35 mill. 

Jamaica (Adams) ; Marco, No Name Key and Key West, Florida 
(Hemphill). 

Chiton papillosm AD., Proc. Bost. Soc. N. H. 1845, p. 9. 0. 
(/sc/wo.) papillosm SHUTTLW. Bern. Mittheil. 1853, p. 77. Isch. 
j>/>illonu8 DALL, Catal. Mar. Moll. S.-E. U. S., in Bull. 37, U. S. 
Nat. Mus., p. 172. 

This is the smallest of our Florida or West Indian Ischnoids. It 
has much the same sculpture as the small Leptochitons, being uni- 
formly granulated and having the lateral areas very indistinctly 
defined. It is readily known from other Ischnochitons by these 
characters. The original description is as follows: 

Shell small, wide ; greenish, closely maculated with whitish and 
black; papillose; areas separated by a slender riblet; girdle very 
finely scaly, alternately greenish and white. 

Length 5-25, breadth 3'25 mill. 

I. PUNCTULATISSIMUS Sowerby. PI. 21, figs. 35-38. 

Shell oval, moderately elevated, the dorsal ridge bluntly angular, 
side slopes nearly straight. Surface apparently smooth, but seen 
under a lens to be minutely and evenly granulated all over. Lat- 
eral areas ill-defined. Flesh colored, speckled or dotted all over 
with light brown, and often maculated on some of the valves or 
along the dorsal ridge with dark brown. 

Lateral areas demarcated by a very low and obtuse ridge, obsoletely 
sculptured by the intersection of two series of obliquely radiating 
curved impressed lines ; central areas similarly sculptured by 
obliquely longitudinal lines. Umbo of posterior valve in front of 
the middle, the posterior slope concave. Interior blue-white, having 
9-12 slits in the end valves, 1 in the median valves; teeth acute; 
eaves moderate ; sinus wide, flat. Girdle covered with solid, flat- 
tened, striated imbricating scales. Length 17, breadth 10 mill. 

Bays of Callao, Mexilloiies, Iquiqui and Arica, Peru, and Chili, 
on dead shells, 6-10 fms. 



1 1 6 ISCHNOCHITON. 

Ch. pundulatlssimus SOWB., P. Z. S. 1832, p. 58 ; Conch. Illustr. 
f. 9, 26; Moll. Beechey's Voyage p. 149, t. 40, f. 3, 3. REEVE, 
Conch. Icon. t. 20, f. 129. 

The typical form of this species is described above, and figured 
on my plate. It is characterized by the almost effaced but even 
granulation, which is the same on both central and lateral areas, 
although differing in direction ; by the minutely freckled color pat- 
tern, etc. 

Sowerby mentions a white variety with a black border and some- 
what varied with black. This form I have not seen. It has been 
illustrated by the figures in Captain Beechey's Voyage, H. M. S. 
' Blossom,' and fig. 9 of the Conchological Illustrations. The latter 
figure I have copied on my plate. 

I. IMITATOR Smith. PI. 21, figs. 29-34. 

Shell elongate-ovate, moderately elevated, subangularly arched at 
the middle, dirty white. Valves narrow, with a single notch on 
each side, exhibiting small, slightly raised lateral areas, which 
towards the margin have a few transverse strong grooves or marks 
of growth. Front margin sloping very slightly on each side from 
the middle in a posterior direction ; hind margin straight. Sculpt- 
ure consisting of close flat granulation, exhibiting a somewhat 
serial arrangement. Laminse of insertion [sutural plates] very thin, 
with a wide sinus between them. Anterior valve sculptured like 
the others, with fourteen fissures within, the thirteen teeth between 
them being sharp and straight edged. Posterior valve with a cen- 
tral mucro, from which there is a faint ridge on each side to the lat- 
eral extremity, also marked with concentric lines of growth at 
intervals and with the inner marginal fissures twelve in number. 
Scales of the mantle minute, imbricating, ovate, arranged length- 
wise ; under the microscope they appear very coarsely transversely 
grooved. Length 11 mill.; diam. of fourth valve 5 mill. (Smith.} 

Tom Bay, Patagonia, on the shore. 

Ch. (Ischnochitott) imitator E. A. SMITH, P. Z. S. 1881, p. 35, t. 
4, f. 13. 

6. Group of I. comptus. 

Surface evenly, minutely granulated, the lateral areas having 
radiating riblets. Girdle scales nearly smooth. Japan, etc. 



ISCHNOCHITON. 117 

I. COMPTUS Gould. 

Shell 'small, thin, elliptical ; green or scarlet, frequently banded, 
dotted or maculated with whitish or yellow. Valves short, the end 
valves radiately ribbed and punctate; central areas quincuncially 
punctate. Lateral areas elevated and sculptured with 4-5 radia- 
ting grooves. Interior green. Girdle narrow, imbricated with 
small elongated grooved scales. Length 15, diam. 10 mill. (Old.} 
Oosima, Japan ; Bonin and Liu-Kiu Is. (Stimpson). 

C. (Leptochiton) comptus GOULD, Proc. Bost. Soc. N. H. vii, p. 
163 ; Otia, p. 117. Isch. comptus CPR., MS. 

Carpenter writes : Entire surface punctate ; central areas having 
the lines of points either parallel or bending toward the acute 
jugum ; lateral areas having small radiating wrinkles, at first 3 to 4 
in number, then splitting into 6 to 8. End valves having 40 deli- 
cate, hardly apparent radiating wrinkles. Mucro slightly in front 
of the middle, slightly elevated. Interior: posterior valve with 
13, central valve 1, anterior valve 14 slits; teeth acute; eaves 
moderate, acute ; sinus wide, flat. Girdle having large, solid 
imbricating scales, sometimes very slightly striated. Length 17i, 
breadth 10 mill. ; divergence 120. Philippines, Mus. Cuming No. 

II. Dr. Gould strangely placed this species in Leptochiton, 
although the scales are as large, solid and regular as in Chiton. 
The above diagnosis is written from Mr. Cuming's beautiful speci- 
mens, which are broad and externally curiously like the young of 
Chiton, (var.) patulus: In the typical specimens, the stimulation of 
the scales can seldom be seen, having apparently lived in exposed 
situations. The variation in color is extraordinary, being (a) 
densely clouded with olive; (6) light ditto mottled with dark and 
lilac; (c) four central valves chestnut, the rest olivaceous; (d) 
brown with olive, with broad white streak down the centre ; (e) 
light reddish-chestnut mottled ; (/) ditto, shading into olivaceous ; 
(g) sixth, seventh and part of eighth valve dark olive-brown, the 
rest light ashy ; (A) the whole light ash. The sutures are always 
regularly spotted, as in T. pseudodentiens. In the typical specimen 
examined there were only eleven slits in the terminal valves. 

I. LEPIDUS Gould. Unfigured. 

Shell small, elliptical, roof-shaped, yellow-green streaked with 
olive ; front valve semi-circular, radially striated ; posterior valve 
crescentric, beaked, radially grooved behind and longitudinally in 



118 ISCHNOCI1ITON. 

front; lateral areas elevated, sculptured with 6 radiating sulci ; 
central areas irabricately sulcate. Girdle narrow, banded with 
olivaceous, covered with minute scales. 

Length 13, breadth 9 mill. (Old.) 

Interior: terminal valves with about 14, central valves 1 slit; 
teeth very acute, but a little serrated at the edge. Eaves large ; 
sinus narrow, vaulted, scarcely laminate. Girdle irregularly 
imbricated with transverse, solid, neatly smooth scales. (Cpr.) 

China Sea, Lat. 24 N. 

Chiton (Lepidopleura) lepidns GLD., Proc. Bost. Soc. N. H. vii, p. 
164 ; Otia, p. 118. Ischnochiton lepidus CPR., MS. 

The girdle scales are those of Lepidopleurus, [==zLepidozona~\ 
except that the imbrication is irregular. The species is remarkable 
for the narrow, arched sinus; and for the slight serration of the 
insertion plates which are yet normally sharp and protected with 
broad eaves. I have not been able to re-examine the type since I 
matured a plan of arrangement for the sections of the genus. ( Cpr.) 

I. PETALOIDES Gould. PI. 23, figs. 92, 93. 

Shell small, delicate, elliptical, roundly arched, very slightly car- 
inated, the valves not beaked, of a pale lemon-yellow ground color, 
reticulated along the centre, with delicate, angulated, pale-violet 
lines ; these areas are also rugosely lineate-punctate longitu- 
dinally, especially toward the margin ; lateral areas very prominent, 
rugosely granulate, and with about four, fine radiating stria3 ; pos- 
terior valve acutely umbonated and crossed by an acute, transverse 
rib. Margin cream-colored, very finely gran ulate-i rubricate. 



Interior : posterior valve having 9, central 1, ant. v. 9 slits ; teeth 
acute ; eaves acute, hardly spongy ; sinus very wide, short, smooth. 
Girdle imbricated with flat, scarcely striated scales. (Cpr.~) 

Length 12J, breadth 10 mill. 

Kauai and Oahu, Sandwich I*. 

C. petaloides GLD., Proc. Bost. Soc. N. H. ii, p. 144, July, 1846 ; 
U. S. Expl. Exped., Moll. Sh., p. 328, f. 435 ; Otia Conchol., p. 6 ; 
C. (Lucia) petaloides GLD., Otia p. 242. Lophyr as petaloides PSE., 
Amer. Journ. of Conch, vii, p. 194. Ischnochiton i>d1oides CPR. 
MS. 

The scales are rather large for the size of the shell, but thin. 
Fresh specimens have sometimes an appearance of minute striula- 



ISCHNOCHITON. 119 

tion, from the contraction of the epidermal film. Dr. Gould sur- 
mised that this species ought to be a Lucia, because it came from 
the Pacific Is. ; but it is a normal Ischnochiton in all respects 
except the nou-striation of the scales. (Cpr.~) 

I. BISCULPTUS Carpenter, n. sp. 

Shell small, oval ; jugum acute; mucro median, rather elevated ; 
ashy, maculated with olivaceous. Entire surface minutely granu- 
lose ; central areas having about 10 distant, acute, subparallel lirse, 
sometimes subgranose, the interstices wrinkle-decussated. Lateral 
areas scarcely raised, having distant, small, much raised grains, sub- 
radiately arranged in 2-4 series, the end valves having 16-20 such 
series. Interior: posterior valve having 7, central valves 1, ante- 
rior 10 slits ; teeth rather obtuse, roughened but scarcely pectinated 
at the margin. Eaves small ; sinus small, deep, smoothly laminate. 
Girdle rather regularly imbricated with decidedly transverse, con- 
spicuously striated scales. Length 11, breadth 6 mill. ; divergence 
120. (Q;r.) 

/ Hong Kong (Stimpson, N. P. E. E.). 

" Chiton f pulcherrimus Sby." GOULD, MS. -f C. (Leptochiton) 
craticulatus GLD., Otia, p. 117, pars. (Cpr.). 

The shells forming the five species, pulcherrimus, craticulatus, cul- 
tratus, bisculptus and asperior were included by Dr. Gould under 
the first two names. They need a careful examination of the 
details of sculpture, as well as of the mantle scales, in order to sep- 
arate them. Of these pulcherrimus and bisculptus have the striated 
scales of Ischnochiton ; craticulatus and cultratus, the strong, smooth 
scales which belong to Lepidopleurus ; and asperior is intermediate 
between Trachydermon and Chsetopleura. The decided rugosity of 
the insertion plates and short eaves of this species form a transition 
toward Chiton. The whole group appears to have a slight lamina 
at the sinus, marked oflf by a slit from the sutural wing. (Q?r.) 

7. Group of I. inter stinctus. 

Small, finely granulated shells, the lateral areas radially ribbed. 
Scales striated. Species of the west coast of North America. 

I. INTERSTINCTUS Gould. PI. 11, figs. 40, 41 ; pi. 21, fig. 39. 

Shell oval-oblong, rather elevated, the dorsal ridge obtusely 
keeled, side slopes nearly straight. Surface apparently smooth, but 



120 ISCHNOCHITON. 

under a lens it is seen to be very minutely punctulate, the indistinct 
lateral areas being obsoletely radiately lirate also. Dark reddish, 
mottled with light on the dorsal ridge. 

The lateral areas are scarcely perceptibly raised and besides being 
microscopically punctulate like the rest of the surface they have low 
radiating ribs, about 6 or 7 in number. Central areas evenly 
punctulate ; end valves punctulate and radiately multilirate. 
Umbo of posterior valve in front of the middle, rather elevated. 
Inside: posterior valve with 12, anterior valve 10, median valves 
1 slit ; teeth acute, eaves moderate ; sinus wide, flat. 

Girdle densely covered with small, suboval, delicately striated 
scales. Length 15, breadth 8 mill.; divergence 110. 

Sitka Harbor south to Monterey and the Santa Barbara Ig. t Cali- 
fornia. 

Chiton interstinctus GLD., Proc. Bost. Soc. Bost. N. H. ii, p. 145 ; 
Moll. U. S. Expl. Exped., p. 315, pi. 23, f 423 ; Otia, p. 230, 242. 
Ischnochiton interstinctus CPR., MS. 1891, and DALL, Proc. U. S. 
Nat. Mus. 1878, p. 331. 

This is a small reddish species, characterized by the fine puncta- 
tion of the whole surface and the rather coarse but low radiating 
riblets of the lateral areas and end valves. The sculpture is not 
well shown in Gould's figures. It is drawn from a specimen before 
me in fig. 39 of pi. 21, representing an enlarged half-valve. 

I. NEWCOMBI Carpenter, n. sp. Unfigured. 

Shell small, wide, tumid, with obtuse rounded jugum. Mucro 
median, rather elevated. Ashy or olivaceous, elegantly clouded ; 
central areas and ei tire surface granulated, the granules being 
quincuncially arranged, close and regular; lateral areas scarcely 
defined, having about 4 lines of tubercles which are hardly elevated. 
Posterior valve having about 30, anterior valve 40 such lines. Inte- 
rior : posterior valve having 12, median 1, anterior valve 11 slits ; teeth 
acute ; eaves apparent ; sinus wide, short, scarcely laminate. Girdle 
imbricated with large striated and rather regular scales. Length 
8-1, breadth 61 mill.; divergence 100. (Qor.) 

Sta. Catalina Is. (Newc.). 

The plan of sculpture somewhat resembles that of J. interstinctus, 
though coarser and different in detail. It resembles 1. radians 
in most respects except in the rounded beak and larger scales. 
(Qpr.) 



ISCHNOCHITON. 121 

I. RADIANS Carpenter, n. sp. Unfigured. 

Shell rather large, wide, elevated, the jugum acute ; olivaceous, 
elegantly radially streaked with brown. Interior blue-green with 
two brown rays. Valves delicate, flat, produced in the sinus in 
front ; mucro in front of the middle, scarcely elevated ; entire sur- 
face quincuncially granulated ; lateral areas scarcely denned, and 
with the end valves obsoletely sublirulate. Interior : posterior 
valve having 9-10, central valves 1, anterior valve 10-11 slits; 
teeth acute; eaves small; sinus wide, short, scarcely laminate. 
Girdle regularly covered with solid, coarsely striated, moderate sized 
scales. Length 21, breadth 15 mill.; divergence 110. (Qor.) 

Monterey, California. 

The internal color-rays are seen in all the dead valves; the 
external painting resembles Mopalia vespertina. The sculpture is 
on the plan of/, interstinctus. One central valve of one specimen, 
on one side only, had a second slit. (Qpr.) 

8. Group of I. scabricostatus. 
I. SCABRICOSTATUS Carpenter. Unfigured. 

Shell small, orange colored, elevated ; valves gothic arched, jugum 
acute. Entire surface very closely granulated ; lateral areas well 
denned, with 3 subobsolete, radiating series of large granules ; 
beaks scarcely apparent ; umbonal margin slightly turned inward, 
and having dark spots giving a false appearance of teeth. Central 
areas having separated longitudinal series of narrow, subobsolete 
riblets, furnished with large granules. End valves having similar 
radiating granulous riblets. Umbo of posterior valve scarcely cen- 
tral, little projecting. Interior: sutural plates separated by a large 
flat sinus ; insertion plates subobtuse, the end valves having 10-12, 
central valves 1 slit; eaves moderate, sui)conspicuous. Girdle 
wide, closely clothed with imbricating, elongated, transversely 
striated scales. Length 7*, breadth 41 mill, ; divergence 100. 

(Qpr.) 

Catalwa Island, California, in 10-20 fms. 

Lepidopleurm scabrieostatus CPR., Rep. Brit. Asso. Adv. Sci. 
1863, p. 649 ; Proc. Cal. Acad. N. S. ii, p. 212. Ischnochiton seabri- 
costatus CPR., MS. 

The sinus has a thin, smooth lamina separated by a slit on each 
side from the sutural laminae. It is a small, arched orange species, 
with rows of prominent granules over a shagreened surface. ( Cpr.) 



122 ISCHNOCHITON. 

I. VEREDENTIENS Carpenter. Un figured. 

Shell small, whitish, tinged with roseate; valves gothic-arched, 
the jugum subacute; entire surface minutely granulose ; lateral 
areas conspicuously defined, having strong diagonal and sutural 
ribs, provided with well projecting rounded grains; end valves hav- 
ing subobsolete radiating riblets; central areas having about 8 dis- 
tant, raised subgranulose longitudinal ribs on each side, the ribs 
obsolete at the jugum ; interstices latticed with subradiating riblets ; 
umbones conspicuous, the umbonal margin deeply toothed by a wart- 
bearing rib, the teeth 8 to 10, obsolete toward the jugum ; margin 
scarcely intorted. Umbo of posterior valve submedian, slightly pro- 
jecting; margin elegantly pectinated. Interior: sinus large, flat, 
sometimes serrate ; insertion-plates acute, broadly unifissate, end 
valves having about 8 slits ; eaves conspicuous. Girdle having large 
flat, striated scales. 

Length 61, breadth 2J mill.; divergence 90. (Cpr.) 

Catalina Island, 20-30 frns. 

Ischnochiton veredentiens CPR., Rep. Brit. Asso. Adv. Sci. 1863, 
p. 649 ; Proc. Cal. Acad. Sci. iii, p. 211. 

A small arched species, sculptured like J. mertensii, but with two 
rows of bosses, one of which dentates the sutures. The girdle scales 
are rather large, flattened and striated, as in typical Ischnochiton. 

I. SERRATUS Carpenter. Un figured. 

Shell small, ashy, dotted here and there and especially at the 
sutures with olive, sometimes spotted with red ; oval, subdepressed, 
the sutures indistinct; entire surface most minutely granulated; 
lateral areas strongly denned, provided with two to five very wide, 
obtuse ribs, no interstices; posterior margins elegantly serrated. 
Central areas having about 12 acute parallel ribs on each side; 
jugum obtuse, scarcely umbonate ; with subradiating latticing ribs, 
interstices impressed. Mucro median, obtuse. End valves having 
about 20 obtuse ribs, like the lateral areas. Interior: median 
valves bifissate, end valves with about 9 slits. Sutural plates large. 
Girdle imbricated with large, scarcely striated scales. 

Length 82, breadth 5 mill. ; divergence 115. (O' r -) 

Cape St. Lucas, Lower California. 

Ischnochiton serratus CPR., Ann. & Mag. Nat. Hist. (3) xiii, p. 
315, 1864. 



I8CHNOCHITON. 123 

I. AUREOTINCTUS Carpenter, n. sp. Un figured. 

Shell resembling I. scabrieostatus, but the lateral areas are 
scarcely defined, radial and longitudinal series of lira? none. 
Entire surface equally granulated. Orange spotted with red. 
Interior: posterior valve having 11, central valve 1, anterior valve 
13 slits. Length 61, breadth 4 mill.; divergence 100. (Cpr.) 

Catalina Island, Gal., 80 fms. 

This species is known from Tr. flaxus by the valves not being 
beaked, and by the large striated scales of the margin, which 
resemble those of /. scabrieostatus. ( Cpr.~) 

I. DECIPIENS Carpenter, n. sp. Unfigured. 

Shell exactly like I. pectinulatus, but reddish, elevated, the ju gum 
acute; scales of the girdle small, striated. 

Length 15, breadth 1\ mill.; divergence 105. (Cpr.~) 

Monterey, California. 

This very puzzling shell differs from /. sinudentatus in its normal 
sinus and smaller scales ; I cannot help suspecting that when more 
specimens have been examined, it will be found that some characters 
generally constant between species and even groups, are occasionally 
variable in the same species. (Qor.) 

I. CORRUGATUS Carpenter, n. sp. Unfigured. 

Shell similar to Ch. sanguineus in form and varied coloring ; 
entire surface granulose ; central areas having impressed punctate 
wrinkles, hardly lirate ; lateral areas strongly longitudinally corru- 
gated. Interior: posterior valve with 8-10, anterior valve 10-9, 
central valves 1 slit. Sinus wide, flat. Girdle thin, covered with 
very close, very small striatulate imbricating scales. 

Length 13i|, breadth 7 mill.; divergence 90-100. 

Catalina Is., beach to 40 fms. (Cooper, Cal. State Coll. Nos. 1066, 
1070, 1074) ; Todos Santos Bay (Hemphill), California. 

Differs from Stenoplax sanguineus in sculpture as well as in the 
plan of mantle-ornamentation. A specimen from Todos Santos 
Bay (under a stone between tides) collected by Henry Hemphill, is 
about the size of limaciformis from Mazatlan, and it would natur- 
ally be so called ; the sculpture, however, is sensibly different, both 
from that and from fallax. The central areas are minutely, the 
jugal areas very minutely, wrinkle-punctate, wrinkles angular, 
irregular; lateral areas moderately defined and elevated, and, 



124 ISCHNOCHITON. 

together with the end valves, irregularly, subconcentrically and 
strongly corrugated. Mucro median, planate. This species is a 
Stenoplax in form, but a true Ischnochiton in its imbricated scales, 
which are, however, extremely minute. This specimen is regularly 
arched, much less elevated than the type, with which, however, it 
agrees well in particulars. Length 21, breadth 9 mill. (Q>r.) 

I am unable to see why this should not be considered a Stenoplax, 
unless it be on account of the smaller girdle scales ; but, as I have 
not seen specimens, I deem it best to leave the species where Car- 
penter placed it. 

I. SUBCLATHRATUS Pilsbry. Un figured. 

Shell subrotund, depressed (at an angle of 130); brown-olive; 
valves very wide, the margins lobed, interstices nearly straight. 
Intermediate valves granulated at the dorsal ridge and more or less 
all over, having two strongly tuberculate ribs, one diagonal, the 
other in front of the suture; lateral areas small, granulate; central 
areas having four longitudinal bars on each side, the bars tuber- 
culate, interstices granulated. Front valve having about eleven 
rounded, subtuberculate radiating ribs. Girdle very wide, having 
close small scales ; valve-margins simple, the anterior having 9 slits. 

Length 4}, breadth 3 alt. '5 mill. 

Mazatlan, under stones. 

Lepidopleurus clathratus CPU., Mazat. Cat., p. 195 (1857) , Ischno- 
chiton clathratus CPR., MS. Not Ch. clathratus REEVE, Conch. 
Icon., pi. xviii, f. 113 (1847.) 

I have not seen this species, the name of which has been already 
used by Reeve. Carpenter writes as follows: 

One very small specimen was discovered on a stone to which a 
Crucibulum had been attached, beautifully perfect except in the loss 
of the anterior valve. A dead anterior valve was found of a much 
larger specimen displaying a marginal structure like that of L. 
sanguineus. The shell is remarkable for the strong bars across the 
central areas, and the stout rows of tubercles which run, the one 
diagonally, the other along the interstitial margin. The mantle is 
very broad and crowded with minute scales. (C)>r.) 

I have no opportunity of re-examining the type of this minute 
shell, to see whether the very minute scales are striated. If so, it 
must closely resemble the young of /. expressus. The paucity of 



ISCHNOflHITON. 125 

genuine Ischnochitons in the Gulf fauna is remarkable, especially as 
so many species are found further north. (Cpr. MS.) 

Section Lepidozona Pilsbry, 1892. 

Lepidopleurus CARPENTER (Table of Regular Chitons, 1873) ; 
DALL, Proc. IT. S. Nat. Mus. 1878, p. 331, type L. mertensii Midd. 
Not Lepidopleurus of Risso, Hist. Nat. Eur. Merid. iv, p. 267, 
1826, nor of H. & A. ADAMS, 1858, nor of CARPENTER, Mazat. 
Cat. 1857. 

Valves having sharp but somewhat rugose and thick insertion 
teeth, and (typically) the sinus is delicately toothed within. Girdle 
covered with convex scales, usually smoothish. Type I. mertensii. 

This section differs from Ischnochiton not only in having the gir- 
dle scales convex and smooth or but slightly striated, but also in 
the toothed sinus. It is, however, an artificial group, the species 
being more closely related to a number of diverse Ischnochitons than 
to each other. Numerous transitions from the smooth convex 
scales to flat striated scales occur, the variation in degree of stria- 
tion being considerable in some species. This section in its present 
limits is therefore merely a temporary expedient for convenience in 
identifying species. It should rank as a section under Ischnochiton 
s. s., rather than under Ischnoradsia, to which group these species 
have no especial affinity. The status of the name Lepidopleurus 
has been discussed on page 2 of this volume. 

I. MERTENSII Middendorff. PL 26, figs. 20-26. 

Shell oval, elevated, with angular dorsal ridge, and straight side- 
slopes. Varying in color from orange-red to claret-red, or even 
dark red-brown, and either unicolored or speckled and blotched 
with white. 

The lateral areas are elevated, and sculptured with radiating rows 
of elevated pustules standing upon a smooth, almost flat ground; 
the pustules of the sutural row often irregular. Central areas hav- 
ing acute, narrow, parallel raised riblets, the intervals between them 
regularly latticed across, except at the dorsal ridge, where the 
riblets have a tendency to diverge, and the cross-hatching is obsolete. 
End valves radially pustulose. Mucro central, low, flat and incon- 
spicuous. 

Interior white or blue-white, the median valves when detached 
showing broad red-brown rays posteriorly, the end valves with cres- 



126 ISCHNOCHITON. 

cents of the same color. Sutural plates low ; sinus flat, angular, finely 
toothed. Anterior valve having 1011, central valves 1, posterior 
valve 10 slits ; teeth rather short and obtuse, and usually distinctly 
roughened ; eaves rather wide. 

Girdle firm, compactly covered with regular, solid, oval, shining 
scales, which are usually smooth, but frequently are superficially or 
obsolctely striated (figs. 22, 23.) , 

Length 35, breadth 21 mill. 

Length 38, breadth 23 mill. 

Sitka south to Monterey, California. 

Chiton mertensii MIDD., Bull. Acad. Sc. St. Petersb. vi, p. 118, 
1846. Chiton (Phwnochiton, Hamaehiton, Stenosemus) mertensii 
MIDD., Mai. Koss., p. 34, 125, t. 14, f. 1-3, 1847,Leptochiton 
mertensii H. & A. AD., Gen. Rec. Moll, i, p. 473, 1854. Lepido- 
pleurus mertensii CPU., MS., and DALL, Proc. U. S. Nat. Mus. 1878, 
p. 332. 

This species may be known by the more or less red coloring, the 
shining convex oval scales of the girdle, which are usually almost 
smooth, and by the strongly developed sculpture. Attention has 
already been directed to the similarity of the Chcetopleura gemmea 
of Cpr. (p. 31), which differs mainly in its sparsely hairy girdle. 

Southern examples of this species are larger and more frequently 
variegated with white than those from the northern part of its 
range ; and the girdle scales seem to be more distinctly striated. 
They seem to be almost or entirely smooth in most northern speci- 
mens, as far as my material shows; and I do not doubt that Car- 
penter's figure (pi. 26, fig. 23) was drawn from a specimen collected 
north of San Francisco. In almost all of the specimens from the 
south which I have examined, the scales show a delicate striation 
when illuminated from the side, or at right angles to the direction 
of the striae. This is shown in figure 22, drawn by the author from 
a Monterey specimen. The sculpture of the valves is peculiar; the 
jugal area has diverging line, with smooth intervals. This is 
always most pronounced on the second valve (fig. 24), the other 
valves often having the Iira3 more nearly parallel, and the intervals 
not all smooth. This is. shown in fig. 25, representing a fourth 
valve ; but in some specimens the divergence is even less pro- 
nounced than in this. The pustules upon the front valve occas- 
ionally become soldered together into riblets, but those of the tail 
valve seem to remain distinct. 



ISCHNOCHITON. 127 

I. COOPERI Carpenter, n. sp. PL 26, figs. 27-30. 

Shell oval and elevated, with angular dorsal ridge and straight 
side-slopes. Sculpture like /. mertensii. Color olivaceous, or dull 
earthy brown, indistinctly clouded more or less with light blue, 
especially upon the side areas. The lateral areas are raised, and 
bear irregular rows of rounded pustules, the young having four rows, 
the adult 6 to 8. A strong lens reveals a fine, subobsolete granula- 
tion of the nearly flat surface between the pustules. The central 
areas have a fine but distinct and even radial striation, over which 
run acute narrow raised threads parallel to the dorsal ridge ; upon 
the ridge these threads are seen to be more or less diverging, 
especially upon the second valve. The end valves are radially 
ridged, the ridges bearing elongated pustules, or showing scars 
where such pustules have been. Mucro low, flat. 

Interior bluish, the valves marked under their umbones with dark 
olive. Head valve having 11, central valves 1, tail valve 11 slits ; 
teeth roughened but rather sharp; eaves wide, dark, minutely 
punctulate, but solid, not spongy. 

Girdle compactly covered with small imbricating, deeply striated 
scales)(fig. 28). Length 40, breadth 24 mill. 

Santa Cruz and Bolinas, California. 

This species closely resembles I. mertensii in shape and sculpture, 
but it differs entirely in the smaller, distinctly striated or grooved 
scales, in the sombre coloring both outside and within, in the closer 
pectination of the inter-liral spaces of the central areas, and in the 
more developed microscopic granulation of the lateral areas. It 
cannot be claimed that all or any one of these characters is invari- 
able, but the balance of them taken together, seem to indicate that 
differentiation has proceeded to a stage we may call specific. The 
following species is allied to this in coloring, but differs sufficiently 
in sculpture, as well as in the girdle-scales. 

The details of sculpture and the scales of all three species are 
drawn to the same scale. The third valve of /. cooperi is shown in 
figs. 29, 30. It must be remembered that the valves behind this, and 
usually even the third, have less markedly divergent sculpture than 
the typical form here shown. 

The specimens herein described and figured are from Bolinas, 
north of San Francisco, and since no diagnosis has been published 
hitherto, these will be considered the typical specimens. Carpenter's 
specimens were from Sta. Cruz. 



128 ISCHNOCHITON. 

I. RINUDENTATUS Carpenter, n. sp. Unfigured. 

Shell oval, much elevated, reddish ; jugum acute; mucro median, 
scarcely elevated ; entire surface minutely granulose. Central 
areas having about 12 subparallel bars, which pectinate the front 
margin, their interstices decussated ; lateral areas having 3-4 gran- 
ose radiating line, the anterior valve with 26, posterior valve 24 
such lira?. Interior: anterior valve with 10, central 1, posterior 
valve 9 slits; teeth acute; eaves conspicuous, subspongy, crenulated 
by the sculpture ; sinus wide, short, laminate with about 6 teeth. 
Girdle having moderate sized, wide, conspicuously striated, rather 
regularly imbricating scales. Length 15, width 7 1 mill. ; diver- 
gence 100. (Q>r.) 

Monterey, California. 

This shell has the color of I. mertensii, nearly the sculpture of 
/. peetinulatus and the normal scales of this group. Like /. regu- 
larix, it has the denticulate sinus of Chiton. (Q>r.) 

I. CLATHRATUS Reeve. PI. 26, figs. 31-34. 

Shell oval or oblong, elevated, the back carinated ; side slopes 
straight ; lateral areas and end valves radially granulate-lirate, cen- 
tral areas latticed. Color dingy yellow, clouded with black, or rarely 
unicolored yellow or olivaceous. 

The lateral areas are raised and sculptured with about 5 radia- 
ating, closely and conspicuously granose riblets, the posterior rib 
wide or bifid ; strongly pectinated along the sutural edge. Central 
areas having longitudinal narrow bars parallel to the dorsal ridge, 
decussated by bars of almost equal prominence vertical to them, 
producing the effect of a grating. Mucro depressed. 

Interior whitish, with olive or leaden rays under the umbones. 
Sinus flat, denticulate; anterior valve having 11-12, central valves 
1, posterior valve 14-16 slits; teeth rather sharp, but not thin 
eaves solid; 

Girdle compactly covered with very convex scales, which are 
quite obsoletely striated. 

Length 27, breadth 17 mill. 

Length 34, breadth 18 mill. 

Monterey and San Diego, California,' to La Paz, L. California* 



ISCHNOCHITON. 129 

Chiton clathratus KEEYE, Conch. Icon., t. 18, f. 113, April, 1847. 
Lepidopleurus pectinatus CPE., Proc. Califa. Acad. Nat. Sci. iii, p. 
211, 1865; not L. pectinatus CPE. in Brit. Asso. Rep. 1863, p. 649, 
(=1. cooperi CPE.), nor Chiton pectinatus SOWEEBY, also an Ischno- 
chiton (ant., p. 64). Lepidopleurus pectinulatus CPE. MS., and of 
American collectors and writers. 

Carpenter's diagnosis in Proc. Cal. Acad. Sci. seems to have 
included both this species and J. cooperi, but he afterward distin- 
guished them upon receipt of better material, and re-named the pres- 
ent form "pectinulatus" 

This species seems to replace I. mertensii south of Monterey. It 
is a dingy, lusterless shell, resembling mertensii in the shape of the 
girdle scales, which are, however, not so bright and clean in the 
clathratus. It has decided riblets on the lateral areas, and the 
lattice-work of the central areas is strong and much less finely cut 
than in cooperi or mertensii. From J. cooperi, the different scaling 
of the girdle, as well as the sculpture of the valves, separate this 
form. 

The second valve has divergent sculpture on the dorsal ridge, but 
upon the other valves the riblets are parallel or nearly so there, and 
the interstices are latticed. 

I. COEEANICUS A^dams & Reeve. PI. 27, fig. 50, (enlarged.) 

Shell ovate, rather elevated, terminal valves and lateral areas of 
the rest radiately grooved, interstices convex, peculiarly grained, 
grains prominent, round, solitary ; posterior terminal valve um- 
bonated, extremity radiate, small, short ; central areas longitudinally 
very finely granosely ridged, interstices between the ridges hollowed ; 
lateral areas blackish-green, grains yellowish, central areas yellow- 
ish blotched and variegated with black ; ligament finely granosely 
coriaceous, tessellated dark and pale green. 

The sculpture of this species is not much unlike that of C. luridus ; 
still it is distinct, and accompanied with a very characteristic style 
of painting. The central areas of the shell are of a yellowish 
ground, blotched and variegated with black. The terminal and 
lateral areas are very dark green, with the prominent granules con- 
spicuously tinged here and there with yellow. The ligament is 
strikingly tessellated with dark and pale sea-green. (Eve.') 

Korean Archipelago, under stones (Belcher.) 
9 



Of THE 

UNIVERSITY 




130 ISCHNOCHITON. 

Chiton coreanieus REEVE, P. Z. S. 1847, p. 24; Conch. Icon., t. 
26, f. 128. ADAMS & RVE., Voy. ' Samarang ' Zool.,Moll., t. 15, f. 
9. SCHRENCK, Reis. u. Forsch. im Amur-Lande, ii, p. 281, f. 1-6. 
Lophyrus coreanieus DKR., Ind. Moll. Mar. Jap., p. 157. 

Carpenter (MS.} compares this to I. pectinulatus and 1. cooperi. 
Schrenck 'reports it from the Bay of Hakodadi, on the authority of 
Lindholm. 

I. PULCHERRIMUS Sowerby. PI. 27, figs. 47, 48. 

Shell oval, elevated; jugum acute; mucro conspicuous, elevated, 
median, the slope behind it concave. Color red, variously clouded 
or streaked with ashy. Jugal area hardly defined, smooth at the 
prominent beaks ; central areas having 16 to 18 acute, subparallel 
lirae on each side, meeting over the jugum but otherwise nearly 
parallel ; interstices crenulated ; entire surface granulated. The 
interstices are decussated by the buttresses, as it were, of the cren- 
ulated sides. Lateral areas with 3 principal rows of close knobs, 
increasing to 5 rows by intercalation. End valves having 16 to 20 
such rows, the interstices crenulated. Sutures with sharp rows of 
granules in addition to the contiguous ribs. Interior: anterior 
valve with 7, central 1, posterior valve 10 slits; teeth obtuse, 
striated, slightly pectinated ; eaves small ; sinus deep, flat, dentic- 
ulate. Girdle tessellated, imbricated with large, solid, more or less 
striated rounded scales. Divergence 97-l 07. (Qpr.) 

Length 24, breadth 13 mill. 

Island of Bo hoi, Philippines. 

Chiton pulcherrimus SOWB., P. Z. S. 1841, p. 103. REEVE, 
Conch. Icon., t. 20, f. 132. 

This species, says Carpenter, is very close to I. mertensii. The 
striation of the scales is conspicuous in some specimens, on others 
scarcely seen, yet they all appear conspecific. The species is exactly 
intermediate between the two genera, Chiton and Ischnochiton, the 
teeth being scarcely pectinate enough for Chiton, and yet it has the 
balance of its characters. One specimen has very little light, 
clouded with dark ; one almost entirely light, with one dark streak 
on both sides of the central areas ; other specimens are inter- 
mediate. ( Cpr.) 

I. CRATICULATUS Gould. Unfigured. 

Mucro central, scarcely elevated ; central areas having 18-22 
bars; on the acute, much elevated jugum scarcely obsolete; 



ISCHNOCHITON. 131 

Interstices transversely wrinkled. Lateral areas having close, little 
elevated graniferous riblets, 4 in young, 8 to 10 in adult individuals; 
anterior valve having about 50 such riblets. Interior: posterior 
valve having 11, central valves 1, anterior valve 10 slits; teeth 
short, not very acute, outside and at the margins in front rugulose, 
almost pectinated in front. Eaves small, obtuse; sinus short, 
narrow, slightly denticulate. Girdle irregularly, closely imbricated 
with small, smooth, solid scales. 

Length 25, breadth 15 mill. ; divergence 93. (Cpr.~) 

China Seas, or Japan (Stimpson, N. P. E. E. ; 1 specimen in Mus. 
Smithsonian.) 

Chiton (Leptochitoii) craticulatus GOULD, Proc. Bost. Soc. N. H. 
vii, p. 161, Dec. 1859; Otia Conch., p. 117. Lepidopleurus cratic- 
ulatus CPR., MS. 

Dr. Gould appears from his diagnosis to have had several species 
under his eye when he wrote the description of this species. From his 
calling it a Leptochiton, he might have looked at the minute, chaffy 
scales of Trackydermon asperior ; when he wrote of long striated 
scales, he was probably observing Ischnochiton bisculptus. Again 
when he noted the great variation of the ridges (from 4 to 8), he 
probably had under his eye both I. cultratus and the species above 
described. Of the four, the balance of characters inclines me to 
retain the name for the shell last mentioned, although only one spec- 
imen was returned of it, mixed with the other three. Outside, the 
species is recognized by the solid smooth scales, and details of 
sculpture; inside by the blunt, somewhat rugulose teeth, which (in 
part of the anterior valve) are almost pectinate. ( Cpr.^) 
I. CULTRATUS Carpenter, n. sp. Unfigured, 

Shell similar to " L. craticulatus"; mucro central, planate, but 
central areas having about 14 to 20 very acute, strongly developed 
subparallel lirse, becoming less acute, somewhat obsolete, on the dorsal 
ridge ; sutures elegantly pectinated, interstices cancellated with small 
wrinkles; lateral areas having 4 low, graniferous lirulse, and a 
fifth line of granules at the sutures, the grains sparse, small, but 
strongly projecting. Posterior valve having about 18 similar lirulse, 
anterior valve 24. Interior: posterior valve having 9, central 
valves 1, anterior valve 8 slits ; teeth acute ; eaves projecting ; sinus 
small, deep, sensibly laminated, smooth. Girdle regularly imbri- 
cated with flat, smooth scales. ( Qor.) 

.Length 27, breadth 17 mill. 



1 32 ISCHNOCHITON. 

Hakodadi, Japan (Stimpson,N. P. E. E. Smithsonian Mus., No. 
1672.) 

Chiton pulcherrimus (pars') GLD., MS., not SOWB. Leptochiton 
cratieulatus GLD., pars, Otia, p. 117. (Q>r.) 

This species differs from /. pulcherrimus Sowerby in having five 
rows of extremely fine, distant, but strongly expressed granules, 
instead of three (rarely four) of very coarse ones. This has the 
space between the very sharp, knife-like central ridges but faintly 
cancellated with rugose lines ; while in pulcherrimus the cancella- 
tion is so strong as to make the ridges appear granular. But the 
principal distinction is that pulcherrimus has strong striae on the 
mantle-scales, while those of cultratus are smooth and larger in 
proportion. It has the same general aspect as I. cratieulatus ; but 
differs in having the central ridges further apart and sharper ; the 
side rows of points scarcely half as numerous, and the scales much 
larger and more regular. (Cpr., MS.} 

I. MUSCARIUS Reeve. PI. 24, figs. 9, 10. 

Shell oval, jugum rather sharp, mucro at the anterior third, 
rather raised, the slope behind it very concave. Color a peculiar 
ash, with irregular brown spots over the central areas, and brown 
crescentic lines over the lateral areas; and valves with spots of 
dark shaded with light. The central areas have a conspicuous 
quincuncial granulation. Lateral areas somewhat raised, with about 
7 very indistinct small riblets, also quincuncially granulated, and 
having an appearance of being concentrically sculptured, caused by 
the color-markings. Interior : posterior valve having 12, central 1, 
anterior valve 12 slits ; teeth very sharp ; eaves moderate, not 
spongy. Girdle covered with imbricated, smooth, moderately large, 
stout oval scales. 

Length 18?, breadth 11, divergence 119. (Cpr. from type in 

B. M.) 

Mazatlan. 

Chiton muscarius REEVE, Conch. .Icon., t. 24, f. 164. Lepido- 
pleurus muscarius CPR., MS., p. 120. Lepidopleurus ? macandrei 
CPR., Mazat. Catal., p. 196. Isclmochiton macandrece CPR., MS., 
p. 88. 

Carpenter seems to have decided that the L. macandrei of his 
Mazatlan Catalogue was identical with Reeve's C. muscarius, 
although he remarks that he would not have known it from the 



ISCHNOCHITON. 133 

figure and description given by Reeve. 

I. PUSIO Sowerby. 

Shell oval, smooth ; olivaceous, ornamented with numerous green 
dots; front and side margins of the valves rugulose. Marginal 
ligament scaly. Length 12, breadth 7? mill. (Sowb.) 

Valparaiso, on Amphidesma solidum, 30-50 fms. ; sand bottom. 

Chiton pusio SOWERBY, P. Z. S. 1832, p. 105. 
I. DALLII Haddon. PI. 25, fig. 1-10. 

Shell evenly covered with closely set minute low tubercles, which 
give it a granular appearance ; with straight-sides meeting at an angle 
of 110. Anterior valve closely granular, with twenty-six short radial 
rows of tubercles, each row consisting of four or five tubercles, which 
diminish in size from the periphery towards the apex ; the posterior 
row is the broadest, and is partially bifid. 

Intermediate valves. Central area: jugum coarsely granular; 
pleura with about 12 or 13 distinct horizontal ridges; lateral areas 
granular, with three main radiating rows of tubercles, the anterior 
and posterior often partially double. Posterior valve remarkably 
flat, coarsely granular, with nineteen rows of three tubercles each, of 
which the outermost is the largest ; umbo scarcely, if at all, raised 
above the surface ; anterior border coarsely granular, with the 
granules passing into oblique ridges on the pleura. 

Girdle medium breadth, upper surface with smooth imbricating 
scales in oblique rows, about seven or eight in a row, those nearest 
the shell being the smallest. Color greyish -white. 

Length 11, breadth 6, height about 3 mill. 

Gills extending to about three-quarters the length of the foot, 
diverging posteriorly and hidden by a slight swelling of the longitu- 
dinal band on the under surface of the girdle ; about twenty-one in 
number, largest about the fifth from the posterior end, and gradually 
diminishing in size anteriorly. (Haddon.) 

Lat. 51 27' 30" S., long. 74 3' W., 400 fms. blue mud. 

Lepidopleurus dallii HADDON, Challenger Polyplac., p. 19, t. 1, f. 
6, t. 3, f. 6a-6i. 

I have associated this species with the name of my friend Mr. W. 
H. Dall, of the Smithsonian Institution, Washington, U. S. A. 
(Haddon.) 



134 ISCHNOCHITON. 

I. NEBULOSUS Carpenter, n. sp. Unfigured. 

Shell oval, little elevated, the jugum acute; mucro slightly 
elevated ; brown-olive, elegantly dotted and clouded with darker,, 
and sometimes maculated with ashy or roseate. Central areas gran- 
ulated in a somewhat quincuncial manner, rather regular line& 
radiating from the jugum. Lateral areas scarcely elevated, having 
3 to 5 scarcely projecting radiating wrinkles; end valves having 30 
to 40 subobsolete radiating wrinkles, and granulated like the central 
areas. Interior: posterior valve having 11, central valves 1, ante- 
rior valve 11 slits; teeth acute; eaves large; sinus moderate, flat,, 
smooth. Girdle variegated, regularly covered with solid, large, sub- 
rotund smooth scales. 

Length 15, breadth 10 mill.; divergence 110. (Cpr.) 

St. Vincent, Cape Verde Is^ 

Curiously like /. comptus in color and sculpture, but that species 
has the scales extremely finely striated, the side areas a little more 
decided, the granulation less regular, the painting more sombre and 
the sutures tessellated. These minute differences, joined with the wide 
separation in locality, probably denote a different origin. (Qor.) 

The type is no. 88 of the Cumingian collection. 

I. OBTUSUS Carpenter, n. sp. Unfigured. 

Shell small, strongly elevated, oval, the jugum little acute; mucro 
median, conspicuous. Reddish-brown, variously maculated with 
paler. Central areas having about 10 subparallel deep sulci on each 
side, obsolete upon the jugum ; lateral areas with 3 to 4 radiating 
wrinkles, sometimes divaricating, the end valves having 20 to 40, 
here and there interrupted by wrinkles of growth. Interior : pos- 
terior valve having 8, central valves 1, anterior valve 9 slits; slits 
small, teeth very short and obtuse, sometimes rugulose or almost 
pectinated ; calloused inside ; eaves small ; sinus moderate, excurved,. 
smooth. Girdle furnished with very close, small, very solid, rounded, 
smooth scales. 

Length 12|, width 11 mill.; divergence 85. (Qur.) 

Portugal (Mus. Cum., no. 105.) 

A remarkable shell, presenting some general resemblance to 
mertensii in the appearance of the valves. The girdle scales are as 
small as in Trachydermon, but very solid. The specimen is much 
worn outside, which may account for the bluntness and callosity of 
the teeth. (Qor.) 



ISCHNOCHITON. 135 

I. LENTIGINOSUS Sowerby. PI. 27, fig. 44. 

Shell oval, carinated, smooth ; back elevated ; lateral areas incon- 
spicuous. Color tawny brown, ornamented with rounded blue spots. 
Margin minutely scaly. Length 15, breadth 9 mill. (Sowb.} 

" Newcastle, Australia" 

C. lentiginosus SOWB., The Magazine of Natural History, con- 
ducted by Edw. Charles worth, iv, new series, p. 293, June, 1840 ; 
Conch. Illustr., f. 120. 

Chiton cyaneopunctatus KRAUSS, Die Siidafric. Moll., p. 40. 

Except in being somewhat larger, and said to be from a different 
locality, this seems to be absolutely the same as I. cyaneopunctatus 
Krauss. It is likely that the Australian habitat assigned to lenti- 
ginosus is a mistake. The description of cyaneopunctatus here 
follows : 

C. cyaneopunctatus Krauss. (PI. 27, figs. 40-43). Shell small, 
oblong-ovate, thin, semi-pellucid, convex, carinated, shining, ashy, 
orange or brown, closely painted with dots and lines of blue ; very 
minutely punctulate ; intermediate valves narrow, subrectangular ; 
lateral areas slightly distinct ; end valves delicately concentrically 
striolate. Girdle ashy and rufous banded, scaly, the scales distinct, 
subrotund, polished, shining. 

Length 10-1, breadth 6 mill. (jg>.) 

Cape of Good Hope. 

The valves appear smooth to the naked eye, but under the lens 
delicate, elevated points are visible upon the central areas ; and on 
the slightly raised lateral areas and the end valves, there are very 
delicate concentric strise. The head valve has 12, the posterior 
valve 13 slits. The median valves are very narrow (5*2 mill, wide, 
1*2 long), with one slit in the insertion-plates. The scales of the 
girdle are as large as those of C. capensis Gray, shining, convex and 
rounded. The color is very various : gray, blue-gray, yellowish and 
reddish-yellow to brown shells occurring, but all show under a lens 
sky-blue dots, which frequently coalesce into lines. The girdle has 
darker transverse bands. (KraussJ) 

I. DORSUOSUS Haddon. PI. 25, figs. 11-19. 

Shell remarkably compressed laterally, the two sides meeting at 
an angle of 75. Anterior valve concentrically rugose, with about 
26 radiating low irregular ridges, some of which bifurcate. Central 
areas, with jugum and anterior border striated, the pleura with dis- 
tinct horizontal ridges. Lateral areas distinct, concentrically rugose, 



136 ISCHNOCHITOX. 

usually with three main radiating low ridges, the anterior and pos- 
terior of which are often bifid. Posterior valve concentrically 
rugose, with fifteen irregularly arranged low radiating ridges. The 
anterior ridge is broader than the others, and may be slightly bifid, 
umbo rudimentary ; anterior border smooth, with slight concentric 
lines of growth. Laminae of insertion moderate in size. 

Girdle narrow. Upper surface with ovoid, slightly overlapping, 
somewhat granular scales ; edge with minute projecting spicules ; 
under surface, with long, narrow, closely applied scales. Color 
white. 

Length 21'5, breadth 7'5, height 6 mill. (Haddon.) 

Prince Edward's Island, Lat. 46 41' S., long. 38 10' W. 310 
fms. 

Lepidopleurus dorsuosus HADDON, Challenger Polyplac., p. 18, t. 
1, f. 5; t. 3, f. 5a-5i. 1886. 

Gills extending to more than half the length of the foot, twenty in 
number, the middle somewhat larger than the remainder. The 
name dorsuosus, full of ridges, is applicable to this species on 
account of its numerous longitudinal and radiating ridges, and at the 
same time recalling the steep ridge of the shell itself. (Haddon.) 

I. ADELAIDENSIS Reeve. PL 24, figs. 7, 8 (enlarged.) 

Shell somewhat shortly ovate, very minutely reticulated through- 
out, under the lens ; terminal valves and lateral areas of the rest 
finely ridged, ridges waved, central areas smooth, lateral areas not 
raised; livid olive and yellow, flamed with brown in the middle, 
posterior edges of the valves articulated with brown ; ligament 
granately coriaceous, grains very large. (Rve.) 

Port Adelaide (Rve.) ; Port Nolle, Queensland (Coppinger), Aus- 
tralia. 

Chiton adelaidensis REEVE, Conch. Icon., t, 19, f. 123. C. (Isch- 
nochiton /) adelaidensis E. A. SMITH, Zool. H. M. S. ' Alert,' p. 
79, 1884. Lepidopleurus adelaidensis CPU., MS. 

Smith gives the following notes on the specimens collected at 
Port Molle by Coppinger : 

The entire surface of this species is minutely granosely reticulated, 
the front valve, the lateral areas of the narrow central valves, and 
the hinder area of the posterior are in addition somewhat irregularly 
radiately sulcate. The prevailing color is pale greenish, streaked 
and dotted with red, the posterior margin of the valves being paler 



ISCHNOCHITON. 137 

than the general tone of the shell, and conspicuously spotted with 
the same red color. The grains of the mantle are smooth, arranged 
in alternate greenish and reddish patches, and individually have a 
dark spot generally on the outer side, which is only seen under a lens ; 
those near the valves are considerably smaller than those situated 
toward the edge of the girdle. Having parted the valves of one of 
the specimens I find the front one has the margin of insertion 
divided into seventeen unequal, squarely cut, slightly crinkled, sharp- 
-edged teeth, of which the two outer on each side are the largest. 
The sixteen slits between the teeth are very small and shallow. 
The second, third, fourth, fifth, and sixth valves have on each side 
a single very small narrow central notch, from which a groove or 
depression runs to the apex of each valve ; the seventh is probably 
abnormal, having a single notch on the right side and two on the 
left, and the terminal valve has nineteen similar slits. 

I. milleri (Gray) Reeve. (PI. 24, figs. 18, 19). Shell ovate, 
smooth ; central areas under the lens most minutely reticulated ; 
lateral areas very finely striated. Olive or sometimes white, blotched 
and dotted with black. Ligament coriaceous, tessellated with black 
and yellow. (Rue.) 

" Eastern Seas." 

Chiton milleri ("Gray,") REEVE, Conch. Icon., t. 23, f. 156a; t. 
24, f. 1566,c. 

This species was not described by Gray, although Reeve refers to 
the Spicilegia Zoologia. It has been stated by d'Orbigny to be a 
synonym of punctulatisswms. Carpenter seems to think it the same 
as adelaidensis. The types should be re-examined in order to settle 
the point. 

I. SMARAGDINUS Angas. PL 60, fig. 20. 

Shell oblong-elliptic, elevated, most minutely punctured, dull 
bluish-green, delicately freckled with olive, the hinder edges of the 
valves ornamented with very small white spots bordered with olive ; 
the terminal valves and lateral areas faintly concentrically striated, 
the central valves carinated, with the dorsal areas faintly trans- 
versely striated, the lateral areas slightly elevated ; the mantle- 
margin pale green marbled with black, and covered with small 
smooth imbricated scales. Length 12 mill. (Angas.) 

Lilac, variegated with bluish, the side areas distinct, slightly 
raised, more variegated and darker than the central areas. Jugum 



138 ISCHNOCHITON. 

sharp ; mucro not much raised, situated at the front fourth, posterior 
slope a little concave. Valves square, not beaked ; glossy, with very- 
fine quincuncial granulation. Inside : posterior valves having 10 or 
11, central valves 1, anterior valves 11 slits; teeth sharp, thin, and 
rather long; sinus broad, deep, flat, not channelled at the sides . 
eaves projecting, granulated in quincunx but not spongy. Girdle 
with rather large, stout, smooth roundish scales. (Cpr., from 
types). Length 13?, breadth 8 mill. ; divergence 120. 

Port Jackson, New South Wales, Australia. 

Lophyrus smaragdinus ANGAS, P. Z. S. 1867, p. 115, t. 13, f. 28 ; 
t. c., p. 222. Lepidopleurus smaragdinus CPR., MS. 

I. SULCATUS Quoy & Gaimard. PI. 38, figs. 24, 25, 26. 

Shell oval-oblong, quite convex, obtusely triangular, with narrow 
girdle ornamented with little, rounded scales, each of which is green, 
ish with a brown dot. The valves are wide, arcuate, almost without 
carina, very prettily grooved lengthwise on the sides, and zigzag 
in the middle. The lateral areas are triangular, granulose, and 
elevated. The anterior valve is simply granulated, with 11 or 12 
teeth; the posterior valve is larger with 13 teeth, and above it is 
striated in front, and with marginal granulations. The sutural- 
plates are short and separated. All of these parts are of a hand- 
some clear green varied with white. The base of each of the lateral 
triangles is white. Each valve has at the summit a green spot 
surrounded with whitish, or sometimes with rose, in which case the 
interior also is roseate. Length 30, width 18 mill. 

Port of King George, S. Australia. 

C. sulcatus Q. & G. Voy. Astrol. iii, p. 385, t. 75, f. 31-36. (Not 
Chiton (Radsia) sulcatus Wood.) 

The generic position of this species cannot be known until the 
characters of the insertion-plates are more exactly described. The 
above description is from Quoy, who remarks that the species has 
considerable resemblance to C. viridis Q, & G. (C. quoyi Dh.), 
differing in the sculpturing of the valves, especially the end valves. 

I. TESSELLATUS Quoy & Gaimard. PI. 24, figs. 13, 14, 15. 

A small oval species, nearly flat, having a rounded carina. Gray- 
ish all over, but under a lens showing white and brown elongated 
spots. The valves are very finely granulous, the lateral areas 
sulcated radially. The two end valves have smooth teeth, 12 in 
the head valve, and more on the last valve. The girdle is scaly, 



ISCHNOCHITON-RADSIELLA. 139 

yellowish or greenish, and regularly spotted with brown. The foot 
is narrow, yellowish ; the gills almost reach the head. 
Length 18, breadth 12, alt. 4 mill. 

Port Carter et, New Ireland. 

Chiton tessellatus Q. & G., Voy. de PAstrol., Zool. iii, p. 396 ; 
atlas, t. 75, f. 43-47. 

The description is from that of Quoy and Gaimard. The coloring 
is probably less vivid than shown in their plate. The artist of the 
' Astrolabe ' seems to have had an irrepressible fondness for green. 

I. ARBUTUM Keeve. PI. 24, figs. 16, 17. 

Shell ovate, terminal valves and lateral areas of the rest reticulately 
decussated with grained stride diverging off posteriorly ; central areas 
very closely sculptured with blunt squarish granules ; green or red- 
dish, dotted with black ; ligament squamately coriaceous, tessellated. 
(five.) 

Port Essington. 

C. arbutum Rv., Conch. Icon., t. 24, f. 162. 

Carpenter thinks this is probably a color variety of J. adelaidensis. 
He gives the following notes on the 8 specimens in the Cuming 
collection : Shell ovate, tolerably elevated, rather broad ; jugum 
more or less obtuse. Reddish orange, olivaceous or light ash, more 
or less spotted and clouded, but always with a very fine tessellation of 
dark and light along the sutures. Mucro in front of the middle, 
the slope behind it concave ; intermediate valves oblong, not beaked ; 
central areas coarsely and very regularly quincuncially granulated 
with large grains ; lateral areas very slightly raised, with about 6 
rows of larger grains. End valves with similar grains, which are 
radiating but scarcely in lines. Interior: anterior valve having 

II, central valves 1, posterior valve 16 slits: teeth quite sharp, 
typically Ischnoid ; eaves large, not spongy. Girdle tessellated with 
olive and light, covered with imbricating short roundish and quite 
smooth scales. Length 12 i, breadth 8 mill. 

Section Radsiella Pilsbry, 1 892. 

Radsiella PILS., Manual of Conch. (I) xiv, p. 54 (July 25, 1892). 
Type, /. tridentatus Pils. 7sc/morac?sm CARPENTER MS. and DALL, 
Proc. U. S. Nat. Mus. 1878, p. 331. Not Ischnoradsia SHUTTLW., 
1853. 

Valves and girdle entirely similar to those of the normal Ischno- 



140 ISCHNOCHITON-RADSIELLA. 

chitons, but insertion-plates of the intermediate valves having two or 
several slits. 

The present section differs from Ischnoradsia Shuttleworth (Lep- 
idoradsia Cpr.), in having the girdle covered with flat, striated scales, 
whilst in the latter group the scales are transformed into smooth, 
solid, pebble-like bodies. Radsiella differs from the Radsioid section 
Stenoradsia in having the short contour and anterior mucro of the 
true Ischnoehitons, and in the normal foot and gills. 

Carpenter's use of the name Ischnoradsia, Shuttlw. for this group 
is clearly indefensible, as Shuttleworth mentions none of the 
species now included herein, whilst his diagnosis covers all Radsioid 
forms of Ischnoehiton. I have therefore restricted the name Ischno- 
radsia to the forms grouping around Shuttle worth's first species, 
australis. 

I. TRIDENTATUS Pilsbry, n. sp. PI. 18, figs. 35, 36, 37, 38, 39. 

Shell small, oval, moderately arched, slate-color with white spots 
and dots, or white mottled with slate ; the girdle tessellated with 
alternate dark and light, the interior blue, with a leaden spot under 
ach sutural-plate, and short dark rays from the apex. 

The valves are evenly arched. The posterior valve (fig. 39) has 
a central, rather depressed umbo, the slope behind it concave. 
Lateral areas raised a trifle, but scarcely distinguishable; central 
areas evenly, closely and finely pitted in quincuncial pattern ; the 
lateral areas are a little more coarsely sculptured with close low 
-diamond-shaped granules ; the granulation generally less regularly 
arranged on the end valves than on the lateral areas. 

Interior with low, arched sutural-plates and wide, flat, angular 
sinus; anterior valve with 13, posterior 12, central valves 2 slits. 
Teeth sharp, smooth. Eaves very narrow. 

Girdle covered with imbricating striated scales (fig. 36.) 

Length 15, breadth 10 mill. 

La Paz, Lower California (Lockington) ; Gulf of California 
(Gabb.) 

? ? Ischnoradsia dispar CARPENTER, MS. not SOWERBY. 

This species is easily separated from /. dispar Sowb. by the 
apparently similar sculpture of central and lateral areas, the sculpt- 
ure in dispar being obviously diverse on these areas. I suppose this 
to be what Carpenter considered dispar merely because it has 
Radsioid valves ; but Carpenter has given no description of his shells. 



ISCHNOCHITON-RADSIELLA. 141. 

The foot is not produced forward beneath the head, as it is in 
Stenoradsia. The gills extend from the front end of the foot to 
within somewhat less than the width of a valve from the tail end. 

I. VIRIDULUS Couthouy. PI? 17, figs. 32, 33. 

Shell small, oblong, rather elevated and decidedly carinated ; 
creamy yellow, or " of a very pale olive or drab color." Surface 
smooth to the naked eye, but under a lens it is seen to be every- 
where covered with low granules quincuncially arranged. The 
lateral areas are a trifle raised, but not distinctly so, and upon them 
the granulation is somewhat effaced, and a few very obsolete radiat- 
ing sulci are generally distinguishable, as well as several rather 
strongly indicated growth-periods. " Interior: posterior valve hav- 
ing 13-14, (rarely 17), anterior valve 14-16, central valves 2-3 
slits. Teeth acute, distant ; eaves acute, projecting, hardly spongy ; 
sinus wide, short, flat. Girdle covered with rather large, wide 
scales, deeply and distantly striated." Length 13, breadth 7 mill. 

Orange Harbor, Terra del Fuego. 

Ch. viridulus COUTH. MS., GOULD, Proc. Bost. Soc. N. H. ii, p. 
144, 1846; Otia Conch., p. 5 ; U. S. Expl. Exped., Moll., p. 318; 
atlas, f. 413. Ischnoradsia viridulas CPR., MS. Lepidopleurus viri- 
dulus ROCHEBR., Miss. Cape Horn, Polyplacophores, p. 140. 
? Ischnochiton viridulus Gld., HADDON, Challenger Rep., p. 16,1886. 

A small form, evenly granulated, and having indistinct lateral 
areas. I have taken the description of the internal parts from 
Carpenter's MS., as I have not examined the interior of the single 
specimen before me, which is one of the original lot. 

I. TRIFIDUS Carpenter. PI. 18, fig. 40. 

Shell rather large, rather elevated, regularly oval ; red-chestnut, 
maculated with lighter and darker; jugum acute, gothic. Mucro 
median, flat ; entire surface very minutely granulated ; central areas 
having about 8 strongly punctate lines perpendicular to the jugum ; 
lateral areas strongly defined, having 2 to 4 obsolete ribs, sometimes 
punctate in the interstices. 

Interior whitish flesh-colored, with two reddish-purple rays diverg- 
ing from the flat umbones ; posterior valve having 13, anterior 13, 
central valves 2 slits ; teeth acute, sometimes serrated at the edge, 
sometimes striated outside, sometimes smooth. Eaves subspongy ; 
sinus small, laminate, the lamina slit at the sides and sometimes in 



142 ISCHNOCHITON-RADSIELLA. 

the middle. Girdle having very small, solid, smooth scales. Gills 
almost ambient. ( Cpr.} 

Length 40, breadth 26 mill.; divergence 135. 

Sitka to Puget Sound, 9-18 fms. 

Trachydermon trifidus CPE., Suppl. Kep. B. A. 1863, p. 649; 
Proc. Acad. Nat. Sci. Phila. 1865, p. QQ.Isehnoradsia trifida CPU., 
MS., and BALL, Proc. U. S. Nat. Mus. 1878, p. 331. 

I have not seen this species. The figure is from a rude sketch in 
Carpenter's MS. Dr. Dall writes of it as follows: 

This rare and fine species is not particularly handsome, being of 
dull and livid colors, but is peculiarly characterized by the straight 
transverse ribs on the dorsal areas with spongy interspaces, and by 
the pretty regular division of the lateral areas into three well 
marked radiating costse, which are separated in the insertion plate 
by two fissures. No other species of the region resembles this in 
sculpture. Muzzle with a pectinated margin in front produced into 
rounded lappets at the corners. Gill rows as long as the foot, con- 
taining each 28-35 branchiae. Veil absent. Mantle edge plain, 
narrow. There is a small spherical lump on each side of the girdle 
just behind the posterior ends of the gill-rows, which are turned out 
toward the girdle and widely separated behind. The anus is large 
median, and crenate, opening on the upper part of the hinder end of 
the foot. No ovarian openings could be detected, and the species 
presents some peculiarities which call for further research with more 
material. (Dall.*) 

I. REGULARIS Carpenter. PI. 18, figs. 41-46. 

Shell oblong, elevated, dorsally carinated, the side-slopes straight. 
Surface appearing almost smooth to the naked eye. Color a uni- 
form olive or slaty-blue, the girdle having more or less of a blue or 
purple " bloom." 

The lateral areas are very little raised, and are sculptured with 
numerous delicate radiating threads, occasionally branching toward 
the lower margin, and freely branching along the posterior edge of the 
valve. The terminal valves have similar delicate radii. The central 
areas have numerous longitudinal, somewhat beaded threads, 
separated by flat intervals. The posterior valve is elevated, with 
anterior umbo. 

The interior is light blue. Sutural plates low, connected across 
the sinus by a narrow plate which is sulcate above and cut into 



ISCHNOCHITON-RADSIELLA. 143 

about 10 teeth by delicate slits. Anterior valve having 14-16, 
central 2-3, posterior 22 slits. Teeth even and sharp, slightly 
striated or grooved outside. Eaves solid. Girdle wide, flat, cov- 
ered with solid, regularly and closely imbricating striated scales 
(fig. 46). Length 35, breadth, 19 mill. 

Monterey, California. 

Chiton regularis CPU., P. Z. S. 1855, p. 232. Ischnoradsia 
regularis CPR., MS. 

This species is of a very regular form, and a uniform drab, olive 
or blue color. It is not closely allied to any other West Coast form. 
The number of slits in the posterior valve is unusually large. 

I. TIGEINUS Krauss. PI. 19, figs. 60-63. 

Shell oblong, convex, roundly arched, buff-white, unicolored, or 
striped lengthwise with reddish ; rarely roseate. 

Valves without apices. The lateral areas do not extend to the 
middle of the back ; they are raised, and cut into radiating riblets 
by 8 or 10 narrow impressed grooves, and there are rather con- 
spicuous concentric wrinkles or waves of growth on the lower part 
of the ;*reas. The end valves are similarly sculptured. Central 
areas closely and regularly pitted all over. Posterior valve rather 
large and depressed, with subcentral umbo. 

Interior white and light brown. Anterior valve having 17-18, 
central valves 2-3, posterior valve 12-13 slits; teeth rather thin, 
but somewhat bevelled and roughened inside; eaves solid. Sinus 
wide and flat, the sutural-plates being rounded. Muscle-scars dis- 
tinctly impressed. 

Girdle rather wide, firm, densely clothed with somewhat convex, 
finely striated scales (fig. 63). Length 22-28 mill. 

Cape of Good Hope. 

Chiton tigrinus KRAUSS, Die Siidafric. Moll., p. 38, t. 3, f. 5. 
? Ischnoradsia subcariosa CPR., MS. 

This species is readily known by its Radsioid valves and the 
beautiful web-like sculpture of the central areas, produced by the 
pattern of regularly arranged rhombic pits. It is like no other 
species, although the young of /. magdalenensis bears a slight 
resemblance in the sculpturing of the central areas. 
. Although technically a Radsiella or Stenoradsia (it is not easy to 
decide which) this species probably was developed from a different 
stock of Ischnochitons. Indeed, the multiplication of side-slits may 



144 ISCHNOCHITON-ISCHNORADSIA. 

be expected to occur in any branch of Chitons; from the genus 
Ischnochiton alone, we have at least four or five independent 
Radsioid branches. 

The typical J. tiyrinus of Krauss is striped longitudinally. The 
unstriped form, of which several specimens are before me, may be 
called var. unicolor. 

The species mentioned by Carpenter as I. subcariosa may be a 
form of I. tigrinus. The type is a single specimen of unknown 
origin, and is in the museum of McGill College, Montreal. 

Subgenus VII. ISCHNORADSIA Shuttleworth, 1853. 

Ischnoradsia SHUTTLW., Berner Mittheil. 1853, p. 65, species cited 
C. australis and C. magdalenensis. Not Ischnoradsia CPR. Lepido- 
radsia CARPENTER, MS. ; and DALL, Proc. U. S. Nat. Mus. 1878, 
p. 331, type C. australis. 

Valves having sharp but rather thick insertion plates, those of 
the median valves with two or several slits. Girdle covered with 
convex, pebble-like, smooth scales. Type Chiton australis Sowb. 

The typical forms of this section are from the Australian seas, but- 
several species have also been found in Japanese waters. 

Carpenter's substitution of the name ' Lepidoradsia ' in place of 
Ischnoradsia, was in direct violation of the rules of nomenclature. 

Key to species. 

a. Sinus dentate within, albrechti* 

aa. Sinus smooth. 

b. Central areas longitudinally ribbed, australis, luyubris. 
bb. Central areas minutely granulated. 

c. Outside green, inside green and pink ; scales very convex, 

novcehollandice. 
cc. No green or pink ; scales small, convex, hakodadensis. 



I. AUSTRALIS Sowerby. PI. 18, figs. 57, 58, 59. 

Shell oval-oblong, moderately elevated, the dorsal ridge sub- 
angular, side-slopes nearly straight. Color dark olive-brown, the 
apices of the valves pink when eroded. 

Lateral areas somewhat raised and sculptured with close, uneven 
riblets, which usually bifurcate or branch freely, especially toward 
the posterior margin of the area. Central areas closely and evenly 



ISCHNOCHITON-ISCHNORADSIA. 145 

sculptured with finer longitudinal riblets, obsolete on the ridge, 
where they give place to a dense microscopic granulation. The worn_ 
apices of the valves are pink in mature shells. End valves sculpt- 
ured with close radiating riblets, those of the posterior valve irreg- 
ularly granose ; mucro rather depressed ; posterior slopes of the tail 
valve depressed and concave. 

Interior light blue-green, with two wide pink rays in each valve, 
and behind them two olive-brown rays. Sutural plates rounded, 
whitish or yellowish ; sinus wide, flat, not in the least toothed. 
Insertion plates having 16-21 slits in the anterior, 2 or 3 in the 
median, and 17-21 in the posterior valve ; teeth rather thick and 
stumpy, and a little rugose, but sharp edged. Eaves wide and solid. 
Girdle (fig. 57) wide, closely covered with conspicuous, convex, 
pebble-like scales, which toward the outer edge are subcarinated in 
the middle. 

Length 62, breadth 35 mill. 

Port Jackson, Australia. 

Chiton australis SOWERBY, Mag. of Nat. Hist. (Charlesworth's), 
June, 1840, p. 290; Conch. Icon., f. 46. REEVE, Conch. Icon., t. 2, 
f. 10. Lophyrus australis ANGAS, P. Z. S. 1867, p. 221. Lepido- 
radsia australis CPR., MS. and DALL, Proc. U. S. Nat. Mus. 1878, 
p. 279, t. 2, f. 19 (dentition) ; p. 333 (branchiae). HADDON, 
' Challenger ' Rep., Polyplac., p. 1 9. Chiton (Ischnoradsia) australis 
SHUTTLW., Bern. Mittheil., 1853, p. 66. C. evanidus SOWERBY, 
Mag. Nat. Hist, iv, June, 1840, p. 291 ; Couch. Illustr., f. 139. C. 
metallicus RVE., Conch. Icon., t. 17, f. 104, 1847. 

This species is distinguished from the following by the fine longitu- 
dinal ribbing of the central areas. The synonymy given above is 
unquestionable. 

Occasionally one or more of the teeth is cloven into a number of 
small ones ; the number of teeth varies considerable. 

Dall found the gill rows to extend the whole length of the foot, 
and to contain forty-seven branchiae in each. Mantle-edge plain, 
thin ; muzzle plain, semicircular, without a veil. 

I. NOV^EHOLLANDI^E (Gray) Reeve. PI. 19, figs. 67, 68, 69. 

Shell oval-oblong, elevated, the dorsal ridge angular, side-slopes 

nearly straight: Color green, minutely marbled with olive, the 

lateral areas darker. 

10 




146 ISCHNOCHITON-ISCHNORADSIA. 

Lateral areas somewhat raised, sculptured with low, uneven, some- 
what nodulous radiating riblets, and some concentric growth-wrinkles. 
Central areas smooth except for a very dense and regular microscopic 
granulation. End valves having radiating riblets ; mucro rather 
prominently raised ; posterior slope concave. Interior blue-green, 
with pink and olive rays. Sutural plates rounded ; sinus smooth, 
not toothed. Anterior valve having about 19, central valves 3-4, 
posterior valve 18 slits. Teeth thick but sharp ; eaves wide, solid. 

Girdle covered with smooth, solid, pebble-like scales, which toward 
the outer edge, are subcarinated. Length 43, breadth 23 mill. 

Adelaide, S. Australia. 

Chiton novcehollandice (GRAY, MSS. in Brit. Mus.) KEEVE, Conch. 
Icon., t. 21, f. 142, May, 1847. 

This species has much the appearance of I. australis, but it differs 
totally in the sculpture of the central areas, and somewhat in that 
of the lateral areas. The girdle is just like that of australis, except 
that the pebbly scales are smaller in a specimen of the same size. 
Carpenter erroneously considered this species a synonym of Chiton 
(Radsia) goodalli. 

I. LIJGUBRIS Gould. Unfigured. 

Shell small, solid, punctate, elongate-ovate, slightly carinated, 
emerald-green. Central areas sculptured with longitudinal lirse, 
smooth at the apices. Lateral areas elevated, having . branching 
nodulous lirse. End valves radiated at the margins, umbo sub- 
central. Girdle wide, covered with large transverse convex scales. 
(Old.-) _ 

Interior : end valves having 19-24, central valves 2-4 deep slits ; 
teeth acute, sometimes a little rugose at the margins ; eaves very 
short, spongy ; sinus broad, flat, smooth. Girdle imbricated with 
very solid narrow, nearly smooth scales. ( Qpr.) 

Length 25, breadth 15 mill. (Old.} 

Habitat unknown. 

Chiton (Lophyrus~) lugubris GOULD, Proc. Bost. Soc. Nat. Hist, 
vii, p. 163, Dec., 1859 ; Otia Conch., p. 116. Lepidoradsia lugubris 
Gld, CPR., MS. 

The girdle, says Carpenter, is very like that of I. australis, from 
which the strong sculpture distinguishes this species. 



ISCHNOCHITON-ISCHNORADSIA. 147 

I. HAKODADENSIS Carpenter, n. sp. PL 19, figs. 64, 65, 66. 

Shell oval-oblong, moderately elevated, back rather roundly arched, 
scarcely keeled. Soiled buff, maculated and striped with blackish- 
brown. 

Lateral areas slightly raised, cut into 6 to 9 low flat unequal 
riblets by radiating impressed lines, the riblets ipade uneven by con- 
centric wrinkles of growth ; central areas very minutely pitted all 
over, the surface being something between a quincuncial granulation, 
and a succession of vvw-like zigzags. End valves having fine radiat- 
ing riblets cut by some cencentric growth-sulci. Mucro in front of 
the middle, rather prominent. 

Interior blue- white ; sinus smooth ; sutural plates low, rounded ; 
anterior valve having 15-20, central valves 2-3, posterior valve 15 
narrow slits ; teeth rather sharp, sometimes slightly roughened ; eaves 
short, narrow, solid. 

Girdle covered with small, solid, convex, smooth scales (fig. 66). 

Length 25, breadth 15 mill. 

Halcodadi, Japan. 

This species, which was collected by Wm. Stimpson of the North 
Pacific Exploring Expedition, has very much the aspect of I.fruti- 
cosus Gld. of Australia, the sculpture of the central areas being of 
the same zigzag character. From all species of the J. longi- 
cymba group, however, this is distinguished by its smooth, convex 
girdle scales, and by the plurality of slits in the side insertion-plates. 
The above description and figures are drawn from part of the 
original specimens. 

I. ALBRECHTI Schrenck. PI. 19, figs. 70-74. 

Shell large, oval, elevated, the dorsal ridge acute ; mucro median, 
nearly flat. Reddish maculated with darker, the interior having 
rays of reddish-brown. 

Entire surface minutely and closely punctate ; central areas with 
about 30 lines of granules on each side of, and parallel with, the 
jugum ; lateral areas having in the young 4 to 6, in the adult 10 to 
12 radiating, distantly granose riblets; the end valves having 50 
riblets. 

Interior : posterior valve having 12, central valves ) to 3, ante- 
rior valve about 17 slits ; teeth acute, sometimes rugose or lobed at 
the edges, outside ; sinus moderate, 8 to 12 dentate. 



148 CHITONINJE. 

Girdle pretty regularly covered with large narrow, solid, smooth 
scales. ( Q?r.) 

Length 40, breadth 25 mill., divergence 112. 

Hakodadi, Japan. 

Chiton albrechtii SCHRENCK, Bull. Acad. Imp. Sci. de St. Petersb., 
v, p. 511 ; Reisen u. Forsch. ini Amur-Lande, ii, Zool., p. 283, t. 13, 
f. 7-17. Chiton (Lepidop leurus} albrechti E. A. SMITH, Ann. & 
Mag. Nat. Hist., (4), xvi, p. 115, 1875. Lepidoradsia granofilosus 
CPE., MS. 

The form collected by H. C. St. John, R. N. at Endermo Harbor, 
Japan, is larger, (length 65, breadth of central valves 28 mill.), the 
lirations on the lateral areas are not granulated, and all the valves 
are distantly concentrically sulcated. 



Subfamily 

Lophyroidea Gpn.,-\-Acanthoidea lophyroidea and Acanthoidea 
typiea CPU., table of Regular Chitons, 1873, and in Dall, Proc. U. 
S. Nat. Mus. 1881, p, 284 (1882). Chitonidce and Acanthopleuridce 
(part) DALL, Catal. Marine Moll. Southeast Coast, Bull. 37, U. S. 
Nat. Mus., p. 172 (1889.) 

Regular Chitons having the insertion-plates well-developed on all 
of the valves, and closely grooved or pectinated outside and at edge. 

The retention of Carpenter's groups Lophyroidea and Acanthoidea 
in anything like the limits given by their author, is simply impos- 
sible. On the other hand, a perfectly natural group is obtained by 
uniting these two groups, after excluding the "Acanthoidea isch- 
noidea" Cpr., and the group CraspedocMton Shutt., which have 
special characters not yet noticed in print. 

Within the group thus constituted, four genera having well- 
defined characters are distinguishable, all of them agreeing in the 
pectinated insertion-plates, though varying in the degree of pectina- 
tion. 

Synopsis of Genera. 

A. No eyes developed on the valves. 
a. Girdle scaly. 

Genus XII. CHITON Linne. 

Valves having one or several side-slits in each insertion-plate, and 
a deticulated sinus separating the sutural plates ; girdle scaly, the 



CHITON. 149 

scales rounded and solid, closely imbricating, rarely separated. 
Type C. tuberculatus Linne. 

aa. Girdle with short bristles. 

Genus XIII. EUDOXOCHITON Shuttleworth. 

Valves having several side-slits in each insertion-plate, the 
sutural-plates continuous across the sinus, which is represented by a 
mere wave; girdle leathery, beset with short, stiff bristles. Type C. 
nobilis Gray. 

AA. Eyes developed on end valves and lateral areas. 
a. Girdle leathery, nude or nearly so. 

Genus XIV. TONICIA Gray. 

Valves having pectinated insertion-plates ; sutural-plates separated 
by a squared denticulate sinus; eyes developed in more or less 
regular rays on forward part of lateral areas and on end valves. 
Girdle leathery, naked or with a few hairs. Type C. elegans 
Frembly. 

aa. Girdle covered with spines or spinelets. 

Genus XV. ACANTHOPLEURA Guilding. 

Valves having pectinated insertion-plates with one or several side- 
slits, the teeth in the posterior valve directed forward instead of out- 
ward ; sinus denticulate or smooth ; eyes small, scattered among the 
granules of the surface. Girdle bearing long calcareous spines, or 
closely clothed with short ones. Type C. spinosus Brug. 

Genus CHITON Linne, 1758. 

Chiton L. Syst. Nat. edit, x, p. 667 (first recognizable species C. 
tuberculatus) ; edit, xii, p. 1006. SPENGLER Skrivter af Naturhist. 
Selsk., 1797 (first species C. tuberculatus). LAMARCK, Prodr. 
Anim. s. Vert., p. 90, 1799 (sole example cited, C. tuberculatus). 
WOOD, Gen. Conch, and Index Test. (C. tuberculatus the first 
species). GUILDING, Zool. Journ. v, p. 27, (example, C. squamosus 
SowB.=fre&ercM/afaa). GRAY, P. Z. S. 1847, p. 65, 66. SHUTTLW., 
Bern. Mittheil. iv, p. 72. CARPENTER & DALL, Proc. U. S. Nat. 
Mus. i, p. 300 (1878), type C. tuberculatus. Not Chiton H. & A. 
AD., Gen. Rec. Moll, i, p. 474 (1858.) 

Lophyrus (in part) POLI, Test. utr. Sicil. i, multivalvia, p. 2, 4, etc. 
H. & A. ADAMS, Gen. Rec. Moll, i, p. 469 (in part.) 



150 CHITON. 

Lepidopleurus (in part) Risso, Hist. Nat. Eur. Merid., p. 267. 

Oymnoplax GRAY, in The London Medical Repository, Monthly 
Journal and Review, xv, p. 234 (Jan .-June, 1821.) 

Valves wholly external, the beak of the tail valve median or 
anterior ; insertion-plates longer than the eaves, slit into teeth which 
are deeply and finely pectinated, and typically project outward on 
all the valves. Girdle covered with closely imbricating, convex, 
smooth or striated scales. Gills extending the entire length of the 
foot. 

History of names for Chiton. In the tenth edition of his Systema 
Naturce, Linne includes in the genus Chiton the following species: 
hispidus, (" C. testa sexvalvi striata. Habitat . . "), tuberculatus, 
aculeatus and punctatus. Of these the first, hispidus, is now univer- 
sally admitted to be unidentifiable, as no information or reference 
further than that quoted above is given. The next species is a well- 
known West Indian form, and has been cited as the first species or 
type of the genus by Spengler, Guilding, Gray, and nearly all 
authors. Linne's third species, aculeatus, is apparently unidentifi- 
able, but probably belongs to the genus Acanthopleura ; the fourth, 
punctatus, is if possible less recognizable ; and even its modern genus 
cannot be determined. The name Lophyrus Poli has been used for 
the group by Messrs. Adams, but it can have no standing on account 
of the fact that Poli proposed that name for the soft parts only y 
retaining the name Chiton for the shells, in accordance with his 
"curious system of double naming. Poli's first species of Lophyrus is 
L. melphictensis, which is the soft part of Chiton cinereus L. ! Only 
one of Poli's four species belongs to the restricted genus Chiton. 
The history of the name Lepidopleurus is given on page 2 of this 
volume. The history of the name Gymnoplax is as follows : 

Gray, in his article "A Natural Arrangement of the Mollusca 
according to their internal Structure" (Med. Repos.), under the 
head of " Ord. 10 Polyplacophora," enumerates the synonyms of that 
term, defines the order, and offers the following arrangement : 
" a. Plates placed on the back of the mantle. 

1. Gymnoplax or gymnoplacidae. Acanthochitona. Chiton 
facicularis. Leptochitona. Chiton marginatus. 

b. Plates sunken in the back of mantle. 

2. Cryptoplax. Chiton larvseformis." 

The inference from this would he that Gray intended to include 
in "Gymnoplax or gymnoplacidse " all Chitons having exposed 



CHITON. 151 

valves, a meaning also favored by the etymology ; but in P. Z. S. 
1847 he places Gymnoplax under Chiton s. s. as a synonym. In 
any case, the name Gymnoplax cannot be used, as it has never been 
diagnosed except in the general way quoted above, and no species 
has ever been expressly designated as belonging to it. The name 
has been used by Gray only in the instances above mentioned and 
was, as we have seen, considered a synonym by him in his later 
writings ; but it should be noted that the irrepressible Rochebrune, 
still uses Gymnoplax in a generic sense, in order presumably, to 
disguise his species ; an unnecessary precaution, for his diagnoses of 
Chitons generally defy indentification of either genus or species. 

In conclusion : it is obvious that the name Chiton must be retained 
for a group typified by one of Linne's original species ; and since the 
tuberculatus is the only one of the original list which has been or 
can be identified, that species becomes the type of the genus. No 
other position on this question is reasonable or tenable. 

The most natural primary division of Chiton is into two groups ; 
one to include all American and some Old World species, in which 
the mucro is anterior and the scales smooth, the other to include Old 
World species having the mucro subcentral and the scales striated. 
As this division is based upon characters not always easy to see, the 
following division into sections is more convenient. 

Section CHITON (restricted.) 

Median valves having a single slit in each insertion-plate; sinus 
generally denticulate ; scales closely imbricating. 

Section RADSIA Gray. 

Median valves having two or more slits in each insertion-plate. 
Section SCLEROCHITON Cpr. 

Median valves having a single slit in each insertion-plate ; teeth 
of tail-valve tending forward ; sinus smooth ; scales of girdle 
separated. 

Section CHITON s. sir. 

Artificial key to species of Chiton. 

A. LATERAL AREAS RADIALLY SCULPTURED. 

a. Central areas having longitudinal riblets. 

b. Sides and ridge of central areas both sculptured. 



152 CHITON. 

c. Urnbo of tail valve distinctly in front of the middle. 
d. Riblets of lateral areas rather smooth and fine. 
e. Dotted or spotted with blue. 

/. Large, black, dots small, magnificus. 

ff. Small ; dots large, murrayi. 

ee. Concentrically lineated with brown or dark, cumingi. 
eee. Unicolored or blotched. 

f. 17 slits in head and tail valves together, perviridis. 

ff. 22-24 slits in head and tail valves together, quoyi. 

fff. 35 slits in head and tail valves together, subfuscus. 

ffff. 30 slits in head and tail valves together, bowenii. 

dd. Riblets of lateral areas granulose, irregular, or much 

forking. 

e. Lateral areas with 3-4 rows of pustules, granosus. 

ee. Lateral areas with forking or meshing riblets. 

/. Riblets 8-10, fine ; slits in head and tail valves 
together about 40, virgulatus. 

ff. Riblets coarser, netted ; slits fewer, stokesii. 

cc. Umbo of tail valve about central. 

d. Mucro depressed, slope behind it hardly concave, 

pellisserpentis. 

dd. Slope behind mucro very concave, burmanus. 

bb. Central areas with a smooth band or triangular on ridge of 

each valve. 
c. Mucro in front of the middle. 

d. Riblets of central areas curved or converging, 

e. Lateral areas sparsely pustulose-1 irate, viridis. 

ee. Lateral areas with interrupted or netted lirse, 

tuberculatus. 

dd. Riblets of central areas parallel or diverging forward. 
e. Lateral areas and end valves pustulose, granosus. 

ee. Lateral areas and end valves granose-ribbed, 

canaliculatus. 

eee. Lateral areas 1 irate, nigrovirens, perviridis, densiliratus. 
cc. Mucro about central. 

d. Lateral areas with low, smooth riblets, olivaceus, cereus^ 

affinis. 

dd. Lateral areas with feebly granose riblets, insularis. 

ddd. Lateral areas with granose or nodose ribs. 

e. Lateral areas with 3-4, pleura 25 riblets, discolor. 



CHITON. 153 

ee. Lateral areas with 2-3, pleura 14 riblets, muricatus. 
aa. Central areas smooth, lacking longitudinal ribs. 
b. End valves granose-lirate or pustulose. 

c. Front of diagonal line obviously wrinkled or pitted. 

d. Shell and girdle uniform dark green, rusticus. 

dd. Shell variegated, girdle-scales striated, sinclairi. 

ddd. Shell or girdle varied, scales smooth, viridis. 

cc. Front of diagonal line smooth. 

d. Pustules scattered ; shell and girdle uniform blackish, 

marquesanus. 

dd. Finely beaded ; shell and girdle banded, squamosus. 

bb. End valves finely striated. 

c. Shell oblong, divergence about 110. subfuscus. 

cc. Shell elongated ; divergence about 98. bowenii. 

AA. LATERAL AREAS SMOOTH OR CONCENTRICALLY SCULPTURED. 

a. Whole surface smooth. 
b. Mucro near the anterior margin. 

c. Color black and olive-yellow, with snowy lines, albolineatus. 
cc. Purple or olive mottled. 

d. Sutural-plates within dark-blotched at base ; sinus nar- 
row, Icevigatus. 
dd. Sutural-plates within not blotched ; sinus wide, 

marmoratus. 

bb. Mucro central, tulipa. 

aa. Central areas longitudinally sculptured, (species not tabulated.) 

West Indian species. 

Mainly large forms, with smooth scales and notably anterior 
mucro. They are closely allied to the species of the Panamic 
region. 

C. TUBERCULATUS Liime. PI. 33, figs. 58, 59, 60. 

- Shell oval-oblong, rather elevated, carinated, the side-slopes nearly 
straight. Color varying from light olive to dark green or dark 
olive-brown, unicolored sometimes, but generally speckled on the 
side-areas and end-valves, often clouded on the central areas; some 
of the valves having a dark stripe on the ridge. 

Lateral areas raised, sculptured with about 5 cord-like radiating 
riblets, which are sometimes subcontinuous, but usually are much 



154 CHITON. 

interrupted and broken, and bearing a few low tubercles. Central 
areas smooth along the ridge, the sides sculptured with longitudinal 
riblets curving inward, becoming coarser outwardly and diverging. 
End valves closely tuberculate all over, the pattern resembling that 
of an engine-turned watch case. ' Urnbo of tail valve near the front 
margin. 

Interior blue-green, very smooth, the sutural plates lighter; sinus 
narrow, toothed. Anterior valve having 13, central valves 1, pos- 
terior valve 14 slits; teeth blunt, pectinated. Slit-rays hardly or not 
punctate. 

Girdle white, buff or light green, alternating with patches of dark 
green or blackish. Scales rather coarse, convex, polished. 

Length 60, breadth 33 mill, (average Jamaica specimen.) 

Length 90, breadth 55 mill, (specimen from Nassau, N. P.) 

Bermuda, Florida and Texas to Trinidad. 

Chiton tuberculatus LINNE, Syst. Nat. x, p. 667 (1758). 
HANLEY, Shells of Linn., p. 12. Chiton squamosus BORN, Test. 
Mus. Cses. Vindob., p. 5, t. 1, f. 1. CHEMN., Conchyl. Cab. viii, 
f. 788-790. REEVE, Conch. Icon., t. 3, f. 16. H ADDON, Chall. 
Polyplac., p. 20, and of all modern authors. NOT Chiton squamosus 
Linne. Chiton undatus SPENGLER, Skrivter af Naturhist. Selska- 
bet iv, p. 68 (1797). C. bistriatus WOOD, Gen. Conch., p. 7 (1815). 
/ C. tessellatus WOOD, 1. c., p. 23. 

This species has been generally considered to be the squamosus of 
Linnseus, but that the Linnsean name belongs to another species 
must be regarded as established. The references quoted by Linnseus 
in the tenth edition of [the Systema clearly show that this is the 
species which he called tuberculatus. In the twelfth edition other 
references not applicable to the species are added ; and the figures 
given by Chemnitz, Born, and others under the incorrect name 
" squamosus " have caused subsequent authors to adopt the latter 
name. 

This species is the commonest Chiton of the West Indies, and is 
readily known by its (typically) strong, curved ribs and peculiar 
sculpture upon the end-valves, which Reeve aptly compares to that 
of a lathe-turned watch case. It is extremely difficult to draw a 
line between this species and C. assimilis of Reeve ; so difficult, in 
fact, that I have been unable to satisfactorily distribute a portion of 
the specimens before me between the two. Linnaeus describes tu- 



CHITON. 155 

berculatus as seven-valved ; and oddly enough, one of the specimens 
collected by Dr. B. Sharp at Tobago is also apparently seven-valved, 
having two of the valves firmly soldered together the result of an 
early injury. It is likely that the seven and six-valved Chitons 
described by early authors were partly abnormal specimens of this 
character, and the rest were founded upon careless and incorrect 
figures. 

Color-var. Color a uniform dull blackish ; riblets of the central 
areas finer and converging near to the median line. Area behind 
the sinus inside, and the slit-rays solid, not spongy or porous. 

Bermuda. 

I have seen a great number of specimens, but mostly so eroded 
that the permanence of the characters could not be decided. 

Var. ASSIMILIS Reeve. PI. 33, figs. 61, 62. 

Fawn colored, with white dots on the lateral areas, the carina 
banded with brown ; girdle light green. Central areas sculptured 
with very fine, close riblets. Interior having the slit-rays and the 
area behind the sinus porous. 

St. Thomas to Barbados. 

Chiton assimilis REEVE, Conch. Icon., t. 14, f. 76 (right hand 
figure) ; f. 77b. (March, 1847.) 

Color-var. ater. (pi. 33, fig. 63). Shell having the close fine 
sculpture of assimilis, but black in color, dark green-blue inside. 

St. Kitts (Rush) ; Trinidad (Sharp.) 

C. SQUAMOSus Liune. PI. 35, figs. 80, 81, 82. 

Shell oblong, elevated or rather depressed, carinated, the side- 
slopes somewhat convex. Surface of lateral areas minutely beaded* 
central areas smooth ; lusterless. Color buff (pale or deep in tint)' 
the central areas regularly and conspicuously striped longitudinally 
with gray or black, most valves having a wider dark blotch on each 
side of the keel, and a series of spots along the back edge. 

The lateral areas and end valves are raised and sculptured with 
radiating rows of fine beads, the number of rows increasing by inter- 
polation ; and under a lens the surface is seen to be minutely punctate. 
Central areas not sculptured, save for inconspicuous growth-lines. 
Mucro of posterior valve near the front margin. 

Interior dark blue-green, the sutural plates lighter. Sinus rudely 
denticulate. Anterior valve having 12, central valves 1, posterior 



156 CHITON. 

valve 13 slits. Eaves narrow, short, somewhat spongy ; sinus and 
slit-rays hardly porous. Teeth pectinated. 

Girdle alternately light green and whitish, covered with smooth 
convex-flattened scales. 

Length 60, breadth 32 mill. 

Length 45, breadth 28 mill. 

Cuba, Jamaica, St. Thomas and St. Croix, West Indies. 

Chiton squamosus LINNE, Mus. Ulricas, p. 465 (1764). Chiton 
squamosus L., Syst. Nat. xii, p. 1107. SPENGLER Skrivter af Natur- 
historie-Selskabet iv, p. 67, t. 6, f. 2 (1797). HANLEY, Shells of 
Linnaeus, p. 15 (1855). NOT Chiton squamosus of authors. Chiton 
tigris SPENGLER, L c., p. 68 (a depressed form ; see Chemn. viii, f. 
792, 793). Chiton scaber variegatus CHEMN. Abh., p. 31, t. 1, f. 3 ; 
Conchyl. Cab. viii, p. 276, t. 94, f. 792, 793. Chiton fasciatus WOOD, 
Gen. Conch., 1815, p. 10, t. 1, f. 4, 5 (excl. syn.). SOWB., Conch. 
Illustr., f. 153. SHUTTLW., Bern. Mittheil. 1853, p. 74. Chiton 
chemnitzii PFR., Krit. Register zu Mart. u. Ghemu., p. 78, 1840. 
Chiton marmoreus REEVE, Conch. Icon., t. 12, f. 64 (not of Chemn. 
nor Fabr.) 

This species is colored in much the same fashion as some striped 
forms of C. marmoratus, and it also agrees with that species in the 
smooth central areas; but the dullness of the surface and the 
minutely beaded lateral areas at once separate the two forms. 
Specimens vary greatly in degree of elevation and consequently in 
the size of the angle of divergence. 

Linnaeus gives an unusually full description of this species, amply 
sufficient to distinguish it from the shell which Born, Gmelin, and 
later authors confused with it. Spengler correctly identified it in his 
monograph of 1797, and gave a most excellent figure and a good 
description. Hanley found Linnaeus' original type still preserved in 
his collection, but the C. squamosus of authors is not present there. 
It should be noted that Linnaeus' specific names of Chitons were 
intended to be descriptive of the girdle, not the valves. 

C. VIRIDIS Spengler. PI. 33, figs. 64, 65, 66, 67. 

Shell oval, moderately elevated, carinated, side-slopes slightly con- 
vex. Color varying from gray-white to olive, irregularly marked 
on the central areas or on the ridge with blackish ; sometimes black- 
brown all over. 



CHITON. 157 

Lateral areas strongly raised, and sculptured with three or four 
low radiating ribs bearing at irregular or regular intervals low 
rounded pustules ; or having no radiating ribs, the pustules few and 
irregularly scattered; posterior border of each valve generally den- 
ticulated. Central areas smooth in the middle, but sculptured along 
the diagonal lines with a series of short ribs bent in the shape of a 
reversed $ (figs. 66, 67). End valves bearing radiating series of tuber- 
cles, or with only a few scattered tubercles. Mucro near the front 
margin. 

Interior light blue or light green. Sutural plates lighter, highly 
arched, the sinus deep, narrow, angular, the straight dentic- 
ulate portion from i to i the length of a sutural-plate. Anterior 
valve having 13, central valves 1, posterior valve 12 slits. 

Girdle alternately whitish and brown or green, finely scaly. 

Length 36, breadth 22 mill. 

St. Thomas and St. Croix (Swift) ; Jamaica. 

Chiton squamosus denticularis, etc., CHEMNITZ, Conchy]. Cab. x, 
p. 372, t. 173, f. 1689. Chiton viridis SPENGLER, Skrivter af 
Naturhistorie-Selskabet. iv, p. 70, t. 6, f. 5 (1797). WOOD, 
General Conch., p. 15 (1815). Chiton foveolatus SOWERBY, Charles- 
worth's Mag. of Nat. Hist. 1840, p. 290; Conch. Illustr., f. 60. 
REEVE, Conch. Icon. t. 6, f. 28. Chiton costatus C. B. AD., Proc. 
Bost. Soc. Nat. Hist. 1845, p. 8. Chiton (Lophyrus) gemmulatus 
SHUTTLEWORTH, Bern. Mittheil. 1853, p. 75. 

Doubtful references: Chiton squamosus, testa septen-valvi-striata, 
etc., CHEMNITZ, /. c. x, p. 374, t. 173, f. 169Q,= Varietet af Chiton 
undatus, SPENGLER, Skrivter af Naturhistorie-Selskabet, iv, p. 69 
(1797). Cftifcw tessellatus WOOD, Gen. Conch., p. 23 (1815). 
Chiton excavatus (Gray) SOWB., Conch. 111., f. 131 (never de- 
scribed.) 

This species is well distinguished by the series of short curved 
wrinkles along the diagonal latero-posterior edges of the otherwise 
smooth central areas, and by the sutural denticulation, when this is 
developed, which is by no means always the case. The diagnostic 
features of the species are stated with great clearness by the Danish 
naturalist Spengler, and also by Chemnitz, but the figures given by 
them are poor. There is great variation in the development of the 
pustules upon the lateral areas and end valves. 



158 CHITON. 

C. MARMORATUS Gmelin. PI. 34, figs. 72, 73, 74, 75, 76. 

Shell oval, rather elevated, the dorsal ridge varying from roundly- 
angular to distinctly carinated; side-slopes convex or straight. Sur- 
face smooth, polished. Color varying from olive to dark brown or 
purple-brown, variously marked with darker spots or blotches and 
light longitudinal stripes or lines. 

The lateral areas are a little raised ; the whole surface showing a 
very minute quincuncial pattern of granulation under the lens, and 
marked with inconspicuous growth-lines. Mucro close to the front 
edge of the tail-valve, as in C. Icevigatus. 

Interior blue-green, each valve often having darker or olive pos- 
terior rays. Sinus deep, angular, having a jagged convex row of 
denticles, half as long as a sutural-plate. Anterior valve having 11- 
14, central valves 1, posterior valve 13-17 slits; teeth deeply finely 
pectinated. Eaves, slit-rays and triangle behind the jugal sinus 
very porous. 

Girdle alternately blotched with green and light blue. 

Length 56, breadth 32 mill. 

Length 48, breadth 26 mill. 

Texas (Dall) ; Bermuda (Heilprin) ; Jamaica (Cpr.) ; Cuba ; St. 
Thomas (Swift) ; St. Croix ; St. Vincent (Sharp) ; Barbados (Rush) ; 
and Carthagena, U. S. Columbia (Krebs.) 

Chiton marmoratus GMEL., Syst. Nat. xiii, p. 3205. (Chiton 
marmoreus CHEMNITZ, Conchyl. Cab. viii, p. 282, t. 95, f. 803-805. 
Not C. marmoreus REEVE). C. marmoratus SOWB., Conch. Illustr., 
f. 148-150. REEVE, Conch. Icon., f. 6. SHUTTLW., Bern. Mittheil. 
1853, p. 74. DALL, Cat. Moll. S.-E. U. S., p. 172.^0. scarabceus 
REEVE, Conch. Icon., t. 12, f. 66. 

This species is excessively variable, but with all its variety I have 
seen no specimens having the pattern of the West Mexican C. 
IcKvigatus and articulatus. The following color-patterns are 
commonly met: 

1. Entire surface of valves blackish-brown. This is not an 
uncommon form, being the C. scarabceus of Reeve. 

2. Olive, with fine flecks and lines of whitish, becoming confluent 
toward the middle. 

3. Either purple-brown or olive, having longitudinal zebra-like 
stripes on the side-slopes. 



CHITON. 159 

This species is amply distinguished from C. Icevigatus by the wider 
sinus, different coloring, and by the much more porous lines radiat- 
ing toward the slits, and the conspicuously porous triangle under the 
dorsal ridge of each valve, as shown in fig. 75. 

Species of the West coast of the Americas. 

This is a natural group of large species, characterized by the 
generally somber color, large smooth scales, and anterior mucro. 
Radsia is a tangent from this circle of species. 

C. L^EVIGATUS Sowerby. PI. 34, figs. 68, 69, 70, 71. 

Shell oval, subdepressed or elevated, carinated, the side-slopes 
somewhat convex. Surface smooth. Colors soft and blended, vary- 
ing from purple-gray to olive, lighter in the middle, where there are 
three irregular longitudinal series of black or dark blotches ; back 
edge of each valve often articulated with light and dark spots. 

The lateral areas are a little raised ; whole surface polished, show- 
ing a microscopic quincuncial granulation under the lens. Mucro 
unusually close to the front edge of the tail valve, almost marginal. 

Interior dark green-blue ; the sutural plates lighter but having a 
large dark green or blackish blotch at the base of each. Sinus deep, 
square, with a convex row of jagged teeth. Anterior valve having 17, 
central valves 1, posterior valve 21 narrow slits ; teeth blunt, deeply 
laciniate ; eaves short, narrow, spongy. 

Girdle wide, tessellated with alternate light and dark. 

Length 55, breadth 38 mill. 

Length 85, breadth 55 mill. 

Gulf of California to Acapulco. 

Chiton Icevigatus SOWB., P. Z. S. 1832, p. 59 ; Conch. Illustr., f. 
18*. EEEVE, Conch. Icon., t. 7, f. 35. Chiton articulatus SOWERBY, 
P. Z. S. 1832, p. 59; Conch. Illustr., f. 18. REEVE, Conch. Icon., 
t. 2, f. 7. 

Sowerby's description of lajvigatus precedes that of articulatus in 
the P. Z. S., and since the two forms prove to belong to one 
species, the former name must be accepted. Fig. 69 represents the 
articulatus. 

There is considerable variation in the degree of elevation and in 
the contour, but the extremes seem to be connected most intimately 
by specimens intermediate in form. This species has a general 



160 CHITON. 

resemblance to the West Indian smooth Chiton, C. marmoratus; 
but it differs in the plan of coloring both inside and out, the West 
Indian species lacking the dark blotches upon the bases of the 
sutural-plates, which are so characteristic of Icevigatus. The 
marmoratus, morever, has a proportionately wider sinus, the straight 
toothed space between the sutural-plates being half as long as each 
plate, whilst in Icevigatus it is only one-third as long. This last 
character, together with the internal coloring, will always distinguish 
the two species. 

C. ALBOLTNEATUS Sowerby. PI. 32, fig. 57. 

Shell oblong, parallel-sided, moderately elevated, carinated, 
smooth ; lateral areas, end valves and dorsal keel black, marked with 
snow-white radiating lines. Sides of the central areas light olive- 
green, some of the valves occasionally black. 

The lateral areas are a little raised ; entire surface most minutely 
granulated in the usual quincuncial pattern. Beak of posterior 
valve anterior. 

Interior light blue, the sutural plates paler. Anterior valve 
having 15-16, central valves 1, posterior valve 16-17 narrow slits ; 
teeth strongly pectinated. Eaves narrow, short, spongy. Sinus 
denticulate. 

Girdle firm, blue-gray, compactly covered with convex-flattened 
polished imbricating scales. 

Length 35, breadth 18 mill. 

Todos Santos Bay, L. California (R. E. C. Stearns) : Mazatlan 
(Cpr.) ; Acapulco (Ruschenberger.) 

C. albolineatus SOWB., Zool. Journ. iv, p. 368 ; in Zool. Beechey's 
Voy., p. 149, t. 40, f. 4 ; Conch. 111., f. 39. C'. albilineatus REEVE, 
Conch. Icon., t. 2, f. 11. Lophyrus albolineatus CPR., Maz. Cat., p. 
191. 

The apparently smooth surface and the conspicuous snowy stripes 
render this a very distinct specific type. Each scale of the girdle 
when examined under a lens is seen to be of a delicate blue-green 
color, edged broadly with white. 

C. MAGNIFICUS Deshayes. PL 30, figs. 23, 24. 

Shell large, oval, moderately elevated or somewhat depressed, the 
dorsal ridge indistinctly carinated, side-slopes a little convex. Color 
black, with minute blue dots scattered rather thickly over the valves; 
girdle black. 



CHITON. 161 

The lateral areas are very little raised, and sculptured with about 
10 small subobsolete radiating riblets ; central areas closely and 
finely sculptured with longitudinal riblets separated by deeper 
interstices. Posterior valve having the umbo near the front margin, 
the slope behind it straight. 

Interior light blue; sutural plates wide; sinus square, finely 
toothed. Anterior valve having 9-12, central valves 1, posterior 
valve 1 2-14 slits ; teeth stout, blunt, deeply pectinated. Eaves very 
short and narrow, spongy. 

Girdle (fig. 24) strong, covered with shining, convex, imbricating 
scales. 

Length 95, breadth 60 mill. ; divergence 120. 

Valparaiso., Chili. 

Chiton magnificus DH., Diet. Class, des Sc. Nat. xii, p. 455 ; 
Encycl. Meth., p. 680.; Lam., An. s. Vert., ed. Dh., vii, p. 498. 
REEVE, Conch. Icon., t. 1, f. 3. Chiton latus SOWERBY, Catal. Sh. 
Tankerv., appendix, p. v, (not Ch. latus Lowe). Chiton olivaceus 
FREMBLY, Zool. Journ. iii, p. 199, Suppl. pi. 16, f. 4. Chiton 
striatus BARNES, Amer. Journ. of Science vii, p. 70, t. 3, f. l.(1824). 
Not C. striatus of authors. 

This large olive-black, blue-dotted species is remarkable for the 
evenness and smoothness of its sculpture. It is an unusually hand- 
some Chiton. 

C. MURRAYI Haddou. PI. 29, figs. 15-21. 

Shell apparently smooth, but really very closely and finely 
striated, the striae being roughened or interrupted ; greatly depressed. 

Anterior valve with radial striae ; under surface with eleven dis- 
tinct square slits, radial grooves distinct and perforated ; teeth of 
insertion plate serrate. Intermediate valves narrow, flattened, 
non-carinate, with sharp depressed umbo, surface striae longitudinal 
in central areas, radial in the lateral areas ; lateral areas distinct, 
with slight-concentric rugae, and with three or four scarcely apparent 
peripheral radial ridges, which die away toward the apex ; sutural 
laminae shallow, a single lateral slit, lateral insertion plates serrate ; 
jugum with nine rounded teeth, the central being very small. Pos- 
terior valve flattened, slightly umbonate, striae longitudinal on 
the anterior area, radial on the posterior area ; under surface with 
seventeen distinct slits, teeth serrate ; jugum finely toothed. 
11 




162 CHITON. 

Color, upper surface ground color of shell a greenish-grey, slightly 
clouded with dark brown and black ; umbones lighter ; on each side 
of the latter the ground is yellowish; whole surface sprinkled with 
pale blue spots, which are bounded externally by a black line ; on 
the central areas, the spots run in irregular, oblique, backwardly 
diverging lines, and have a slight tendency to confluence, but on the 
lateral areas and terminal valves the spots are irregularly scattered ; 
under surface, pale sea-green, darker along the jugum, and with a 
dark spot at the umbones of the terminal valves. 

Girdle : upper surface with large imbricate scales, of which the 
exposed portion is smooth, the hidden portion being usually finely 
striated longitudinally ; color, dark green, with a tendency to form 
darker bands opposite the valves ; in the angles between the valves 
a few of the scales are paler and yellowish in color; under surface 
with long narrow oblong white scales arranged in transverse series. 

Gills extending along the whole length of the foot, about fifty-five 
or sixty in number. 

Length 12'5, breadth 7'5 mill. 

The following Chitons also have blue spots : Chiton magnificus 
Desh. and Chiton disjunctus Fremb. The latter is also from 
Valparaiso, but it would be impossible to mistake these for Chiton 
murrayi. Superficially, this species bears some resemblance to 
Lepidopleurus lentiginosus Sow. (G. B. Sowerby, 1840, Charles- 
worth's N. S. London's Mag. Nat. Hist., and Conch. Illust., 1841, 
figs. 120, 121 ; Reeve, Conch. Icon., 1847, pi. xxiv, fig. 165,= Chiton 
cyaneopunctatus KRAUSS, Die siidafrikanischen Moll., 1848, pi. 
iii, fig. 2) ; but apart from the generic distinction, Sowerby's species 
can be distinguished by the perfectly smooth shell, inconspicuous 
lateral areas, paler color of the shell generally, and absence of the 
external black border to the blue spots. I have given myself the 
pleasure of dedicating this pretty and distinctive little Chiton to Mr. 
John Murray of the Challenger Expedition. (HaddonJ) 

Valparaiso, C/iili, on the shore. 

Chiton murrayi HADDON, Challenger Polyplac., p. 21, t. 1, f. 7 ; 
t. 3, f. la-le. 

C. SUBFUSCUS Sowerby. PL 38, figs. 19, 20, 21, 22. 

Shell oblong-oval, elevated, carinated, the side-slopes nearly 
straight. Surface rather shining. Color dark olive-brown, or olive- 



CHITON. 163 

chestnut rayed with brick-red, (or " copperas-green or reddish, more 
or less flamed with jet-black.") 

The lateral areas are somewhat raised, and sculptured with 
numerous (8 to 10) low radiating strice, which are finely, unevenly 
interrupted by growth-lines. Central areas sculptured by some 
growth-wrinkles, and by fine longitudinal threads, which are gener- 
ally obsolete or absent except on the front of the dorsal ridge of each 
valve. End valves having radii like the lateral areas, their uneven- 
ness giving the valve a superficially pitted or finely netted appear- 
ance. Beak of tail valve near the anterior margin. 

Interior pale bluish, the sutural-plates whiter. Anterior valve 
having 15, central 1, posterior valve 20 slits; teeth rather sharp- 
edged, strongly crenulated inside and out; sinus-area spongy ; slits 
and slit-rays coarsely spongy. Eaves short. 

Girdle densely covered with fine, smooth, convex, shining, black 
or olive-black scales. 

Length 42, width 24 mill. ; divergence 110. 

Island of Chiloe (Cuming) ; Chili. 

Chiton subfuscus SOWEKBY, P. Z. S. 1832, p. 26. Chiton striatus 
Barnes, SOWB., Conchol. Illustr., f. 3, 41 (excl. synon.). C. striatus 
REEVE, Conch. Icon., t. 1, f. 36. Not Chiton striatus BARNES. 

This species is closely allied to C. magnificus, but differs in being 
smaller, narrower and more elevated, in lacking blue dots, and in 
the partial obsolescence of the longitudinal striation of the central 
areas. Figure 19 represents the form which judging by his measure- 
ments Sowerby considered typical. He afteward united olivaceus, 
latus and striatus (all of which -magnificus Dh.) with subfuscus. 
Reeve adopted the name striatus, and figured the shell represented 
by Sowerby's fig. 3 of the " Conchological Illustrations." This is 
copied in our fig. 20. We are constrained by the terms of Sowerby's 
original description to adopt the following arrangement. 

Typical subfuscus Sowb. PL 38, fig. 19. 

Pale ashy olivaceous green, streaked and mottled with black ; 
longitudinal sculpture all over the central areas, and radiating 
sculpture on lateral areas, both strongly developed, the latter a little 
interrupted into rugulations. 

The relations of this form with magnificus require investigation. 



164 CHITON. 

Var. mesoglyptw Pilsbry. PI. 38, figs. 20, 21, 22. 

Olive-brown or brown, unicolored or rayed with brick or blood- 
red, the latter sometimes predominating. Central areas having a 
group of longitudinal striae on the dorsal ridge, but smooth or nearly 
so on the pleura. Smaller than the preceding. 

I have seen a considerable number of this form, which is the 
" var." described by Sowerby and figured in Conch. Illustr., fig. 41. 
I am unable to say whether it intergrades with the true subfuscusor 
not. 

C. BOWENII King. PI. 38, fig. 23. 

Shell large, elongated, elevaced, the dorsal ridge carinated ; red- 
dish-chestnut, olive, or ashen streaked with olive. Mucro in front of 
the middle, the slope behind it straight. 

Central areas smooth, sometimes with delicate longitudinal stride 
at the ridge ; lateral areas elevated, delicately radiately striated, the 
end valves similarly sculptured. The entire surface is microscopic- 
ally granulated in quincunx pattern. 

Inside having 13 slits in the anterior, 1 in the central, 17 in the 
posterior valve; teeth pectinated, eaves small; sinus wide, flat, with 
12-16 teeth. 

Girdle olive-brown, in all the varieties of valve-coloring ; scales 
solid, rounded, regularly imbricating, and small for the size of the 
shell. 

Length 82, width 38 mill. ; divergence 98. 

Length 68, width 32 mill. 

Straits of Magellan. 

Chiton bowenii KING, Zoolog. Journ. v, p. 338 (1831 or 1832). 
SOWERBY, Conch. Illustr., f. 37. REEVE, Conch., Icon., t. 2, f. 9. 
SMITH, P. Z. S. 1881, p. 35. ROCHEBRUNE & MABILLE, Moll. Cap 
Horn, p. 141. 

Distinguished by its comparative smoothness, unusually elongated 
form, and highly ridged back. 

C. CUMINGI Frembly. PI. 30, figs. 29, 30, 31. 

Shell oval or oblong, elevated, the dorsal ridge angular, side- 
slopes nearly straight. Whitish or olive, very closely and regularly 
striped with brown or lead-colored lines which are concentric on the 
end valves and lateral areas and converge forward on the central 
areas ; often blotched on some or all of the valves with lead-brown 
or buff. 



CHITON. 165 

The lateral areas are separated from the central areas by an 
oblique curved ridge, but scarcely raised ; sculptured with 6 or 7 
low radiating riblets, somewhat decussated by longitudinal sub- 
obsolete riblets. The central areas are sculptured with longitudinal 
riblets finer than those of the lateral areas. End valves having 
radiating riblets and less distinct concentric lirse, the umbo of pos- 
terior valve near the front margin. 

Interior pale blue ; sinus flat, toothed ; anterior valve having 10, 
central valves 1, posterior valve 13 slits; teeth blunt, pectinated. 

Girdle clothed with smooth, convex, imbricating scales. 

Length 53, breadth 34 mill. 

Length 56, breadth 31 mill. 

Valparaiso, Chili. 

C. cumingsii FREMBLY, Zool. Journ. iii, p. 198, suppl. pi. 16, f. 
3. C. cumingsi DH. in Link., An. s. Vert, vii, p. 500. C. cumingii, 
SOWB., Conchol. Illust., f. 32. REEVE, Conch. Icon., t. 1, f. 2. 

This well-known species is of a bronze-olive color, closely lineated 
with brown or olive. The lines are not distinctly enough shown in 
the. figures. The range of variation in contour and color-pattern is 
considerable. It has been reported from the Cape Verde Is. (Nouv. 
Arch, du Mus. 1881, p. 282), but there cannot be much doubt that 
the citation is based on a false locality label. 



C. STOKESII Broderip. PI. 30, figs. 25, 26 ; pi. 32, figs. 50-53. 

Shell oval, moderately elevated or depressed, the back carinated, 
side- si opes straight. Brownish-black, toward the middle often 
more or less marbled longitudinally with dirty white. 

Lateral areas somewhat raised, closely sculptured with radiating, 
irregularly granulous and anastomosing riblets. Central areas 
sculptured throughout with low close longitudinal riblets, often made 
slightly granose by the lines of growth. End valves covered with a 
net- work of nodose riblets generally very much interrupted ; umbo 
of posterior valve near the front margin. 

Inside smooth, varying from blue-white to light blue, the sutural 
plates paler, all of the valves marked with a spot of dull brown. 
Sinus deep, rather narrow and angular, jaggedly toothed. Anterior 
valve having 16, central valves 1, posterior valve 15-16 slits. 



166 CHITON. 

Girdle (pi. 32, figs. 53) covered with solid, convex, subcarinated 
imbricating scales. Length 68, breadth 50 mill. 

Guaymas, West Mexico, to Panama and West Columbia. 

Chiton stokesii BROD., P. Z. S., 1832, p. 25. Sows., Conch. 
Illustr., f. 24. REEVE, Conch. Icon., t. 1, f. 4. MORCH, Mai. Bl. 
vii, p. 176. Chiton patulus SOWB., Charlesworth's Mag. Nat. Hist. 
1840, p. 291 ; Conch. Illustr., f. 134. REEVE, Conch. Icon., f. 30. 
C. interruptns CPR., MS. 

The sculpture of the lateral areas is peculiar, being something like 
the meshes of a stretched net, but the cords or riblets are irregularly 
granulose. In uniting the C. patulus of Sowb. to stokesii, I quite 
agree with Carpenter, who writes as follows: The form patulus is 
typically " engine-turned " on the terminal valves, with strong rugse 
on the sides, and larger scales on the girdle. A young specimen 
sent by Mr. Cuming has only 18 slits in the tail plate. The typical 
stokesii has the terminal rugse radiating, and sometimes a row of 
color dots at the sutures. The bulk of the Panama and San Juan 
specimens (of which I have examined many hundreds) are so 
variously intermediate between the two forms that I find it impos- 
sible to separate them even as varieties. The scales are extremely 
deciduous, and specimens in good condition are not often found. 
It was often the custom of Mr. Cuming to select extreme forms for 
his cabinet; and these being described and figured as the normal 
types of species are very apt to mislead students who work by single 
specimens. 

C. VIRGULATUS Sowerby. PI. 32, figs. 54, 55, 56. 

Shell oblong, parallel-sided, rather elevated, the dorsal ridge car- 
inated, side-slopes straight. Lateral areas and end valves olive- 
brown, or like the central areas which are green, longitudinally 
clouded with blackish ; girdle firm and xolid, transversely or longitu- 
dinally banded. 

The lateral areas are raised and sculptured with nnmerou* (8-10) 
radiating ribletx, which have a tendency to xplit or branch. Central 
areas sculptured with longitudinal riblets which at the sides diverge 
a little and are nearly as coarse as those of the lateral areas, but 
become finer and parallel to the ridge toward the middle. End 
valves having close radiating riblets; apex of tail valve anterior. 

Inside dark blue-green; sutural-plates high, blue-green. Sinus 
deep angular and toothed. Anterior valve having 21-22, central 



CHITON. 167 

valves 1 or 2, posterior valve 19-20 wide spongy slits; teeth wide, 
blunt, pectinated ; eaves short, narrow, spongy. 

Girdle compactly covered with solid, shining convex scales (pi. 
32, fig. 56.) 

Magdalena Bay, L. California; Gulf of California. 

Chiton virgulatm SOWB. in Charlesworth's Mag. Nat. Hist. 1840, 
p. 291 ; Conch. Illustr., f. 132. KEEVE, Conch. Icon., t. 21, f. 140. 

This species is allied to 0. stoke*ii, but differs in being narrower, 
more elevated, differently colored, in having the riblets finer, more 
numerous and less anastomosing, in the color of the interior and in 
the number of slits, which is much greater in the end valves of this 
species than in those of C. stokettii, and in some of the intermediate 
valves there are two slits in one or both sides. The entire surface, 
as usual in this genus, is microscopically granulated. The girdle- 
scales are finer and smoother than in C. xtokexii, and the sutural- 
plates are different in form. 

A square mm. of the girdle is shown by the dotted line in fig. 56. 

It has been reported from Australia, but erroneously. Many spec- 
imens are before me from the localities given above. 

The remarkable feature of this species is that it forms a perfect 
transition between the restricted genus Chiton and the section 
jRadsia. Some specimens have two slits in one end of one valve 
only ; others have two slits in the majority of the valves ; and 
scarcely two are alike in the arrangement of 1-and 2-slit insertion- 
plates. I have examined the interior in about a dozen individuals 
and have always found at least one insertion-plate Kadsioid, but 
probably a larger series would reveal specimens with the normal 
plates of Chiton 8. >-. 

* 

C. GRANOSUS Frembly. PI. 30, figs. 27, 28. 

Shell oval-oblong, moderately elevated, scarcely carinated, the 
side-slopes somewhat convex. Black, having a white stripe on each 
side of the central line, clouded with whitish between the stripes. 

Lateral areas bearing three or four rows of bead-like pustules, on a 
smooth ground ; central areas having a narrow smooth dorsal band, 
the *ides (pleura) covered with close, fine longitudinal riblets, which 
are more or less crenulated by the growth-lines. End valves hav- 
ing rounded pustules in radiating rows or irregularly scattered ; 
umbo of tail valve near the front margin. 



168 CHITON. 

Interior whitish clouded with olive-plumbeous posteriorly and on 
the sutural-laminre ; sutural-plates wide, sinus rounded, toothed; 
anterior valve having 14-15, central valves 1, posterior valve 15-18 
slits ; teeth blunt, pectinated ; eaves short, spongy. The sutural 
lamina? are smooth inside, the anterior-median tract is finely ivrinkled 
transversely, the posterior tract is punctate. 

Girdle clothed with coarse, angularly-convex, imbricating scales. 

Length 40, breadth 26 mill. 

Gulf of Pendas, Patagonia ; Valparaiso, Chili. 

Chiton granoxns FREMBLY, Zool. Journ. iii, p. 200, suppl. pi. 17, 
f. 1 (1827). DH. in Lmk., An. s. Vert, iii, p. 500. SOWB., Conch. 
Illustr., p. 2 ; Moll. jBeechey's Voyage of H. M. S. ' Blossom,' t. 
40, f. 5. REEVE, Conch. Icon., t. 5, f. 27. Lophyru* granosn* TAP. 
CAN. Viag. ' Magenta ' p. 75. 

The pustulose lateral areas and end valves and the black, two- 
striped color-pattern are the stronger features of the exterior of this 
species; and the interior is no less strongly marked by the trans- 
verse wrinkling of the front part of each valve, which may be readily 
seen under the lens without dis-articulating the shell. This wrink- 
ling in other species is confined to a band the width of the sinus, and 
is much less strongly developed. The second valve is broad and 
beaked, with only a narrow smooth dorsal line : the following valves 
have a distinct smooth band. 



C. STRIATOSQUAMOSUS Carpenter. 

Shell subrotund, depressed, pale brown-olive; entire surface of the 
valves densely granulated ; lateral areas rather distinct, valves wide, 
slightly curved, scarcely beaked; jugum scarcely distinct, very 
delicately longitudinally striated, lateral margins plauate ; mucro 
superior, slightly distinct. 

Girdle furnished with solid, oval, large hardly crowded scales, 
part deeply striated ; margins of the valves serrated ; median valves 
with a single slit on each side, end valves having about 12 slits; 
sutural-plates large, strongly arcuate. 

Length 41, breadth 3, alt. 1 mill.; divergence 140. (Cjpr.) 

Mazatlan, on Spondylus caldfer. 

Lophyrus striato-xqnamosus CPR., Cat. Mazat. Sh., p. 192. 



CHITON. 169 

Species of Japan, East Indies, Polynesia, etc. 

C. AQUATILIS Reeve. PI. 38, figs. 33, 34. 

Shell ovate, valves very closely elevately striated throughout, 
striae here and there but rarely, bifurcately-divergent, interstices 
rather excavated. Bronze-green, yellowish in the middle, with nar- 
row transverse green bands. Ligament squamately coriaceous, 
scales pale sea green. 

A peculiar smoothly bronzed shell, painted across the middle with 
narrow bands or ripples of green. (Reeve.) 

Tsu-sima, Japan. 

C. aquatilis REEVE, Conch. Icon., f. 73. 

Reeve gives no locality for this species. The figures on my 
plate are copies of his. 

Carpenter writes as follows of Reeve's type specimen : One spec- 
imen made up of two, only the valves stuck together. I counted 
just eleven scales in one corner, though Reeve describes and figures 
it as complete. The very insertion-plates are in great measure 
rubbed off. It may equal my C. dendliratu* in poor condition. 
Anterior valve having 10, central valves 1, posterior valve 13 slits; 
teeth pectinated ; eaves short. Shell rather elevated, the dorsal 
ridge sharpish. Central areas with extremely close fine parallel 
strise, jugal area not defined. Lateral areas not elevated, having 
18 radiating lines, extremely close and fine, as on central areas, but 
rather more developed ; the end valves similarly sculptured, mucro 
in front of the middle ; posterior slope very concave. Marked 
"? Japan " ; and the habitat of a specimen sent by Damon for pur- 
chase is Tsu-sima, Japan. The valves alone, without girdle, and 
irregularly placed measure : 

Length 40, breadth 23 mill.; divergence 105. 

C. DENSILIRATUS Carpenter, n. sp. 

Shell oval, solid, elevated, the jugum acute; mucro scarcely 
prominent, subanterior. Ashy or pale brown, irregularly clouded 
with chestnut or black, often elegantly dotted with darker or paler. 

Central areas having about 25 riblets on each side of the jugum 
and parallel with it, obsolete at the ridge; lateral areas well defined, 
having 8-10 line, sometimes bifurcating; end valves having 60-70 
such lira?. 



170 CHITON. 

Inside: anterior valve having 8; central valves 1, posterior 
valve 18 slits; teeth normal, very closely pectinated ; sinus narrow, 
having about 12 minute denticles. 

Girdle unicolored or tessellated, bearing normal imbricating scales 
which here and there are very minutely striatulate. 

Length 58, width 33 mill.; divergence 110. 

Japan (Mus. Cum., no. 16.) 

This species, says Carpenter, from whose MS. the above descrip- 
tion is taken, is easily recognized by the very close ribs, arranged like 
miniature whale bone. 

C. MARQUESANUS Pilsbry, n. sp. PL 36, figs. 98, 99, 100. 

Shell oval-oblong, depressed, obtusely carinated, the side-slopes 
nearly straight. Surface smooth and polished on the central, granose 
and lusterless on the lateral areas. Color dark olive-green, almost 
black on the lateral areas and end valves. 

Lateral areas but slightly raised, sculptured with about seven 
uneven and unequal rows of separated low warts, and under a lens 
seen to be covered with a minute granulation ; central areas shining, 
having a few low growth-wrinkles and covered with a partly effaced 
microscopic granulation. End valves closely granose in indistinctly 
radiating pattern; mucro near the front margin of the tail valve. 

Interior light blue, stained at sinus and under the beaks with 
purple-brown ; sinus rather shallow and toothed. Anterior valve 
having 21, central valves 1, posterior valve 25 slits. 

Girdle dark green, covered with convex scales, which in the 
middle of its breadth are larger and carinated. 

Length 46, breadth 26 mill. 

Marquesas Is. (Garrett.) 

The papillose lateral areas, smooth central areas and uniform dark 
olive-green color are the more striking features of this species. The 
large number of slits is also noteworthy. The specimen before me 
was presented to the Academy by the late Andrew Garrett, and it 
was labelled " C. marquesana;" but whether this name was given by 
Garrett or by Tryon I do not know. 

C. PERVIRIDIS Carpenter. 

Shell small, narrow, elevated, the jugum acute ; color an intense 
green. Entire surface very minutely scaly under a lens ; lateral 
areas and end valves radially lirate, the line obtuse, little con- 
spicuous, 4 or 5 on side-areas, 20-25 on end valves. Central areas 



CHITON. 171 

having about 12 little impressed, distant sulci, parallel to the dorsal 
ridge. Mucro anterior-subcentral, moderately projecting. Interior 
having 8-9 slits in end valves, 1 in median valves; teeth acute, 
deeply pectinated ; eaves short ; sinus wide, flat, toothed. Girdle 
furnished with large, solid, imbricating but striated scales. 
Length Hi, width 6i, alt. 3 mill. 

Tahiti (Pease.) 

Chiton (Lophyrus) perviridis CPU., P. Z. S. 1865, p. 511. Lophy- 
rus perviridis PEASE, Amer. Journ. Conch, vii, p. 194. 

A solitary specimen of this interesting species is very like C. vires- 
cens Eve. in general appearance ; but the mantle of that species is 
nearly smooth and the valves scarcely sculptured. This shell is of 
a uniform bright green. It has the aspect of Lepidopleurus [Lepid- 
ozona] ; but the insertion-plates though sharp, are deeply pectinated. 
It differs from most other Chitons in having the scales distinctly 
striated, as in (7. striatosquamosus. (Cpr.~) 

C. BURMANUS Carpenter, n. sp. 

Shell elevated, with acute dorsal ridge; olivaceous or red, having 
a white blotch on the tail valve behind the mucro. 

Whole surface of the valves finely quincuncially granulated ; 
central areas having about 20 sharp and distinct ribs on each side, 
parallel to the dorsal ridge, upon which they are finer and closer ; 
lateral areas having 3 to 5 rows of stout granules, some of the rows 
not reaching to the apex. End valves having 25 (or fewer) rows of 
stout granules. Mucro of the tail valve median, the slope behind it 
very concave. 

Interior having 8 slits in the anterior, 1 in the median, 11 in the 
posterior valve ; teeth sharp but distinctly pectinated ; eaves short. 

Girdle covered with rather roundish oval scales of large size. 

Length 19, breadth 10* mill.; divergence 96. 

Coast of Arakan, British fiurmah, under stones at low water. 

The British Museum contains four specimens, of which three are 
olivaceous, the other red. The above description is from Car- 
penter's MS. 

Species of Australia, New Zealand, etc. 

The species of these regions are mostly of moderate or small size, 
and generally the mucro is central and the scales microscopically 
striated. 



172 CHITON. 

C. QUOYI Deshayes. PI. 37, figs. 6, 7, 8. 

Shell oval, rather elevated, carinated, the side-slopes straight. 
Surface having a smooth and polished appearance but very finely 
striated. Color generally a very dark olive-green, but sometimes 
yellowish- brown marked with olive on the sides and ends, or clear 
yellow with rays of olive or brown. 

Lateral areas slightly raised, sculptured with numerous narrow, 
delicate and slightly crenulated radiating threads. Central areas 
covered with still finer longitudinal striae. End valves sculptured 
like the lateral areas, the two about equal in size; mucro of the 
rather raised tail valve a little in front of the middle. 

Interior sky-blue, marked under the beaks with olive-brown rays. 
Sinus rather square, finely denticulate. Anterior valve having 9- 
10, central 1, posterior 13-14 slits; teeth crenulated outside. 

Girdle covered with smooth convex imbricating scales, mostly 
light blue, but often having dark brown scales mingled with them. 

Length 37, breadth 22 mill. 

Auckland to Dunedin, New Zealand, in pools under stones, between 
tides. 

Chiton viridis Q. & G., Voy. Astrol. iii, p. 383, t. 74, f. 23-28 
(1834). Not Chiton extu* virtdis, intus candid us of Chemnitz, Con- 
chyl. Cab. viii, p. 277, t. 94, f. 794, 795 (1785), nor 07*. viridis 
Spengler, q. v. Chiton quoyi DESH. in Lam., Anim. s. Vert, vii, p. 
509 (183(5). REEVE, Conch. Icon., t. 13, f. 68 (1847). Chiton 
glaucus HUTTON, Man. N. Z. Moll., p. 112 (1880.) 

? Chiton glaucu* GRAY, Spicilegia Zoologica pt. i, p. 5 (1828). 
? Lophyrus glaucus ANGAS, P. Z. S. 1867, p. 222. 

This species differs from all other true Chitons of New Zealand in 
its finely sculptured, comparatively smooth surface, resembling in 
this respect the C. magnificu* of South America. It is a well known 
New 7 Zealand form, and has also been reported from Port Jackson, 
Australia, by Angas, under the name glancu*; but I have not been 
able to confirm this by the comparison of specimens from the latter 
locality, which may safely be omitted until authoritatively con- 
firmed. 

The locality of Gray's C. glaucus was unknown, he did not figure 
his specimen, which had lost its girdle, and he states that it was 
white inside, glaucus green outside. The identification of Quoy and 
Gaimard's well described and figured shells from New Zealand with 



CHITON. 173 

Gray's species is therefore highly hypothetical ; especially since no 
one seems to have seen Gray's type, and its generic characters are 
wholly unknown. I have never seen a "glaucus green" specimen 
of this species "white inside.;" they are always blue. The change 
of name made by Deshayes must be adopted on account of the 
earlier C. viridis of Spengler. 



C. PELLISSERPENTIS Quoy & Gaimard. PI. 37, figs. 14, 15, 16, 17, 

18. 

Shell oval', rather elevated, hardly carinated, the side-slopes some- 
what convex. Surface lusterless. Color a rather dull and dingy 
olive or olive-green marked with black along the ridge and on the 
sides of some valves. 

The lateral areas are moderately raised and sculptured with 3 or 
4 rows of distinct tubercles. Central areas having strong, irregular 
growth wrinkles, and fine longitudinal riblets. Anterior valve larger 
and much more elevated than the posterior, both being sculptured 
with numerous regular rows of distinct tubercles, the rows increasing 
by splitting. Posterior valve depressed, the low mucro in front 
of the middle. 

Inside blue, indistinctly blotched with olive-green. Sutural- 
plates rounded, the sinus broad and deep, smooth or hardly dentic- 
ulate. Anterior valve having 12, central valves 1, posterior valve 
12 slits ; teeth blunt, pectinated. Eaves broad. 

Girdle wide, alternately light and dark ; scales (pi. 37, fig. 17) 
rather large and wide, often showing a slight tendency to carination 
in the middle, microscopically striated. 

Length 30, breadth 23 mill. 

New Zealand. 

Chiton pelliserpentis Q. & G., Voy. de 1'Astrolabe, Zool. iii, Moll., 
p. 381, t. 74, f. 17-22 (1834). DESH., in Lam., An. s. Vert, vii, p. 
508 (1836). Chiton pellis-serpentis REEVE, Conch. Icon., t. 15, f. 
84. HUTTON, Cat. Mar. Moll. N. Z. 1873, p. 46; Man. K Z. Moll. 
1880, p. 111. HADDON, Challenger Polyplac., p. 22. 

This is one of the most abundant New Zealand Chitons. Its 
sculpture is frequently obscured or lost by erosion. C. sinclairi is 
closely allied, but it differs in color-pattern, in the polished central 
areas, whilst the surface of pellis-serpentis is lusterless, and in the 
sculpture of the central areas. The median valves of pellisserpentis 



174 CHITON. 

are rather strongly arched backward, and the broad sinus is remark- 
able for the absence or obsolescence of teeth. The interior, except 
just behind the sinus, is smooth ; the callus in each valve is heavy 
and smooth. Figures 14, 15, 17 are drawn from Auckland, N. Z. 
examples, furnished by Mr. G. W. Wright. 

C. SINCLAIR: Gray. PI. 36, figs. 1, 2, 3. 

Shell oval, rather elevated, the dorsal ridge rounded, side-slopes 
rather straight ; broivn-black, each valve irregularly and raggedly 
striped with whitish ; the head valve pale with dark rays. Some- 
times the white predominates. 

The lateral areas are raised and sculptured with three or four 
radiating grano*e rib*, often subobsolete. Central areas smooth in the 
middle except for a few growth-wrinkles, but having fine short longitu- 
dinal riblets at the tide* in front of the diagonal line. These riblets 
are sometimes almost obsolete. Head-valve sculptured at first with 
about 15-18 granose riblets, but as these have a tendency to split as 
the valve grows, the number in a grown specimen is usually 24-30. 
Tail-valve having a low, obtuse mucro, decidedly in front of the 
middle. 

Interior bluish. Sinus rather widej denticulate, the area behind 
it porous. Anterior valve having 11, central valves 1, posterior 
valve 14 slits; teeth obtuse, strongly crenulated. Eaves broad, 
spongy. 

Girdle (pi. 36, fig. 3) covered with large, convex scales, which 
are very finely, sharply striated. 

Length 28, breadth 18 mill. 

Length 17, breadth 11 mill. 

New Zealand (Sinclair, Hutton, Wright.) 

Chiton sinclairi GRAY, in Dieftenbach's Travels in IS". Z. ii, p. 263 
(1843). HUTTON, Trans. K Z. Inst. iv, p. 177; Man. N. Z. Moll, 
p. Ill (1880). SMITH, Zool. 'Erebus' and 'Terror,' p. 4, t. 1, f. 
17. REEVE, Conch. Icon., t. 22, f. 143. 

The smooth, polished central areas, grooved only along the 
diagonal line at the sides, and the granose-ribbed lateral areas and 
end valves are characteristic, and remind one of the West Indian (7. 
viridi*. The black-and-white coloring also is rather constant. The 
sculpture of the side-areas varies greatly in strength. This species 
has been reported from Tasmania, but on doubtful authority. 



CHITON. 175 

C. DISCOLOR Souverbie. PI. 60, figs. 3, 4. 

Shell ovate-oblong, the back carinated, urabones subrostrate ; 
gray-green or yellowish-red, with longitudinal more or less pallid 
and more or less numerous spots. End valves ornamented with 
about 20 radiating series of quite strong tubercles (some of the rays 
being short, intercalated between the others) ; lateral areas having 
three series of tubercles and a fourth intercalated shorter series. 
Central areas sculptured on each side of the smooth dorsal carina 
with impressed, subobliquely longitudinal grooves. Girdle leathery 
and scaly. Dimensions, exclusive of the girdle, which is very incom- 
plete in our two examples (probably immature) ; length 19, breadth 
9* mill. (Sow.) 

Art Island, N. Caledonian Archipelago (Mus. Bordeaux.) 

Chiton discolor Souv., Journ. de Conch. 1866, p. 252, t. 9, f. 1, la. 
C. miniaceus CPU., MS., Mus. Cuming. 

Carpenter's unpublished species seems to be the same as this, 
although until the types of discolor are examined, we cannot be 
certain. Carpenter's description here follows : 

0. miniaceus Cpr. Shell elevated, oval, the jugum acute; vivid 
vermilion, the margin tessellated with paler. Mucro median, little 
elevated. Entire surface minutely punctate ; central areas having 
about 25 subparallel grooves on each side, obsolete on the dorsal 
ridge; lateral areas elevated, bearing 3-4 strong, radiating line, 
which are strongly nodose. End valves having about 20 lirse. 
Interior : anterior valve having 8, central 1, posterior 10 slits ; teeth 
deeply pectinated ; sinus wide, minutely denticulated. Girdle 
covered with normal imbricating scales. 

Length 27*, breadth 20 mill.; divergence 100. 

New Caledonia. 

Mus. Cum., no. 59. Easily recognized by the strong sculpture 
and brilliant vermilion color. ( Cpr.) 

C. MURICATUS A. Adams. PI. 37, figs. 12, 13. 

Shell oblong, much elevated in the middle; black-brown and 
white variegated. End valves and lateral areas radiately ribbed, 
the ribs ornamented with elevated acute grains ; tail valve umbon- 
ated in the middle. Central areas longitudinally deeply lirate, the 
umbones smooth, elevated, somewhat produced. Girdle scaly, the 
scales mucronated, imbricating, with suberect apices. (Ad.) 



176 CHITON. 

This species is remarkable for the somewhat triangular imbricate 
scales of the ligament ending in sharp pointed mucrones; the liga- 
ment is tessellated with pale fuscous and dark brown ; the ribs on 
the lateral areas are four, muricated with sharp granules. (Ad.) 

Sydney, JV. S. Wales, Australia, under stones at low water. 
(Strange.) 

Chiton murieatus A. AD., P. Z. S. 1852, p. 91, t. 16, f. Q.Lophy- 
rus murieatus ANGAS, P. Z. S. 1865, p. 186; 1867, p. 222. Chiton 
limans and C. earnosu* CPU., MSS. 

Varies in color from dull green to orange and buff. 

Carpenter examined Adam's type of this species, and ascertained 
it to be identical with his own unpublished C. limans ; the descrip- 
tion of which here follows : 

Shell oval, elevated, the jugum acute; mucro median, subprom- 
inent ; olivaceous, maculated with paler ; entire surface minutely 
punctate ; central areas having about 14 grooves on each side, 
obsolete in the middle ; lateral areas having two riblets, sometimes 
bifurcating or with another intercalated, furnished with strong acute 
tubercles, interstices smooth ; end valves with 10-20 such riblets. 
Interior : anterior valve having 8, central 1, posterior valve 9 slits ; 
teeth normal ; sinus moderate, with about 15 denticles. Girdle 
furnished with large and small wide, distinctly striated, elevated, 
acutely pointed scales. 

Length 231, breadth 12J, divergence 100. 

The points of the striated scales project, as in Isch. australis, so as 
to give the girdle a rasp-like appearance. 

Var. aurantius Cpr. Shell smaller, pale orange colored, dotted 
with more intense; posterior valve with 10 slits. 

Length 17*, breadth 10 mill.; divergence 100. 

Like the preceding in all important characters, but differing 
remarkably in color and pattern. 

A form in which the sculpture of the side areas is less developed 
received the name carnosus Cpr. The original description in Carp- 
enter's MS. before me, indicates the following as the most important 
characters of carnosus: Central areas having about 18 subparallel 
sulci on each side, more prominent toward the margin, obsolete 
toward the jugum ; lateral areas and end valves having irregularly 
(at the sutures strongly) nodose wrinkles, 4 in number on the side 
areas, 22 on the anterior, 14 on the posterior valve, sometimes 



CHITON. 177 

bifurcating. Interior: anterior valve with 8, central 1, posterior 
valves 10 slits. Length 30, breadth 15 mill. ; divergence 105. 

Sydney. 

Easily recognized by the fleshy color and small, beaked, mantle- 
scales ; the side sculpture of limans (with which this species agrees 
in the scales) is. very different in pattern. (CprJ) 

C. CANALICULATUS Quoy & Gaimard. PI. 36, figs. 4, 5, 6. 

Shell small, oblong, strongly elevated, carinated, the side-slopes 
straight, steep. End valves and lateral areas pink, central areas 
yellowish, dorsal ridge pink with an olive-green stripe on each side. 
Sometimes olivaceous, or olive and rose. 

The lateral areas are strongly raised and sculptured with 4 or 5 
radiating ribs which are regularly cut into low beads, and which 
often split toward the lower margin. Central areas having a narrow 
smooth space upon the ridge, sculptured on each side with about 16 
strong longitudinal ribs, separated by deep intervals ; posterior mar- 
gins of valves crenulated. Anterior valve having about 22 granose 
radiating ribs ; posterior valve having about ] 6 granose radiating 
ribs, the umbo slightly in front of the middle, the slope behind it a 
little concave. Interior whitish; sinus rather deep and narrow. 

Girdle covered with compactly imbricating, convex, shining obso- 
letely striated small scales (pi. 36, fig. 6.) 

Length 14, breadth 11 mill. 

Taxman Bay's (Q. & G.), and Stewart Island (Hutton), New Zea- 
land. 

Chiton canaliculatus Q. & G., Voy. Astrol. Zool. iii, p. 394, atlas, 
t. 75, f. 37-42 (1834). Chiton stangeri REEVE, Conch. Icon., t. 22, 
f. 150 (1847). Chiton inscidptus A. ADAMS, P. Z. S. 1852, p. 91, t. 
16, f. 4. c/. HUTTON, Man. N. Z. Moll. 1880, p. Ill, 112. 

Allied, in its acutely elevated contour, to G.jugosus,l>ut differing 
markedly in the granose-ribbed lateral areas. It is usually very 
brilliantly colored with rose-pink and buff, but olivaceous forms also 
occur. The latter may be distinguished from C. sinclairi by the 
differently sculptured central areas. Professor Hutton (in Hit.) 
suggests to me the identity of stangeri and inscidptus. The latter 
seems to agree altogether with Quoy's canaliculatus. 

The girdle-scales (pi. 36, fig. 6) are smaller than in C. jugosus, 
and they are much less distinctly striated than in 0. sinclairi or (7. 
pellisserpentis. 
12 



178 CHITON. 

C. JUGOSUS Gould. PL 36, figs. 91, 92, 93, 94, 95. 

Shell oblong, much elevated, carinated, the side-slopes straight 
and steep. Central areas sulcate at the sides, smooth in the middle, 
lateral areas smooth. Color light green, the ribs of the central areas 
orange t lateral areas with fine alternating concentric lines of yellow 
and green. 

The lateral areas are strongly raised and smooth, painted with 
close lines parallel to the dorsal keel. Central areas having a smooth 
triangle in the middle, the sides sculptured with 11-14 strong 
rounded orange colored ribs, separated by deep, blue intervals of 
the same width. Head valve smooth, concentrically lineated ; tail 
valve concentrically lined at the sides, having a broad triangular 
buff or orange ray behind, extending across the girdle ; apex project- 
ing slightly behind the middle, posterior slope strongly concave. 

Interior blue-white, the sutural plates white. Sinus narrow and 
angular, denticulate. Anterior valve having 8, central valves 1, 
posterior valve 12 slits; teeth blunt, pectinated. Eaves spongy. 

Girdle (fig. 95) buff and greenish, irregularly alternating, covered 
with compactly imbricating, polished convex scales, which are obso- 
letely striated. Length 35, breadth 20 mill. 

Port Jackson, Sydney, N. S. Wales, Australia. 

Chiton jugosus GOULD, Proc. Bost Soc. N. H. ii, p. 142 (1846) ; 
Expl. Exped. xii, Moll. & Sh:, p. 317, atlas, t. 28, f. 430 (1852). 
SMITH, Zool. Coll. H. M. S. 'Alert/ p. 78 (1884). HADDON, Chall. 
Polyplac., p. 22 (ISS^.Lophyrus jugosus GLD., Otia, p. 3, 242 
(1862). ANGAS, P. Z. S. Lond. 1867, p. 222. Chiton concentricus 
REEVE, Conch. Icon., t. 16, f. 95 (1847). Lophyrus concentricus 
ANGAS, P. Z. S. 1867, p. 221. 

The peculiar and beautiful coloration separates this species from 
its allies. The second valve is frequently blood red, or blotched at 
the sides with dark sepia ; and occasionally all or many of the valves 
have blotches of buff interrupting the longitudinal color-lines. The 
light triangle radiating backward from the umbo of the tail valve is 
present in every specimen I have seen. The tail valve, indeed, 
reminds one somewhat of that of an irregular Chiton. 

The painting of the lateral areas gives the impression that they 
are longitudinally ribbed, as Reeve and Angas have described ; but 
even in Reeve's types these areas are quite smooth, as they are in all 
the specimens I have seen. 



CHITON. 179 

This species has been reported from New Zealand, but probably 
incorrectly. 

C. PULVINATUS Carpenter, n. sp. 

Shell small, oval, subelevated, with acute jugum ; mucro median ; 
apices of the valves prominent; olivaceous and brown variously 
clouded and irregularly painted. Entire surface minutely punct- 
ulated ; central areas having about .16 deep sulci on each side; lateral 
areas well defined, nearly smooth, as are the end valves also. 

Interior: anterior valve having 10, central valves 1, posterior 
valve 9 slits ; teeth acute, deeply serrated ; sinus moderate, dentic- 
ulate. 

Girdle covered with large smooth scales. 

Length 9, width 4 mill.; divergence 110. (Q?r.) 

New Ireland (Mus. Cuming, no. 78.) 

Distinguished from luzonicus by the smooth scales and side-areas, 
which display a velvety appearance under the microscope. 



C. CEREUS Reeve. PI. 36, figs. 96, 97. 

Shell oblong-ovate, angularly raised in the middle ; valves rudely 
impressly striated throughout, umbonal eminence smooth. Dull 
green ; ligament granosely coriaceous. 

The color is a uniform dull green except along the rubbed 
umbonal summit, where it has a copperas hue. (Eve.} 

New Zealand (Earl.) 

Chiton cereus REEVE, Conch. Icon., t. 7, f. 36 (1847). Chiton 
(Leptochitor,) cereus SMITH, Zool. Voy. ' Erebus ' and ' Terror' Moll, 
p. 4, t. 1, f. 9. Ch. siculoides CPU., MS. 

This species has been referred by Smith to C. sieulus Gray. The 
locality requires confirmation, as it rests solely upon Cumingian 
specimens. Hutton (Man. N. Z. Moll.) reprints Reeve's diagnosis 
without comment. 

Carpenter's notes on Reeve's type are as follows : Central areas 
having about 20 furrows on each side, not deep, continuing until 
they are rubbed off in the middle ; lateral areas having 4-8 divari- 
cating riblets, much worn, broken up by the concentric rugse of 
growth ; crenate at the sutures ; end valves with about 30 riblets. 
Mucro in front of the middle, posterior slope concave. Interior 



180 CHITON. 

bluish, sinus with 5-13 denticles, deep, narrow ; girdle scales stout, 
roundish. Length 39, breadth 23, divergence 94. 

One specimen, New Zealand, in Mus. Cuming. 

Species of the Mediterranean and African Seas. 

The species are allied to those of Australia and New Zealand, the 
mucro in many of them being central, and the scales striated. 

C. OLIVACEUS Spengler. PI. 35, figs. 87, 88, 89, 90, 91, 92. 

Shell oblong, elevated, carinated, the side-slopes straight. Surface 
ribbed and microscopically punctulate. Color very variable ; either 
black, brown, scarlet or olive-green, unicolored or clouded or 
mottled. 

Lateral areas raised, sculptured with 4-6 flat low radiating ribs, 
the posterior rib widest, separated by narrow shallow grooves. 
Central areas having a smooth triangle on the ridge of each valve, the 
sides (pleura) bearing strong longitudinal ribs, which become 
stronger toward the outer margin. End valves having low radiating 
riblets. Tail valve having a conspicuous central apex, the posterior 
slope somewhat concave. 

Interior light bluish, marked with brown rays in each valve. 
Sutural plates rounded ; sinus deep, square, denticulate. Anterior 
valve having 7-8 ; central valves 1, posterior valve 8-10 slits; 
teeth blunt, pectinated. Eaves spongy. Girdle, wide, banded with 
alternate light and dark, compactly covered with minute smooth, 
convex scales. Length 36, breadth 20 mill., often less. 

Mediterranean and Adriatic Seas ; Cape Verde Is. 

Chiton squamosus POLI, Test. utr. Sicil. i, t. 3, f. 21, 22 (1791) 
and of PAYRAUDEAU, COSTA, and PHIL., Enum. Moll. Sicil. i, p. 
106, t. 7, f. 3 ; and of Granger, Moll. France, p. 170, t. 12, f. 16 
(1885). Not of Linne. Chiton olivaceus SPENGLER, Skrivter af 
Naturhistorie-Selskabet, iv, p. 75, t. 6, f. Sa-c (1797). Jeffreys, Kep. 
Brit. Asso. Adv. Sci. 1873, p. 113. MONTEROSATO, Enum. e Sinon. 
p. 17. BUQ. DAUTZ. et DOLLF., Moll. Mar. du Rouss. i. p. 489, t. 
61, f. 4-6, t. 62, f. 4. LOCARD, Coq. Mar. des Cotes de Fr., p. 232 
(1892). Ch. sukatus Risso, Hist. Eur. Merid iv, p. 268. TIBERI, 
Bull, della Soc. Malac. Ital. iii, p. 145. Chiton siculus GRAY, 
Spicil. Zool., p. 5; PHIL., Enum. Moll. Sicil. ii, p. 82. WEIN- 
KAUFF, Conchyl. des Mittelrn. ii, p. 408. REEVE. Conch. Icon., t. 
2, f. 5 ; t. 16, f. 97 (lowest fig.) ; t. 19, f. \1l.-Glymnoplax sicnlus 



CHITON. 181 

ROCHEBR., Nouv. Arch, du Mus. 1881, p. 242. Chiton polii DESK. 
(not Phil.)., Exped. Sci. de Moree, iii, p. 132 ; Lamk. edit. Dh., vii, 
p. 504. C. squammulosus DOLLFUS, Catal. Palavas, p. 3. 

Doubtful synonyms : Lophyrus siculus forma africana ROCHE- 
BRUNE Journ. de Conchyl. (3) xxi, p. 42 (1881). Chiton striatus 
CHIEREGHINI MS. BRUSINA Ipsa Chier. Conchyl. p. 44 (1870). 
Ch. estuarii CHIER., MS. BRUS., /. c., p. 45. 

This common Mediterranean species is very variable in color, as 
the figures show, but quite constant in sculpture. The valves are 
generally very much elevated, like a gothic roof. The prominence 
of the mucro or beak of the tail-valve, and its central position, are 
characters showing the strong bond of affinity between olivaceus and 
the Australasian species, and sundering it from the somewhat 
similarly sculptured West Indian forms. Issel and the authors of 
Mollusques Marins du 'Roussillon classify the color-forms of this 
species into two groups : (1) those which are variously marbled and 
spotted, and (2) those which are unicolored, forming the 

Color-var. unicolor Issel. Entirely white, tawny or red. It is 
likely that C. rubellus of Nardo was founded upon an individual of 
the last color. 

I regard it as probable that the Lepidopleurus corallinus of Risso 
(Hist. Nat. PEur. Merid. iv, p. 268) was based upon a red example 
of C. olivaceus. Monterosato has suggested that corallinus is the 
same as rubicundus Costa,-\-scytodesma Sc&c.,-{-freelandi Fbs.-(- 
pulcliellus Phi\.-\-philippii Issel (see Journ. de Conch. 1878, p. 146). 
This identification seems to me to be quite inadmissible. 

Rochebrune describes a ' forma ' Africana as follows : Allied to 
L. siculus, but differs in having the valves obtusely carinated, the 
sulci of the central areas very delicate, straight. Length 26 mill. 
Promontory of Cape Verde, and Table Bay, Cape of Good Hope. 

The reference of this form to the present species is doubtful. 

C. AFFINIS Issel. PI. 35, fig. 93 (enlarged.) 

Shell oblong, subcarinated, smooth, painted with various colors ; 
end valves radiately ribbed, the front valve having about 21 ribs, 
concentrically striated ; the other valves having longitudinal 
arcuate grooves ; lateral areas narrow, triangular, transversely tri- 
sulcate. Girdle minutely scaly. 

Length 18, breadth 11, alt. 6 mill. (Issel.) 

. Gulf of Suez. 



182 CHITON. 

SAVIGNY, Descript. de 1'Egypte, Gasterop., t. 3, f. 9. Chiton 
affinis ISSEL, Malac. Mar Rosso, p. 234 (1869). C. siculus Gray, 
COOKE, Ann. Mag. N. H. 1885, p. 275. E. A. SMITH, Proc. Zool. 
Soc. Lond. 1891, p. 392. 

I have not seen this species, which is considered by Cooke and 
Smith to be synonymous with the common Mediterranean C. siculus 
of Gray (otivaceus Spengl.). Smith says that it " may be regarded 
as a strongly marked form of the Mediterranean species. There is 
also a species found in New Zealand, C. siculoides Cpr., M8S.= C. 
cereus Reeve, which is also inseparable." As I do not know that 
Mr. Smith's opinion is founded upon a study of the inside as well as 
the external characters, I prefer to retain C. affinis as a distinct 
species for the present, although it is certainly closely allied to C. 
olivaceus. Issel gives both figs. 8 and 9 of Savigny's plate as illus- 
trations of his species, but his description applies only to figs. 9. 
Savigny's figs. 8 represents, in all probability Callistochiton adenensis 
Smith. 

C. RUBICUNDUS Costa. PI. 45, figs. 73, 74, 75. 

Shell similar in form and color to Trachydermon ruber, but much 
smaller ; subelongate, much elevated, the valves beaked ; dorsal 
ridge very acute ; mucro median, elevated. Entire surface micro- 
scopically granulose, the central areas having spaced, longitudinal 
parallel sulci, 6 to 9 on each side ; lateral areas subelevated, smooth. 

Inside having 8-10 slits in the anterior valve, 1 in the central 
valves, 9 in posterior valve ; teeth acute, but all distinctly serrated ; 
eaves moderate; sinus moderate; sutural-plates joined by a small 
serrated lamina. 

Girdle regularly imbricated with large, solid, smooth scales. 

Length 8?, breadth 5 mill. ; divergence 80. 

Length 6, breadth 2? mill. 

Naples (Philippi) ; Dalmatia (Mus. M'Gill Coll. and Acad. Nat. 
Sci., Phila.) 

Chiton rubicundus O. G. COSTA, Catalogo sistematico e ragionato 
de' Testacei della due Sicilie, p. i, iii, 1. 1, f. 2 (Naples, 1829); Fauna 
di Napoli, Anim. Molli, Chiton, p. 8. Chiton pulchellus PHILIPPI, 
Enum. Moll. Sicil. ii, p. 83, t. 19, f. 14. Chiton rubellm CPR., MS. 
olirn, and C. ? corallinus CPR., MS. 

Doubtful synonyms : Ch. freelavdi FORBES, Rep. Aeg. Invert., 
in Rep. 13th meeting Brit. Asso. Adv. Sci., for 1843, p. 188 (1844). 
C. scytoderma SCACCHI, C. philippii ISSEL. 



CHITON. 183 

The prominent features of this little species are its ruddy color, 
great elevation, like a gothic roof, and the sculpture. 

This species is not identical with the Lepidopleurus corallinus of 
Risso, as Monterosato has said. It is impossible for me to believe 
that Risso would have used the words " avec les elevations laterales 
bisulquees" if he had been describing C. rubicundus. The identi- 
fication of the learned authority on Mediterranean shells was not 
founded upon an examination of Risso's type. 

C, HAMYI Rochebrune. PI. 35, figs. 85, 86. 

Shell ovate-elongate, carinated, green, painted longitudinally und 
regularly with alternating lines of ivhite, blue and buff. Head valve 
lateral areas and posterior areas of the tail valve sculptured with strong 
concentric ridges, which are irregular and as if imbricated ; central 
areas having 7 strong, wide, obliquely curved ribs, the middle smooth. 
Girdle scaly, scales rounded, very shining. 

Length 23, width 12 mill. (Eochebr.~) 

Strait of St. Lucie, Cape Verde Is. 

Gymnoplax hamyi ROCHEBR., Bull. Soc. Philom., Oct., 1881 ; 
Nouv. Arch, du Mus. (2) iv, p. 242, t. 17, f. 13o, c (1881.) 

Allied to C. concentricus Reeve, but distinguished by the imbrica- 
tion and irregularity of the concentric strise of the end valves and 
lateral areas, by the width and small number of grooves on the sides 
of the central areas, and the absence of a mucro on the tail valve. 
(Rochebr.) 

The references to the figures of this species and C. insularis are 
transposed in Rochebrune's publication. 

C. INSULARIS Rochebrune. PI. 35, figs. 83, 84. 

Shell ovate, elongate, subcarinated, the carina obtuse ; olivaceous, 
sparsely spotted with white; anterior valve and posterior part of the 
tail valve sculptured with radiating, interrupted, feebly granose ribs; 
median valves having the central areas smooth in the middle, sulcated 
at the sides, the sulci unequal, lanceolate, pointed at the ends, con- 
centrically arranged ; lateral areas having branching radiating ribs. 
Girdle olive marked with white spots, scaly, the scales minute. 
(Eochebr.') Length 27, breadth 15 mill. 

Strait of St. Vincent, Cape Verde Is. 

Gymnoplax insularis ROCHEBR., Nouv. Archiv du Mus. (2) iv, p- 
243, t. 17, f. 12a, b. (1881.) 

Compare Ch. olivaceus Spengl. 



184 CHITON. 

C. LYRATUS Sowerby. PL 31, figs. 35, 36. 

Shell oval, smooth ; back subaDgulated ; lateral areas subelevated, 
smooth ; central areas longitudinally lirate at the sides ; girdle broad, 
minutely scaly. Length 37, breadth 15 mill. (Sowb.*) 

This shell is so thin as to be nearly transparent ; it is smooth, 
rather angulated in the center, the lateral areas smooth, slightly 
elevated, the central areas marked with faint longitudinal ribs. The 
margin is covered with regular, minute scales. The general color 
is drab, variegated with brownish concentric lines at the sides and 
reddish-brown dorsal bands on some of the valves. (Sowb.) 

Habitat unknown. 

Chiton lyratiis SOWB. in Charlesworth's Mag. of Nat. Hist. 1840, 
p. 293 ; Conchol. Illustr., f. 126. KEEVE, Conch. Icon... f. 110. 

This shell should be compared with c-anarieim* Orb. and dis- 
similis Reeve. 

Carpenter has described a C. semilcevis in MS. from Cumingian 
specimens of unknown locality. It will probably prove to be a form 
of the above species. 

Reeve reports C. lyratus from Prince Island, West Africa, under 
stones. 

C. DISSIMILIS Reeve. PI. 37, fig. 11. 

Shell oblong-ovate; terminal valves and lateral areas longitu- 
dinally grooved, smooth in the middle ; variegated with reddish- 
brown ; ligament granosely coriaceous, tessellated. Approximating 
in some measure to the C. tulipa. (Reeve?) 

Habitat unknown. 

C. dwsimifa REEVE, Conch. Icon., t. 25, f. 170 (May, 1847.) 

Reeves description does not correspond very well with his figure; 
and the species will probably prove to be the same as C. canariensis 
Orb. 

Carpenter notes that in Reeve's type specimen the whole surface 
is conspicuously quincuncially granulated. The anterior valve has 
9, central 1, posterior valve 13 slits; teeth sharply pectinated. It 
measures, length 18, breadth 9 mill. ; divergence 90. 

C. CANARIENSIS d'Orbiguy. PI. 34, figs. 77, 78, 79. 

Shell oblong ; carina smooth, central areas of the valves longitu- 
dinally sulcated, lateral areas smooth ; ends smooth ; margin 
granulate-scaly. Length 24, width 12 mill. (Orb.) 



CHITON. 185 

The shell is oblong, a little carinated ; the intermediate valves are 
smooth at the carina, marked ou each side with strong ribs separated 
by deep grooves ; the lateral areas are entirely smooth, as well as the 
end valves. The girdle is wide, extensible, covered with little 
oblong, smooth and polished scales, largest in the middle of its 
width. 

The colors are very variable ; sometimes marbled with black and 
brown spots on a white ground, sometimes with some valves quite 
black or green, the others spotted. The girdle is radiated with 
black, gray and white. (Or 6.) 

Canary Is. (Webb and Berthelot.) 

C. cannrieims ORB., in Webb & Berth., Hist. Nat. des lies Canaries, 
Moll., p. 99, t. 7, f. 16-19. Chiton (Lop hunts) canariensis, SHUTTLW., 
Bern. Mittheil. 1853, p. 81. 

Allied to C. olivaceu*, but differs in having the lateral areas and 
end valves smooth. The interior, according to Shuttleworth, is 
green, with spots of rose and purple. This species should be com- 
pared with C. lyratus Sowb. 

C. TULIPA Quoy & Gaimard. PL 31, figs. 43-49. 

Shell oval-oblong, elevated, acutely carinated, the side-slopes 
nearly straight. Surface smooth and polished throughout. Ground- 
color buff or whitish, suffused and closely mottled all over with red- 
dish-chestnut, fawn, or purple-brown ; usually longitudinally streaked 
on the central areas, zigzagged or tessellated on the end valves, and 
articulated on the diagonal lines with the darker color. Sometimes 
parts of some valves, or several whole valves are of a uniform dark 
brown color (figs. 43, 45.) 

The central areas are smooth except for slight growth-lines and a 
microscopic granulation which covers the whole surface. Lateral 
urea* well raised, flat, rarely with slight radii, smooth. In the 
excavation at the diagonal line a lens shows a few very short longitu- 
dinal grooves, in some specimens. Tail valve elevated, with central 
umbo. 

Interior very light blue-green, each valve rayed with brown at 
the beaks. Anterior valves having 8, central valves 1, posterior 
valves 12 slits; teeth pectinated. Eaves short, spongy, grooved 
along the teeth. Sinus narrow, denticulate. 




186 CHITON. 

Girdle solid, closely covered with smooth, convex scales. 
Length 43, breadth 25 mill. ; divergence 105. 
Length 38, breadth 27 mill.; divergence 100. 
Length 33, breadth 24 mill.; divergence 112. 

Cape of Good Hope. 

Chiton tulipa QUOY & GAIMARD, Voy. de 1'Astrol. Zool., iii, p. 
389, t. 74, f. 35-36 (1834). KRAUSS, Die Siidafric. Moll., p. 37. 
C. cymbiola SOWERBY, Charlesworth's Mag. of Nat. Hist. 1840, p. 
292 ; Conch. Illustr., f. 45, and var., f. 85, 86. REEVE, Conch. Icon., 
t. 3, f. 18. 

? C. politus SPENGLER, Skrivter af Naturhist.-Selskabet, iv, p. 
89, 1797. 

A smooth, polished species, excessively variable in color and 
pattern. The short traces of grooves at the diagonal line are rarely 
visible without a lens, and are completely obsolete in many spec- 
imens. The smooth surface and unusual coloring are the more 
striking characters of the species ; but the strongly raised lateral 
areas and the central mucro at once separate it from C. Icevigatus, 
marmoratus, etc. 

C. RUSTICUS Deshayes. PL 31, figs. 32, 33, 34. 

Shell ovate-oblong, depressed, the jugum rounded ; very dark 
green, much paler beneath. 

Entire surface quincuncially granulose. Central areas with no 
other sculpture, but at the diagonal line there are on each side 10-15 
very short but deep grooves. Lateral areas swollen, and having a few 
indistinct, obsolete swelling ribs, or rather, obsolete knobs irregularly 
coalescing in to* indistinct ribs; blotched with paler. End valves 
similarly sculptured and blotched, beak of the tail valve in front of 
the middle, the slope behind it a trifle concave. 

Interior: anterior valve having 9, central valves 1, posterior 
valve 12 slits; teeth pectinated ; eaves short; sinus moderate, with 
about 13 teeth. 

Girdle dark olive, like the valves ; covered with very large stout 
scales. 

Length 24, breadth 15, alt. 6 mill. 

Length 20, breadth 13 mill.; divergence 115. 

I ii-ii ii ion and 



CHITON. 187 

C. ntstieiis DH., Moll. Reun., p. 39, t. 6, f. 1-3. CPR., MS. ii, p. 
25. C. (Lepulopleunis) rusticus MTS. in Mobius' Reisenach Mauri- 
tius, p. 300. 

This species has considerable resemblance to C. nigrovirens, but 
the lateral areas and end valves are less strongly sculptured and the 
longitudinal riblets are lacking on the central areas except at the 
diagonal lines. The above description is from Carpenter's MS. 

C. ANGUSTICOSTATUS Quoy & Gaimard. PL 31, figs. 37, 38. 

Shell ovate, wide, little elevated, depressed behind by the prom- 
inence of the anterior valve. The third to the seventh valves are 
excessively narrow, arcuated behind, with a little median projection, 
which contributes to form a dorsal carina. The last valve is the 
largest of all, nearly orbicular ; the second valve is next in size, the 
intermediate valves being about equal. Sutural plates narrow, 
separated by a wide, flat, sinus ; insertion-plates denticulate. The 
end valves have striated teeth. The entire interior is a pretty green ; 
and this we suppose to be the color of the outside, but it is eroded. 
We think it is striated like our C. viridis. The girdle is scaly, the 
scales oval. Length 22, width 16, alt. 8 mill. 

Isle of France. 

C. angusticostatus Q. & G., Voy. Astrol. iii, p. 398, t. 73, f. 4, 4'. 

The entire substance of Quoy's description is rather freely trans- 
lated in the above paragraph. It is very likely that this is merely a 
greatly worn specimen of C. pellisserpentls Q. & G. 

C. NIGROVIRENS Blainville. PI. 31, figs. 41, 42 (enlarged.) 

Shell ovate, moderately elevated, the dorsal ridge obtuse ; black- 
ish. Mucro in front of the middle, little raised, the slope behind it 
straight. 

Valves obtusely beaked ; entire surface minutely quincuncially 
granulated; jugal area smooth, often eroded; central areas having 
about 30 delicate lirulse on each side, parallel to the dorsal ridge, 
sometimes eroded ; lateral areas moderately raised, having 6 to 8 
delicate granulose riblets, the intervals flat. 

Interior: anterior valve having 12, central valves 1, posterior 
valve 14 slits ; teeth short, obtuse, coarsely pectinated ; eaves 
small; sinus wide, flat, 12-toothed. 

Girdle covered with solid, smooth, large and rounded imbricating 
scales. Length 17, breadth 10 mill.; divergence 117. 

Cape of Good Hope. 



188 CHITON-SCLEROCHITON. 

Chiton nli/i-ortrcn* BLAINVILLE Diet. Sci. Nat. xxxvi, p. 538 
(1825). HADDON, Challenger, Polyplac.,p. 22. C. copen^ GRAY, 
Spicil. Zool., p. 5 (1828). HANLEY, in Wood, Index Test. Suppl. 
t. 1, f. 11. REEVE, Conch. Icon., t. 22, f. 151. KRAUSS, Die 
Siidafric Moll., p. 37. 

C. TENUISTRIATUS Sowerby. PI. 38, figs. 27, 28. 

Shell oval, cariuated, the back elevated ; valves all over very 
finely radially striated ; girdle scaly. 

Length 25, width 15 mill. (Smvb.) 

A neat little shell of a dark olive-green color, oval, elevated, 
nearly smooth in appearance, but finely striated ; margin lighter 
green than the rest of the shell ; inside bluish-green. (Sowb.) 

Habitat -unknown (Mus. Stainforth.) 

C. temiistnatus Sows., in Mag. Nat. Hist. 1840, p. 291 ; Conch. 
Illustr., f. 135, 135. 

This is apparently a typical Chiton, closely allied to qitoyi or 
nigrovirens, but it seems to be more elevated than either. 

C. MAURITIANUS Quoy & Gaimard. PL 31, figs. 39, 40. 

Shell small, oval, elongated, the valves elevated, carinated, trans- 
versely finely striated and having lateral areas over which the striae 
pass. It is a very dark green, lighter at the ridge, and at the edge 
of the girdle, which is covered with fine, close, rounded scales, and 
marked with 18 brown bands. Branchial leaflets about 38 on each 
side. Length 18, breadth 10, alt. 6 mill. 

Mauritius. 

C. manrltnnius Q. & G., Voy. Astrol. iii, p. 397, t. 73, f. J-3. 
Lepidopleitrus mauritianus MARTENS, in Mobius' Reise nach 
Mauritius, p. 300. 

Known only by the original description, which is far from being 
satisfactory. The interior has not been described. It is a more 
carinated species than C. quoyi, and the striation is in a different 
direction ; the girdle also being banded with brown. 

^ Section SCLEROCHITON Carpenter, 1892. 

Scleroc.hiton CPR., MS., in Ball, Proc. U. S. Nat. Mus. 1881, p. 
284, 287, 289 (no type mentioned.) 

Teeth of the tail valve turned forward, blunt and pectinated ; 
sinus smooth, not denticulate ; scales of girdle solid, striated, 
separated. 



CHITON-RADSIA. 189 

This section or subgenus represents a further development of the 
Acanthopleuroid characters which some Australasian species of the 
restricted genus Chiton assume. In Ch. pellisserpentis, for example, 
the mucro is median, the posterior teeth tend forward somewhat, the 
sinus is smooth or only very obsoletely denticulate, and the girdle- 
scales are striated and rather separated. In Selerochiton the mucro 
is slightly more posterior, the teeth slightly more tilted forward ; 
the sinus is smooth, and the girdle scales still more separated. Ch. 
pellisserpentis could be placed almost as well in Scleroehiton as in 
Chiton s. s. ; the necessity of reducing Selerochiton to the rank of a 
section under Chiton will therefore be apparent. The girdle-scales 
bear a certain resemblance to those of Enoplochiton, but this is a 
purely accidental similarity, dependent upon their separation on the 
surface of the girdle. 

C. MILES Carpenter, n. sp. PI. 46, figs. 1, 2, 3, 4, 5. 

Shell solid, rugose, oval, depressed, generally eroded; dorsal 
ridge rounded, hardly defined ; mucro behind the middle, nearly 
flat; apices of the valves prominent, obtuse. Ashen, spotted with 
black-brown. Central areas transversely pretty regularly rugulose, 
the wrinkles appressed ; lateral areas hardly elevated, moderately 
well defined, conspicuously rugose, rugae subradiating, granose ; the 
end valves similarly sculptured. 

Interior having the anterior valve with about 11, central 1, pos- 
terior valve obscurely 9-11, slits. Teeth of posterior valves directed 
forward, strongly callosed inaide above the slits, sulcate outside ; 
the rest of the valves having the teeth sulcate outside and pect- 
inated at the margins. Eaves moderate, solid, deeply grooved. 
Sinus deep, wide, wavy, smooth ; sutural laminse united. 

Girdle (pi. 46, fig. 1.) maculated, ornamented with large, solid, 
more or less separated scales which are striated outside ; no hairs. 
(Cpr.}. Length 30, breadth 17 J mill. ; divergence 130. 

Torres Straits (Mus. Cuming, no. 42.) 

A variety is described as being a little narrower, and blackish, 
hardly maculated. 

Section KADSIA Gray. 

Rad&ia GRAY, P. Z. S. 1847, p. 126. Type Ch, barnesii. 
Girdle and shell like Chiton, except that the insertion-plates of 
the intermediate valves have two or several slits. 



190 CHITON-RADSIA. 

Carpenter's opinion of the small importance of the character upon 
which this group is founded, is fully supported by the material 
studied by myself. He writes as follows : " The bi- or tri-slitting 
of the laminae appears to me a character of very secondary impor- 
tance, as being merely numerical, not structural, and as being very 
variable even in the same specimen. In one specimen of Dr. Gray's 
type which I received from Mr. Cuming, only one valve had two slits 
on each side; most of the other valves had one only ; sometimes a 
second slit was seen on one side. For such a specimen it would have 
been as useless to establish a genus as for Ch. virgulatus, or for C. 
boivenii in which Dr. Gray found the same abnormality (vide P. Z. 
S. 1847, p. 127). Another specimen of C. barnesii had the valves 
either with one slit or with two slits on each side, or with one on one 
side and two or three on the other. Under these circumstances I 
cannot regard the number of slits as a generic character." 

Compare alse the notes under C. virgulatus. 

Key to species of Radsia. 

a. Surface smooth, goodalli. 

aa. Surface sculptured with riblets. 

b. Ribs strong and coarse ; color black-olive, uniform, 

sulcatus. 

bb. Riblets fine; color variegated. 

c. Ribets of central areas nearly obsolete ; of lateral areas 

granose, barnesii. 

cc. Riblets of central areas fine, distinct ; shell olive mottled 

with dark, virgulatus, 

C. BARNESII Gray. PL 29, figs. 10, 11, 12. 

Shell oval, depressed, scarcely carinated. Black-brown, yellowish 
toward the ridge where each valve generally has a dark triangular 
spot, and having a buff-white longitudinal stripe on each side ; 
girdle green. 

Lateral areas raised, sculptured with about 6 irregular, uneven, 
rather nodulous radiating ribs. Central areas sculptured with fine 
longitudinal riblets, subobsolete toward the dorsal ridge, and some- 
what latticed by growth-lines. End valves having radiating 
nodulous ribs; umbo of the posterior valve very near the front mart/in. 

Interior whitish ; sinus finely and rather unevenly toothed. 
Anterior valve having 15-16, central valves 2, (occasionally 1 on 



CHITON-RADSIA. 191 

one side, 2 on the other), posterior valve 18-19 slits. Teeth blunt, 
pectinated; eaves narrow, spongy. 

Girdle covered with shining, convex, minutely striated scales. 

Coquimbo, Chili. 

Chiton barnesii GRAY, Spicil. Zool., p. 5, t. 6, f. 22. SOWB. in 
Moll. Beechey's Voy., p. 149, t. 41, f. 10; Conchol. Illustr., f. 2. 
KEEVE, Conch. Icon., t. 1, f. 1 ; t. 21, f. 137. 

Entirely different from the other species of Radsia in form and 
sculpture. The riblets upon the central areas are very fine and 
their interspaces shallow. Occasionally a specimen occurs having 
some of the valves with a single slit one side. 

C. GOODALLII Broderip. PI. 29, fig. 9 ; pi. 28, figs. 5-8. 

Shell very large, oval, moderately elevated, carinated, the side- 
slopes nearly straight or rather convex. Surface nearly smooth. 
Color blackish, olive-black or brown-black, generally showing an 
obscure olive-green stripe on each side of the keel. 

The lateral areas are a little raised, separated by an obtuse ridge 
from the central areas, and in most specimens they are somewhat 
terraced by concentric marks of growth-arrest. There is no other sculpt' 
ure on either central or lateral areas except an extremely minute and 
even granulation over the whole surface. The umbo of the posterior 
valves is unusually near the front margin. 

Interior white, each valve having a pair of posterior rays and a 
central spot of brown. Sutural plates broad, sinus rather shallow 
having about 8 teeth. Anterior valve having 25-26, central valves 
2-3, posterior valve 26-28 slits ; teeth stout, blunt, deeply pectin- 
ated ; eaves very spongy. 

Girdle covered with coarse flattened-convex scales. 

Length 110, breadth 70 mill. 

Galapagos Is. 

Chiton goodallii BROD., P. Z. S. 1832, p. 25. C. godallii SOWB., 
Conch. 111., f. 34, 40. C. goodalli REEVE, Conch. Icon., f. 8. 
Radsia goodalli CPR., MS. 

This very large smooth species is quite, unlike any other. 

C. SULCATUS Sowerby. PI. 28, figs. 1, 2, 3, 4. 

Shell oval or oblong, moderately elevated, carinated, the side- 
slopes nearly straight ; of a uniform olive-black, or having the 
lateral areas obscurely purple-black. 



192 EUDOXOCHITON. 

Lateral areas very strongly radiately ribbed and grooved, the pos- 
terior rib of each valve broad and crenulated, the other ribs unequal, 
varying in number, usually split toward the outer edge of the shell. 
Central areas sculptured with numerous strong but smaller riblets, 
which near the dorsal ridge converge forward, but on the pleura 
they diverge strongly, End valves having strong radiating ribs, 
which split toward the periphery. Umbo of posterior valve prom- 
inent, in front of the middle. 

Interior blue-green'; sutural plates broad ; sinus rather deep and 
square, finely toothed. Anterior valve having 23-26, central valves 
2-3, posterior valve 18-20 slits ; teeth stout, blunt, finely and 
strongly pectinated. Eaves coarsely spongy. 

Girdle covered with coarse convex scales, larger toward the 
periphery. Length 95, breadth 55 mill. 

Galapagos Is. 

Chiton suleatus WOOD, Gen. Conch., p. 16, t. 3, f. 1. SOWB., 
Conch. Illustr., f. 12. REEVE, Conch. Icon., f. 15. Radsia sulcata 
CPR., MS. 

This is one of the most strongly sculptured of all Chitons, and is 
correspondingly easy to recognize. There are usually two slits in 
each side insertion-plate, but the second valve occasionally has as 
many as four. 

C. (Radsia) ccerulescens Shuttleworth, Diagn. n. Moll., no. 4, in 
Bern. Mittheil. 1853, p. 65. No description of this species has been 
published. It is said to be from California. Possibly founded on a 
Ch. virgulatus, q. v. 

Genus XIII. EUDOXOCHITON Shuttleworth, 1853. 

Eudoxoehiton SHUTTLW., Bern. Mittheil. 1853, p. 67, type A. 
nobilis GRAY. Acanthopleura sect. * * f, GRAY, P. Z. S. 1847, p. 
68, non Guilding. Maugeria sect, f, GRAY, Guide, p. 184, 1857. 
Chwtopleura ADS. et aL, non SHUTTLW. 

Valves entirely exposed, smoothish, lacking eyes ; mucro flat ; the 
sutural plates broad and connected across the sinus ; insertion-plates 
of all valves blunt, closely and deeply cleft, the median valves with 
3 or 4, end valves with many short slits. Girdle leathery, setose. 
Gills extending the entire length of the foot. 

The valves, when eroded, are seen under the lens to be densely, 
evenly and regularly punctured all over. The interior is white, and 



EUDOXOCHITON. 193 

of a dense, porcellanous texture. The laciniated insertion-plates, 
cut into many short teeth, combined with the harshly setose girdle 
and continuous sutural-plates, are the most striking generic char- 
acters. 

From Acantliopleura and Maugeria, groups to which some 
authors have referred the type of this genus, Eudoxochiton is 
sundered by the lack of eyes in the valves, the multiplicity of slits, 
depressed mucro, etc. 

Besides the following, Ch. linter (CLem.) Reeve may belong to 
this genus, but its generic characters are entirely unknown. See 
appendix. 

E. NOBILIS Gray. PI. 46, figs. 88-95. 

Shell oblong, elevated, the valves well arched, and very obtusely 
angular on the dorsal ridge, side-slopes convex. Color uniform dark 
brown, a little mottled toward the beaks, and marked with scarlet 
there ; girdle rusty-brown. 

Valves broadly A-shaped, not beaked, the lateral areas moder- 
ately raised, smooth except for the microscopic granulation and a 
few excessively indistinct radii. Central areas having indistinct 
growth-lines. Posterior valve (figs. 92, 93, 94) elevated in front, the 
mucro flat, central ; posterior margin gently emarginate behind. 

Interior ^porcelain-white, immaculate; smooth and poreless. 
Sutural plates squared, continuous across the sinus, which is indicated 
by a median bay or notch. Insertion-plates having broad, blunt 
edges, irregularly and deeply pectinated, and having in the head- 
valve 30, median valves 3-4, tail- valve 24-25 short slits. Eaves 
very narrow, deeply grooved along the teeth and slightly spongy 
there. 

Girdle (fig. 95) leathery, rust-colored, bearing short rigid black 
spinelets. Length 60, breadth 35 mill. ; divergence 100-110. 

Auckland, Cooks 1 Strait ; Martin's Bay, New Zealand. 

Acantliopleura 'nobilis GRAY, in Dieffenbach's New Zealand, ii, p 
245 (1843). Chiton (Eudoxochiton) nobilis Gray, SHUTTLW., Bern. 
Mittheil. 1853, p. 67. Chiton (Chcetopleura*) nobilis Gray, SMITH, 
Zool. Erebus and Terror, p. 4, t. 1, f. 8 (1874). HUTTON, Man. N. 
Z. Moll, p. 115 (1880.) 

This species differs from the following in its more elongated and 
much more elevated contour, and in the stronger valves. The 
13 



194 TONICIA. 

seventh valve is represented in figs. 89, 90 ; and a square millimeter 
of the girdle is indicated in fig. 95. 

E. HUTTONI Pilsbry, n. sp. PI. 46, figs. 96-100. 

Shell oval, depressed, with convex side-slopes. Color dark brown, 
the girdle greenish-brown. Valves broadly A-shaped, not beaked, 
rounded at the ends ; the lateral areas well raised. Entire surface 
smooth except for a microscopic punctulation and slight growth- 
lines. Posterior valve (figs. 98, 99) depressed, the mucro plane, 
central ; posterior margin hardly marginate. 

Interior white, smooth. Sutural plates continuous across the 
sinus which is indicated by a shallow wave or bay. Insertion- 
plates blunt, deeply pectinated, the anterior valve having 17, central 
3, posterior 19 short slits. Eaves very narrow and grooved along 
the teeth. 

Girdle leathery, bearing numerous short, rigid, dark brown spine- 
lets. Length 50, breadth 34 mill. ; divergence 135-140. 

New Zealand. 

This species is closely allied to E. nobilis, from which it differs in 
the proportions of the valves, depressed form, fewer slits, etc. The 
seventh valve is represented in figs. 96, 100. The specimen 
illustrated was sent me by Professor Hutton. 

Genus XIV. TONICIA Gray, 1847. 

Tonicia GRAY, P. Z. S. 1847, p. 65, 67 ; Guide Syst. Dist. Moll. 
B. M., p. 185 (1857), and of authors. Probably Toniehia GRAY, 
Synops. Contents B. M., 42d edit., p. 153, 1840 (name only.) 

Generic characters. Valves external, all having pectinated inser- 
tion-teeth ; sinus denticulate ; lateral areas and end valves bearing 
radiating rows or bands of eye-dots. Girdle leathery, naked or 
sparsely hairy. Gills extending the whole length of the foot. 
Type C. elegans Frembly. 

Besides the fundamental characters above recounted, the species 
of this genus mostly agree in having the valves smooth ish, the 
second valve notably larger than the following five, and often differ- 
ently sculptured on the ridge ; the sculpture is generally fine or 
minute, the colors much variegated or uniform black-brown, and the 
eaves are hardly spongy. 

From Chcetopleura and Tonicella this genus is very strongly 
differentiated by the presence of eyes, and also by the more distinctly 



TONICIA. 195 

pectinated insertion-plates. The genus Onithochiton has similar 
smooth valves, but the posterior valve lacks slits and teeth of 
insertion. 

The species of Tonicia inhabit mainly the shores of the southern 
and tropical Pacific, being found from Middle America to Cape 
Horn, and from the Philippines to Australia and New Zealand. 
They may be grouped thus : 

A. Valves not immersed or separated, imbricating, section Tonicia. 

1. Species of West America. 

2. Species of the West Indies. 

3. Species of New Zealand, Australia, Red Sea, Philippines. 

B. Valves partly separated, the girdle encroaching on them at the 

sutures, section Fannettia. 



Section Tonicia s. sir. 
1. Species of West American shores. 

T. CRENULATA Sowerby. PL 45, figs. 69, 70, 71, 72. 

Shell oblong-ovate, slightly more narrowed in front, moderately 
raised, the back carinated. Ground-color buff or slightly rose- 
tinged, having oblique dark olive irregular stripes, often marked on 
some valves with rich brown ; apices of valves pink when eroded. 

The lateral areas are raised and well-defined, and except the pos- 
terior third or fourth, are studded closely with black eyes; the suture 
is prominently and coarsely crenulated, and there are some irregular 
radiating rows of granules on the back part of the areas, and some- 
times a row or two dividing the eye tract. Central areas having a 
smooth keel in the middle, bounded on each valve by a V formed by 
two low divergent waves, crossed by convergent riblets ; pleura or sides 
sculptured with longitudinal-diverging rugae or ribs. Anterior 
valve high, with radiating rows of weak granules alternating with 
rays crowded with eyes. Tail valve with slightly posterior, elevated 
mucro. 

Interior white, with a large red tract in each of the median valves. 
Slits in anterior valve 8, central 1, posterior 14; teeth obtuse and 
short in the posterior, acute and longer in the anterior valves, sulcate 



196 TONICIA. 

outside and at edge. Sinus square, denticulate ; sutural-plates and 
insertion -plates white. 

Girdle leathery, thin, yellowish-green, naked. 

Length 34, breadth 20 mill. 

Length 50, breadth 33 mill. ; divergence 115. 

Pearl Island, Bay of Panama (Cuming, et al) ; Mazatlan 
(Reigen.) 

Chiton crenulatus BROD., P. Z. S. 1832, p. 27. SOWERBY, Conch. 
Illustr., f. 43. REEVE, Conch. Icon., no. 29, t. 6, f. 39 (error for 29). 
"/ Tonicia" forbesii CPE., Mazatlan Catal., p. 193 (1856.) 

This species is readily distinguished from the other West Amer- 
ican forms by the greater width of the lateral bands of eyes, the 
crenulated sutures, and the beautiful sculpture of the central areas. 
The second valve is not so prominent as in most species of Tonicia, 
and it is sculptured like the other intermediate valves. 

T. ELEGANS Frembly. PL 41, figs. 22, 23, 24 ; pi. 42, figs. 31, 32, 

33, 34, 35. 

Shell elliptical-oblong, not much elevated, the dorsal ridge 
rounded, side-slopes straightened. Color umber-brown at the sides, 
becoming chestnut in the middle, delicately and peculiarly speckled 
and blotched and streaked with buff or buff-white. 

Lateral areas hardly raised, but separated from the central areas 
by an obtuse diagonal ridge bearing a series of low tubercles, some- 
times subobsolete ; sculptured with subradiating rows of small gran- 
ules, and showing a band of irregularly placed black eyes on the for- 
ward part. Central area of second valve having in the middle, a 
keel or a group of liraB ; central areas of the other valves having a nar- 
row smooth dorsal band with several longitudinal furrows on each side 
of it; and at the sides there are longitudinal diverging delicate rows 
of granules. End valves radially subgranulate, and crowded with 
eye-spots subradially arranged. Mucro in front of the middle, 
moderately elevated. 

Interior porcelain white, with a spot or " V " of red-brown under 
the beak of each valve. Sinus flat, distinctly but finely denticulate. 
Slits short, in the anterior valve 8, in the central 1, in the posterior 
valve 9-12 ; teeth blunt, long and very finely, deeply pectinated out- 
side ; slit-rays regularly puncticulate. 

Girdle naked, leathery, of a chestnut-yellow color. 

Length 48, breadth 32 mill.; divergence 125. 

Callao to Valparaiso. 



TONICIA. 197 

Chiton elegans FREMBLY, Zool. Journ. iii, p. 203, suppl., pi. 17, f. 
6. SOWB., Conch. lllustr., no. 75. REEVE, Conch. Icon., t. 4, f. 19. 
C. sparsus SOWB., Conch. lllustr., f. 73, 74 (young.) 

The type species of Tonicia. The sculpture is well shown in fig. 
22 ; the color-pattern in the figure between 22 and 24. 

Subspecies CHILENSIS Frembly. PI. 41, figs. 19, 20. 

Shell rather heavier and thicker than T. elegans, with thicker 
girdle. Color a uniform dark chocolate brown, except near the beaks 
where there is a large or small area the shape of the valve which is 
light delicately mottled with reddish ; girdle dark brown, wide at the 
sides, narrow at the ends. 

The diagonal line is surmounted by a series of small tubercles; 
lateral areas showing fewer and less conspicuous eye-spots than T. 
elegans, and otherwise nearly smooth, the granulation being obsolete ; 
central areas striated on each side of a median smooth band, and 
more or less (variously) roughened at the sides ; second valve sub- 
carinate, striated in the middle. End valves radially, sparsely 
granulate and dotted with eyes, the umbo of the tail valve obtuse, 
conspicuous, elevated, a little in front of the middle. 

Interior white, marked with reddish under the beaks. Sinus 
toothed. Sutural plates broad, especially at the outer-anterior portion. 
Anterior valve having 7, central valves 1, posterior valve 8 slits; 
teeth very thick and blunt, strongly, closely pectinated. 

Girdle leathery, naked, rather thick. 

Length 38, breadth 28 mill.; divergence 130. 

Length 68, breadth 43 mill. 

Valparaiso, under stones. 

C. chilensis FREMB., Zool. Journ. iii, p. 204, suppl., pi. 17, f. 8. 
REEVE, Conch. Icon., t. 3, f. 17. Tonicia chilensis ROCHEBRUNE, 
Nouv. Arch, du Mus. 1881, p. 240 (Reported from the Canaries, on 
the authority of specimens so labelled in the Paris Museum, but 
undoubtedly false.) 

This form is very closely allied to T. elegans, differing mainly in 
the (a) dissimilar coloration, (6) more numerous striaB on each side 
of the median smooth band, (c) generally obsolete granulation of the 
lateral areas, (d) thicker insertion-teeth, and in the thicker girdle ; 
a still better distinction is in the tail-valve, which in chilensis has a 
more prominent umbo, nearer the center than in elegans, and the area 
in front of the umbo is striated, whilst in elegans it is smooth. All 



198 TONICIA. 

of these differences however, do not avail to name specimens in 
which various characters of elegans are combined with other char- 
acters of chilensis ; so that while when typically developed the forms 
may readily be separated, it is, I believe, impossible to classify 
occasional synthetic specimens. I have therefore considered chilensis 
a phase or variety of elegans. 

Subspecies LINEOLATA Frembly. PI. 41, figs. 25, 26, 27. 

Shell oblong, moderately raised, the ridge rather rounded. Sur- 
face smooth ish. Ground color light fawn or fleshy, each valve 
closely and finely lineolate with chestnut, the lines concentric to the 
umbones; fifth valve marked with brown at the ridge, and often 
some of the other valves are marked with dark brown or are entirely 
of that color. 

Lateral areas closely, finely granulated, and having two or three 
rows of eyes extending down near the low, smooth diagonal. Central 
areas smooth except for a group of engraved grooves on each side of 
the smooth narrow dorsal band. Second valve either smooth or hav- 
ing a median carina. End valves granulate toward the periphery, 
closely dotted with eyes in irregularly radiating rows. Umbo of 
tail valve anterior, the space in front of it smooth. 

Inside white, each valve marked with reddish under the beaks. 
Sinus delicately denticulate. Anterior valve having 8-9, central 1, 
posterior valve 9-10 slits; teeth blunt, pectinated. 

Girdle leathery, nude, yellowish-brown. 

Length 25, breadth 15 mill.; divergence 110. 

Length 40, breadth 23 mill. 

Valparaiso, Chili. 

Chiton lineolatus FREMBLY, Zool. Journ. iii, p. 204, suppl., pi. 17, 
f. 7 (Good). SOWERBY, Conch. Illustr. (as syn. of elegans), f. 154. 
REEVE, Conch. Icon., t. 7, f. 34. Tonicia lineolatus CPR. 
? Chiton bruguieri Pot. & Mich. Galerie, i, p. 534 (1838.) 

The distinguishing characters of typical lineolatus are the lack of 
larger tubercles along the diagonal ridge, and the fine concentric 
line-painting. The characters of both sculpture and color-pattern 
however, are in some specimens inextricably united with these of T. 
elegan*, of which species I am therefore compelled to consider this a 
variety. 

Many specimens show several valves of uniform black-brown; 
others are blotched on many valves with the same. The species 



TONICIA. 199 

somewhat resembles Tonicella lineata Wood (see p. 42, pi. 11, figs. 
25-28), but differs sufficiently in sculpture and the possession of 
black eye-pits, as well as in the entirely different insertion-plates. 
T. swainsoni resembles lineolata in color-pattern, but it differs 
entirely in having the entire central areas longitudinally, and the 
lateral areas and end valves radially costulate. 

T. FASTIGIATA (Gray) Sowerby. PI. 41, fig. 21 ; pi. 42, figs. 36, 

37, 38, 39. 

Shell oblong, moderately elevated, subcarinated ; the side-slopes 
nearly straight ; surface smoothish. Color olive-brown, sometimes 
whitish, having indistinct concentric darker streaks ; rarely unicolored 
black-brown. 

Lateral areas hardly raised, indistinctly separated from the central 
areas by a smooth, low or obsolete diagonal ridge. Entire surface 
of lateral and central areas covered with a microscopic granulation, 
the granules sometimes coalescing into short wrinkles in front of the 
diagonal at the sides. Dorsal ridge having a very narrow smooth 
band in the middle, on each side of which there are several deeply 
engraved longitudinal grooves. Second valve either smooth or 
having a group of striae in the middle. End valves showing numer- 
ous rays of eyes ; the mucro of the posterior valve prominent, in 
front of the middle. 

Interior white, marked under the apex or suffused throughout the 
jugal tract with reddish. Sinus toothed. Anterior valve having 7, 
central 1, posterior valve 10 slits; teeth rather thin, crenulated out- 
side and at the edge. 

Girdle leathery, nude, dark brown. 

Length 54, breadth 34 mill. ; divergence 110. 

Length 48, breadth 26 mill.; divergence 110. 

Sts. of Magellan. 

C.fastigiatus GRAY, in SOWB., Conchol. Illustr., f. 11, 35. REEVE, 
Conch. Icon., f. 26. SMITH, P. Z. S. 1881, p. 35. 

? Chiton cliiloensis SOWB., P. Z. S. 1832, p. 58 ; Conch. 111. (as syn. 
of elegans), f. 13*, 10, 29, 30. REEVE, Conch. Icon., t. 3, f. 14. 

The main distinguishing characters of this species are its even fine 
granulation, lack of tubercles on the low diagonal ridge, few 
engraved grooves on each side of the smooth narrow dorsal band, 
and the obscure concentrically streaked style of coloration. 



200 TONICIA. 

I do not know whether the C. cldloensis of Sowerby belongs to this 
species or to C. elegans. It is represented on pi. 42, fig. 40. 

T. GEANIFERA Sowerby. PI. 43, figs. 44, 45. 

Shell ovate, chestnut varied with white and black; dorsum 
elevated ; front valve radially granose ; lateral areas and posterior 
area of posterior valve subradiately graniferous; central areas 
longitudinally granose-lineate, marginal ligament smooth. 

Length 25, breadth 15 mill. (Sowb.*) 

Conception, Chili ; on Mytilus in 9 fms. (Cuming.) 

C. graniferus SOWB., P. Z. S. 1832, p. 104 (Conch. 111., f. 8 ?). 
KEEVE, Conch. Icon., t. 15, f. 86. Tonieia grani/era CPU., MS. 

Evidently closely allied to T. elegans, having much the same 
sculpture. 

T. GRAYI Sowerby. PI. 43, figs. 46, 47. 

Shell oblong, pale, varied with brown and rufous ; anterior valve, 
lateral areas and tail valve radially granose-striate ; anterior margins 
of lateral areas elevated, posterior margins [sutures] creuulated. 
Central areas obliquely longitudinally granulose-striate ; third to 
seventh valves longitudinally bi*nlcate in the middle. Marginal 
ligament smooth. Length 30, breadth 17? mill. (Sowb.~) 

Island of St. Lawrence, Bay of Callao, Peru, on shells in 17 fms. 
(Cuming.) 

Chiton gfayii SOWB., P. Z. S. 1832, p. 57 ; Conch. Illustr. f. 8. 
REEVE, Conch. Icon., t. 17, f. 105. Tonieia grayi CPR., MS. 

This form is evidently closely allied to T. elegant, etc. The 
italics of Sowerby's description translated above are my own. 

Carpenter thus describes the type specimens : Jugular areas with 
deep grooves on each side of the central smooth rib, but both grooves 
and rib are evanescent on the second valve. Central areas with a 
second set of granules parallel to the diagonal and more or less con- 
tinued into faint riblets, somewhat diverging from the more prom- 
inent apices. Lateral areas with a very decided row of rugose 
granulations along the diagonal, inside of which is a smooth space 
crowded with metallic dots [eyes] ; then two or more rows of very 
rough irregular granules, ending in sharply crenate sutures. End 
valves with about eleven obsolete riblets, irregularly granose, with 
rows of metallic dots between each. Mucro in front of the middle, 
swollen, but the slope behind it concave. Anterior valve having 8 



TONICIA. 201 

central 1, posterior valve 14 slits ; teeth very sharp, pectinated. 
Sinus flat moderately deep and broad, with up to 16 teeth. 
Length 30, breadth 17 mill.; divergence 105. 

T. ATRATA Sowerby. PI. 41, figs. 28, 29, 30. 

Shell oval-oblong, smooth, subcarinated ; valves nearly straight, 
subrostrate ; lateral areas inconspicuous ; margin [girdle] smooth. 

Length 25, breadth 12 mill. (Smvb.) 

The smooth, narrow, slightly angulated species above described is 
of a blackish-brown color; the lateral areas are not distinctly 
marked except by rays of lighter color in some specimens on them, 
and on the terminal valves. (Sowb.~) 

Falkland Is. (Sowb.) ; Orange Harbor (U. S. Ex. Exped.) 

Chiton atrata SOWB. in Charlesworth's Magazine of Nat. Hist. 
1840, p. 294 ; Conch. Illustr., f. 57, 58. REEVE, Conch. Icon., 1. 17, 
f. 103. GOULD, U. S. Expl. Exped., p. 329, f. 4l5. Tonicia atrata 
H. & A. ADS., Gen. Rec. Moll, i, p. 474. ROCHEBRUNE, Polyplac. 
Cap Horn, p. 138. T. bcetica CPR., MS. olim. 

I have not seen this species. Carpenter writes : Mucro more or 
less elevated, tumid behind. Inside having 8 slits in the anterior, 
1 in the middle and 12 in the posterior valve; teeth acute, outside 
and at the edge sulcate, scarcely pectinated ; sinus moderate, flat, 
with 13-20 denticles. 

Hutton reports this species from Macquarie Island, N. Z., but 
says : " Our species agrees very well with Reeve's figure, but not 
with his description. The anterior terminal' area is distantly 
radiately ribbed, and the lateral areas are sometimes defined by a 
single rib. The umbone of the posterior valve is more posterior 
than in the drawing, and the valves are of a uniform brown color. 
The mantle is of the same color as the valves." These characters 
seem to me to indicate a distinct species, which may be called 
Tonicia subatrata. 

T. SWAINSONI Sowerby. PL 43, figs. 41, 42. 43, 

Shell oval, moderately or decidedly elevated, somewhat carinated, 
the side-slopes nearly straight. Ground-color light pinkish-buff, 
painied all over with a multitude of red or red-brown lines, concentric 
to the beaks ; often having some valves striped at or on each side of 
the ridge, or more or less completely covered with dark red-brown. 

Lateral areas little raised, sculptured uith about 8 radiating 



202 TONICIA. 

riblets. the riblets sometimes broken into rows of distinct granules. 
Central areas longitudinally costulate except for a narrow, smooth 
dorsal band on the latter 6 valves. End valves radially ribbed, 
with rows of eyes in the intervals. Umbo of tail valve anterior, 
elevated. 

Interior white, some or all of the valves having a small reddish 
spot under the apices. Sinus narrow, denticulate. Anterior valve 
having 8, central 1, posterior valve 10-12 slits; teeth pectinated. 

Girdle yellow or brown, leathery, thin. 

Length 34, breadth 20 mill.; divergence 100-110. 

Callao, Peru. 

C. swainsonii SOWB., P. Z. S. 1832, p. 27 ; Conch. Illustr., f. 5. 
REEVE, Conch. Icon., t. 7, f. 38. Lophyrus swainsonii TAP.-CAN. 
Viag. Magenta, p. 75. 

This species is well differentiated from forms of the elegans group, 
by the longitudinal ribbing of the entire central areas. The ribs 
vary much in prominence, however, and in many individuals the 
riblets of the lateral areas are broken into granules. The color- 
pattern is similar to that of T. lineolata, but finer. 

T. RUBRIDENS Pilsbry, n. sp. PL 44, figs. 65, 66, 67. 

Shell oblong, elevated, the dorsal ridge roundly angular, side- 
slopes straight. Surface smooth. Tawny-brown, sometimes uni- 
colored, but generally having dotted light rays on lateral areas and 
end valves, and a dark dorsal band. A light fawn color sometimes 
predominates over the dark. 

Valves rounded at the front corners, moderately beaked ; sutures 
not crenulated. 

Lateral areas not perceptibly raised (except on the second valve), 
sculptured with minute granules sparsely and irregularly scattered, 
varying much in number; and along the forward part there is one 
series of small black eye-dots, becoming an irregularly double series 
on the lower half of the slope. End valves weakly granulose and 
having radiating rows of eyes. Central areas entirely smooth except 
for growth-lines, having no grooves along the dorsal ridge. Beak of 
tail-valve obtuse, behind the middle. 

Interior of a peculiar red-brown color, the callus of each valve 
whitish. Sut Ural-platen thin, red-brown. Sinus delicately dentic- 
ulate, the area behind it, extending to the beak, transversely 
wrinkled. Slits in anterior valve 8, central valves 1, posterior valve 



TONICIA. 203 

9; teeth finely crenulated outside and at edge, rather thin, and 
colored red. As in other species having a posterior mucro, the tail- 
valve teeth are directed forward. 

Girdle yellowish, leathery, nude and smooth. 

Length 28, breadth 15 mill. ; divergence 108. 

Callao ; and Chili (U. S. E. E.) 

This species differs from all of the T. elegans group in lacking 
sculpture upon the central areas and engraved grooves along the 
dorsal ridge; and from other species of Tonicia in the red sutural- 
plates, teeth, etc. The blunt mucro is posterior, and the teeth in the 
tail-valve are directed forward. The posterior margin of the tail 
valve is broadly waved upward in the middle, as in Eudoxoehiton. 

T. HORNIANA Kochebrune. PI. 43, figs. 50, 51. 

Shell ovate-elliptical, carinated, rufous, marbled with buff and 
roseate ; anterior valve radially costate, posterior valve small ; inter- 
mediate valves having the central areas minutely concentrically 
striated ; lateral areas multi-sulcate and ornamented with two lines 
of dots. Marginal ligament dull roseate. 

Length 19, breadth 14 mill. (Bochebr.') 

Orange Bay, Patagonia. 

T. horniana EOCHEBR., Polyplac. Cap Horn, p. 139, t. 9. f. 7. 

T. MARTIELI Rochebrune. PI. 43, figs. 48, 49. 

Shell ovate-elongate, strongly carinated, the ends of the valves 
curved backward, brown-rose, anterior valve radially strongly 
costate ; posterior valve small ; intermediate valves having the 
central areas transversely lineated, lines denticulate; lateral areas 
granulated and margined by a squamate band. Marginal ligament 
violaceous-rufescent. Length 21, breadth 14 mill. 

Straits of Magellan. 

T. martieli ROCHEBR., Polyplac. Cap Horn, p. 139, t. 9, f. 8 
(1889.) 

T. LEBRUNI Rochebrune. PI. 43, figs. 52, 53. 

Shell ovate-elliptical, carinated, shining, violaceous or greenish- 
roseate. End valves radially most minutely striated ; intermediate 
valves having the lateral areas covered with tubercles ; the central 
areas concentrically sulcate, the sulci wavy ; marginal ligament 
narrow, leathery, whitish-violaceous. 

Length 29, breadth 12 mill. (Rochebr.} 

Punta Arenas, Orange Bay, St. of Magellan. 



204 TONICIA. 

Tonicia lebnuii ROCH., Bull. Soc. Philomath. Paris, 1883-'84, p. 
35 ; Polyplac. Cap Horn, p. 138, t. 9, f. 6. 

T. FONTAINE: Rochebrune. Uw figured. 

Shell ovate, broad, subcarinated, gray, with brown spots. Ante- 
rior valve, lateral areas of intermediate valves, and posterior part of 
posterior valve very delicately striatulate and sparsely covered with 
conic tubercles ; central areas sculptured with beaded longitudinal 
waved lines. Marginal ligament rather wide, leathery, rufous. 

Length 11, breadth 9 mill. (Rochebr.} 

Chili (M. Fontaine) ; Paris Museum. 

Tonicia fontainei ROCHEBR., Bull. Soc. Philom. de Paris, 1881- 
1882, p. 193. 

The foregoing species are not defined with sufficient exactness to 
insure their indentification, Rochebrune being a century behind the 
times in 'descriptive zoology. 

T. ARGYROSTICTA Philippi. Unfigured. 

Girdle smooth. Valves smooth, subcarinated ; lateral areas hav- 
ing a single series of distinct silvery impressed dots. 

Length 4, breadth 3 lines. 

This small species is sufficiently distinguished by the peculiar 
impressed silvery-shining points, which remind one of the similar 
marking on some Carabidse. On both end valves they stand in 
several concentric rows. The coloring varies ; the brown-red color 
predominating; in one example there are whitish flecks and trans- 
verse stripes, in another longitudinal stripes. (P/w7.) 

Straits of Magellan. 

Chiton argyrostictus PHIL., Archiv fiir Naturg. 1845, p. 59. 

T. ZSCHAUI Pfeffer. PI. 40, fig. 12. 

The animal is much elongated, the breadth hardly one-half the 
length. The inner region of the girdle is covered with very minute 
granules, hardly visible under a strong lens, arranged in not entirely 
regular oblique series, and separated by about their own dimensions. 
Under a low-power lens the girdle appears quite naked. Toward 
the margin these granules grow into transparent, short spines. The 
28 branchiae reach the entire length of the foot. 

The valves are quite shining, and sculptured with close growth- 
strive ; otherwise they appear smooth under a weak power of the 
lens ; under strong magnification a fine granulation is visible. The 
median valves have only a low angle separating central and lateral 



TONICIA. 205 

areas ; the growth wrinkles, which on the lateral areas are close and 
prominent, are weaker on the central areas, the posterior part of 
which appear sculptureless. The umbo seems to be produced back- 
ward [beaked] in young shells, but in this specimen it is so upon the 
2d valve only. The dorsal ridge is bluntly angular. The head 
valve is long compared with its breadth, the length of the front 
slope equalling that of each of the posterior margins ; it shows weak 
concentric sculpturing of striae. The tail-valve is small and narrow, 
not much more than two-thirds as broad as the head valve, and also 
notably shorter ; its forward area is not shining ; the posterior 
segment is shining and sculptured like the head valve. 

The lateral areas and the outer anterior parts of the central areas 
are yellowish-red with red marbling. The central area shows on 
its middle part, a group of beautiful chocolate-brown and violet- 
white striae, radially diverging from the umbo. On the anterior 
median valves are seen also a few clear brown streaks on the outer 
part of the central areas. 

The single specimen before me is fastened on pasteboard, and 
measures 13*5 by 6 mill.; the broadest valve is 5 mill., so that the 
girdle is but '5 mill., wide. The third median valve of this specimen 
is abnormal in being pure white. 

South Georgia. 

Chiton zschaui PFFR. in Moll. Siid-Georgien, Jahrb. Hamb. 
Wisseusch. Anstalten iii, p. 105, t. 3, f. 2 (1886.) 

This is placed in Tonicia with much doubt, for the presence of 
eyes is not noted in Pfeffer's description, above. 

T. TEHUELCHUS d'Orbigny. PL 40, figs. 13, 14, 15. 

Shell oblong, elevated, strongly carinated ; brown with two white 
longitudinal zones ; head-valve and lateral areas radially sulcate- 
bifurcate ; central areas longitudinally punctate-sulcate. 

Length 27 mill. (Orb.') 

Bay of San Bias, Patagonia. 

Chiton tehuelchus ORB., Voy. dans 1'Amer. Merid., p. 488, t. 65, 
f. 7-13. 

The sculpture reminds one of Chcetopleura fulva Wood. The 
generic position is not certain. 

2. West Indian species. 
T. SCHRAMMI Shuttleworth. PL 43, figs. 54, 55, 56. 

Shell oblong, moderately elevated, roundly angular. Surface 
polished. Ground-color buff, mottled, speckled or sometimes suffused 



206 TONICIA. 

with bright reddish-brown. Valves strongly beaked, the umbo of the 
tail-valve far to the posterior (fig. 54). Central area* smooth 
throughout ; lateral areas separated from the central by a prom- 
inent, rounded, curved diagonal rib, and smooth except for a broad 
band of black eye dots, variously arranged, on the forward half; 
sutures feebly or obsoletely crenulated. Head-valve smooth except 
for 8-10 broad rays of eye-spots. 

Interior white, stained with crimson along the jugal tract. Sinus 
obsoletely denticulate. Anterior valve having 9-10, central valves 
1, posterior valve 14 slits; teeth deeply and regularly pectinated on 
outer face and edge. Posterior border of each valve inflexed and 
maculated with reddish. 

Girdle leathery, tawny, flesh-colored. 

Guadalupe ; Florida Keys ; Bermuda. 

Chiton ( Tonicia) schrammi SHUTTLW., Journ. de Conchy 1. 1856, 
p. 171, t. 6, f. 9. T. schrammi HEILPRIN, The Bermuda Is., p. 176. 
DALL, Catal. Moll. S. E. U. S., p. 174. 

This form differs markedly from those of Western South Amer- 
ica in the non-sculptured central areas, prominent diagonal rib (like 
that of T. crenulata), and broad bands of eye-spots. The umbo of 
the tail-valve is far backward, and in most specimens the posterior 
margin of the same valve is distinctly emarginate in the middle, the 
teeth being much shorter there and irregular. In this it resembles 
Eudoxochiton. The diagonal rib is more prominent, and the eyes 
far more numerous than in T. rubridens. The nearest ally of 
schrammi is the very differently sculptured T. crenulatus. 

3. Species of Australia, New Zealand, Philippines, etc., etc. 

T. SUEZENSIS Reeve. PL 40, figs. 16, 17. 

Shell oblong ovate, valves very closely concentrically wrinkled 
at the sides, with oblique wrinkles toward the middle ; yellowish, 
delicately stained with pale scarlet and green ; ligament horny. 

(Reeve) 

Gulf of Suez. 

C. suezensis REEVE, Conch. Icon., t. 20, f. 134 (May, 1847). 
ISSEL, Moll. Mar Rosso, p. 235. COOKE, Ann. Mag. K H. 1885, p. 
276. ? SAVIGNY, Descr. Aegypte, t. 3, f. 4. Tonicia f suezensis 
CPU., MS. 

Carpenter writes: Mucro subposterior-median, rectangularly 
elevated. Interior : anterior valve having 8, central 1, posterior 
valve 13 slits; posterior teeth shorter, bending forward, anterior 



TONICIA. 207 

teeth sharper, very deeply pectinated. Eaves wide ; sinus 
minutely denticulated. This species and the following, with 
truncata, are intermediate between Tonicia and Acanthopleura ; but 
they agree with this genus in the porcellanous texture, deep slits, 
angular denticulated sinus and pectinated teeth. The slight lanuga- 
tion of the girdle appears to be a secondary character. 

T. NIGROPUNCTATA Carpenter. Unfigured. 

Shell small, rather elongated, elegantly clouded olivaceous and 
brown ; moderately arched, the dorsal ridge obtuse. Lateral areas 
moderately defined, ornamented with radiating and longitudinal 
wrinkles irregularly decussating, with black dots scattered between 
them. Central areas having subparallel, subdecussating, scarcely 
regular ribs, obsolete at the jugum. Mucro posterior, elevated. 

Interior having 8-10 slits in the anterior, 1 in the central, 12-14 
in the posterior valve ; teeth in the posterior valve solid, sloping, 
short ; sinus broad, denticulate. Girdle copiously clothed with hair- 
like scales. Length 12, breadth 6'2, alt. 1-7 mill. (Qpr.) 

Tahiti. (Pease.) 

Acanthopleura nigropunctata CPU., P. Z. S. 1865, p. 511. PEASE, 
Amer. Journ. Conch, vii, p. 194. Tonicia nigropunctata CPU., MS. 

This species is most closely allied to T. suezensis, but the latter 
has the valves more beaked and curved, and the central rugae per- 
pendicular to the diagonal lines, while in this they are nearly 
parallel to the dorsal ridge. ( Opr.} 

T. FORTILIRATA Reeve. PI. 40, figs. 3, 4 (enlarged.) 

Shell ovate ; valves somewhat beaked in the middle ; posterior 
valve umbonated, blunt; lateral areas rather concave, granulated 
anteriorly; central areas strongly arcuately ridged. Yellowish 
variegated with green, stained with red in the middle. Ligament 
horny. (Reeve.) 

Raines Island, Torres Sts. (Ince) ; Port Darwin, 8-10 fms. sand 
and mud (Coppinger.) 

Chiton fortiliratus"Rvv., Conch. Icon., t. 18, f. 112. C. (Tonicia) 
fortiliratus SMITH, Zool, ' Alert ' p. 84. 

Carpenter writes of the type : Anterior valve having 6, central 
valves 1, posterior valve 13 slits ; teeth short, numerous, very sharply 
pectinate ; short at the hinder end but gradually becoming a little 
longer. Eaves short, slightly rugose, not spongy ; sinus with about 
20 teeth, rather broad, flat. Interior whitish. Outside ashy 



208 TONICIA. 

variously pencilled and marked with olivaceous; beaks small, con- 
spicuous. Jugal area very small, smooth in front. Central areas 
with about 20 smooth riblets, curving toward the middle on the 
median part of the areas, and toward the outside of the areas radiat- 
ing outward. Lateral areas scarcely raised, having faint rows of 
granules ; at diagonal rib and at sutures having slight elongated 
granules toward the sutural ribs and rows of metallic dots next the 
diagonal ribs. Anterior valves with granules and irregular rows of 
metallic dots alternating ; crenate at suture. Posterior valve with 
median, raised, swollen mucro ; posterior slope straight. Length 28, 
breadth 18 mill. 

The single specimen collected by Coppinger is thus described by 
Smith : It is of a greyish-pink color, copiously blotched with black 
along the sides of some of the valves. The headplate & & * 
insertion edge is much thickened, coarsely striated externally, and 
is divided by 8 short narrow slits. The exterior surface is coarsely 
subsquamately granulated throughout, and exhibits numerous black 
raised dots, disposed in rather irregular radiating series. The 
second valve is long in comparison with those which follow, feebly 
peaked behind ; the fourth, fifth and sixth plates are about equal in 
size and a trifle broader than the third and seventh. All the inter- 
mediate valves are very coarsely ridged and sulcated on the central 
areas, and coarsely grained and minutely black-dotted on the sides 
(lateral areas). The ridges are flat-topped, clean-cut, nearly smooth, 
attenuated posteriorly, wavy, converge on each side toward the front, 
and the intervening grooves are feebly punctate. All have the 
hinder margin nearly straight and but feebly pointed at the poste- 
rior apex, x -x- & The posterior valve is strong and thick, obtusely 
mucronated in the center, very coarsely striated and serrated upon 
the thickened insertion-margin, which is subdivided by about 10 dis- 
tinct notches. The interior of the valve is light livid bluish, with a 
reddish stain along the middle of all, with the exception of the last. 
The mantle, as described by Reeve, is simply " horny." Length, 
without girdle, 18, diam., of fifth valve 9 mill. Reeve's type is a 
larger specimen, being 24 mill, long, 13 wide, without girdle. 

T. CARPENTERI Angas. PI. 40, fig. 7. 

Shell ovate, elevately convex, carinated, ashy white, ornamented 
at the hinder edges of the valves with pale spots, the spaces between 
which are very dark olive, melting into confused bands of a paler 
hue which extend nearly across the valves ; valves rostrate, undul- 



TONICIA. 209 

ately concentrically subimbricately sculptured throughout; the 
lateral areas not raised but separated from the dorsal areas by an . 
elevated rib. Posterior valve strongly gibbous, the umbo almost 
terminal ; mantle margin brown. Length 9 lines. (Angas.} 

Port Jackson, Australia. 

Tonwia carpenteri ANG., P. Z. S. 1867, p. 116, 223, t. 13, f. 30. 

Carpenter gives the following descriptive notes : 

One specimen without anterior valve. The specimen as it stands 
measures length 17, breadth 15 mill. ; but measuring the valves only 
and allowing for the missing anterior valve it would be length 16, 
breadth 10 mill. Shell oval, moderately elevated, the dorsal ridge 
acute; olive clouded with dark, tessellated with light so as to appear 
toothed at the sutures. Mucro central, swelling, elevated, the pos- 
terior slope convex. Jugal area a rather narrow, nearly smooth 
dorsal line. Central areas with about 16 finely, rugosely sculptured, 
nearly concentric, but faint, grooves on the otherwise smooth surface. 
Lateral areas slightly raised by the curved diagonal ; having lines 
of stumpy granules and concentrically rugosely grooved in continua- 
tion of the sculpture of the central areas, obsolete at sutures. Pos- 
terior valve concentrically grooved like the rest, all around. Girdle 
nearly smooth, very slightly lanugate. Posterior valve with 11 
slits ; teeth rather sharp, grooved outside ; eaves very small. Sinus 
broad, flat, deep, having about 17 very slight teeth. 

This species is a transition toward Acanthopleura in the thrown- 
forward teeth, but girdle and sinus are more Tonicioid. (Cjpr.) 

T. LAMELLOSA Quoy & Gaimard. PL 40, figs. 8, 9, 10, 11. 

Shell small, oval-elongate, subelevated, carinated ; valves trans- 
versely scaly-striated, variegated with gray or ferruginous ; girdle 
thick, smooth, reddish marked with radiating brown lines. Anterior 
valve having 10 crenulated teeth, posterior 9, and a much project- 
ing tuberosity. Color of valves grayish-yellow, varied with brown, 
red or greenish. Girdle usually yellow. ( Q. & G.) 

Length 15, breadth about 8, alt. 5 lines. 

Tonga Tabu. 

Chiton lamellosus Q. & G., Zool. Astrol. iii, p. 386, t. 74, f. 29-32. 



This species has the mucro more posterior than any of the preced- 




210 TONICIA. 

T. CONFOSSA Gould. PI. 57, figs. 33-36. 

Shell oblong, solid, elevated, the side-slopes straight, dorsal ridge 
carinated. Ashy white, delicately maculated with various shades of 
reddish and purple-brown, the darker color irregularly tessellating 
the posterior margin of each valve. 

The median valves are moderately beaked ; the lateral areas a 
little raised, and posteriorly and on the diagonal are very peculiarly 
sculptured with transverse narrow ledges, like the edges of shingles 
imbricating from the outer margin of the valve upward ; median por- 
tion of the lateral areas smooth, dotted in a widening band ivith eyes. 
Central areas peculiarly marked with sparsely scattered subtriangular 
pits, in some places arranged in irregular transverse rows. Anterior 
valve having radiating series of ^-shaped imbricating large scales, 
alternating with narrow bands sparsely dotted with eyes. Posterior 
valve having the prominent mucro near the posterior end, the slope 
behind it vertical, in front of it horizontal ; a narrow band of eye 
dots is behind each diagonal, and they are very sparsely, scattered 
over the rest of the posterior area. 

Interior white. Sutural plates separated by a moderate sinus, 
which is delicately denticulate except in the second valve. Anterior 
valve having 8, median 1, posterior 15 slits; the teeth sharply and 
deeply pectinated outside; posterior teeth somewhat directed for- 
ward, deeply pectinated, the slits rather shallow. Eaves narrow, 
slightly projecting downward near the teeth, and very narrowly 
grooved just outside of them. 

Girdle blackish-brown, rather fleshy, nude. 

Length about 18, breadth 11 mill.; divergence 120. 

Fiji Is. 

Chiton confossus GOULD, Proc. Bost. Soc. Nac. Hist, ii, p. 143 
(July, 1846) ; Expedition Shells, p. 5 ; Wilkes' Expl. Exped. Moll., 
p. 327, atlas f. 434, a, b, Otia Conchologica, p. 5. Chiton (Lucia) 
confos*us GOULD, Otia, p. 242. Lucia confossa GOULD, Proc. Bost. 
Soc. viii, p. 283. Lucilina confossa DALL. 

The prominent, posterior mucro, and the peculiar sculpture 
render this species easily identified. It belongs to that numerous 
East Indian group (see p. 206) characterized by a rather swollen 
posterior or post-median mucro, forward-tending posterior teeth, and 
by the generally punctured grooves of the surface-sculpture ; but in 
this species the character of the sculpture is unique in the total 
obsolescence of concentric or forwardly converging riblets on the 



TONICIA. 211 

central areas, and the development of angular scattered pits there. 
The tail-valve is emarginate behind as in Eudoxochiton and many 
Tonicias. Fig. 33 represents the interior of the second valve, which 
is longer than the following valves, as usual in Tonicia. 

It is not easy to see how Gould could write so confidently of the 
plurality of side slits, unless he examined the figures in the Explor- 
ing Expedition Atlas instead of the specimen itself; but this is no 
doubt the case. The artist of the expedition in drawing these figures, 
mistook the deep pectination for veritable slits, and represented them 
as such. In the figured specimen, now before me, the girdle in dry- 
ing has parted from the eaves, partially exposing the deeply pectin- 
ated insertion-plates, as represented in figures 434 b of the Atlas ; 
but as I have above explained, the deeper grooves of the pectination 
have been very erroneously drawn in those figures as slits. The fact 
is that although the grooves are strong and deep on the outside of 
the plates, they scarcely crenulate the summits of the teeth, and are 
as different as possible from true slits. 

The genus or subgenus Lucia (Lucilina) has therefore no stand- 
ing whatever, but becomes a synonym of Tonicia. This species can- 
not be included in Acanthopleura on account of the different arrange- 
ment of the eyes, the smooth girdle (which in this species seems to 
be more fleshy than leathery), and the denticulate sinus. 

T. PICTA Reeve. PI. 40, figs. 5, 6. 

Shell ovate ; valves, the posterior terminal truncated, ornamented 
with short, sharply undulated wrinkles, the interstices between which 
are punctured ; anterior edge of the lateral areas keeled ; pinkish- 
white, showily painted with green and scarlet spots. Ligament 
horny, transparent. (Rve.*) 

Bailie's Island, Torres Sis. (Capt. Ince.) 

C. pictus REEVE, Conch. Icon., t. 15, f. 79 (March, 1847.) 
Allied to C. truncatus, distinguished by its sculpture and flattened 
growth. (Rve.~) 

T. TRUNCATA Sowerby. PL 40, figs. 1, 2. 

Shell oblong, rather elevated, the dorsal ridge rounded ; ashy- 
flesh colored, variegated with darker or olivaceous, dotted with 
black, and sometimes rose-tinted along the dorsal ridge. 

Valves much rounded and separated at the ends ; entire surface 
granulose ; central areas engraved with superficial waved grooves ; 



212 TONTCIA-FANNETTIA. 

lateral areas hardly elevated, irregularly rugulose. Mucro behind 
the middle, much elevated. 

Inside having 10 slits in the anterior, 1 in the median, 14 in the 
posterior valve ; teeth of the tail valve directed forward ; those of 
the central and front valves sharper, deeply serrated outside and at 
the edge. Sinus moderate, deep, flat, with about 20 delicate denti- 
cles. Length 38, breadth 20 mill. 

Siquijor, Philippines. 

Chiton truncatus SOWB., P. Z. S. 1841, p. 61. REEVE, Conch. 
Icon., 1. 16, f. 93.Acanthopleura ? truncate GRAY, P. Z. S. 1847, p. 
68. Tonicia truncata ADS., Genera i, p. 474, and of SHUTTLW. and 
CPU. 

Resembles Tonicia (Fannettia) disjuncta in the partial separation 
of the valves at the sutures. The tail-valve is formed much like 
that of Acanthopleura. 

A variety with nearly smooth valves has been noted from Samar. 
Carpenter described in MS. a Cumingian specimen as T. jugosulcata, 
said to be from Tasmania, but he later regarded it as a form of 
truncata. The locality Tasmania is very doubtful. 

Section Fannettia Dall, 1878. 

Tonicia * * , GRAY, P. Z. S. 1847, p. Q7.Fannyia GRAY 
Guide Moll. B. M., p. 185 (1856). Fannia CPR., not Fannia Rob- 
ineau Desvoidy, 1830. Fannettia DALL, Proc. U. S. Nat. Mus. 
1882, p. 284, 287, 289. 

This section is like Tonicia in all respects except that the mucro 
is flattened, the teeth of insertion are somewhat longer, and the 
broad girdle encroaches upon the valves at the sutures, nearly 
separating them. 

T. DISJUNCTA Fretnbly. PI. 39, figs. 35-41. 

Shell oblong-ovate, reddish-brown, with green and straw-colored 
markings ; valves smooth, glossy, the anterior margins of the dorsal 
valves are arcuate, the beak only of the next forward valve cover- 
ing them, giving the valves a disjointed appearance. Lateral areas 
low ; mucro of tail valve median, subplanate. 

Inside white; anterior valve having 9, central 1, posterior valve 
9 short slits; teeth elongated and strongly grooved outside; 
delicately serrated at the acute margins ; teeth of tail valve short 
and solid behind, elongated in front. Eaves narrow; sinus dentic- 
ulate. 



ACANTHOPLEURA. 213 

Girdle smooth, broad, extending between the valves, and when 
living marbled with vivid red, green and blue. 
Length 62, breadth 37 mill. 

Valparaiso, Chili. 

Chiton disjunctus FREMBLY, Zool. Journ. iii, p. 203, suppl. pi. 17, 
f. 5 (between Oct., 1826 and May, 1827). EEEVE, Conch. Icon. t. 
4, f. 21. GOULD, U. S. Expl. Exped., Moll, and Sh., p. 329. 
Fannyia " dispuncta " [err. typog.] GRAY, Guide, p. 185. Fannia 
disjuncta CPR., MS. 

" The transitions between this species and the normal Tonicice are 
so gradual, that it scarcely seems entitled to generic rank. The 
valves are not much more covered than in T. truncata ; but instead 
of the lateral sinuses being angular, they are gradually rounded, and 
extended to the apices of the valves. The principal peculiarity is 
in the flattening of the mucro ; the creature, having devoted itself to 
lateral expansion, had no need to push its tail up into a hump. 
The slits are as short as if the valves were fully exposed, only extend- 
ing up one-third of the teeth in the anterior valve and one-half in 
the others. Inside, however, the gums rise to the level of the slits, 
so that, when seen from within, the shell appears perfectly normal. 
According to Gould, E. E. Moll., p. 329, the girdle is "distinctly 
cleft" behind. This is duly represented in the Atlas, f. 417. I 
have not, however, been able to trace it in either of the specimens 
examined. That in Dr. Gould's own cabinet, although in good con- 
dition, shows no trace of it. Neither Frembly nor Gray allude to it. 



Genus XV. ACANTHOPLEURA Guilding. 

Acanthopleura GUILD., Zool. Journ. v, p. 28 (in part), -f Core- 
phium GRAY, Maugeria GRAY, Francisia CPR. 

Valves exposed, beaked, generally lusterless or eroded ; provided 
with eyes on the forward part of the lateral areas and the end 
valves ; mucro posterior ; interior colored, the tegmentum broadly 
inflexed at the posterior margin of each valve. Insertion-plates all 
conspicuously pectinated outside, and directed forward. Girdle 
thick, covered with small or large calcareous spines. 

History of the name Acanthopleura. Under Acanthopleura, 
Guilding defined seven sections, naming a representative of each. 
His scheme is here reproduced, the modern equivalents of the species 
named being added in brackets : 



214 ACANTHOPLEURA. 

* Zona spinosa. Chiton spinosus Sow., Gen. f. 1.. 

[==Acanthopleura spinosa Brug.] 
* * Zona spinulosa. Ch. carmichaeiis Gray, Spicil. 

[=Plaxip hora.~] 
* * * Zona granulosa. Ch. asellus Lowe, Zool. Journ. 

[==Lepidopleurus, p. 13.] 
# * * * Zona rugoso-granulosa. Ch. asselloides Lowe. [= 

Trachydermon albus L., p. 70.] 
***** Zona crinita. Ch. crinitus Wood, Index. [=Acan- 

thochites.'] 
****** Zona villosa. Ch. peruvianus Frembly. [= Chwto- 

pleura, p. 28.] 

******* Zona farinosa. Ch. cinereus Lowe. [== Trachyder- 
mon, p. 68.] 

As neither of these sections were selected by Guilding as the typical 
group, we are obliged to select a type for ourselves ; and of course 
the choice must be limited to the species actually enumerated by name 
in Guilding's scheme of sections. We must first exclude such species 
as are already provided with generic names ; and glancing down the 
list we therefore, eliminate section * * *, which falls into Risso's 
earlier genus Lepidopleurus, and section * * * * *, which belongs to 
Acanthochites Risso. Of the five sections remaining, * * was 
separated by Gray in 1847 under the name Plaxiphora. Section 
****** was denominated Chcetopleura by Shuttleworth in 1853 ; 
and for the species included in sections * * * * and * * * * * * *, 
Carpenter established the genus Trachydermon, in 1863. These 
successive dismemberments have left only the first section of Guild- 
ing's arrangement, to represent the original genus ; and Chiton 
spinosus, therefore, becomes the type of Acanthopleura Guilding. 

Unfortunately for science, few authors have arrived at this 
result ; but the fact that it rests upon principles of nomenclature 
from which there is no appeal, will, it is believed, be evident to all. 

Since Guilding's publication of the name, it has been considered 
by the following systematists : 

1840. SWAINSON defines the genus (which he calls " Canthapleura 
Guild."), and names " C. spinosus, Sow. Gen., f. 1 " as the 
representative or type. No other species is mentioned. 

1847. GRAY defines the genus, including in it sections as follows : 

* A. peruviana Lm., bicolor Ad., hennahi Gray, watsonii Sowb. 
[= Chcetopleura -f- Ceratozona.~\ 



ACANTHOPLEURA. 215 

* * This divides into three subsections : 

f A. nobilis Gray. [=EudoxochitonJ] 

f f A. picea Sow., spinigera Sow., owenii Gray, spinosa Brug., 

brevispinosa Sow., magnified Gray. [=MaugeriaJ\ 
1 1 t A. f gigas Gmel. [==Dinoplax] ; A / truncata. [=Ton- 
icia.~] 

Neither of these sections is selected by Gray as typical ; but in his 
" List of the Genera of Recent Mollusca, their synonyma and types " 
P. Z. S. 1847, he gives on p. 168, no. 413, " Aeanthopleura Guild. 
1835; Gray, 1847. Canthapleura Swains., 1840. Ch. spinosa." 
It appears then that not only Swainson, but Gray himself selects C. 
spinosus as the type species. 

1853. SHUTTLEWORTH, in a most scholarly essay, divided Gray's 
Aeanthopleura of 1847 into three sections : Chcetopleura [equivalent 
to Gray's sect. * and part of f f t an( ^ including C. rugosus (Gray) 
Sowb., peruvianus Lm., gigas Chem.] ; JEudoxochiton [for C. nobilis 
Gray]; and Acanthopleura, restricted, [equal to Gray's Aeantho- 
pleura sect, f t pl us Corephium, . with some other miscellaneous 
species]. 

In 1856, GRAY a^ain made a cruel onslaught upon the genus ; 
and here he restricts Acanthopleura to the sect. * of his 1847 
arrangement, ignoring the fact that Shuttleworth had meantime 
given a new name, Chcetopleura, to that section, and apparently 
forgetting that he had himself said in a former paper that C. spinosus 
was the type of Acanthopleura ! In the same paper, he proposes a 
new genus, Maugeria, for the following species, which he arranges in 
two sections : f, M. nobilis \_Eudoxochiton Shuttl. 1853]. f t> 
M. picea Sow., spinigera Sow., owenii, spinosa Sow., brevispinosa 
Sow., magniftca Sow., C. 111., f. 52. He also retains his genus Core- 
phium for C. echinatum Sow., 111., f. 47. 

1858. Messrs Adams, in their Genera, reunite Acanthopleura and 
Corephium, with a choice assortment of other forms, under the 
genus " Chiton Linnceus" As the status of this generic name has 
been fully discussed by me on p. 150, comment here would be super- 
fluous. 

1873-1882. Carpenter, in his MS. arrangement of Chitons (an 
abstract of which was published by Dall, Proc. U. S. Nat. Mus. 1881, 
p. 284, 287), proposes to retain the name Acanthopleura for the 
group of Ch. piceus; Corephium for C. echinatus; and Francisia 
Cpr., nov., for Ch. spinosus. This arrangement is not acceptable 



216 ACANTHOPLEURA. 

because (1) Ch. piceus is not mentioned in Guilding's essay, and 
therefore cannot be the type of his genus. We are not concerned 
with the shadows of species dimly visible upon Guilding's pages, but 
with the species actually enumerated by him, with name and refer- 
ence. (2). Franciisia being founded upon the type of Guilding's 
Acanthopleura, falls as a synonym. 

The eyes, in this genus, are generally obliterated by erosion 
except at the edges of the valves, but they are present in young 
individuals, as in Tonieia. They are smaller than in Tonicia, and 
more numerous. In Mesotomura they are excessively numerous, 
minute and oval. In Acanthopleura spiniger they are larger, cir- 
cular, and scattered around the bases of the tubercles on the lateral 
areas. In Maugeria granulata they are more numerous and more 
scattered. 

The interior layer of the valves is very solid and dense, as in 
Eudoxochiton and Tonicia, even the jugal tract inside and the slit- 
rays lacking punctures. The tegmentum is deeply grooved ov 7 er 
the teeth and sutural-plates. 

Although but few well- differentiated species of Acanthopleura are 
known, the range of individual and local variation is great, and con- 
sequently an extensive literature has arisen, and the synonymy of 
the species is exceptionally involved. It is not improbable that 
some other valid species exist, but if so, they have not yet been 
recognizably defined. 

The group Lucia Gld. (Lucilina Dall) has been considered a sub- 
genus of Acanthopleura, but it proves to be a synonym of Tonicia. 

The genus Acanthopleura differs from Tonicia mainly in the duller 
and sculptured valves, having the tegmentum more broadly inflexed 
over the posterior margins ; in the more numerous, smaller eyes, the 
fleshy girdle clothed with large or small calcareous spines, etc. It 
is not especially allied to any other genus, but some species of 
Liolophura, a genus near Onithochiton, are externally very similar 
to species of the subgenus Maugeria. They may be distinguished at 
once by the smooth toothless ridge in place of the insertion-plate in 
the tail valve. 

All of the species can be readily identified by the following key, 
whether the girdle-covering be preserved or not. It is necessary to 
remove the posterior valve of a specimen, which may be done by 
soaking it for some hours in warm water. The arrangement here 
given is believed to be perfectly natural. 



ACANTHOPLEURA. 217 

Key to subgenera and species of Acanthopleura. 

A. Insertion-plate of tail-valve long, crenulated outside, and 
with a median slit behind, other slits subobsolete or wanting ; 
girdle beset with spike-like spines ; sinus denticulate ; inte- 
rior purple-brown in the cavity and transversely engraved ; 
the sutural-plates white, (Mesotomura) , A. echinatwn. 

A A. Insertion-plate of tail-valve long, crenulated outside, and cut 
by numerous slits ; median valves much wider across the 
sutural-plates than across'the tegmentum or outer coat of the 
valve ; interior not engraved (Acanthoplenra s. s.) 

a. Interior purple in the cavity, sutural-plates white ; 
median valves occasionally Radsioid ; sinus of second 
valve feebly denticulate ; girdle broad, with long black 
spines ; exterior black, A. spinosa. 

aa. Interior livid-flesh or livid purple-colored ; median 
valves 1-slit ; sinus smooth ; girdle wide, with numer- 
ous spinules; exterior dull, generally eroded, 

A. spinigera. 

A A A. Insertion-plate of tail-valve short, blunt ; median valves as 
wide or wider measured across the tegmentum than across 
the sutural-plates ; sinus smooth. 

a. Insertion-plate of tail- valve cut into teeth by 7-11 well- 
developed, subequal slits (Maugeria.} 

b. Interior sea-green (intense or faded), with a 
black tract behind the sinus ; spines of girdle 
very small, valves generally eroded, 

A. granulata. 

aa. Insertion-plate of tail valve crenulated, having an 
oblique slit on each side, the ridge between them either 
continuous or unevenly serrated (AmphitomuraS) 

b. Median portion of tail insertion-plate irregularly 
serrated, but without true slits like the lateral 
tail slits ; cavity of valves purple-black, sutural- 
plates white ; valves usually not eroded outside, 
uniform black, granulated at the sides ; girdle- 
spines rigid, black, tipped with buff, 

A. brevispinosa. 




218 ACANTHOPLEURA. 



bb. Interior of valves blue-white, with a black tract 
behind the white-edged sinus; exterior black 
with a light stripe on each side of the dorsum, 
sides granulated ; girdle black, A. borbonica. 



Subgenus MESOTOMURA Pilsbry, 1893. 

Mesotomura PILS., in the Nautilus vi, p. 105 (Jan., 1893). Core- 
phium GRAY, P. Z. S. 1847, p. 65, 68. Not Corephium BROWN, 111. 
Conch. G. B. edit. I, 1827. 

Acanthopleura : Valves transversely engraved inside, and having 
the sinus denticulate ; tail valve having a long, continuous insertion- 
plate, slit only in the middle. Girdle beset with spike-like spines. 

A monotypic subgenus related to typical Acanthopleura. It is 
remarkable for the stout spines of the girdle, the long, continuous 
insertion-plate of the tail valve, and the finely engraved interior. 
In the last character it can only be compared with Enoplochiton 
niger, which also resembles the present form in having oval eyes in 
the shell. In Mesotomura these eyes are excessively numerous, 
exceeding those of other Acanthoids in number. 

A. ECHINATUM Barnes. PI. 47, figs. 6-17. 

Shell oval or oblong, solid, rather depressed but carinated on the 
dorsal ridge, the lateral slopes slightly convex. Dark brown ; where 
eroded soiled white. 

Valves strongly beaked, having a narrow, smooth and elevated 
dorsal band, with a shallow groove on each side of it, the sides of 
the central areas closely and deeply engraved ivith fine flexuous 
grooves. Lateral areas but little raised, shining, having several radial 
rows of pustules standing upon a smooth ground, which is closely 
studded with minute eyes, or the pits left by their destruction. 
Anterior valve having radiating, spaced rows of pustules ; posterior 
valve having the inucro elevated and near the posterior margin. 

Interior white, unicolored or stained with reddish in the depth of 
each valve ; under a lens it is seen to be finely, closely engraved 
with transverse lines and elongated punctures on the forward slope 
of the central callus, and on the jugular area (fig. 12). Slits in 
anterior valve 8, central valves 1, posterior valve 1 ; teeth long, 
strongly pectinated. Sinus finely denticulate in all valves. 



ACANTHOPLEURA. 219 

Girdle broad, fleshy, beset with strong spike-like spines. The 
gills extend the whole length of the foot. 

Length 100, breadth 55 mill. ; divergence 115-120. 

Length 63, breadth 40 mill. 

Payta, Peru (Dr. W. H. Jones) ; Galapagos (P. Ac. Coll.) ; Val- 
paraiso, Chili (Frerably.) 

Chiton echinatus BARNES, Amer. Journ. Science and Arts, (Silli- 
man's) vii, p. 71, t. 3, f. 4, 46. (1823). SOWERBY, Conch. Illustr., 
f. 47 (young). Chiton tuberculiferus SOWERBY, Cat. Tankerv., p. 
29, no. 688 (1825). Chiton spiniferus FREMBLY, Zool. Journ. iii, 
p. 196, Suppl., pi. 16, f. 1 (1827). Chiton aculeatus REEVE, Conch. 
Icon., t. 9, f. 49. Not C. aculeatus of DESK, et al, nor of Linn. 
Chiton (Corephium) spiniferus Frembl., STEARNS, Proc. U. S. Nat. 
Mus. xiv, 1891, p. 334. 

This large, spiney species is not likely to be confused with anjr 
other, being very distinct in external features as well as in the 
peculiar insertion-plate of the tail-valve, the engraving of the inte- 
rior (reminding one of Enoplochiton niger and Chiton granosus*), and 
the denticulate sinus. The girdle spines are frequently encrusted 
with a white calcareous deposit, converting them into globular 
pellets. The young shell also lacks slits in the posterior insertion- 
plate (figs. 15-17, x 2) ; and the adults sometimes show an addi- 
tional shallow notch or two near the median caudal slit. 

Subgenus ACANTHOPLEURA, s. sir. 

Aeanthopleura GUILDING, I. c. (part), and PILSBRY, The Nauti- 
lus vi, p. 105, Jan. 2, 1893. Francisia CARPENTER in DALL, 
Proc. U. S. Nat. Mus. 1881, p. 284, 289, 290 (1882.) 

Aeanthopleura: Tail valve having a long, many-slit insertion- 
plate, crenulated outside ; median valves much wider across the 
sutural-plates (or articulamentum) than across the exposed portion 
(tegmentum.) 

The facts which cause me to consider this the typical group of 
Aeanthopleura have been discussed above. The affinities of the sub- 
genus are with Maugeria and with Mesotomura. With the latter it 
agrees in the coarsely spiney girdle, interior coloring, denticulate 
sinus and long insertion-plates; but it differs from that group in 
having a many-slit tail-plate, in the frequent (or usual) plurality of 
side-slits, the nearly smooth exterior, etc. In the form and dentic- 



220 ACANTHOPLEURA. 

ulation of the valves, and in interior coloring, A. spinosa is very 
closely allied to A. spiniger Sowb., from which the occasional radsi- 
oid slitting, and the feeble denticulation of the sinus in the second 
valve, separate it specifically. Dr. Carpenter's subgenus Francisia 
included A. spinosa only. 

A. SPINOSA Bruguiere. PL 45, figs. 80-87. 

Shell oblong, depressed, smoothish and black ; girdle wide, covered 
with long, brittle black spines. 

The valves are smooth except for growth-lines on central areas 
and some inconspicuous radial wrinkling or obscure granulation on 
the very feebly defined, small, lateral areas. End valves somewhat 
rugose-granose radially, the mucro posterior. 

Inside purple-red in the middle, white on the sutural-plates and 
the region of the lateral slit-rays. Sinus of second valve cut into 
delicate square denticles by short linear slits, but in the other valves 
the denticulation is obsolete. Slits in anterior valve 15, central 
valves 1 or 2, posterior valve 10 ; teeth of end-valves long, grooved 
outside and crenulated at the edges, the posterior teeth vertical; 
teeth of intermediate- valves triangular, the posterior tooth, when 
present, very small. Sutural plates long, separated by a deep sinus 
broader than the plates. 

Girdle wide, rusty, beset with long brittle black spines (fig. 86.) 

Length 50, breadth 28 mill. 

Albany Island, Cape York, North Australia (Challenger.) 

Chiton spinosus BRUGUIERE, Journal d'Histoire Naturelle, i, p. 
25, t. 2, f. 1, 2 (1792). LAMARCK, An. s. Vert, vi, p. 321 (1819). 
SOWERBY, Genera of Shells, Cephala, Chiton, f. 1 ; and Conch. 
Illustr. p. 1, f. 151. REEVE, Conch. Syst. ii, p. 12, t. 134, f. 151 ; 
and Conch. Icon., t. 9, f. 51. Francisia spinosa CARPENTER MS. 
Maugeria spinosus GRAY, Guide Moll, B. M., p. 184. Francisia 
spinosa HADDON, Challenger Rep., p. 30. 

The radsioid slitting of some of the valves and the lack of distinct 
areas and valve sculpture, well distinguish this species. The slits 
are really very short, but are continued on the outside as grooves, 
up to the eaves. The eyes appear as minute amber colored beads, 
sparsely scattered down the forward half of the lateral areas, but 
scarcely arranged in rows. Poorly preserved or very old specimens 
show their pits only. 



ACANTHOPLEURA. 221 

Nuttallina scabra Rve. bears a slight resemblance to this species, 
but it is differently sculptured, has smooth teeth and less spiny 
girdle. The tail-plate of A. spinosa is like that of Katharina tun- 
icata, on account of the long, vertical teeth. 

A. SPINIGER Sowerby. PL 48. 

Shell oblong-oval, moderately elevated or depressed, lusterless, 
microscopically granulated and having a more or less developed 
sculpture of granules which either stand distinct or coalesce to form 
concentric wrinkles. Color dead-leaf brown or soiled whitish where 
eroded ; generally black at dorsal ridge and sides of each valve or 
some of the valves ; on each side of the black dorsal stripe there is 
generally a streak of green. Girdle broad, black or alternated with 
whitish.' The valves are rounded at the ends, somewhat beaded ; 
lateral areas but little raised, granulated or wrinkled, the forward 
part crowded with microscopic bead-like amber eyes. Central areas 
having wrinkles of growth and sometimes low, scattered granules, 
more numerous and stronger at the sides. Posterior valve having 
the mucro somewhat behind the center. 

Interior of a purple-brown color, darker in front of the callus of the 
valve and on the sutural plates, lighter behind the callus of the 
valve. Sutural-plates broad, extending laterally much beyond the 
rounded ends of the tegmentum. Sinus rounded, sometimes black- 
edged. Anterior valve having 9-11, central valves 1, posterior 
valve about 7 (6-10) slits ; teeth pectinated, those of the tail-valve 
much longer than the eaves. 

Girdle broad, closely covered with calcareous black or buff spines 

Length 70, breadth 43 mill. 

Fiji Is. ; Viti Is.; New Caledonia (A. Garrett in Phil. Acad. Coll.) ; 
Cagayan, Isl. of Mindanao, and Siquijor, Philippine Is. (Cuming) ; 
New Guinea, New Ireland, and Tonga-Tabu, (Quoy and Gaimard) ; 
Port Essington (Jukes) ; Port Molle and Clairmont and Bird Island 
(Coppinger); Lat. 10 36' S., Long. 141, 55' E., Albany Island, 
Cape York, North Australia, in 6 fms. (Challenger.) 

? Chiton aculeatus LINNE, Syst. Nat. x, p. 667 (founded upon 
Rumphius Amboinische Rariteitkamer, pi. 10, fig. 4.) 

Chiton nicobaricus aculeatus, CHEMN. Conch. Cab. x, p. 375, f. 
1692. Chiton aculeatus SPENGLER, Naturhist. Selskabet, iv, p. 78. 
Chiton aculeatus QUOY & GAIMARD, Voy. de T Astrolabe, Zool. 
iii, p. 373 ; atlas, t. 74, f. 1-5 (1834), 



222 ACANTHOPLEURA. 

C. spiniger SOWB., Mag. of Nat. Hist. 1840, p. 287, Suppl. pl.xvi, 
f. 2 ; P. Z. S. 1841, p. 61 ; Conch. Illustr., f. 68. REEVE, Conch. 
Icon., t. 14, f. 75. Maugeria spinigera GRAY, Guide Moll. B. M., 
p. 184 (1857). Acanthopleura spinigera CPR., MS. and DALL, Proc. 
U. S. Nat. Mus. 1882, p. 80. Chiton (Acanthopleura') spiniger 
SMITH, Zool. Coll. H. M. S. ' Alert,' p. 81 (1884) ; P. Z. S. 189J, p. 
420. Acanthopleura spiniger HADDON, Challenger Polyplac., p. 
23. Acanthopleura balansce ROCHEBR. Bull. Soc. Philomath. Paris, 
1881-2, p. 197. 

?? Maugeria owenii GRAY, Guide Moll. B. M., p. 184 (no descrip- 
tion or figure). ? ? Chiton gemmatus BLAINV., Diet. Sc. Nat. xxxvi, 
p. 544. 

It is now impossible to prove that this is, or is not, the Chiton 
aculeatus of Linne ; but any one who will consult the original 
description, " C. testa octovalvi ztriata, corpore subaculeato" then turn 
to Rumphius' figure cited as an illustration, will be prepared to 
acquiesce in Hanley's suggestion (Ipsa Linn. Conch.) that the 
species be dropped as unidentifiable. Gmelin had no better informa- 
tion upon this species than we ; and therefore his additional citations 
of figures are valueless. The mere fact that the figure cited by 
Linne represents an oriental species is offset by the absolute impos- 
sibility of knowing that it was an Acanthopleura. 

Besides the localities given above, this species has been reported 
from Suez by Issel (Mai. Mar Rosso p. 235, and see also Cooke, 
Ann. Mag. N. H. 1885, p. 276), from Aden by Haddon (Challenger 
Polyplac., p. 24). It has been figured from the Red Sea by Savigny 
(see pi. 3, figs. 4, 1-2 of his folio). Probably Savigny's figs. 7, 1-3 
of the same plate represent a young shell of the same, although I 
have seen none closely corresponding in sculpture. The eyes are 
distinctly drawn by the artist, a rather remarkable circumstance 
when we remember that no subsequent illustrations of Chitons show 
them ! Additional localities are New Zealand reported by Q. & G. 
and Hakodadi, Japan by Schrenck (Amurl. Moll. p. 275) ; but 
these two localities must be regarded as doubtful until confirmed by 
either fresh specimens or a critical re-examination of the specimens 
and data in each case. 

The study of the Indo-Pacific Acanthopleuras may be somewhat 
simplified by the elimination of (1) A. borbonica, characterized by a 
bifissate tail-valve (pi. 45, fig. 77) and (2) the " Acanthopleura " 



ACANTHOPLEURA. 223 

incana of Australia and the so-called Acanthopleuras of Japan, 
which are characterized by a flat crescentic callus in place of the 
teeth in the tail- valve (pi. 53, fig. 35). 

The variation of this species is great, and a number of subspecific 
or varietal forms will probably be distinguished eventually. My 
material is not extensive enough to permit me to diagnose these, or 
to indicate their areas of distribution ; and I therefore offer below 
the original descriptions of the several described forms. 

Typical SPINIGER is characterized by the possession of longer 
spines than any of the other forms. It is thus described by 
Sowerby : 

C. spiniger Sowb. (pi. 48, fig. 22). Shell depressed, ovate-elong- 
ated, all over granulated ; valves reclining, ends rounded ; girdle 
wide, furnished with numerous subarcuate spines. .Length 2*1, 

width 1'5 inch. Habitat ? Mus. Stainforth. Another spini- 

ferous species, rather narroAV in proportion to its length ; depressed 
and finely granulated ; the valves are rounded at the lateral extrem- 
ities, with their apices leaning backward, and their lateral areas 
scarcely distinguished ; numerous slightly curved spines, nearly one- 
half an inch long, cover the margin ; general color like a faded leaf, 
with dark patches of reddish-brown covering the lateral and part of 
the central areas of some of the valves, and a dark dorsal band 
bordered by bright green and white (Sowb. in Mag. Nat. Hist.) 

The fig. 22 is a copy of the original one published in Mag. Nat. 
Hist., and fig. 23 of that in the Conchological Illustrations, which 
probably represents the same specimen. Note the length of the 
girdle-spines. 

Reeve's figure (pi. 48, fig. 27) represents a larger specimen, 
collected by Cuming in the Philippines. In this the spines are 
much shorter. Figs. 24-26, pi. 48, represent valves from a specimen 
very similar in all respects to Reeve's figure (see pi. 48, fig. 27). 
The granulation is rather obscure, or transformed into low wrinkles. 
The spines on the very wide girdle are both long and short (1-11 
mill.) 

Figs. 31, 32, pi. 48, are drawn from a specimen from the Viti Is. 
collected by Andrew Garrett. In this specimen the dorsal ridge has 
a blackish -green band with a wider fleshy-white triangle on each 
side of it, and a streak of green, the rest of the surface of the valves 
being black except the large ashy-eroded patch on each side of the 
black (eroded) beaks. The central areas have some scattered gran- 



224 ACANTHOPLEURA. 

ules on the light bands, and toward the diagonal lines ; the lateral 
areas have rather coarse, irregular granules. The girdle is covered 
with alternate black and whitish patches of spines, these being all 
curved like a Dentalium, rather blunt, the longer of them measuring 
about 2? mill, in length. 

Another specimen, from New Caledonia, is similar, but has no 
white patches on the girdle, the spines being 3-3? mill, long, and 
black, often tipped with light color. 

The C. macgillivrayi Ad. (P. Z. S. 1855, p. 120) seems to be very 
similar, to this variety, if not identical ; the original description 
follows : 

C. macgillivrayi A. Ad. Shell oblong-oval, a little elevated ; 
black, the central areas painted with two pale longitudinal stripes; 
valves obtuse, under a lens seen to be most minutely granulated, 
ornamented with concentric undulating rugose-grained line ; ter- 
minal valve umbonated in front, umbo rather smooth, slightly pro- 
duced ; girdle set with black, curved, slightly obtuse calcareous 
spines. Feejee Islands, on the reefs ( J. Macgillivray). This is a 
well-marked and handsome species, rather more than two inches in 
length ; the surface of the valves is finely granulated and orna- 
mented besides with subgranulated, wavy, concentric elevated lines ; 
the central areas have a pale greenish band on each side of the 
umbo. (Ad.~) 

Carpenter gives the following notes upon the types : Four spec- 
imens, with A. Adams' autograph label. Bristles rather long for 
the group, crowded and curved, black, but often tipped with light 
as in brevispinosa. Sculpture with granules like borbonica in the 
young, but soon changing to concentric wrinkles. Mucro prominent, 
somewhat antemedian, the posterior slope convex. Jugal area 
granose ; in one specimen only are there white streaks making V's on 
the valves. Sculpture of central areas gradually changing from 
grains into wrinkles toward the diagonals. Lateral areas scarcely 
distinguished ; concentric wrinkles predominating. On the terminal 
valves the sculpture is much finer, the rugulse breaking up into 
grains. Inside color dark. The divergence is very variable, one 
specimen being quite elevated, the others flatter ; measuring 103, 
126, 114, 129. 

The granatus of Reeve seems to be an unusually granose example 
of spiniger, such as that figured on pi. 48, fig. 28. The description 
here follows : 



ACANTHOPLEURA. 225 

C. granatus Reeve (pi. 48, figs. 29, 30). Shell oblong-ovate ; 
valves strongly, roughly grained, especially at the sides ; umbos 
smooth ; dirty ash or stone color, grains blackish, umbonal eminence 
blotched with black ; ligament horny, jet black. Habitat - ? 
{Reeve.} 

The figured type, according to Carpenter, has lost it's anterior 
valve and girdle spines. The tail-valve should be examined in order 
to tell whether it is a specimen of spiniger or of borbonica, but I am 
disposed to believe it the former. 

Fig. 28, of pi. 48 is drawn from a large specimen belonging prob- 
ably to the granatus form. The dorsum has a green band flanked 
by creamy-flesh colored wider bands, more or less suffused with 
green. The surface is very strongly granulated. 

Reeve's C. CUNNINGHAMI, to which piceus Rv. non Gmel. and 
obesus Shuttlw. may be added, probably represents a variety char- 
acterized by the large size, fine girdle-spines, etc. 

C. cunninghami Reeve (pi. 49, figs. 33, 34). Shell oblong-ovate, 
valves rather thick, concentrically ridged throughout, radiated from 
the umbones with raised striae ; posterior terminal valve retusely 
umbonated ; lateral areas scarcely distinguished; greenish-black, 
valves longitudinally painted in the middle with a brown band ; 
ligament horny. (Reeve.} 

Australia. 



., Conch. Icon., t. 27, f.181, Oct. 1847." C. 
magnificus Gray?" SOWB. Conch. Illustr., p. 2, fig. 52 (not 
described.) 

The identity of the undescribed 0. magnificus (Gray) Sowb. non 
Desh., with Reeve's C. cunninghami, is evident, the figures being 
extremely similar. 

Carpenter gives the following notes on the type : " One specimen, 
marked by Baird (and rightly, I think) to be the same as piceus 
Rve. The valves are remarkably well grown, in quiet waters, and 
the sculpture is rather differently developed in consequence. The 
girdle has dried in around the valves, and the hairs are worn off" 
except in the sutures, where they are short, crowded and black. 
Reeve's figure is very good except that the jugular parts appear too 
decided; they are simply worn smooth. The mucro is elevated, 
central, posterior slope convex ; jugular area eroded ; central areas 
wrinkle-granose, rugulse radiating forward, more or less inter- 



226 ACANTHOPLEURA. 

rupted into granules by wrinkles of increment ; lateral areas scarcely 
defined. Divergence 127. 

The following is believed to be practically identical : 

C. picem Reeve. (PI. 49, figs. 38, 39). Shell ovate, rather thick, 
valves concentrically flatly ridged, interstices between the ridges 
elevately striated and sometimes grained, umbos a little beaked; 
pitch-black, greenish on each side the umboual summit ; ligament 
horny, profusely beset with whitish short calcareous bristle-like pro- 
cesses. New Holland, on the rocks (Cunningham). This I believe 
to be the true C. piceus ; it is a thick ponderous shell, of which the 
ligament, when in a good state of preservation, is covered with 
calcareous bristle-like processes, as in C. spiniger but much finer. 
(Reeve.) 

Chiton pieeus REEVE, Conch. Icon., t. 13, f. 70, March, 1847. 
ANGAS, P. Z. S. 1867, p. 223. TAPPARONE-CANEFRI, Zool. Viag. 
Magenta, Malacologia, p. 77 (1874). C. obesus SHUTT., Bern. 
Mittheil. 1853, pp. 67, 79. 

Angas says that this species is freely distributed on most parts of 
the coast of New South Wales. The specimen commented upon by 
Canefri was collected at Sydney ; but both may be founded upon 
wrong identifications. Carpenter writes of the types as follows : 
"Four specimens from Australia. The figure of Reeve is much 
larger than the type, and would stand well for a perfect 
cunning hami. The largest shell measures : length 77, breadth 49 
mill., divergence 108. This is a more raised shell than cunning- 
hami, probably from its having grown in rougher water. Spines 
very short, black, sometimes white. Sculpture almost entirely worn 
away in all the specimens ; when seen it consists chiefly of concentric 
wrinkles more or less broken into granules. The lateral areas are 
scarcely distinguishable; mucro very perfect, post-median like 
cunninghami, but rather more elevated, as is the rest of the shell." 

Subgenus MAUGERIA Gray, 1857. 

Maugeria GRAY, Guide Syst. Dist. Moll. Brit. Mus., p. 183 (in 
part). Acanthopleura CARPENTER, Table Reg. Chit. 1873, and 
Dall, Proc. U. S. Nat. Mus. 1881, p. 284, 289, 290 (in part) ; Not 
Acanthopleura Guilding, q. v. 

Exterior lusterless; tail valve having numerous (7-12) slits in 
the short crenulated insertion-plate, median valves 1-slit, the exposed 
coating or tegmentum wider than the articulamentum or inner layer ; 



ACANTHOPLEURA. 227 

sinus not toothed, the sutural plates connected across it ; girdle 
thick, densely beset with calcareous spinelets. Type Ch. granulatus 
Gmel. 

This subgenus or section differs from Acanthopleura and Mesoto- 
mura in the shorter, blunt tail insertion -plate, and the proportionate 
breadth of the outer and inner layers of the median valves. It 
differs from Amphitomura in having numerous equally developed 
slits in the insertion-plate of the tail valve. 

A. GRANULATA Gmel. PI. 50. 

Shell oblong, moderately elevated or roundly arched. Surface 
almost always eroded, dull, ashy or cinereous, generally with a 
patch of dead-leaf brown on the ridge of each valve ; when not 
eroded, it is tawny-brown or black-brown, with a pair of diverging 
whitish, buff or pinkish stripes. 

The valves are beaked, solid and thick, with somewhat raised but 
ill-defined lateral areas. When not eroded, the lateral areas and 
pleura are closely granulated all over, and the end valves likewise ; 
but this sculpture is generally preserved only at the lateral extrem- 
ities and the protected anterior margin of each valve. The mucro 
is swollen and posterior. 

Interior sea-green, often varying toward lead-blue, or on the 
sutural-plates fading to nearly white ; each median valve having a 
black or purple- black tract between the sinus and the summit of the 
callus, fyis tract being square or 2-branched at the ends. Anterior 
valve having normally 8-10, central 1 (rarely 2), posterior valve 9, 
(occasionally 7-14) slits; teeth long and very deeply pectinated 
outside; teeth of tail-valve short and obtuse, directed forward, very 
deeply pectinated outside and on the edge. Sinus slightly concave, or 
convex and notched at the sides, not denticulate. 

Girdle thick and fleshy, densely covered with short, unequal spine- 
lets (pi. 50, figs. 40, 41, x 13) which are short, calcareous, and either 
black or white ; the black spines (fig. 41) being frequently longer 
than the white, and straight or nearly so ; the white spines (fig. 40) 
are short, very unequal and shaped like the shell of Cadulus. 

Bermuda; Bahamas; Charlotte Harbor, Vaccas Key, etc., west 
Florida ; entire West Indies, southward to Trinidad and the Spanish 
Main. 

Chiton magellanicus GMELIN, Syst. Nat. xiii, no. 12, p. 3204. 
( Chemn. viii, p. 279, pi. 95, f. 797, 798, Chiton magellanicus'). 



228 ACANTHOPLEURA. 

WOOD, General Conchol., p. 18, t. 3, f. 6 (1815). Chiton granulatus 
GMEL., /. c. no. 16, p. 3205 (=Die pechschwarze granulirte Chiton 
CHEMNITZ, Conchyl. Cab. viii, p. 284, t. 96, f. 806). WOOD, Gen. 
Conch., p. 9. d'ORB., Moll. Cuba (Ramon de la Sagra, Hist.), ii, p. 
200 (1853). Chiton piceus GMEL., I. c. no. 17, p. 3205 (Chernn. viii, 
p. 285, t. 96, f. 807-810). WOOD, Gen. Conch., p. 8, t. 1, f. 3. 
SOWERBY, Conch. Illustr. f. 147. SHUTTLW., Bern. Mittheil. 1853, 
p. 78, and of most later writers on the Antillean fauna. Chiton 
occidentalis REEVE, Conch. Icon., t. 14, f. 77a. (1847). Chiton sala- 
mander SPENGLER, Skrivter af Naturhist. Selskabet, iv, p. 80 ( 
Chemn. viii, f. 806. Chiton tubereulatus L., SCHROETER, Einleit. 
iii, p. 494, t. 9, f. 19 ("Der cylindrische Chiton ") ; not C.tubercula- 
tns Linne. Chiton unguiculatus BLAINVILLE, Diet. Sc. Nat. xxxvi, 
p. 544. C. convexus BLAINV. 1. c. Chiton (Acanthopleura) blauneri 
SHUTTL. Journ. de Conchyl. 1856, p. 170. ? C. (A.} mucronulatus 
SHUTTL., Bern. Mittheil. 1853, p. 79. 

This species is the common Chiton of the West Indies, being 
abundantly distributed throughout the group, the specimens before 
me being from the following localities : Bermuda (Heilprin) ; Key 
Vaccas, Florida (Calkins, Hemphill) ; Bahamas (H. C. Chapman, 
J. J. Brown, F. Stearns) ; Jamaica (Johnson and Fox) ; San Dom- 
ingo (Gabb) ; St. Thomas (Swift) ; Dominica (Sharp) Monos, 
(Sharp) ; Atlantic coast of Costa Rica (Gabb). The specimens 
are almost always eroded, the original color and sculpture being 
quite lost. Although the species is very variable, no local forms 
deserving varietal rank are known to me. 

Figures 39-41 represent a St. Thomas specimen, eroded in the 
usual manner. Fig. 48 is also drawn from a St. Thomas specimen 
in which the sculpture is perfectly preserved, and the color uncom- 
monly dark. 

Figures 44-47 represent valves of examples from St. Domingo. 
The non-eroded forward part shows a central brown band, with a 
flesh-colored band on each side of it. This coloring is also found in 
most specimens from Florida Keys (fig. 43), Jamaica, St. Thomas. 
Specimens from the Bahamas have the two light stripes blue-white, 
and are strongly corrugated. 

The tail-valve varies greatly in respect to the prominence of the 
mucro. In some specimens (fig. 46) it projects beyond the pos- 
terior edge of the valve ; in others it hardly attains the edge; but 
these variations do not seem to be correllated with other characters. 



ACANTHOPLEURA. 229 

The identity of C. magellanicus Gm. and Chemn. with the West 
Indian species, although extremely probable, cannot be regarded as 
absolutely established. At all events the name is hardly acceptable, 
for no Acanthopleura of this type has been collected at or near the 
Strait of Magellan. Rochebrune's citation (Moll. Cap Horn) is 
worthless, on account of his ignorance of generic and specific charac- 
ters in this group, and his false synonymy in the case of this species. 
Gmelin's C. granulatus, the next name in order of priority, was 
founded upon specimens from St. Thomas excellently described and 
figured by Chemnitz. The identity of the next form described 
by Gmeliu, piceus, is also moderately sure. Reeve's C. occidentalis 
(see pi. 50, fig. 42) is an ordinary form of granulatus. 

Shuttleworth has described two West Indian Acanthopleuras of 
which I have not seen authentic examples. His descriptions here 
follow : 

C. {Acanthopleura) mucronulatus. Shell oblong-ovate, elevated, 
narrowed in front, black-brown, unicolored ; valves all over very 
minutely concentrically punctate-striate, carinated dorsally, pro- 
duced backward in a short apex ; lateral areas slightly elevated. 
Girdle spotted with white, having scattered very minute, sand-like 
grains. Length 9, breadth 6 mill. Porto Rico, Blauner ! Described 
from a single specimen ; distinguished from the young of granulata 
by the form and especially the very minutely sanded girdle. Shell 
inside dull whitish, slightly greenish. 

This may prove to belong to some other group. C. {Acantho- 
pleura) blauneri Shuttl. was founded on a single black-brown spec- 
imen from Porto Rico, having unicolored black girdle densely 
clothed with very minute spines, more minute than in piceus, from 
which blauneri also differs in being more depressed and more 
minutely sculptured. Length 52, breadth 32 mill. I do not see 
that this falls outside of the well understood range of variation of 
A. granulata. 

The following unfigured form may prove to be a distinct species if 
the locality be confirmed. 

Chiton (Acanthopleura) piceolus Shuttl. Shell ovate, wider 
behind ; obscure olivaceous, maculated with black at the middle of 
the back and at the sides; valves all densely and minutely pus- 
tulose-granulate ; areas entirely obsolete. Girdle minutely and very 
densely sandy-spin ulose, alternately maculeated brown and white. 
Length 10, breadth 6 mill. (Shuttl. Bern. Mittheil. 1853, p. 82.) 

Tenerife, Canaries, (Blauner) ; rather common. 



230 ACANTHOPLEURA. 

Intense black-green inside. Color, pattern and sculpture are as 
in young C. piceus Grnel., but it differs in the much smaller, more 
delicate girdle spicules. (Shuttl.) 

Subgenus AMPHITOMURA Pilsbry, 1893. 

Amphitomura PILS., The Nautilus, Jan., 1893, p. 105. Type Ch. 
borbonicus Dh. 

Girdle and all valves but the eighth formed as in Maugeria. Tail 
valve having the insertion-plate very short, with blunt, crenulated 
edge, and a single shallow oblique slit on each side, and sometimes 
some uneven serrations in the middle. 

The Mopaloid slits of the tail- valve are very peculiar, but the 
structure is fore-shadowed in some forms of Maugeria. 

A. BORBONICA Deshayes. PI. 45, figs. 76, 77, 78, 79. 

Shell oblong, rather elevated, solid, roundly arched, dull black 
with a white stripe on each side of the median black band; rusty 
blackish and gray when eroded ; girdle black. 

The lateral areas are but slightly raised, and are densely, finely 
sculptured with close radiating rows of granules ; the sides of the 
central areas are also granulated adjacent to the lateral areas, but 
toward the middle this sculpture disappears, leaving only a faint 
microscopic granulation. End valves radially, densely, granulated, 
the mucro posterior, rather elevated. 

Interior blue-white, each median valve having a broad black square- 
ended crescent in front of the callus, the inflexed posterior margin 
ashy-olive, lateral triangles lead- white. Sinus deep, rounded. 
Anterior valve having 10, central valves 1, posterior valve 2 slits 
(figs. 76, 77) ; teeth pectinated, those in the front of the head-valve 
short. Eaves wide, black, channelled along the teeth. Muscle 
impressions on sutural plates and end valves deep. 

Girdle fleshy, black, covered with black spinules about 1? millim. 
long. 

Length 50, breadth 30 mill. ; divergence about 125. 

Mauritius ; Reunion. 

Chiton borbonicus DH., Moll. Reunion, p. 37, t. v, f. 12, 13. C. 
(Acanthopleura) borbonicus Dh., MARTENS in Mobius' Reise nach 
Mauritius, p. 300. ? ? Chiton nebulosus WOOD, Index Test, Suppl., 
t. 1, f. 4. 



ACANTHOPLEURA. 231 

Readily recognized by the black, granulated sides, and smoother 
two-striped ridge, in connection with the peculiar insertion-plate of 
the tail valves. Smith has placed the species with doubt in the 
synonymy of A. spiniger, where it certainly does not belong ; and 
Martens, also erroneously, suggests its identity with Ch. petholatus 
Sow. 

The insertion-plate of the tail-valve, while in some specimens 
somewhat uneven, is not often so serrated as in A. brevispinosa. It 
further differs from that species in the striped back and the interior 
coloration. The crescent-shaped black patch behind the sinus inside 
is square or forked at the ends, as in A. granulata, and the edge of 
the sinus is white. 

A. BREVISPINOSA Sowerby. PI. 47, figs. 18, 19, 20, 21. 

Shell oblong oval, depressed, each valve beaked and concentrically 
rugose-granulated. Color black, the girdle narrow, clothed with 
white-tipped black spinelets. 

The valves concentrically wrinkle-grained at the sides of the 
central areas, and the ill-defined lateral areas are cut into granules 
by concentric and radiating grooves. End valves finely grooved radi- 
ally, finely wrinkled concentrically ; mucro posterior, prominent and 
rather acute. 

Interior blackish-broivn or purple-brown except the sutural- and 
insertion-plates which are white. Sinus broad, deep, rounded. 
Anterior valve having 7-8, central 1, posterior 2 slits and a number 
of irregular serrations ; anterior teeth moderately long, finely pect- 
inated outside ; posterior teeth very short, blunt, obsoletely pectinated. 

Girdle rather narrow, clothed with rigid black spinelets tipped 
with buff. 

Length 42, breadth 26 mill. ; divergence about 130. 

Johanna, Comoro Is. (Cuming, Cpr.) ; Zanzibar (Cpr.) ; Cape of 
Good Hope and Madagascar (Paris Mus.) ; Strait of Saint Vincent, 
Cape Verde Is. (Cessac.) 

Chiton brevispinosus SOWB., Mag. of Nat. Hist. 1840, p. 287, t. 
xvi, f. 1 ; Conchol. Illustr., f. 136. REEVE, Conch. Icon., f. 52. 
Acanthopleura brevispinosa ROCHEBR., Nouv. Arch, du Mus. 1881, 
p. 240. 

Part of the localities given above are probably incorrect. A good 
many shells procured at " Cape of Good Hope" and "Zanzibar" 



232 LIOLOPHURINA:. 

never grew at those places. The evidence in favor of the Comoro 
Is. is more satisfactory. 

This species is closely allied to A. borbonica in sculpture, but it 
differs in having flatter, thinner valves, longer, white-tipped spines, 
in lacking the white dorsal stripes as well as in the color of the inte- 
rior. Finally, the characters of the tail insertion plate differ. 

Subfamily LIOLOPHUKIN^. 

Median and anterior valves provided with eyes, and having well- 
developed insertion-plates with slits, the teeth pectinated outside, not 
thickened at the edges of the slits. Posterior valve with the mucro 
posterior and terminal ; its insertion-plate obsolete, reduced to a low 
ridge or flat ledge of callus, which is unslit (except in ScJiizochiton) 
and continuous posteriorly or interrupted in the middle by a caudal 
sinus. Gills as long as the foot. 

This group is closely allied to Chitonidce and has doubtless been 
derived from the Tonicioid branch of that stock. It is separated 
from them on account of the degeneration of the posterior valve and 
especially its insertion-plate, a character of vastly less importance 
than Carpenter supposed. The median notching of the tail valve 
behind is also extremely variable, as is exemplified by such closely 
allied forms as Lorica volvox and L. angasi. All of the genera of 
Chitonidce, Chiton, Eudoxochiton, Tonicia and Acanthopleiira, show 
species in which the tail valve has an incipient caudal sinus, or in 
which the insertion-plate is becoming obsolete, or both conditions. It 
is only necessary to mention Chiton jugosus (p. 178), Eudoxochiton 
(pp. 193, 194), Tonicia confossa (p. 210); Acanthopleura spinigera, 
ail showing more or less posterior emargination ; Acanthopleura 
granulata and the section Amphitomura have the posterior insertion- 
plate very short, some forms of the latter having it nearly deprived 
of slits. Compare with these Schizochiton and Lorica, the latter 
having the insertion-plate short but distinctly crenulated. It is 
probable that deposits ,not older than . Miocene will furnish the 
generic links now missing between the series of forms here included 
in Toniciince and those grouped in Liolophurince. 

It is a notable fact that the generic groups of Toniciince and Lio- 
lophurince seem to mutually correspond to one another, as though 
the several generic stocks of the former subfamily had been simul- 
taneously modified in the same manner, thus : 



Toniciinse. 



Tonieia 



Maugeria 



LIOLOPHURINSE. 

f Eyes disposed in radiating bands ; 1 
I valves polished and bright colored I 
} outside, porcellanous within ; girdle f 
(^leathery, nude. 

f Eyes scattered among the tubercles 1 
J of the surface, which is rough and 
I lusterless ; interior dark ; girdle 
(^clothed with calcareous spines. 



233 

Liolophurinse. 



~ . , ,. 

Omthochiton. 



Liolophura. 



{Eyes very minute, oval, scattered ; 1 
surface of valves brown and polished 7 ,. 
, . *. 'i r Jbnoploc niton. 

outside when not eroded, peculiarly 
sculptured inside. 

The genera Loriea and Schizochiton have no representatives in the 
Toniciince, for while they are closely allied to the latter, they have 
been differentiated along a line away from that taken by Onitho- 
chiton and its immediate allies. 

Synopsis of Genera. 

A. Median valves having eyes developed only on the diagonal ribs. 
Sinus notably narrow and small. Insertion-plate of tail valve a low, 
rounded, rugose ridge more or less notched or waved upward in the 
middle behind, or sharp, long and pectinated. 

B. Eyes large, situated on the diagonal ribs and on the ribs of the 
head valve, the latter corresponding to slits in the insertion-plate. 
Girdle having minute calcareous spines. 

Genus XVI. SCHIZOCHITON Gray. 

Much elongated. Posterior valve having a deep caudal sinus 
with one or two notches on each side of it in the insertion-plate. 
Head valve with few (about 6) slits. Girdle sparsely, finely spinulose, 
slit behind. 

BB. Eyes reduced to minute, functionless punctures on the summit 
of the diagonal ribs, and entirely absent on the head valve, the riblets 
of the latter not corresponding to internal slits. Girdle densely scaly. 

Genus XVII. LORICA H. & A. Adams. 

Oval or ovate, elevated. Posterior valve having a deep caudal sinus 
or a shallow wave, the insertion-ridge otherwise uninterrupted. 



234 SCHIZOOHITON. 

Head valve with numerous (8-10) slits. Girdle densely clothed 
with minute, convex, crowded scales. 

Section LORICA s. str. Caudal fissure deep ; sinus v-shaped ; 
girdle widest at the sides, slit behind. 

Section LORICELLA Pils. Caudal fissure reduced to a shallow 
wave ; sinus bilobed ; girdle widest in front, not slit behind. 

AA. Eyes developed upon the lateral areas. Sinus wide and large. 
Insertion-plate of the tail valve reduced to a smooth ledge or ridge,, 
having no posterior sinus or wave. 

Genus XVIII. ENOPLOCHITON Gray. 

Valves polished or deeply eroded, dark brown outside and within, 
having excessively minute eyes scattered over lateral areas and 
head valve (when not eroded) ; interior very densely and minutely 
and peculiarly grooved and punctured. Girdle fleshy, bearing 
separated rude scales. 

Genus XIX. ONITHOCHITON Gray. 

Valves polished, colored outside, porcellanous and smooth within,, 
having the eyes disposed in radial bands on each lateral area and 
the head valve. Girdle leathery, microscopically velvety. 

Genus XX. LIOLOPHURA Pilsbry. 

Valves lusterless, granulated, having the minute eyes scattered 
over the lateral areas, sides of the central areas and head valve. 
Girdle densely covered with stout calcareous spines. 



Genus XVI. SCHIZOCHITON Gray, 1847. 

Schizochiton GRAY, P. Z. S. 1847, pp. 65, 68, 169. 

Valves exposed, elongated, beaked, bearing a single row of eyes 
upon each diagonal rib of intermediate valves and each radiating 
rib of the head valve, the ribs of the latter corresponding in position 
to slits in the pectinated insertion-plate. Sinus narrow. Posterior 
valve having a deep posterior fissure, and several slits on each side 
of it. Girdle slit behind, bearing small calcareous spinelets. Type 
Ch. incisus Sowb. 

This genus might as readily be referred to Toniciince as to Liolo- 
phurinw, for the posterior insertion -plate is well developed. The 



SCHIZOCHITON. 235 

posterior sinus, however, is unlike the former group, in which the 
tail valve approaches the head valve in form ; and the arrangement 
of the eyes is the same as in Lorica, which has a degenerate tail 
insertion-plate. At the same time, it must be granted that the differ- 
ences between Schizochiton and Lorica are greater than between most 
genera of the same family ; for in Schizochiton the slits of the head- 
valve are numerically related to the external ribs; the latter bear 
eyes, and the tail valve has a well developed slit and pectinated 
insertion-plate. 

S. INCISUS Sowerby. PI. 51, figs. 1-8. 

Shell much elongated, narrow, the valves elevated, somewhat car- 
inated ; surface lusterless, grayish, obscurely mottled with olive and 
purplish. 

Median valves elongated, beaked, the lateral areas small, slightly 
raised. Entire surface sculptured with flattened longitudinal riblets, 
as wide as their interstices, converging toward the dorsal ridge and 
somewhat irregular or wavy on the lateral areas ; each riblet where it 
passes over the diagonal, enlarged for the insertion of an eye. Ante- 
rior valve (figs. 2, 4) having 6 (sometimes 7 or 8) radiating curved 
ribs, each bearing a series of eyes, the intervals sculptured with close 
v-shaped riblets. Posterior valve (figs. 6, 7, 8) having the mucro 
posterior, the latero-posterior areas tricostate, otherwise sculptured 
like -the median valves ; posteriorly it has a wide, deep fissure, extend- 
ing up to the mucro (fig. 8.) 

Interior whitish, stained with purple-brown in the middle of each 
valve. Sutural plates well developed. Sinus V-shaped. Anterior 
valve having 6, central valves 1 or 2 slits ; posterior valve, on each 
side of the posterior fissure, 3 slits ; teeth thin, distinctly cren- 
ulated outside. 

Girdle broad, alternately buff and dark colored, the light stripes 
wider, and as usual, sutural ; rather thinly but in places densely 
clothed with minute, cylindrical, shelly spinules, part brown, part 
white. Length 50, breadth 18 mill. 

Zebu, (Cuming), and Samboangan, (Challenger), Philippines ; 
Raines Island, Torres Straits (Ince) ; Clairmont and Bird Is., 
N. E. Australia (Coppinger) ; Sulu Sea (Capt. Chimmo.) 

Chiton incisus SOWB., P. Z. S. 1841, p. 61. REEVE, Conch. Icon, 
f. 43. Schizochiton incisus GRAY, P. Z. S. 1847, p. 169. SHUTTL., 
Bern. Mittheil. 1853, p. 68. H. & A. AD., Gen. Rec. Moll, i, p. 477, 



236 LORICA. 

t. 54, f. 6, 6a. SMITH, Zool. Coll. H. M. S. ' Alert ' p. 82. HADDON, 
Challenger Polyplac. p. 31. MOSELEY, Journ. Roy. Microscop. Soc. 
xxv, p. 37, pi. iv, figs. 1-5 ; vi, f. 5 (eyes). Chiton elongatus REEVE, 
Conch. Icon., f. 40. Schizochiton polyophtalmus ROCHEBRUNE, Bull. 
Soc. Philomath, de Paris, 1881-'82, p. 191. 

This species is so unlike other forms that comparisons are 
unnecessary. The eyes are larger than in any other form known 
to me. A single eye is shown in fig. 3, magnified 200 diameters. 

The girdle is not well shown in fig. 1, the spines being too evenly 
distributed over it. They are always closer at the sutures. 

Genus XVII. LORICA H. & A. Adams, 1852. 

Lorica H. & A. Ad., Annals and Magazine of Natural History, 
(2) ix, p. 355 (April, 1852). Only species L. cimolia, Chiton cimo- 
lius RVE. Aulacochiton SHUTTL., Bern. Mittheil. p. 68 (June, 1853), 
type Chiton volvox REEVE. 

Valves exposed, not beaked, the lateral areas and end valves with 
many fine riblets or pustules. Eyes confined to B single series 
along the summit of each diagonal rib. Insertion-plates blunt, 
obsoletely pectinated, the slits in head-valve not corresponding to 
external ribs ; sinus very small. Posterior valve having the mucro 
posterior and terminal, insertion-plate unslit, obsolete, being reduced 
to a convex ridge of callus ; posteriorly cleft to the mucro by a deep 
rounded sinus, or waved. Girdle slit or waved behind, densely 
scaly. 

This is one of the few genera of " irregular " Chitons having a 
scaly girdle. The eyes seem to be nearly obsolete, and possibly are 
not functional, although they still are pigmented. In most spec- 
imens a good hand-lens shows the series of ocular punctures along 
the diagonal ridge, immediately in front of the anterior row of 
pustules. 

The non-correspondence between slits and external ribs, the scaly 
girdle, the transverse, unbeaked valves and the toothless posterior 
insertion-plate, are all characters widely sundering this genus from 
Schizochiton. 

Section Lorica s. sir. 

Sinus in tail valve deep; jugal sinus v-shaped; girdle widest at 
the sides, cleft behind. 



LORICA. 237 

L. VOLVOX Reeve. PL 52, figs. 14-21. 

Shell oblong, strongly elevated, the dorsal ridge angular, side- 
slopes nearly straight. Surface lusterless, finely sculptured, variable 
in color; sometimes buff with chestnut streaks and darker angular 
blotches on the central areas, fewer on the lateral areas ; sometimes 
the lateral areas are olive-green, the dorsal region light, the sides of 
the central areas brown or olive. The dorsal ridge is sometimes 
stained with orange on each valve, and the same color often clouds 
the sides also. 

The median valves are not beaked, even when young, but they are 
falsely beaked or narrowly projecting at the sinus in front. Lateral 
areas raised, sculptured with 8-12 low radiating cords bearing 
rounded pustules, which are more or less entirely lost in adult spec- 
imens. Central areas sculptured with numerous narrow raised 
threads parallel to the dorsal ridge, their interstices wider than the 
threads, and closely latticed across. Anterior valve strongly 
elevated, curving forward at the summit, the anterior slope being con- 
cave; sculptured with many radiating riblets which are pustulose 
when not eroded. Posterior valve small, much depressed, with pos- 
terior, terminal, elevated mucro ; posterior-lateral margins bounded 
by an elevated rib ; posterior area extremely small, vertical, 
perpendicularly ribbed, having a deep rounded excavation behind. 

Interior white ; tegmentum reflexed and sculptured along the pos- 
terior margin of each valve ; sutural-plates broad, separated by an 
extremely small v-shaped sinus in the middle. Anterior valve hav- 
ing 8, central 1 slit ; slits minute ; teeth short, blunt, finely but 
obsoletely pectinated outside, and crenulated on the edge. Posterior 
valve having a low, rounded callus ridge in place of the insertion- 
plate, its edge unslit, finely and rather obsoletely striated, interrupted 
by a deep rounded sinus in the middle behind. Eaves narrow, 
solid. 

Girdle wide, bluish with inconspicuous dusky cross bars, slit 
behind, its surface very densely covered with minute, closely 
imbricating smooth convex scales (fig. 16.) 

Length 70, breadth 38 mill. ; divergence about 90, the young 
more depressed. 

Port Jackson, Sydney, Watson's Bay and Middle Harbor, N. S. 
Wales; Port Lincoln, S. Australia, under stones at extreme low 
tide. 



238 LORICA. 

Chiton volvox REEVE, Conch. Icon., t. 6, f. 81 (Feb., 1847). Lor- 
ica volvox (Rve.) HADDON, 'Challenger' Polyplac., p. 31. Chiton 
cimolius REEVE, Conch. Icon., t. 21, f. 141 (May, 1847). Lorica 
cimolia H. & A. AD., Ann. Mag. N. H. (2) ix, p. 355. ANGAS, P. 
Z. S. 1867, p. 224; 1871, p. 97. Aulacochiton volvox SHUTTL., Bern. 
Mittheil. 1853, p. 68. ? Chiton rudis HUTTON (see below.) 

The differences between L. volvox and L. cimolia are easily effaced 
when a good series is examined. The young show great variation in 
the pustulation of the lateral areas, the pustules sometimes being 
scattered, radiating, cords obsolete. The dorsal ridge generally 
has a central fine carina with a long narrow smooth triangle on 
each side, but this varies also. The second valve has a rather large 
median patch of scattered or diverging series of pustules. The color- 
ing varies a good deal in the series before me. 

I am disposed to consider Hutton's Chiton rudis a synonym of 
this species, but my opinion is founded upon a study of the original 
description only, which is as follows : 

Chiton rudis Hutton. Oblong ; margin with minute scales ; 
valves elevated, flattened on the sides, not keeled ; apex of anterior 
valve recurved, with its posterior margin slightly convex at the sides 
and deeply concave in the center ; posterior margins of intermediate 
valves straight ; posterior valve rather small ; apex posterior, pointed 
and emarginate. Anterior valve and lateral areas with radiating 
moniliform ribs ; posterior and median areas widely but rather irreg- 
ularly, deeply longitudinally furrowed, with narrow ridges between 
Margin gray, with broad, irregular, reddish-brown transverse 
patches ; valves grayish-brown ; interior grayish-white. Length 1*75, 
breadth '75 inch. Founded on a specimen in the Colonial Museum, 
locality not stated. (Hutton, in Trans. N. Z. Inst. iv, 1872, p. 179, 
and Man. N. Z. Moll. 1880, p. 113.) 

Section Loricella Pilsbry. 

Sinus in tail valve a mere wave ; jugal sinus lobed ; girdle widest 
in front, not cleft behind. 

L. ANGASI Adams and Angas. PI. 51, figs. 9-13. 

Shell ovate, coarctate and angulate behind, pale brown, variegated 
with green. Anterior valve concentrically striated and having 
radiating pustulose ribs ; posterior valve narrow, transversely sulcate 
and densely longitudinally lirate ; median valves subcarinated, the 



LIOLOPHURA. 239 

central areas densely lirate and transversely sulcated ; the lateral 
areas elevated, radially lirate, the lirse pustulose. 

Girdle moderate, olivaceous, beset with minute scales. 

Length 40, breadth 26 mill. (H. Ad. & Aug.} 

Rapid Bay, S. Australia (Angas) ; Camp Cove, Port Jackson, N. 
S. Wales (Brazier). In deep water. 

Lorica angasi H. AD. & ANG., P. Z. S. 1864, p. 193. ANGAS, 
1865, p. 187 ; 1871, p. 97Aulaeochtion angasi CPR., MS. 

I have not seen this species, which is here figured for the first 
time, from drawings made by Emerton for Carpenter, who writes as 
follows : 

" Anterior valve large ; posterior valve small, the mucro terminal, 
much elevated, prominent ; diagonal ridges elevated ; dorsal ridge 
acute. Interior : posterior valve a little sinuated behind, the sinus 
wide; having two callous, subobsolete, slightly roughened ribs in place 
of the insertion-plates. Anterior valve with 10, central valves 1 
slit ; teeth acute, serrated outside and at the edge ; eaves prominent, 
deeply grooved ; sinus narrow, deep ; the sutural plates separated, 
but having a lamina between them which is sometimes bilobate or 
denticulate. Girdle reduced one-half in width behind, and sinuated, 
very closely beset with solid minute scales, seen under a lens to be 
obsoletely bilobate. 

Length 32, breadth 22 mill, ; divergence 110. 

" One of Mr. Cuming's specimens is much broader and somewhat 
tripartite. This species differs from the typical Lorica in the anterior 
projection of the girdle ; in the minute raised scales, which under the 
microscope look like grains of wheat set on end ; in the sinus having 
a separate lamina, somewhat lobed ; in the absence of anterior ' false 
apex' on the valves; and finally in the mucro being terminal and 
but slightly waved, with a correspondingly slight wave in the girdle 
behind." 

The " hairs " shown on the girdle in fig. 9 are foreign to it. 

Genus XIX. LIOLOPHUKA Pilsbry, 1893. 

Liolophura PILS., The Nautilus vi, p. 105 (January, 1893). 
Acanthopleura sp., of authors. 

Valves exposed, dull and somewhat roughened, generally eroded 
outside, with minute eyes irregularly scattered over the lateral areas, 
the head-valve and the sides of the central areas. Interior dark 



240 LIOLOPHURA. 

colored, having anterior and side insertion-plates slit into teeth and 
sharply pectinated outside ; posterior valve with posterior terminal 
mucro, lacking the insertion-plate, which is represented by a flat 
callous ledge. Sinus wide,, deep, smooth. 

Girdle covered with stout calcareous spines or obtuse club-shaped 
processes. Type Chiton japonicus Lischke. 

The species of this genus have been referred to Acanthoplewra, 
Maugeria and Chiton by authors who have mentioned them ; but 
from these groups the characters of the tail-valve at once sunder 
them. Liolophura resembles Onithochiton and Enoplochiion in hav- 
ing a callous ridge in place of the posterior insertion-plate, in the 
pectinated teeth of the other valves, and in the possession of eyes ; 
but it differs from Onithochiton (a) in the somewhat raised instead of 
marginal mucro, (b) in the dullness of the valves externally, (c) in 
the distribution of the eyes upon the sides of the central ureas, whilst 
in Onithochiton they occupy a band on the forward part of the lateral 
areas only; and finally (d) in the covering of the girdle which in 
Liolophura consists of densely crowded calcareous spines, comparable 
to the spines of Maugeria. Liolophura differs from Enoplochiton in 
lacking the interior sculpture and denticulate sinus characteristic of 
that genus, and in the totally diverse development of the girdle 
covering. 



L. GAIMARDI Blainville. PL 53, figs. 30-35. 

Shell oblong, depressed, roundly arched. Surface lusterless, buff- 
gray, marked at sides and on ridge of valves with black. Girdle 
tessellated light and dark, having a light bar opposite each suture, 
or having dark or light larger patches. 

The valves are somewhat beaked, but always considerably eroded ; 
lateral areas but little raised, concentrically wrinkled toward their 
bases, studded with minute scattered eyes appearing as black dots. 
Central areas wrinkled by lines of growth and having scattered eyes 
at the sides. Head valve concentrically wrinkled, studded with 
eyes. Tail valve small, depressed, similar in contour to the median 
valves, the mucro being posterior and terminal, but eroded. 

Interior dark red-brown, whitish on the edges of the sutural-plates 
and the valve-callus; posterior internal margin covered by the 
reflexed blackish-brown tegmentum. Sutural-plates brownish below 
with a white outer edge ; seen from above they are whitish shading 
into reddish-brown toward the median sinus; rounded, broadly 
separated by a very wide, deep, rounded sinus. Anterior valve hav- 



LIOLOPHURA. 241 

ing 9, central valves 1 slit; the teeth deeply, closely pectinated out- 
side. Posterior valve having the eaves projecting beyond the broad, 
flat crescent of callus which occupies the place of an insertion-plate. 

Girdle densely clothed with intermingled minute, larger and large 
calcareous spines, (fig. 31.) 

New South Wales (Wilkes) ; Port Jackson (Blainville, Coppinger 
and Challenger Exped.) Australia. 

Chiton incanus GOULD, Proc. Bost. Soc. Nat. Hist. 1846, ii, p. 145 ; 
U. S. Expl. Exped., p. 315, t. 28, f. 432, 432a ; Otia, p. G.Maugeria 
incanus GLD., Otia, p. 248. Acanthopleura incana E. A. SMITH, 
Zool. Coll. H. M. S. ' Alert,' p. 81, 1884.? Chiton piceus ANGAS, P. 
Z. S. 1867, p. 223. Acanthopleura (?) incana (Old.) HADDON, 
Challenger Polyplac., p. 25 (in part.) Chiton gaimardi BLAINV., 
Diet. Sc. Nat. xxxvi, p. 546, (1825.) 

This species may readily be separated from all forms of Acantho- 
pleura by the peculiar flat callus of the tail valve inside, altogether 
lacking the pectination and slits which are present in Acanthopleura. 
It differs also in having eyes scattered over the sides of the lateral 
areas, and in having some of the girdle-spines striated. It differs 
from the Japanese species in the differently colored interior and 
sutural-plates, in the details of girdle-structure, etc. 

The spines on the white tracts of the girdle are unicolored whitish ; 
on the dark tracts they are of a uniform black-brown color. Occa- 
sional spines are striated like the scales of Ischnochiton. 

L. GEORGIAN A Quoy and Gaimard. PI. 53, figs. 36-40. 

Body oval, thick ; girdle narrow, granulose, whitish with 8 white 
stripes ; valves arcuate, flattened, thickly striated ; brown, black in 
the middle. 

The body is short, oval, much swollen : girdle very thick, little 
dilated at the sides, covered with very small rounded tubercles, white 
with 8 black bands across each side. Foot narrow, yellowish. 
Branchiae reaching to the buccal fringe, which is large. Valves 
very wide, covering nearly the whole body, semicircular, but little 
elevated, narrowed, somewhat heart-shaped, very thick ; having 
concentric striae, the anterior and lateral most marked; of a deep 
brown color at the sides, lighter in the middle with a black dorsal 
line ; fourth and fifth valves equal and wider than the others. 
Inside the valves are of a violaceous brown ; median valves with an 
arcuate thickening. The sutural plates are short, rounded, separated 
by a flat, straight median sinus. Insertion plates slit and crenulated. 
16 



242 LIOLOPHURA. 

Anterior valve having 12 to 15 short, unequal, deeply striated teeth. 
Posterior valve triangular, flattened, with a callus in place of the 
insertion-plate. All of the apophyses (which are of a horny color) 
have a brown spot at the angle. 

Length 19 lines, breadth 1 inch. (Q. & (?.) 

King George Sound, S.- W. Australia (Port du Roi-Georges.) 

Chiton georgianus Q. & G., Voy. de 1'Astrol., Zoologie, iii, p. 379, 
t. 75, f. 25-30. 

This species is apparently still unknown in English and Amer- 
ican collections. It seems to resemble closely the L. incana of New 
South Wales, but differs, if we may trust Quoy's account, in the 
much shorter girdle appendages, which resemble " rounded tuber- 
cles " rather than unequal spines. The figure of a detached valve 
given by Quoy shows a forward wave of the tegmentum at the 
median sinus, more prominent than in any incaiws before me, which 
scarcely show such a wave except on the second valve. The median 
valves of Enoplochiton niger, however, present an exactly similar 
sinuosity of the margin (compare figs. 24, 25, of pi. 52). The sinus, 
moreover, appears in Quoy's figures to be bridged by a lamina con- 
necting the sutural plates, a condition which does not obtain in L. 
incana. It is possible that the small variety mentioned by Quoy is 
more closely allied to the incana, or identical with it. 

L. CURTISIANA Smith. PI. 24, fig. 6. 

I am disposed to believe that CHITON CURTISIANUS Smith, which 
is described on p. 97 and illustrated on pi. 24, fig. 6 (figure enlarged 
and inverted), is a member of this genus ; but as Smith called it an 
Ischnochiton, I included it in that genus provisionally. 

L. JAPONICA Lischke. PI. 53, figs. 41, 42, 43, 44. 

Shell oblong, moderately elevated, arched, not carinated. Surface 
lusterless, generally much eroded and encrusted ; blackish, generally 
showing a wide light stripe on each side of the black dorsal stripe ; 
the wide girdle olivaceous, not distinctly barred. 

The median valves are beaked ; lateral areas hardly raised, sculpt- 
ured with concentric growth-wrinkles and a minute granulation, 
often lost by erosion. Central areas similarly sculptured. The forward 
half or two-thirds of the lateral areas and the outer portion of the 
central areas is black-dotted by the numerous irregularly scattered 
eyes. Anterior valve sculptured like the lateral areas and closely 
studded with scattered black dots (eyes). Posterior valve depressed, 



LIOLOPHURA. 243 

the mucro posterior and terminal, being produced beyond and above 
the posterior eaves. 

Interior black. The sutural plates are black both outside and 
within, and are widely separated by a broad, deep, rounded sinus. 
Head-valve with 8, 9 or 10, median valves 1 slit; teeth short in 
front, longer at the sides, deeply pectinated outside. Posterior 
valve having a broad flat crescentic callus in place of the insertion- 
plate. 

Girdle very broad, densely clothed with short, obtuse black-brown 
spines, tipped with whitish (fig. 43.) 

Length 50, breadth 20 mill, (measurements not including girdle.) 

Japan, at Enoshima (F. Stearns) ; Oosima (' Challenger ') ; Nag- 
asaki (Lischke.) 

Chiton japonicus LISCHKE, Malak. Blatter, xxi, p. 22 (June, 
1873) ; Japonische Meeres-Conchylien iii, p. 71, t. 5, f. 8-11. 
Maugeriajaponica DKR., Index Moll. Mar. Jap., p. 158. Acantho- 
pleura (f) incana HADDON (in part), Challenger Polyplac., p. 25. 
Not Ch. inconus Gould. Ornithochiton caliginosua CPE., MS. (spec- 
imen described from China.) 

? Chiton De Filippii TAPPARONE CANEFRI, Zool. del Viaggio 
intorno al Globo della K. Fregata ' Magenta,' Malacol., p. 77, 
1874. 

Distinguished from L. incana by the uniform black color of the 
inner layer or articulamentum. 

The typical japonica (pi. 53, figs. 41-44) has a broad girdle, 
densely clothed with spinelets which are nearly or quite cylindrical, 
and are about equal in size over the entire area of the girdle. There 
are usually some dusky bars, especially toward the ends ; and 
the individual spinelets are dark brown, tipped with light brown 
or cream-white. 

Var. tessellata Pils. (pi. 53, figs. 45, 46) includes specimens agree- 
ing with the type in valve structure and coloring, but having the 
girdle much narrower, and conspicuously varied with alternate 
patches of white and scorched-brown or blackish. The individual 
spinelets are larger than in typical japonica, and vary much in size, 
being small toward the outer edge of the girdle, large and flattened 
toward the inner edge. Upon the light tracts the spines are uni- 
colored white ; upon the dark tracts they are reddish-brown or 
blackish, unicolored or tipped with lighter. 



244 ONITHOCHJTON. 

Specimens collected by Stearns are before me, from Enoshima, 
where the typical form also is found. 

The type of Carpenter's unpublished Ornithochiton (?) caliginosus 
is shown in figures 41-45 of pi. 54. It was described from specimens 
in the Cuming collection from " China Seas," and C. B. Adams 
collection from Hongkong. I have no doubt of its identity with 
the L. japonica. The latter had not been published at the time 
Carpenter wrote his diagnosis. 

Tapparone Canefri's note on Ch. defilippii is not sufficiently clear 
for me to quote it without the mark of interrogation ; for he com- 
pares with a species from Sydney which he calls Chiton piceus GmeL 
But although he refers to Keeve, fig. 70, I am disposed to believe 
from his text, that what he really had from Sydney was Liolophura 
incana Gld. In this case, there can be little doubt that his defilippii 
is a synonym of L. japonica. 

L. LOOCHOOANA Broderip & Sowerby. 

Valves subscabrous, the marginal areas radially granose. Girdle 

leathery, granose above, the grains elevated. Length 18f, breadth 

7f mill. A very pretty little Chiton, whose margin is covered with 

small grains, resembling very short, blunt spines. (Brod. & Sowb.} 

Shore of Loo Choo Is. (Belcher, Mus. Zool. Soc. Lond.) 

Chiton loo-chooanus BROD. & SOWB., Zool. Journ. iv, p. 368 (Oct. 
1828 Jan., 1829.) 

This species is absolutely unrecognizable by the above descrip- 
tion, but it was perhaps a member of the genus Liolophura which 
the authors had before them. It is not mentioned or illustrated in 
the " Zoology of Captain Beechey's Voyage." See Gray's reference 
to these descriptions in the " Introductory Kemarks," Zool. Beechey's 
Voy., p.. 103. 

Genus XIX. ONITHOCHITON Gray, 1847. 

Onithochiton GRAY, P. Z. S. 1847, p. 65, 68. Onythochiton, GRAY, 
I. c., p. 169 (type Ch. undulatus) ; Guide Syst. Dist. Moll. B. M., p. 
184. Ornithochiton CPR., in Dall, Proc. U. S. Nat. Mus. 1881, 
p. 284. 

Valves exposed, polished, beaked, with indistinct lateral areas ; 
eyes present and disposed in a ray on the forward part of each 
lateral area and in numerous rays on the anterior valve. Interior 
porcellanous ; sinus denticulate, angular ; insertion-plates pectinated 



ONITHOCHITON. 245 

outside, that of the first valve with 8 slits, median valves 1 slit ; pos- 
terior valve depressed, triangular, with posterior terminal and mar- 
ginal mucro, the insertion-plate reduced to a low, smooth and narrow 
callus. Girdle leathery, rendered velvety by very minute chaffy 
hairs. Type 0. undulatus Quoy. 

This genus resembles Enoploeliiton and Liolophura in the char- 
acters of the tail valve. It differs from the former in the unsculpt- 
ured, porcellanous interior, much more delicate structure of the tail- 
valve callus and different type of girdle. Onithoehiton differs from 
Liolophura in the texture both inside and out, the very different 
arrangement of the eyes, more delicate tail-valve callus, and in 
the characters of the girdle. 

The species are distributed from the Cape of Good Hope to New 
Zealand. 

Carpenter emended the name to " Ornithochiton " believing it to 
be derived from ornis, ornithos, in allusion to the resemblance of 
single valves to the conventional representation of a bird on the 
wing ; but if any Greek root was in Gray's mind it was probably 
Onychochiton rather than Ornithochiton. 

Key to species of Onithoehiton. 

a. Lateral areas and anterior valve smooth or radially sculptured ; 
central areas smooth. 
b. Lateral areas smooth or with 4 or 5 low subgranose riblets, 

undulatus. 
bb. Lateral areas closely sculptured with close, subgranose striae, 

semisculptus. 

aa. Lateral areas having concentric sculpture ; central areas or 
pleura with for wardly-con verging sulci. 

b. Length of posterior valve from sinus to mucro distinctly less 
than half the valve's breadth, lyellii, quercinus, rugulosus, 

[amicorum. 

bb. Length of posterior valve from sinus to mucro half the valve's 
breadth. 

c. Valves having a smooth dorsal triangle, maillardi. 

cc. Valves having zigzag sculpture over the ridge, literatus. 



O. UNDULATUS Quoy & Gaimard. PI. 55, figs. 14, 15, 16. 

Shell oblong, moderately elevated, the dorsal angle rounded, side- 
slopes nearly straight. Surface polished; color either (1) olive-buff 



246 ONITHOCHITON. 

or olive-gray, becoming yellow toward the apices of the valves, eacb 
valve elegantly painted throughout with concentric olive or brown 
lines, and having a darker dorsal band ; or (2) olive-green at the 
sides, with a broad light triangle on the ridge of each valve, in the 
middle of which there is a stripe of rich chestnut or of green ; the 
whole concentrically lineolate with irregular green and cream-white 
lines. 

The valves are beaked ; lateral areas but little raised, and either 
smooth or sculptured with 4 or 5 low, more or less obsolete, beaded 
radiating riblets ; and showing under a lens, a band of eye-dots near 
the front margin. Central areas smooth and polished. Anterior 
valve having obsolete radiating riblets, and rays of eyes, the eye- 
rays variable in number, width, and degree of coalescence, the 
individual eyes being very mutable in number and position. Pos- 
terior valve very shortly subtriangular, the distance from sinus to 
mucro being but little more than one-third the width of the valve's 
tegmentuin. 

Interior white, marked with reddish-brown under the beak in each 
valve. Sinus delicately toothed, deep and angular ; sutural-plates 
higher toward the sinus than toward the outer edges of the valves- 
Anterior valve having 8 slits, median valves 1 slit ; teeth obtuse,, 
closely and sharply pectinated outside and on the summits. Poste- 
rior valve having a narrow, slightly convex ridge in place of the 
insertion plate. 

Girdle reddish or brown. 

Length 25, breadth 16 mill. ; divergence 110. 

Length 27, breadth 14 mill.; divergence 110. 

New Zealand, at Bay of Islands (Q. & G.); Auckland to Dunedin 
(Hutton) ; Chatham Is. (Hutton.) 

Chiton undulatus Q. & G., Zool. Astrolabe, p. 393, t. 75, f. 19-24. 
REEVE, Conch. Icon., t. 16, f. 87, 90. Onithochiton undulatus 
ADS., Genera, i, p. 476, t. 54, f. 3. Tonicia undulata HUTTON, 
Man. N. Z. Moll., p. 114 (1880.; 

The comparative breadth of this species is subject to considerable 
mutation, as well as the coloring and the development of weakly 
beaded riblets on the lateral areas. In some specimens these riblets 
are not perceptible. Occasionally the sides of some valves are uni- 
form greenish, lacking brown lines and angular white lines. 

This species has been reported from Tasmania, but on insufficient 
authority. 



ONITHOCHITON. 247 

The sculpture in this form differs markedly from the Australian 
and S. African species. 

O. SEMISCULPTUS Pilsbry, n. sp. PI. 55, figs. 10, 11. 

Shell oblong, elevated, subangular, dark olive-green, having snowy 
angular lines and dots on the lateral areas, and closer, more regular 
transverse lines on central areas. Surface shining and smooth on the 
central areas, closely and finely striated radially on the head valve and 
lateral areas, the striw crowded and subgranose, about 12 in number 
on each lateral area. Interior white. Girdle narrow, brown. 

Length 27*, breadth 16 mill. ; divergence about 95. 

Habitat unknown, 

This species resembles the stout, elevated, dark olive forms of 0. 
undulatus, such as occur at Auckland, N. Z., in contour and colora- 
tion. It differs markedly from undulatus and all other known 
species in the sculpture of the lateral areas. 

Figure 10 shows two half valves, the upper illustrating the color- 
pattern, the lower the sculpture. 

O. LYELLII Sowerby. PL 55, figs. 1-7. 

Shell oblong, moderately elevated, the dorsal ridge rounded or 
slightly subangular. Color extremely variable ; typically green at 
the sides, with a tessellated black or chestnut dorsal stripe in the 
middle of a pink-dotted area ; but other specimens are blotched with 
green at the sides with concentric creamy lines and a creamy area on 
the ridge of each valve, along which runs a band of dark chestnut 
spots often on a bluish ground. Occasional specimens have a large 
black blotch on the sides of some valves. 

The median valves are beaked. Lateral areas a trifle raised, 
sculptured with rather uneven concentric shallow grooves with rather 
wide, flat interspaces ; near the front edge of each lateral area there 
is a narrow band of minute eye-dots. Central areas sculptured at 
the sides with fine, close grooves (continued from those of the lateral 
areas) converging toward the ridge, where there is a narrow smooth 
dorsal band. Anterior valve having about 10 narrow rays of eyes, 
the spaces between sculptured with concentric grooves interrupted 
by the eye-bands into scallops having their convexity upward. Pos- 
terior valve broadly triangular, depressed. 

Interior white with a crimson spot in the cavity of each valve. 
Sinus deep, angular, delicately subdenticulate. Anterior valve hav- 
ing 8, median 1 slit ; the teeth rather long, sharply pectinated out- 



248 ONITHOCHITON. 

side. Posterior valve having a smooth callus in place of the inser- 
tion-plate, separated from the eaves by a groove at each side. 

Girdle leathery, closely clothed with microscopic down, clouded 
brown and whitish. 

Length 42, breadth 20 mill. 

Pitcairn Island, in small hollows, at low water mark (Cuming) ; 
Raine's Island, Torres Sts., under stones at low water (Ince) ; Wat- 
son's Bay, N. S. Wales, Australia, at very low tides (Angas.) 

Chiton lyellii SOWB., P. Z. S. 1832, p. 26 : Conch. Illustr. f. 7. 
REEVE, Conch. Icon., f. 12. Chiton incii REEVE, Conch. Icon* 
no. 94, t. 16, f. 96; detail fig. 94. Chiton puncticulatus REEVE, 
Conch. Icon., t. 13, f. 696 and description in part Onithochiton 
incei ANG., P. Z. S. 1867, p. 223. 

This species differs from O. maillardi in the narrower smooth 
dorsal areas, the less deep, less regular grooving of the lateral areas, 
and the shorter and broader posterior valve. It relations to the 
following species are not clear to me, as I have seen no authentic 
specimen of the latter. 

Figs. 8, 9 of pi. 55 represent the C. incii of Reeve. 

The Chiton puncticulatus of Reeve seems to have been founded on 
a specimen of this species and one of Pallochiton lanuginosus ; but 
Reeve's reference to the punctation seems to apply best to this form. 
In any case, the name is so ill-defined that it cannot in fairness be 
used. 

O. QUERCINUS Gould. PI. 55, figs. 12, 13. 

Shell small, depressed, slightly carinateand beaked, ovate, yellow- 
ish wood or oak color, clouded with olive or dusky slate color at the 
sides. Lateral areas scarcely raised, but distinctly marked by 
coarse longitudinal sulci, which are divided by a radiating furrow 
and sometimes more, and the two portions form somewhat of an 
angle with each other ; central areas with faint, rugose, longitudinal 
lines toward the margin, and scattered punctures about the apex ; 
anterior valve checked with raised spaces formed by concentric and 
more distant radiating furrows, which become more numerous near 
the margin ; posterior valve with the umbo nearly terminal, so that 
the transverse ridge runs nearly parallel to the margin. Marginal 
ligament broad, yellowish, frosted. (Old.) 

Length 22, breadth 15 mill. 

New South Wales, Australia. 



ONITHOCHITON. 249 

Chiton quercinus GLD., Proc. Bost. Soc. Nat. Hist, ii, p. 142 
(1846); U. S. Expl. Exped. Moll., p. 312, f. 437, 437a; Otia 
Conch., p. 3. C. (Onithochiton) quercinus GLD., Otia, p. 242. 

Closely allied to 0. lyelli and 0. rugulosus. 
O. RUGULOSUS Angas. PL 55, fig. 19. 

Shell elongately ovate, a little narrowed in front, raised and car- 
inated, pale yellowish-brown, the central areas of the valves faintly 
spotted with olive, the outer edges bordered with green, upon which 
and extending inward are concentric waved bands of olive brown 
darker at the margin; lateral areas not raised, divided from the 
dorsal areas by radiating nodulous ribs, transversely rugosely, costate ; 
dorsal areas finely longitudinally ridged ; mantle brown, variegated 
with ash-color and clothed with very minute chaff-like scales- 
(Ang.) Length 16 mill. 

Port Jackson, Australia. 

OnithocUton rugulosus ANG., P. Z. S. 1867, p. 115, 223, t. 13, 
f. 29. 

Carpenter gives the following notes upon the type specimen : 
Shell broad, the valves much beaked, dorsal ridge acute. Mucro 
terminal. Jugal area scarcely distinct, smoothish ; central areas 
having about 16 nearly longitudinal, jagged wrinkles, nearly meet- 
ing over the jugum. Lateral areas very sharply rugose, much 
more so than in the other species, the rugae about 12, not developed 
in young shells, very irregular, swelling into granules especially on 
the diagonal lines and sutures. Anterior valve having 8 lines of 
black dots, with two additional, indistinct ones. Inside whitish with 
a brown spot in the cavity ; posterior valve having the mucro 
absolutely terminal, the insertion-plate planed off. Anterior valve 
having 8 slits ; teeth very finely rugose ; sinus deep, flat, tolerably 
broad, with about 20 fine teeth. Girdle covered with minute hairs. 

Length 16i, breadth 12 mill.; divergence 125. 

O. AMICORUM Baird. PI. 54, fig. 46. 

Shell rather elongated, elevated, with acute dorsal ridge. There 
is a line of reddish-brown color along the dorsal ridge, and one or 
two others along the sides. 

Lateral areas much elevated, with very nodulous wrinkles, two or 
three irregularly concentric ; these are partly on the diagonal and 
sutural ribs, with others intercalated. Central areas with about 22 
slightly irregular riblets, nearly longitudinal, but bending toward the 



250 ONITHOCHITON. 

middle, the interstices very narrow. Anterior valve having about 
20 radii, much smaller than those of the lateral areas, but toward 
the sutures becoming coarser than those of the lateral areas. Poste- 
rior valve depressed, the mucro subterminal. 

Interior : anterior valve having about 9 slight slits, not corre. 
spending to the outside dots. Central valves with 1 slit ; teeth 
striated outside and at the broad, but sharp edge. Eaves planed off, 
scarcely grooved. Sinus broad, deep, with about 14 denticles. 

Girdle stout, with shelly spines, exactly like magellanicus, prin- 
cipally whitish, irregularly tessellated with dark. (Cpr., from 
type.) Length 18, breadth 10 J, divergence 90. 

Nine or Savage Island, Friendly Group (Brenchley.) 

Chiton ( Oniihochiton) amicorum BAIRD, in Brenchley's Jottings 
during the Cruise of H. M. S. ' Curacoa ' among the South Sea 
Islands, in 1865. London, 1873, p. 445, t. 40, f. 7. 

The generic position of this species is uncertain, but could be 
readily ascertained by an examination of the type, which is, we 
believe, in the British Museum. It is probably either an Onithochiton, 
a Liolophura or a Plaxiphora. Baird's original description is as 
follows: "Shell ovate, nearly equal at each extremity; mantle 
margin covered with numerous chaify-looking scales, first valve 
larger than any of the others, marked with numerous granular lines ;; 
central valves strongly striated, lateral areas with 2 or 3 granular 
lines ; last valve small and striated. A line of a red color runs 
along the top of all the valves, whilst one or two others run along 
the lateral areas. Length 8 lines, breadth 5 lines." 

O. MAILLAEDI Deshaves. PI. 55, fig. 20. 

Shell oblong, elevated, the dorsal ridge roundly angled, side- 
slopes nearly straight. Surface shining ; color pale buff, with a nar- 
row orange-tinted or brown triangle at the ridge of each valve,, 
several dark-green spots along each diagonal slope, the lateral areas 
and head valve with concentric green-olive sometimes dark brown 
lines. 

Median valve beaked, the lateral areas somewhat raised, having 
near the front margin a narrow radiating band of eye-dots, the width 
of the band greater on the hinder valves ; sculptured with longitu- 
dinal grooves corresponding with the dark color-lines, sometimes 
irregular or branching ; and continuing upon the diagonal slope. 
Upon the central areas these grooves become much more delicate,. 



ONITHOCHITON. 251 

closer, converging toward the dorsal ridge, and often zigzagged ; the 
median triangle of the central areas smooth. Anterior valve having 
8 narrow rays of eyes, occasionally with some eyes scattered between 
along the lower margin ; the intervals between the eye-rays sculpt- 
ured with sulci forming short arcs of concentric grooves. Posterior 
valve depressed, triangular ; its length from sinus to the posterior 
terminal mucro being one-half the greatest breadth of its tegmentunu 

Interior white, with a large spot of rich brown in each valve. 
Sinus delicately toothed, wide and deep. Anterior valve having 8 
slits, median valves 1 slit ; teeth finely and sharply pectinated out- 
side. Posterior valve having a smooth ledge of callus in plate of 
the insertion-plate, flat behind, rounded at the sides. Eaves narrow, 
grooved, solid. 

Girdle fleshy-brown, leathery. 

Length 24, breadth 15 mill.; divergence 110-115. 

Mauritus and Bourbon (Reunion.) 

Chiton maillardi DESH., Moll, de File Reunion, p. 38, t. 5, f. 14. 
Chiton (Tonicia?) maillardi MARTENS, in Mobius' Reise nach 
Mauritius, p. 300. Ornithochiton maillardi CPU., MS. Ornitho- 
chiton sp., MOSELEY Quarterl. Journ. R. Mic. Soc. xxv, p. 54, t. 5 r 
f. 4-7. 

O. LITERATUS Krauss. PL 55, figs. 21, 22, 23. 

Shell ovate, convex ; brown, spotted with whitish and having a 
whitish longitudinal band ; closely sulcate. Interior white, brown- 
ish-violet in the middle. Anterior valve lunate, convex with 
undulating grooves ; posterior valve triangular, depressed, sculptured 
with angular grooves; intermediate valves sinuated in front, 
rounded at the sides, undulately and angularly grooved. Girdle 
rufous-brown, leathery, velvety. 

Length 1 2, breadth 8 lines. (Krauss.") 

Natal 

Chiton literatus KRAUSS, Die Siidafrik. Moll. p. 36, t. 3, f. 6. 

I have not seen this species, which is evidently quite distinct, 
although allied to 0. maillardi. The central areas have angular or 
zigzag grooves ; the lateral areas are not raised, and are sculptured 
with wavy grooves. The back is not carinated. Insertion plates as 
usual in the genus. 



252 ENOPLOCHITON. 

Genus XX. ENOPLOCHITON Gray, 1847. 

Enoplochiton GRAY, P. Z. S. 1847, pp. 65, 69, 169. 

Valves exposed, of a uniform dark brown or chocolate color out- 
side and within ; the lateral areas and head valve irregularly 
studded with extremely minute eyes. Interior minutely laminated 
and punctate in a peculiar pattern ; sinus deep, denticulate. Inser- 
tion-plates of anterior and median valves slit into teeth and sharply 
pectinated outside. Tail-valve having the mucro posterior and 
terminal, and inside with a flat ledge of callus in place of the lack- 
ing insertion-plate. Girdle fleshy, bearing extremely broad and 
short, blunt, separated striated scales. 

The single species comprised in Enoplochiton resembles the larger 
Onithochitons in being polished and sculptured with wavy impressed 
lines (when not eroded) and also in the denticulate sinus, as well as 
in the structure of all the insertion-plates. It differs from Onitlio- 
chiton in the peculiar texture and color of the valves, the sculpture 
of the interior and the structure of the girdle. 

The eyes in this genus, are extremely minute and oval instead of 
round. The megalopores and micropores are arranged in vertical 
lines (pi. 52, figs. 27, 28). The valves resemble those of Mesotomura 
in most respects, excepting the tail valve, which is that of Onitho- 
chiton. 

E. NIGER Barnes. PL 52, figs. 22-29. 

Shell oblong, convex, the valves thick and dark brown outside 
and within. Surface shining when perfect, but generally eroded 
and dull. 

The valves are strongly beaked, and generally much eroded ; but 
when not too much worn the sculpture is as follows : lateral areas 
marked with undulating longitudinal impressed lines ; central areas 
having a series of short impressions in front of each diagonal rib, 
and an impressed V on the ridge of each valve; anterior valve hav- 
ing concentric wavy grooves ; posterior valve much depressed, with 
posterior terminal mucro ; sculptured like the median valves. 

Interior seen under a lens to be sharply, densely laminate in front 
of the valve callus, punctate on the sutural plates and behind the 
valve-callus (fig. 25). Sutural and insertion plates of median 
valves thick, tending forward ; sinus broad, rounded or angular, 
denticulate ; anterior valve having 9 slits, median valves 1 slit ; 
teeth long, deeply, sharply and closely pectinated outside. Posterior 



ISCHNOCHITONID^:. 253 

valve having the mucro projecting beyond the narrow eaves ; inser- 
tion plate obsolete, reduced to a callous ridge, flattened behind, 
rounded at the sides, and pectinated outside where it joins the 
sutural plates. 

Girdle fleshy, bearing numerous wide, short, blunt, striated, sepa- 
rated scales (fig. 29, a young specimen) ; the interstices between the 
scales covered with a velvety pile. 

Length 75-80, breadth 35-40 mill. 

Peru (Capt. Ridgeley) ; Coquimbo Bay (Frembly) ; Valparaiso 
(U. S. Expl. Exped.) 

Chiton niger BARNES, Amer. Journ. of Science and Arts, vii, p. 
71, t. 3, f. 3 (l824*).Enoplochiton niger GRAY, P. Z. S. 1847, p. 69. 
Chiton coquimbensis FREMB., Zool. Journ. iii, p. 197, t. 16, f. 2 
(1827). SOWERBY, Voy. 'Blossom' Zool., p. 149, t. 40, f. 6. 
REEVE, Conch. Icon., f. 22. 

The entire substance of the valves is colored in this remarkable 
species. Specimens as well preserved as the individual figured are 
not common ; but so peculiar is the entire shell that it may readily 
be recognized, however eroded. 

This species like Acanthopleura spinifera, lives upon the rocks 
between tides in situations exposed to the full force of the surf. In 
fig. 27 a portion of the surface of a valve is drawn magnified, show- 
two eyes, megalsesthetes and micrsesthetes ; fig. 28 represents a por- 
tion more highly magnified, showing two megalsesthetes and the 
accompanying micrsesthetes. 

Family ISCHNOCHITONIDJS. 

A number of genera belonging to the Ischnochitonidce were 
omitted by me in my treatment of it in parts 1 and 2 of this volume, 
in deference to the views of Carpenter, who grouped them with 
Acanthopleura and its allies. A more profound study of this and 
related families, enables me now to see traits of relationship unknown 
at the time the synopsis on pages 23, 24, 25 was prepared, and there- 
fore to group the genera more naturally than was then possible. 

Subfamilies of Ischnochitonidce. 

CALLISTOPLACIN^:, in which the slits of the anterior and inter- 
mediate valves correspond in position to radiating ribs on the exte- 
rior. (See p. 259.) 



ISCHNOCHITONIN^E-DINOPLAX. 

ISCHNOCHITONIN^:, in which there is apparently no such relation 
between slits and external ribs. 

This last subfamily includes the majority of species, and a consider- 
able number of genera ; and while there are still some obscure points, 
the light cast by what we already know of their morphology is suffi- 
cient to show us the approximate paths of generic descent, the genera 
falling into three main groups, as shown in the diagram. 



1 

a 





."S 
Ja 




2 


; J 
3 



Ischnochitoniuse 



Callistoplacinse 



It will be noticed that Leptoplax and Spongioehiton are not 
included. These genera belong to the Acanthochitidce. Moreover, it 
must be remembered that Trachyradsia is a synonym of Stereochiton 
(see p. 52) and part of Trachydermon belongs to the Tonicelloid 
branch. These groups were erroneously placed in the text. 

The following genera belong to the Chcetopleuroid branch of 
Ischnochitoninse and should have been inserted after the genus 
Chcetopleura (p. 27.) 

Genus XXI. DINOPLAX Carpenter, 1882. 

Dinoplax CPU. MS., in DALL, Proc U. S. Nat. Mus. 1881, p. 284, 
287 (Jan. 20, 1882). Acanthopleura (in part) GRAY. Chcetopleura 
(part) SHUTTLEWORTH. Chiton s. s. (in part) ADAMS, Gen. Kec. 
Moll, i, p. 474, 475, not of Linn. 

Valves heavy, exposed, the lateral areas high ; teeth of insertion 
sharp, smooth, those of the posterior valve directed forward ; slits of 



DINOPLAX. 255 

anterior valve not corresponding to external ribs. Posterior valve 
having the mucro, posterior. Sutural plates broadly united across the 
sinus. Girdle thick, leathery, with minute bunches of delicate spine- 
lets scattered upon it. 

The position assigned by Shuttleworth to the type of this genus 
was not far from correct. The Ischnoid insertion-plates, solid eaves 
and the leathery spiculose girdle are characters strongly binding 0. 
gigas to Chcetopleura. Upon parting the valves, however, we notice 
that the mucro in C. gigas is situated toward the rear, and the pos- 
terior teeth are thereby thrown forward, as in Pallochiton ; the 
sutural plates are united by a brown " keystone " filling the sinus 
somewhat as in Eudoxochiton (p. 192) ; and the spicules of the girdle 
are gathered into little bunches different from any other Chiton. 
The valves, too, are remarkably solid. This combination of char- 
acters seems sufficient for the establishment of the genus Dinoplax, 
the position of which I take to be near Pallochiton. 

D. GIGAS Gmelin. PL 57, figs. 21-32. 

Shell oval, large, ponderous and strong, elevated, obtusely angled. 
Surface lusterless, eroded, ash-white in color with some brown 
smears, when adult ; the young being prettily streaked or mottled 
with chestnut and bluish on a light ground. 

Median valves not beaked ; lateral areas very much elevated, 
radially striated in young shells and upon the outer edges of adults ; 
central areas closely and finely foveolate in the young, and on the 
protected front edge of adult valves. Anterior valve elevated, its 
surface similar to the lateral areas. Posterior valve depressed but 
roof-shaped, the mucro posterior, the slope behind it nearly vertical. 

Interior whitish, flesh-colored on the sutural plates and marked 
with brown at their bases ; having two broad chestnut rays behind. 
Sutural plates wide, connected across the sinus by a broad key-stone 
shaped lamina. Anterior valve having 8-10, central valves 1, pos- 
terior valve 8-10 slits ; teeth acute, smooth, those of the posterior 
valve rather stumpy, wedge-shaped, directed forward. Eaves solid. 

Girdle fleshy, strong, blackish, beset with numerous tiny bunches 
of minute spinelets (fig. 31.) 

Length 70, breadth 45 mill. 

Length 100, breadth 56 mill. 

South Africa, at Table Bay, Natal, Port Elizabeth and Algoa Bay. 

Chiton maximus a Promontorio Bonce Spei CHEMNITZ, Von einem 
Geschlechte vielschalichter Conchylien mit sichtbaren Gelenken, 



256 PALLOCHITON. 

fig. 10 (1784). Chiton maximus sen gigas CHEMNITZ, Conchyl. Cab. 
viii, p. 292, t. 96, f. 819 (good), 1785. Chiton gigas GMEL., Syst. 
Nat. xiii, p. 3206 (1788). SPENGLER, Skrivter af Naturhistorie- 
Selskabet, iv, p. 101 (1795). WOOD, Gen. Conchol., p. 12 (1814). 
BRUG., Encyclop. Meth., t. 161, f . 3 (copied from Chemnitz). 
LAMARCK, An. s. Vert, vii, p. 490. BLAINVILLE, Diet. Sc. Nat. 
xxxvi, p. 543. REEVE, Conch. Icon., f. 65. KRAUSS, Die Siidafrik. 
Moll., p. 40, t. 3, f. 3 (young). H. & A. ADAMS, Genera Rec. Moll, 
p. 475. SOWB., Marine Sh. of South Africa, p. 50. Chcetopleura 
gigas SHUTTLEW., Bern. Mittheil. 1853, p. 67. Acanthopleura gigas 
GRAY, P. Z. S. 1847, pp. 68, 169. Chiton subgigas BLAINVILLE, 
Diet. Sc. Nat. p. 543 (young specimen). Dinoplax gigas CPR., MS. 
Chiton albus BARBUT, The Genera Vermium of Linnaeus, Pt. 2d. 
(London, Mar. 2, 1788), Vermes Testacea, p. 8, t. 1, f. 1 (not Oh. 
albus Linn.) 

The dull, corroded aspect of this large species seems to be invari- 
able in adults. The strongly raised lateral areas, black, leathery 
girdle, and peculiar contour render it very distinct in appearance. 
The figures of Chemnitz are most characteristic, but that it is impos- 
sible to quote him as authority for the name must be admitted. 
Although the bibliography of this species is rather extensive, the 
only references worth reading are Chemnitz, Krauss and Carpenter. 

Rochebrune has cited this species from the strait of Santiago, Cape 
Verde Archipelago (Nouv. Arch, du Mus. iv, p. 239, 1881), but his 
paper contains such a host of erroneous locality citations that one 
hesitates to accept any of them without confirmation. 

Genus XXII. PALLOCHITON Dall, 1882. 

Hemphillia CARPENTER MSS. 9 type H. lanuginosa Cpr. MSS. 
Not Hemphillia Bland & Binney. Pallochiton DALL, Proc. U. S. 
Nat. Mus. 1878, p. 29.7 (dentition described, but no generic diagnosis, 
and founded on the undescribed species P. lanuginosus. Feb. 13, 
1879). Pallochiton DALL, Proc. U. S. Nat. Mus. 1881, p. 283, 287 
(Jan. 20, 1882).? Arthuria CPR. 

Valves exposed, solid, the anterior and median having sharp 
insertion teeth slightly roughened outside ; slits of anterior valve 
not corresponding to anything in the external sculpture ; tail valve 
having the mucro at the posterior end, the teeth sharp and all 
strongly directed forward ; eaves solid ; sinus notched at sides. 
Girdle leathery, with a few deciduous hairs, but no pores. 



PALLOCHITON. 257 

This genus closely resembles in sculpture as well as structural 
characters, Chcetopleura Shuttlew.; differing only in the posterior 
position of the mucro and the consequent throwing forward of the 
tail-valve insertion-teeth, characters of no great importance. The 
slits correspond in position to nothing in the external sculpture. 
The girdle is decidedly like Chcetopleura, being very sparsely hairy 
(or smooth) and lacking all appearance of pores. 

P. LANUGINOSUS Carpenter, n. sp. PL 56, figs. 1-11. 

Shell oblong or ovate, rather elevated, carinated, the side-slopes 
nearly straight. Surface lusterless, color very variable ; sometimes 
dull brown or purplish-brown ; sometimes green along the ridge and 
purple or lilac dotted with black or olive at the sides ; or having the 
sides of some valves scarlet or even snow-white. 

The median valves are rather acutely beaked in the young, beaks 
eroded in old specimens. Lateral areas but little raised, sculptured 
with gem-like pustules scattered irregularly , on a flat (microscopic- 
ally puncticulate) ground ; the pustules often few, rarely wanting 
on some valves ; central areas sculptured with many closely beaded 
longitudinal threads, which converge slightly at the ridge, and 
diverge toward the outer sides of the valves ; on the second valve 
they diverge at the ridge. Head valve pustulose like the lateral 
areas. Tail valve (fig. 11) much depressed, -the mucro at the posterior 
end; anterior area wide, sculptured like the central areas ; posterior 
area very narrow, vertical, sometimes pustulose. 

Interior bluish-white, darker at jugum and posteriorly; rarely 
flesh or pink tinted. Sutural plates very broad; sinus narrow, 
deep, angular and notched at the sides. Anterior valve having 8-9, 
central 1 slit, the teeth long, sharp, a little rugose outside ; posterior 
valve having 10-11 slits, the teeth chisel-shaped, strongly directed 
forward, smooth and rather sharp. Eaves of anterior and median 
valves narrow, of posterior valve wider, solid. 

Girdle rather fleshy, leathery when dried, somewhat encroaching 
at the sutures, and smooth or clothed with sparse delicate hairlets. 

San Diego, California ; Todos Santos Bay to Pta. Abreojos, Lower 
Gal 

Hemphillia lanuginosa CPU., MS. Pallochiton lanuginosus Cpr., 
DALL, Proc. U. S. Nat. Mus. 1878, p. 297, pi. 3, fig. 21 (dentition). 
Chiton (Pallochiton) lanuginosa (Cpr.) Dall, ORCUTT, Proc. U. S. 
Nat. Mus. 1885, p. 544. 
17 



258 PALLOCHTTON. 

?? Chiton puncticulatus REEVE, Conch. Icon., Chiton, no. 69 (in 
part.) 

The posterior terminal mucro, leathery girdle, and beaded sculpt- 
ure well distinguish this species. The coloring of some specimens 
(such as those from S. Ignacio Lagoon, Lower California, represented 
by fig. 1, 6) is of exquisite delicacy. Old individuals generally lose 
the pustules of the surface except at the base of the valves. One of 
Reeve's illustrations (fig. 69a) is said to represent a specimen of this 
species ; but as the other (fig. 69 b) is certainly an Onithochiton, and 
as the description indicates that rather than the Pallochiton, I 
have preferred to retain Carpenter's name for this species. 

A peculiarity of coloring not mentioned in the description is the 
vertical white stripe extending down the posterior slope from the 
mucro of the tail valve. In the great number of individuals 
examined by me I have never found this lacking. 

Section ARTHURIA Carpenter, 1882. 

Arthuria CPR. MS., in DALL, Proc. U. S. Nat. Mus. 1881, pp. 
284, 287 (Jan. 20, 1882). Type A.filosa Cpr. 

Shell thin ; valves waved ; mucro posterior, produced. 'Insertion 
plates acute, smooth, projecting forward in the posterior valve ; 
sinus flat, laminate, smooth. Girdle leathery, smooth or downy. 
(Cpr., MS.) ^ 

This section seems to present no characters separating it from 
Pallochiton. I have not seen the type and only species, and it has 
not been figured. Comparisons should be made with Pallochiton 
lanuginosns Cpr. 

P. FILOSUS Carpenter, n. sp. 

Shell oval, subelevated, the dorsal ridge acute ; mucro posterior, 
hardly terminal, elevated on a strong marginal ridge, the outline in 
front of it concave. Intense or pale olivaceous. 

Valves delicate, rounded at the margin, making deep sutures. 
Central areas having about 13 distant, beaded subparallel threads on 
each side, sometimes obsolete, and closer and subacute upon the ridge. 
Lateral areas moderately defined, and together with the end valves 
having irregularly scattered rounded granules. 

Interior: anterior valve having 10, central 1, posterior valve 9 
10 slits ; teeth of the posterior valve solid, acute at the edge, strongly 
inclined forward, the slits sloping ; the other valves having very 



CALLISTOPLACIN^E. 259 

acute teeth. Eaves of posterior valve wide, flat, subspongy; of 
other valves moderate, hardly grooved. Sinus narrow, deep, hardly~ 
toothed, slit at the sides, at the junction of the sutural plates. 

Girdle leathery, smooth or most minutely and closely downy. 

Length 29, breadth 16* mill. ; divergence 110-120. 

Habitat unknown. 

Arthuria filosa CPU. MS. and in DALL, Proc. U. S. Nat. Mus. 1881, 
.p. 287 (name only). Types in Mus. Cuming, nos. 23, 38. 

Carpenter's description is given above. He remarks : 

" This shell has the tail plate of Nuttallina, but the other valves 
more resemble Chcetopleura or Tonicella. It is known externally from 
Nuttallina by the nearly smooth girdle ; but would hardly be distin- 
guished from Ornithochiton except by the regular articulation of the 
insertion-plates. In the Ischnoid genera, the posterior profile from 
the mucro is often concave ; in this the anterior. In consequence of 
the great projection of the beak, both in Nuttallina and Arthuria, 
the posterior teeth appear plumulate rather than fissured ; a char- 
acter also seen in Callistochiton. The terminal valve in both the 
specimens examined are exactly alike in color as well as markings; 
but the central valves in one specimen are of a much lighter color, 
with more delicate and well developed sculpture." 



Subfamily CALLISTOPLACIIOS. 

Ischnochitonidse in which the slits of the anterior valve correspond 
in number and position to the radial ribs of the exterior. Teeth 
generally thickened at the edges of the slits. 

In this subfamily, which seems to be a natural division, may be 
placed a number of genera widely scattered in Carpenter's scheme. 
These genera fall into three groups, or branches, lettered a, aa, and 
aaa in the following table. The first of them seems to have affinities 
with the typical Ischnochitons, the second slightly resembles the 
Acanthochitidce, and the third may be somewhat allied to the 
Mopaliidce. 

The number of anterior slits sometimes exceeds the number of 
external ribs, so that the subfamily diagnosis must not be taken too 
literally. The plan of structure is sufficiently obvious; but 
exuberant Nature knows nothing of absolute adherence to rules. 



260 CALLISTOCHITON. 

Key to genera of Callistoplacince. 

a. Surface of valves having strong radial ribs ; girdle densely 

clothed with imbricating scales, CALLISTOCHITON. 

aa. Surface of valves granulated or pebbly ; girdle not densely 

imbricated with scales. 

b. Anterior valve with more than 7 slits ; sinus very spongy ; 

mucro posterior, NUTTALLINA. 

bb. Anterior valve with 5 slits; mucro subcentral, not posterior, 

CRASPEDOCHITON, ANGASIA. 
aaa. Surface of valves wrinkled or ribbed ; girdle naked except for 

hairs or corneous spines. 

b. Valves having very strong radial ribs; girdle naked, with 

sutural tufts, CALLISTOPLAX. 

bb. Valves not very strongly sculptured ; girdle tough, with 

corneous curved spine-like processes, CERATOZONA. 



Genus XXIII. CALLISTOCHITON Carpenter, 1882. 

Callistochiton CPR., Table of Regular Chitons, 1873. D ALL, Proc. 
U. S. Nat. Mus. 1881, p. 283, 289, 290 (Jan.-Feb., 1882). Callo- 
chiton (in part) H. & A. Adams, and of CARPENTER, P. Z. S. 1 865, 
p. 276, not of Gray. 

Valves conspicuously sculptured ; the insertion-plates short, 
smooth or nearly so, festooned, being curved outward at the ribs 
and slit there, thickened outside at the edges of the slits, the latter 
corresponding in position to the ribs of the outer surface. Sinus 
squared. Mucro median or post median, generally depressed. 
Girdle poreless, densely clothed with minute striated or smooth 
scales. Type, Chiton pulchellus Gray. 

This genus differs from Ischnochiton in the peculiar insertion -teeth, 
which are curved into the ribs as if festooned, in the relation of the 
slits to the external ribs, and in the tail valve, which is often 
peculiarly humped. 

The species though not numerous, are widely distributed, Aus- 
tralia, Red Sea, Japan and the Gulf of Mexico together furnishing 
about half, the rest being from the western coast of the Americas, 
from southern California to northern Chili. 

Nearly all of the species have the lateral areas strongly bicostate 
and granose ; the end valves have strong ribs, the number of which 



CALLISTOCHITON. 261 

Is less valuable as a specific character than one would at first suppose, 
on account of their tendency to increase by splitting. When a rib- 
splits, an additional slit appears in the insertion-plate ; so that this 
character also is largely vitiated. 

The best characters for distinguishing species are the sculpture of 
the median portion of the central areas, and the contour of the tail 
valve ; the profile of the latter being especially characteristic and 
constant. 

The following notes from Carpenter's MS. apply more especially 
to the more typical forms : " It is quite possible that in their earlier 
stages these curious shells resemble Ischnochiton ; but as they pro- 
ceed toward maturity, while they spread naturally in the seven ante- 
rior valves, the posterior is simply raised a tier higher ; consequently, 
in the adult, the posterior part of the tail plate resembles a closed 
fist outside; and within the teeth and eaves are very broad and 
blunt. There is an approach toward the throwing forward observed 
in Acanthopleura. In Ischnochiton, whatever be the external sculpt- 
ure, the row of teeth follow the same oval line, and the incisions do 
not correspond (except by accident) with the external ribs ; whereas 
in Callistochiton the tooth line is elegantly scalloped in and out 
of the hollows of the ribs. 

" In general the incisions are in the centre of each rib, and the 
plates are there propped outside, as in Callochiton ; but sometimes a 
separate keystone (as it were) is let into some or all of the arches on 
the terminal valves. The genus appears to culminate on the Cali- 
fornia coast, and reaches its greatest development in C. palmulatus ; 
in which the posterior valve displays the further peculiarity of each 
tooth being broken up into a number of fingers, each fluted, and so 
arranged that the inner margins form a semicircle while the outer 
present the scalloped curve of the genus. The valves are peculiarly 
solid and are easily detached from the thin and narrow zone. The 
sinus has always a lamina, which is generally marked off by slits from 
the sutural laminae, but is scarcely ever dentate. Two of the species 
have minute, smooth scales." 

Key to species of Callistochiton. 

One species, C. heterodon Pils., has pectinated teeth like a typical 
Chiton, and it is placed in this genus with much doubt ; the others 
may be tabulated thus : 



262 CALLISTOCHITON. 

a. Central areas having a pitted or net-like pattern toward the 
beaks. 

b. Mucro posterior, not depressed, tail valve with 7 ribs ;. 

scales smooth, pulchellus. 

bb. Mucro subcentral, the slope behind it concave, scales 

striated, shuttleworthianus. 

bbb. Mucro subcentral, tail valve rapidly sloping backward 

from the front margin ; eaves narrow ; scales striated, 

antiquus. 

aa. Central areas smooth in the middle, decoratus^ 

aaa. Central areas sculptured throughout with parallel lirse. 

b. Posterior area of tail valve swollen above the anterior 
area, palmiilatus.. 

bb. Posterior area not higher. 

c. Mucro posterior ; riblets converging on ridge, 

crassicostalus* 

cc. Mucro subcentral, riblets not converging on ridge. 
d. Profile of tail valve convex, mucro obtuse, 

infortunatus* 

dd. Profile of tail valve rapidly sloping back- 
ward from the front margin, mucro flat, 

gabbi. 

The species elenensis and expressus from western Middle Amer- 
ica, and adenensis from the Red Sea, probably belong in the last 
section of the above table, but I have seen no specimens. C.Jacob- 
ceus of Gould also belongs near infortunatus, probably. 



C. PALMULATUS Carpenter, n. sp. PL 58, figs. 7-16. 

Shell similar to C. pulchellus, but more flattened, the dorsal ridge 
acute ; mucro subcentral, depressed, the posterior area strongly 
swollen; sculpture stronger; central areas having about 10 sub- 
parallel acute lirse on each side, pectinating the sutures, interstices 
deeply cancellated; lateral areas having two strong ribs bearing 
strong tubercles, the sutures dentate, interstices deeply punctate. 
Anterior valve having 11 ribs, of which the outer two are joined; 
posterior valve 7 very strong ribs bifurcating behind. 

Interior: anterior valve having 11 slits, central 1 slit, the teeth 
normal ; posterior valve having 26 slits, the teeth crowded, minute, 
palmate. Eaves very strong; sinus small, strongly laminate, the 



CALLISTOCHITON. 263 

lamina deeply slit on each side. Girdle imbricated with striated 
scales. 

Length Hi, breadth 7* mill.; divergence 135. (Q>r.) 

Sta. Barbara (Cooper, Cal. State Coll. no. 1077) ; Monterey (Can- 
field, coll. Cpr.) 

The above description is quoted from Carpenter's MS. He gives 
the following additional notes : " This species with a general resem- 
blance to pulchellus, is known outside by its stronger sculpture, flat- 
tend anterior and tumid posterior valve ; and by its sharp back with 
flattened sides. It is one of the most remarkable peculiarities of 
Chitons that they are so particular in special adornment of their tails, 
while their heads are covered with very uniform plates. In this 
species this peculiarity culminates. Not only the radiating and fur- 
belowed arrangement of the teeth presents the greatest differentiation 
yet observed in a Chiton, but the fluting of each individual finger- 
like tooth adds special beauty to the complex pattern." 

Figures 7, 8, 13-16 are from drawings prepared for Dr. Carpenter ; 
fig. 12 represents the tail valve of a typical specimen before me, for 
comparison with that of the following variety. 

Var. MIRABILIS Pilsbry, n. v. PI. 58, figs. 7, 8, 9, 10, 11. 

Shell oblong, elevated, the back angular, side-slopes convex. 
Surface lusterless, dull brownish, the lateral areas and end valves 
blackish. 

Valves not beaked; the lateral areas widely separated by the 
eroded beaks, greatly elevated, each split by a deep median sulcus, the 
two ribs thus formed bearing coarse transverse grains. Central areas 
sculptured with about 15 narrow longitudinal cords, parallel at the 
dorsal ridge except on the second valve in which they diverge forward; 
the interstices wider than the cords, and finely latticed across. 
Anterior valve having 9 stout radiating ribs, strongly granose, and 
with the exception of the two outer ones, they are generally not bifid. 
Posterior valve much higher than the anterior, the mucro somewhat in 
front of the middle, the area behind it enormously developed, elevated 
and convex, sculptured with 4, 5 or 6 primary stout ribs, each of 
which splits into two ; the two outer ribs are broader, and split into 
several riblets. 

. Interior bluish- white ; sutural-laminse slightly connected across 
the squarish sinus. Anterior valve having 9, central 1, posterior 
valve 22 slits; teeth short, somewhat roughened. Eaves broad, 
calloused. 



264 CALLISTOCHITON. 

Girdle narrow, thin, covered with very densely imbricating 
minute deeply striated scales (fig. 8.) 

Length 16, breadth 7 mill. 

San Diego, California. 

The form described above was known to Dr. Carpenter by one 
perfect though worn specimen and a single worn posterior valve. 
He gives (MSS. f p. 134) the following notice of it, under C. palm- 
ulatus. 

"? Varied. : ar. centr. liris utr. lat. 16-18; v. post. 5, bifurcatis; 
mucro usque ad dimidium totius altitudinis depresso ; sinus lamina 
vixfissata. Long. 15, lat. 7J, diver g. 110." 

These lines give the essential points of difference between this 
variety and the typical form, viz., the more numerous side riblets of 
the central areas in a shell of the same width, the greatly elevated 
posterior area of the tail valve, the greater proportionate length and 
altitude of the shell and the smaller angle of divergence. The value 
of these characters for distinguishing the two forms remains to be 
seen, and can only be ascertained by the examination of abundant 
material. That this form is not merely a fully grown (ephebic) or 
old (gerontic) state of the original palmulatus is shown by the com- 
parison of small specimens, not exceeding in length the typical palm- 
ulatus before me. 

The enormously swollen posterior area of the tail valve separates 
this from all other species. In several additional details the form 
differs from C. crassicostatus, notably in the strongly two-ribbed 
lateral areas, the more numerous ribs of the anterior valve, the 
riblets of the central areas being parallel at the ridge except on the 
second valve where they diverge ; whilst in C. crassicostatus they 
converge forwardly on all of the median valves. The seventh 
valve of this form is distinctly narrower than the other valves, being 
crowded by the unusually developed tail-valve. 

The type specimen is in the collection of the Academy. 

C. CRASSICOSTATUS Pilsbry, n. sp. PI. 58, figs. 1, 2, 3, 4, 5, 6. 

Shell oblong, elevated, the dorsal ridge very obsoletely angular, 
side-slopes arched. Surface lusterless, green or brown. 

Valves not beaked, the lateral areas extremely prominent, unevenly 
granulated, the concentric riblets being cut by one or several radiat- 
ing grooves. Central areas having strong longitudinal bars, con- 
verging j^-like on the ridge (even on the second valve}, the intervals 



CALLISTOCHITON. 265 

very closely and finely latticed across. Anterior valve having seven 
very strong ribs, each divided by a shallow median groove. Poste- 
rior valve elevated, having the mucro directly over the posterior edge, 
he hinder area not higher than the area in front of it ; posterior 
slope vertical, convex, sculptured with five very strong, deeply 
separated ribs, which are granose above, and subdivide into several 
riblets each toward the lower margin. 

Interior bluish-white ; sutural-plates slightly connected across the 
rounded sinus. Anterior valve having 9, central valves 1, poste- 
rior valve 13-20 slits; teeth short, rather sharp and smooth, hardly 
projecting below the eaves, thickened along the slits outside; eaves 
broad, solid. 

Girdle narrow, thin, covered with excessively minute, closely 
imbricating, striated scales. 

Length 22, breadth 9 mill. 

Monterey, California. 

Callistochiton fimbriatus CPR., MSS. 1875. Not Callochiton fim- 
briatus Cpr. in COOPER, Geographical Catalogue of the Mollusca 
found west of the Rocky Mountains, between Latitudes 33 and 49 
North (Geol. Surv. of Cal.), p. 23, 1867 (no description),^ Callisto- 
chiton pulchellus, Cpr. MSS. 1875. 

? Chiton ( Callochiton) fimbriatus Cpr., ORCUTT, Proc. U. S. Nat. 
Mus. 1885, p. 544 (1885), no description. Not Chiton fimbriatus 
SOWB. 

This species is readily separated from the next by the smaller 
number of ribs on the head and tail valves, the less distinctly bicos- 
tate lateral areas, and the far less elevated tail valve, which has, 
besides, a posterior terminal mucro. 

The specimens before me were collected by Henry Heniphill at 
Monterey. A species under this name has been reported from San 
Diego and from Catalina Island, but the identity of the specimens 
with the present species is open to doubt, although its occurrence in 
those places is not improbable. 

The name of this species is involved in some obscurity, owing to 
the fact that no diagnosis or description whatever has heretofore been 
published, although the name fimbriatus has appeared in several 
lists. This much however is certain : that the original fimbriatus 
Cpr. of Cooper's Catalogue, the unique type of which is said to be in 
the Smithsonian Institution collection, is not the fimbriatus of Car- 
penter's later MSS. ( Vide Carpenter's MSS. vol. I, p. 135) ; and we 



266 CALLISTOCHITON. 

have no means of knowing whether the C.fimbriatus of Orcutt's San 
Diego list was identified from Carpenter's earlier type specimen, or 
his later MSS. Everything considered, the best course open to us- 
seems to be the selection of an entirely new name. The type is in 
the collection of the Academy. 

C. INFORTUNATUS Pilsbry, n. sp. PI. 59, figs. 37-42. 

Shell large, regularly ovate, the dorsal ridge obtuse; valves 
arcuate; mucro obtuse, median. Olivaceous, sometimes spotted with 
paler on the ribs and jugum. 

Central areas having about 12 parallel lirse on each side, decussated, 
v the interstices having square depressions. Lateral areas having two 
very strong rounded tuberculose ribs. Anterior valve with 9, pos- 
terior with 7-8 elegantly spreading ribs. 

Interior: posterior valve having 7-8, central 1, anterior 9 slits ;. 
teeth concave outwardly, obtuse, slit at the apices of the ribs, some- 
times with an intercalated slit or abnormally serrate ; teeth of poste- 
rior valve very obtuse, hardly sloping ; eaves small, delicate. Sinus 
wide, flat, but little angular, sometimes crenulated by the riblets of 
the exterior. Girdle irregularly imbricated with flattened scales, 
each one about 6-striated (fig. 39.) 

Length 17i, breadth 8| mill. 

Equador (Cuming) ; La Paz, W. Mexico (Pease.) 

Callistoehiton pulchellus CARPENTER, MSS. Not C. pulchellus 
Gray, q. v. 

The sculpture of the central and lateral areas resembles that of C. 
palmulatus, but the tail-valve (figs. 38, 42) is entirely different in form. 
This shell was sent to Dr. Carpenter by Cuming as the true C. 
pulchellus of Gray, but it is certainly not that species. The above 
description and the figures are from Carpenter's MSS. and unpub- 
lished drawings of his type. 

The shell recorded by Dr. J. G. Cooper from " Catalina (or other ?) 
I., Cal." under the name Callochiton fimbriatus Cpr. MSS., and by 
Carpenter (in MSS.) from " S. Pedro " (both referring to the same 
specimen) may be a variety of this species, but no definition of it 
has been published, the locality is uncertain, and Dr. Carpenter in hi& 
later MSS. shifted the name fimbriatus to another species, leaving the 
form under discussion as a nameless variety of his C. pulchellus. 
Under these circumstances it has been thought best to expunge the 
name fimbriatus from the list of valid species. 



CALLISTOCHITON. 267 

C. JACOB^EUS Gould. Unfigured. 

Shell small, ashy, elongated, elliptical, hardly carinated ; end 
valves very large, vaulted, ornamented with 10 scaly radiating ribs ; 
central areas cancellated ; lateral areas conspicuous, bicostate. 
Ligament narrow, covered with minute elongated scales. 

Length 12, breadth 5 mill. (Old.) 

Interior: posterior valve having 7, anterior 10, central 1 slit; 
teeth acute, curved outwardly ; eaves solid ; sinus wide, nearly flat, 
laminate, the lamina more or less separated from the sutural plates 
[by notches at the sides of the sinus]. Girdle imbricated with flat, 
striated scales. (Cpr.) 

Simoda, Japan (North Pacific Expl. Exped.) 

C. (Leptochitori) Jacobceus GLD., Proc. Boston Soc. Nat. Hist.vii, 
p. 164 (Dec., 1859) ; Otia Conch., p. 117. Callistochitonjacobceus 
CPU., MSS. 

Carpenter gives the following notes ; but it must be remembered 
that his C. pulchellus is not the true pulchellus of Gray. 

" If this shell had come from Central America, I should certainly 
have regarded it as C. pulchellus with which it exactly agrees in 
sculpture, number of ribs, size and striation of the scales, and general 
aspect. Indeed it can scarcely be separated as a variety, like the 
Californian shell. Inside, however the teeth are somewhat sharper,, 
one of them having an extra slit. The lamina which lines the sinus 
is very thin and sharp, generally (but not always) marked off' from 
the sutural plates by slight slits. In some valves, the lines which 
mark it off are perceptible, but they do not serrate the edges. It i& 
also much broader in some valves than others. Whether the species 
are or are not identical, cannot be decided from the single specimen 
in the Smithsonian Museum. It is very singular that a shell from 
equatorial S. America should be replaced by a very distinct species 
in the Bay of Panama, should reappear in the Gulf of California, be 
still found in the temperate seas of California and lastly display a 
representation on the shores of Japan." (Cjpr.) 

C. ELENENSIS Sowerby. PI. 59, figs. 27, 28. 

Shell oblong, pallid ; back rounded ; anterior valve radiately sul- 
cate ; lateral areas of the intermediate valves swollen, unisulcate ; 
posterior valve retuse, radially sulcate behind ; central areas of the 
intermediate valves irregularly sulcate-scabrous ; margin smooth. 

Length '6, breadth '3 inch. (Sowb.*) 

St. Elena and Panama. 



268 CALLISTOCHITON. 

Chiton elenensis SOWERBY, P. Z. S. 1832, p. 27. C. ellinensis 
SOWB., Conchol. Illustr., p. 6, f. 69. Ischnochiton elenensis CPR., P. 
Z. S. 1865, p. 275. Probably Chiton janeirensis var. f GRAY,Spicil. 
Zool., not of Sowerby and Reeve. 

Sowerby's original description and figures given above. I have 
not seen this species, and place it in Callistochiton with some doubt, 
as its internal characters may demand for it a position in Ischno- 
chiton. Haddon considers it very closely allied to C. decoratus Cpr. 
Carpenter has identified with this species a Panama form collected 
by Prof. C. B. Adams. He gives the following description of it : 

"Outside having the central areas decussated with about 20 
parallel bars ; lateral areas having two strong, swollen, tuberculose 
ribs. Interior having the sutural [posterior] margin reflexed, 
tuberculate, with a small sinus ; insertion plates 1-slit, sinus very 
broad. Front valve having 12 ribs, not very strong, and ten slits 
within, the teeth acute, eaves narrow. Posterior valve having the 
mucro subposterior, depressed ; the slope behind it expanded, con- 
cave, with about 12 subobsolete ribs; inside with 9 slits, the teeth 
short, eaves small, callous within. The central valves of this species 
are normal ; but the posterior valve offers a transition toward Callo- 
chiton L=Callistochiton], the outside being concave posteriorly, the 
insertion-teeth short, and the eaves callous. (Cpr. in P. Z. S.). 
The sinus is unusually broad and shallow, the sutural laminae not 
being marked off. ( Cpr.) 

C. EXPRESSUS Carpenter. Unfigured. 

Shell similar to I. elenensis, but flesh-colored. Central areas hav- 
ing 10 distant closely decussated bars ; dorsal ridge acute, lateral 
areas having two very strong, narrow ribs with narrow tubercles ; 
inside having the posterior margin flat, hardly tuberculose, hardly 
sinuated; sinus narrow, angulated at the jugum. Anterior valve 
having 10 strong, narrow ribs; interior as in elenensis, but with 8 
slits. Posterior valve having a flat posterior mucro, the slope 
behind expanded, hardly concave, with about 7 very strong ribs ; 
inside having about 7 slits, the eaves flat. 

" With a strong general resemblance to J. elenensis, the differences 
in detail in the only two specimens examined, as above stated, 
appear of specific importance. If only varietal, it is equally impor- 
tant to notice how much change is tolerated by the habits of the 
animal. It may be the shell called Chiton clathratus by Professor 



CALLISTOCHITON. 269 

Adams, of which there were no duplicates to compare. It offers a 
still more marked transition to Callochiton, the margin of the pos- 
terior valve being somewhat pectinated by the great projection of 
the ribs. (Q?r.) 

Panama (C. B. Ad.) 

Ischnochiton (f var,~) expressus CPR., P. Z. S. 1865, p. 275. 

This species, like the last, is not known to me by specimens, the 
above description and notes being from Carpenter's paper in the P. 
Z. S. In his MSS. Carpenter places it in the smooth sealed section 
of Ischnoehiton, and gives some additional notes, as follows : " This 
shell is almost exactly like the young of I. serratus, agreeing not only 
in the peculiar and beautiful sculpture, but even in the mantle scales. 
Yet it differs remarkably in the abnormal, narrow pointed sinus, in 
which respect it resembles J. tectiformis. One of these species is 
probably the C. clathratus of C. B. Ad. (Pan. shells, p. 242), and 
possibly of Reeve." 

C. DECORATUS Carpenter, n. sp. PL 58, figs. 17-20. 

Shell oblong, moderately convex, obtusely subangular along the 
dorsal ridge, the side-slopes slightly convex. Surface rather shining, 
varying in color from olive-buff to dark green, uniform or having 
darker flammules and spots. 

Apices of the median valves eroded. Lateral areas raised, each 
rendered bicostate by a central sulcus, and having a few uneven 
longitudinal impressed grooves, giving it a terraced aspect. Central 
areas having numerous parallel longitudinal ribs, the intervals 
closely latticed across, this sculpture obsolete on the ridge, where there 
is a broad V-shaped smooth area, which rarely shows a few diverging 
subobsolete ribs. Anterior valve having 11 rounded ribs. Posterior 
valve less elevated than the anterior, highest at the front margin, the 
mucro depressed, post-median ; posterior area having 9-10 rounded 
ribs. 

Interior bluish, generally marked with olive or green at jugum, 
bases of the sutural-plates, and slit-rays. Sutural plates wide, 
separated by a square sinus notched at each side. Anterior valve 
having 9 or 11, central 1, posterior valve 9-12 slits ; teeth rather 
sharp, smooth ; slit-rays distinct and porous. Eaves narrow. 

Girdle narrow, ashy-brown, covered with minute, striated, closely 
imbricating scales. 

Length 20, breadth 9-10 mill. ; divergence about 110. 
Todos Santos Bay and near San Tomas River, Lower California. 



270 CALLTSTOCHITON. 

Callistochiton decorat us CPR., MSS. Chiton ( Callistochiton) decor- 
atus Cpr., ORCUTT, Proc. U. S. Nat. Mus. viii, p. 544 (1885,) no 
description. 

It has been reported from San Diego by Orcutt and from La Paz 
by Carpenter (Pease coll.) 

The partially sculptured central areas are peculiar and character- 
istic, and the tail valve presents features not found in the other 
species of the same region. The figures 17-20 may be regarded as 
the types, but some individuals show some very obsolete coarse ribs 
in the front part of the jugal smooth tract. 

The type is in the collection of the Academy. 

C. GABBI Pilsbry, n. sp. PL 60, figs. 7-10. 

Shell oblong, convex, rather sharply carinated, the side-slopes 
somewhat convex. Surface lusterless, the central areas light brown, 
lateral areas olivaceous-brown. 

Median valves not beaked ; lateral areas composed of two strongly 
elevated ribs, bearing acute grains, the posterior rib wider, having 
an additional row of smaller grains along the sutural margin ; the 
sulcus between the ribs rather wide, minutely pitted. Central areas 
having about 15 parallel longitudinal riblets, becoming diverging 
toward the outer margins, the interstices very closely, sharply cross- 
latticed ; region of the beaks smoother, pitted and microscopically 
granulate. Anterior valve having 9 strongly elevated ribs separated 
by pitted intervals of the same width as the ribs, the latter bearing 
acute grains; the posterior rib on each side wider, with sutural 
grains ; region of the beak excavated. Posterior valve elevated at the 
front edge, rapidly sloping backward, the mucro about central, much 
depressed ; posterior area sculptured with 7 rather broad wave-like 
radiating ribs surmounted by acute grains. 

Interior light olivaceous, with dark markings under the beaks. 
Sutural plates well developed, separated by a narrow, angular, con- 
vex sinus. Anterior valve having 9, central 1, posterior valve 8 
slits ; teeth rather short, smooth, festooned and slit at the ribs. Eaves, 
especially in the tail valve, extremely narrow. 

Girdle covered with very compactly imbricated, wide, finely 
striated scales, which are arranged in alternate patches of olive-bluish 
and lighter, the light patches being composed of mingled bluish, 
tawny and white scales (fig. 7.) 

Length 14, breadth 8 mill. ; divergence about 110. 

Gulf of California (Gabb.) 



CALLISTOCHITON. 271 

In the depressed mucro and internal coloring, as well as the nar- 
row eaves, this species resembles C. decoratus Cpr. ; but the sculpture 
is much stronger, and is not obsolete at the dorsal ridge of each 
valve. The C. elenensis of Sowerby, a species which I have 
not seen, seems to be similar, but judging from Sowerby's figure the 
mucro of that species projects at the summit of the posterior slope, 
which is far from being the case with the form before me. The form 
described as elenensis by Carpenter differs in having a very wide 
sinus, weaker sculpture, etc. It should be compared with Carpenter's 
unfigured Ischnochiton expresses, a species not known to me autopt- 
ically. 

The type is in the collection of the Academy. 

C. PULCHELLUS Gray. PI. 60, figs. 1-6. 

Shell oblong, rather depressed, the dorsal ridge subangular, side- 
slopes convex. Of a soiled buff color, the girdle darker, ashen. 

Valves not beaked ; lateral areas raised, cut by a sulcus into two 
prominent ribs, of which the posterior is wider, sculptured with low, 
transversely elongated grains, serrating the sutures, the anterior rib 
having less conspicuous grains. Central areas in the middle pitted 
in diagonal series, the pattern becoming coarser on each side, then 
changing into longitudinal fine ribletson the outer half of each side. 
Anterior valve having 10 (or 12) strong rounded ribs, cut into low 
transverse grains by superficial concentric impressed lines. Posterior 
valve abruptly depressed at the mucro, which is behind the middle, the 
forward area level, reticulated, the posterior area bearing 1 stout ribs ; 
the posterior ones are strongly bent. 

Interior whitish ; sutural-plates rounded, separated by a wide 
sinus, which is angular but hardly notched at the sides, and not per- 
ceptibly laminate. Slits in head-valve 10, median valves 1, poste- 
rior valve about 14 ; teeth thin but normal in front and median, 
irregular in the posterior valve. Eaves narrow. 

Girdle narrow, densely imbricated with minute smooth, flattened 
scales. 

Length 10, breadth 5 mill.; divergence 135. 

Arica, Chili (Hennah.) 

Chiton pulchellus GRAY, Spicilegia Zoologica, pt. 1, p. 6, t. 3, f. 9, 
(July 1, 1828). REEVE, Conch. Icon., t. 23, f. 153 (? and perhaps t. 
25, f. 168). Chiton (Callochiton) pulchellus MORCH, Mai. Blat. 
vii, p. 176. C. bicostatus D'ORBIGNY, Voy. dans 1'Amer., Merid., p. 
486, t. 81, figs. 7-9. 



272 CALLISTOCHITON. 

? Chiton pulchellus C. B. AD., Cat. Panama Sh., p. 243 (in part). 
" Chiton pulchellus" CPU., P. Z. S. 1865, p. 27Q. Callistochiton 
pulchrior CPR., MSS. 

Not Callistochiton pulchellus of Carpenter's M8S. Not Chiton 
pulchellus of d'Orbigny, Voy. dans I'Ame'r. Merid., p. 489. 

The netted sculpture of the dorsal areas is unlike other species 
from the western coasts of the Americas. Figures 3-6, drawn by 
the author, should enable any one to identify the species readily. 
The small size is also rather characteristic, as well as the profile of 
the posterior valve (fig. 5.) 

I have but little doubt of the identity of Carpenter's C. pulchrior 
(=0. pulchellus Cpr., P. Z. S. 1865, p. 276) with the true C. pul- 
chellus of Gray. Carpenter separated pulchrior from pulchellus 
after studying specimens supposed to be of the latter species sent 
him by Cuming ; but it is clear to me that Cuming's identification 
was erroneous, and therefore the position taken by Carpenter 
becomes untenable. 

Drawings of the form called pulchrior, prepared for Carpenter, 
are reproduced on my plate 59, figs. 21-26. The sculpture is not 
well rendered, and if the drawing is accurate, the tail-plate differs 
somewhat in profile. 

Gray's description of pulchellus is not as good as Reeve's and his 
figure (pi. 60, fig. 1) is poor. The detail figure given by Reeve is 
copied on pi. 60, fig. 2. Gray's description is as follows : 

Shell oblong, elongate, slightly keeled, yellowish-white. End 
valves distantly, unequally, radiately ribbed; lateral areas of 
the middle valves with two broad, regular ribs ; central area closely 
and deeply punctured. Margin yellowish-white, with very minute 
bran-like scales. The ribs of the lateral areas are rarely bifid. 

Length f, breadth -J of an inch. [=about 9x4 mill.] 

Inhab. Arica, Peru, Rev. W. JELennah, Brit. Mus. (Gray.) 

The species described from Arica by d'Orbigny is in all prob- 
ability the same as Gray's form, but the figures are very poor. The 
original description is here translated : 

C. bicostatus d'Orbigny. (PI. 59, figs. 43, 44). Shell oblong, 
swollen and obtuse, entirely whitish. Anterior and posterior valves 
sculptured with broad, radiating ribs and some concentric lines of 
growth. Lateral areas of the intermediate valves each ornamented 



CALLISTOCHITON. 273 

with two very large, prominent ribs ; median areas wide and 
punctate. Girdle minutely scaly. Length 7 mill. (Orb.') 

Arica, under stones at low water. 

" Allied to C. pulchellus of Gray, differing in the granulous and 
scaly, not smooth, girdle, by the two ribs of the lateral areas instead 
of three, and by the . punctate central areas, which in the other 
species are striated." (0r6.) 

It must be remembered that the " C. pulchellus of Gray " alluded 
to by Orbigny, is not the true pulchellus of Gray, but some totally 
different species of Chcetopleura or of Tonicia. 

C. SHUTTLEWORTHIANUS Pilsbry, n. sp. PI. 21, figs. 42, 43, 44, 45, 

46. 

Shell oval, depressed but dorsally carinated, the side-slopes nearly 
straight ; lateral areas strongly raised, bicostate, the ribs nodose ; 
central areas having a coarse raised net-work in the middle, and 
longitudinally ribbed toward the sides. Girdle broad. Color of 
both shell and girdle intense orange yellow. 

The lateral areas bear two strong ribs which bear stout transverse 
tubercles, the intervening spaces being closely granulate. The central 
areas have coarse net-like sculpture (fig. 45), which becomes much 
finer toward the beaks, and is transformed into a longitudinal cos- 
tulation at the sides. The front valve has 16 or 17 strong, tuberculate 
radiating ribs, the whole covered by a fine granulation. The poste- 
rior valve is depressed, having a rather low but acute and slightly pos- 
terior mucrOy the slope back of it being concave. It is sculptured 
similar to the head-valve, except that the concentric sculpture pre- 
dominates over the radiating. 

The interior is flesh-colored ; anterior valve with 10, central 1 
slit ; sutural plates low and rounded ; sinus shallow, flat. 

Girdle wide, compact, very densely clothed with closely imbricat- 
ing scales, the terminations of which are not striated, although the 
basal portions are distinctly grooved (pi. 21, fig. 46.) 

Length 14, breadth 9 mill. 

Key West, Florida (Henry Hemphill.) 

This handsome species constitutes one of the links between Callis- 
tochiton and Ischnochiton, agreeing in the teeth with the latter genus. 
The sculpture, however, is much more like Callistochiton pulchellus 
than like any Ischnochiton known to me ; but, on the other hand, 
the profile of the tail-valve differs utterly from that West Coast 
species. 

18 




274 CALLISTOCHITON. 

It seems to resemble the unfigured I. lateritius Shuttlew. in color 
and somewhat in sculpture; but Shuttleworth says of his species "valvis 
terminalibus subconcentrice lineatus punctatisque ; mediis non carin- 
atis," etc., and this in no way agrees with the species described 
above. 

The type is in the collection of the Academy. 

C. ANTIQUUS Reeve. PI. 59, figs. 29, 30, 31, 32, 34, 35. 

Shell oblong-elliptical, moderately convex, obtusely carinated,the 
side-slopes convex ; of a uniform soiled buff, or stained with reddish 
along the back ; sometimes tinged with olive-green. 

Valves not beaked. Lateral areas composed of two strongly 
elevated ribs, bearing compressed grains, the posterior rib wider, its 
grains denticulating the suture. Central areas having a honey-comb 
reticulation near the beaks, on the sides changing into fine longitu- 
dinal riblets with minutely latticed intervals. Anterior valve hav- 
ing 11-12 very strong, rather narrow and acutely granose ribs. 
Posterior valve depressed, sloping backward from the front margin, 
the mucro depressed, slightly in front of the center ; the posterior 
area having 8-9 strong granose ribs. 

Interior bluish-white, sutural plates low, rounded, separated by a 
broad shallow sinus. Anterior valve having 9, central 1, posterior 
9 slits, corresponding to the external ribs ; teeth smooth, rather 
sharp, curved and concave outside as usual in Callistochiton. Eaves 
rather narrow. 

Girdle wide, thin, leathery, compactly covered with very small 
convex and apparently smooth brown scales, having light colored 
larger scales mingled among them (fig. 34.) 

Length 17, breadth 10 mill.; divergence 110-120. 

Port Mo lie, Queensland (Coppinger), Port Jackson, N. S. Wales 
(Angas, Brazier, Challenger.) 

Chiton antiquus REEVE. Conch. Icon., t. 25, f. 169 (poor). 
Lepidopleurus antiquus ANGAS, P. Z. S. 1867, p. 223. Callistochiton 
antiquus CPR. MS. and HADDON, Challenger Polyplac., p. 20. 
Chiton (^Callistochiton) antiquus E. A. SMITH, Zool. Coll. 'Alert' p. 
79. Callistochiton sarcophagus CPR., MS, 

This species has the same style of honey-comb or netted sculpture 
toward the beaks that C. pulchellus and C. shuttleworthianus show. 
A specimen in which the number of ribs on the head valve is 
increased by splitting to 17, and on the tail valve to 16 is on record; 



CALLISTOCHITON. 275 

but the number in front is ordinarily from 10 to 12, behind from 
-8 to 12. The tail valve is much depressed, as in C. gabbi. 

Carpenter described a large, fine specimen as 0. sarcophagus, but 
upon examining Keeve's type he concluded that it was merely a well 
developed antiquus. The type is in the British Museum. 

C. COPPINGERI Smith. PI. 59, fig. 36. 

Shell elongate, greenish-white, stained with a dark green color 
along each side near the girdle, with a paler indistinct stripe on 
each side of the central line, the apex of the valves being somewhat 
livid. Central valves with a straight posterior margin, arched, with 
only the faintest indication of a carina at the vertex. Lateral areas 
somewhat raised, with two radiating rows of coarse transverse 
rugae, of which the hinder or marginal are the largest. The surface 
between them is finely granular. Central areas covered with a 
more or less criss-cross granulation, the granules at the center being 
very minute, and gradually increasing in size toward the sides, 
where there is very little of the criss-cross arrangement seen at the 
vertex, but rather a longitudinal disposition of them. The front 
valve is minutely granulated and has about twenty fine radiating 
ridges, here and there some of them bifurcating near the circum- 
ference. Posterior valve rather large, concave behind the sub- 
central mucro, in front of which the surface is sculptured in the same 
manner as the front of the central valves, as is usual with most, if 
not all Chitons. The posterior half is finely grained and sparsely 
covered with pustules of different shapes and sizes. The coarsest being 
near the margin and the smallest near the center. The insertional 
plates are thin, with twelve slits in the last, at unequal distances, 
eleven in the front one, and one on each side of the intermediate 
valves. The interior is pale bluish, the latter valves having an olive- 
brown stain radiating from the vertex behind on each side, and the 
>two terminal valves have marks of the same color near the middle. 

The girdle is covered with alternately pinkish and dark grayish 
patches of fine oval compressed imbricating scales, of which those 
toward the outer margin are much smaller than those near the 
valves. 

Length without girdle 21 millim. ; diameter of fifth central plate 
8 mill. (Smith.) 

Port Jackson, Australia (Coppinger.) 

Chiton ( Callistochiton) copping eri E. A. SMITH, Rep. Zool. Coll. 
H. M. S. ' Alert/ p. 80, t. 6, f. E (1884.) 



276 CALLISTOCHITON. 

The only published figure of this species is very poor. Smith 
writes: closely allied to C. antiquus, but it is differently and more 
finely sculptured, and the scales on the mantle are larger. 

The type is in the British Museum. 

C. ADENENSIS Smith. PI. 59, fig. 45. 

Shell small, depressed, hardly carinated, unicolored pale brown- 
ish. Anterior valve having about 22 granulate radiating ribs. 
Lateral areas composed of two strong granulate ribs ; central areas 
longitudinally granose-lirate, the lirse more delicate in the middle 
than at the sides. Posterior valve having about 25 delicate granulate 
lirce. Girdle pale brownish, very minutely scaly. 

Length 14, breadth 9 mill. (Smith.) 

Aden. 

Chiton (Callistochiton) adenensis E. A. SMITH, Proc. Zool. Soc. 
Lond. 1891, p. 421, t. 33, f. 7. 

The sculpture of this species is of the same character as that of C. 
antiquus Reeve, but not quite so pronounced, and the rays of both 
the terminal valves are more numerous. (Smith.*) 

The type is in the British Museum. The italics of the above 
description are my own. 

C. HETERODON Pilsbry, n. sp c PI. 60, figs. 11-15. 

Shell oblong, rather elevated, carinated, the side-slopes nearly 
straight ; buff-white, sparsely dotted on the ridge with olive-black 
and having one or two spots of the same on the sides of each valve ; 
the girdle yellowish, having, narrow slate-colored bars. 

Valves having rather acute but not backward-projecting beaks. 
Lateral areas raised, having 3 or 4 ribs, being primarily divided by 
a deep sulcus into two ribs, the posterior of which is again divided ; 
and sometimes the front rib also is split into two, especially on the 
second valve ; the interstices are coarsely pitted, and the posterior 
rib is ribbed across, dentating the sutures. The central areas have 
about 11 rather narrow but strong longitudinal riblets on each side of 
a wider dorsal rib ; the interstices nearly smooth. Head valve having 
11 (or 13, by splitting) strong denticulate ribs. Tail valve narrower 
than the head-valve, not depressed, the mucro obtuse, post median; 
posterior slope convex, having 11 radiating ribs. 

Interior pure white. Sutural plates narrow, separated by a square, 
slightly deticulate sinus, which is distinctly laminate and slightly 
notched at the corners. Anterior valve having 8, central valves 1, 



NUTTALLINA. 277 

posterior valve 13 slits ; teeth blunt, finely and deeply pectinated out- 
side and at the edge. Eaves solid. 

Girdle broad, compactly covered with shining, deeply sulcated 
scales, measuring about one-third of a millim. in breadth, and the 
terminal margin of eaeh is smooth (fig. 13.) 

Length about 16, breadth 10 mill. ; divergence about 105. 

Red Sea. 

This species has far fewer ribs on the terminal valves than (?. 
udenensis Smith, although the lateral areas have more ribs. The 
girdle scales are coarser than in other species, and they have the 
peculiarity noted in C. shuttleworthianus, of being smooth at the 
distal end. I have seen no Chitons of other genera having this 
feature. The second valve has several slightly diverging riblets at 
the front of the dorsal area. The teeth are as deeply pectinated as 
in any species of typical Chiton or Acanthopleura ; and it is by no 
means impossible that the species belongs to the former genus. I 
have preferred to retain it in Callistochiton on account of the peculiar 
sculpture, and the relation in which the slits stand to the ribs. 

The type is in the collection of the Academy. 


Yar. SAVIGNYI Pilsbry. PL 60, fig. 16. 

This form is known to me by Savigny's figures, which indicate a 
species closely resembling the last. The head valve has 11, the 
lateral areas two ribs ; the tail valve is smaller, having 9 ribs ; 
central areas with about 9 ribs on each side, and a rather wide 
smooth tract in the middle. Scales of the girdle sulcate, with 
smooth outer edges. 

SAVIGNY, Descript. de 1'Aegypte, Gasterop., t. 3, f. 8-1, 8*2, 8'3. 

Genus XXIV. NUTTALLINA Carpenter, 1879. 

=Nuttallina plus Middendorfia plus Beanella Cpr. 

Valves exposed, granulated, the lateral areas having 2, head 
valve numerous low radiating ribs ; insertion-plates sharp, the slits 
corresponding in position to external ribs. Mucro behind the 
middle, the posterior teeth directed forward. Eaves and sinus very 
.spongy. Girdle varying from spiny to scaly. 

This well-defined genus probably has the same apparently 
anomalous distribution as the coral-red Leptothyras ; species being 
found in the Mediterranean, the Japanese Seas, and the coast of Cali- 



278 NUTTALLINA. 

fornia. Nuttallina is divisible into two closely allied sections or sub- 
genera, as follows : 

Subgenus NUTTALLINA s. sir. Side-slits two in each valve, the pos- 
terior one generally subobsolete, but indicated by a porous slit- 
ray. Teeth hardly or not thickened at the edges of the slits ; 
girdle with minute, often chaffy spinelets and longer round spines. 

Subgenus MIDDENDORFFIA Cpr. Side-slits single. Teeth more or 
less thickened at the edges; girdle clothed with minute striated 
flattened scales and having a marginal row of flat striated 
bristles. 

Subgenus NUTVALLINA Carpenter (restricted.) 

Nuttallina CPR., Table of Keg. Chitons, 1873. BALL, (Amer.. 
Journ. Conch, vii, p. 134), Proc. U. S. Nat. Mus. 1878, p. 333 
(Feb. 14, 1879.) 

Valves exposed, granulated, having long smooth sharp teeth ; the 
slits of the median valves obsoletely doubled, those of the anterior 
valve corresponding in position to the external ribs, the teeth not 
thickened atithe edges of the slits; mucro of posterior valve poste- 
rior, terminal but not marginal ; teeth of posterior valve short, 
chisel-shaped, directed forward. Eaves and sinus spongy. Girdle 
bearing short, rigid spines. Gills extending the whole length of the 
foot. Type N. scabra Cpr.= Ch. californicus (Nutt.) Rve. 

The shell in this genus resembles that of typical Aeanthopleura 
{A. spinosa Brug.) in the elongated valves, double slitting of the 
median valves, and the spinose girdle. It differs in the smoothness 
of the sharp teeth and the spongy sinus, characters of much greater 
importance than those first enumerated. The likeness of Nuttallina 
to Aeanthopleura is, in fact, merely one of analogy, having no mean- 
ing deeper than that story of the development of different stocks 
along parallel lines, repeated so' often in the history of Chitons. In 
its fundamental characters, Nuttallina agrees with Ceratozona ; but 
the more shelly texture of the girdle-spines, the spongy sinus, 
and propless teeth afford sufficient ground for generic distinction. 

Authors and collectors have generally recognized but one Cali- 
fornia species ; but there seem to be two. It is useless to try to* 
study them without separating the valves, as the specific characters 
are not very apparent in specimens preserved in the ordinary 
manner. 



NUTTALLINA. 279 

The white spines are often striated when young, as are the scale- 
like spines of Middendorffia. 

N. CALIFORNIA Nuttall. PI. 54, figs. 23, 24; pi. 56, fig. 12, 13, 

14, 15, 16, 17, 18. 

Shell elongated, more than twice as long as wide, moderately 
elevated, carinated or somewhat rounded. Surface finely corrugated- 
granular, lusterless ; color dark brown, dark olive-brown or black- 
ish, unicolored or having one or three whitish stripes along the 
summit of the second valve. 

Median valves strongly beaked, v-shaped, the anterior margin of 
the tegmentum trilobed; having a smooth shining rounded dorsal 
ridge (sometimes obsolete and often eroded), bounded by a pair of 
diverging, shallow furrows ; the entire sides of the valves (pleura and 
lateral areas} closely granulated, the granules irregularly arranged 
in rows. Lateral areas not raised but indicated by a low curved 
diagonal rib, behind which and parallel to it, there is a shallow 
sulcus. Anterior valve having 11 low rounded radiating ribs, the 
entire surface granulated. Posterior valve depressed, small, the 
mucro posterior and terminal, projecting beyond the posterior margin 
of the eaves. 

Interior bluish, sometimes stained with blackish at jugum and 
bases of the sutural plates. Sutural plates very long, separated by a 
wide, deep, square sinus; behind ivhich is a punctate and laminate 
area. Anterior valve having 11 or 10, median valves with two slits, 
or at least two punctulate slit-rays, the posterior slit being usually 
indistinct or wanting from the more or less complete obsolescence of 
the posterior tooth ; teeth sharp, smooth, long, not thickened at the 
edges of the slits. Posterior valve having 8-9 slits, the teeth chisel- 
shaped, sharp, smooth, very strongly directed forward. Eaves nar- 
row, spongy. 

Girdle closely covered with short, rigid calcareo-corneous spine- 
lets, mostly of a scorched brown color with a few white spines inter- 
mingled (pi. 54, fig. 24.) 

Length 37, breadth 15 mill. (Large specimen from Monterey.) 

Length 26, breadth 13J mill. (Specimen collected by Nuttall.) 

Vancouver Island south to Piedras Blancas, near S. Simeon, San 
Luis Obispo Co., California. 

Chiton californicus NUTTALL in Brit. Mus. and Mus. Phila. 
Acad. REEVE, Conch. Icon., pi. xvi, fig. 89 (March, 1847). Nut- 



280 NUTTALLINA. 

tallina scabra CPR., MS. and of DALL, Amer. Journ. Conch, vii, p. 
134 ; Proc. U. S. Nat. Mus. 1878, p. 333.Acanthopleura scabra CPR., 
Rep, Brit. Asso. 1863, p. 649. STEARNS, Proc. Calif. Acad. iii, p. 
S4Q.Nuttalliana seabra KEEP, West Coast Shells, p. 108, f. 96 
(1887.) Not Chiton scaber Reeve. 

This is the form which has generally been called " N. scabra." 
Reeve's figure is not good, being drawn from a short specimen 
abnormally shortened by contraction. It should be noted that the 
shortest specimen in the large suite before me is also one of those 
collected by Nuttall, who presented a complete set of his Califor- 
nian shells to the Academy. 

In this species the individual valves are longer than in the follow- 
ing form, but on account of their deep imbrication the difference is 
not in most cases noticeable until the shell is dissected. The girdle 
is much more densely clothed with spinelets. 

The areas of distribution seem to be separated, the true calif ornica 
extending southward past Monterey Bay, the southern out-post of 
so many species of the Columbian district, to near S. Simeon, S. 
Luis Obispo Co. The other species, scabra, has not been noticed 
north of Sta. Barbara Island, and San Diego on the mainland. 
There is still a considerable stretch of coast from which we have no 
record, or at least no record in which the two forms are discrimin- 
ated. This coast should be searched for intermediate forms. ' 

Dall gives the following notes on the station of this form : This 
singular species (not yet obtained from Alaska, but which will prob- 
ably be found there), like some Litorinas, seems habitually to prefer 
positions where it can at most be reached by the spray in storms, on 
exposed headlands, where the breeze comes in damp and cool from 
the sea. The pointed valves overlap each other so much that when 
the creature is curled up they project from the girdle, giving a pect- 
inated outline, unusual in Chitons. The valves are almost always 
eroded, even the prominent mucro is often hollowed out, and the 
sculpture can rarely be seen except in young specimens. The color 
is grayish or brownish, with whitish streaks ; the girdle has the 
aspect of dead brownish-black moss, sometimes with ashy spots at 
the sutures. 

N. SCABRA Reeve. PI. 54, figs. 21, 22 ; plate 56, figs. 19, 20. 

Shell similar to N. californica, but having the individual valves 
very much shorter in proportion to their width ; the outer layer of 
the median valves produced at the sides anteriorly, curving broadly 



NUTTALLINA. 281 

forward and laterally upon the sutural plates ; the median ridge 
and sulci more or less obsolete. Tail valve shorter, with less pos- 
terior mucro. Color of valves lighter, more variegated. 

Girdle rusty brown or alternately blackish and white ; bearing 
rather sparsely scattered white spike-like spines, sometimes having 
one or two at each suture. (PL 54, fig. 21). Length 29, breadth 
13 mill. 

Santa Barbara Is. and San Diego to between Seammon's Lagoo i 
and Pta. de Abreojos, Lower California. 

Chiton scaber REEVE, Conch. Icon., t. 17, f. 106 (March, 1847). 
Acantliopleura fluxa CPR., Suppl. Rep. Brit. Asso. 1863, p. 649 ; 
Proc. Cal. Acad. iii, p. 211, (1865.) 

This species has hitherto been confused with the preceding by 
most collectors. Carpenter, however, distinguished it, and gave the 
na.meflu.va. Although the individual valves are much shorter in 
this species than in N. californica, they overlap much less, so that 
the total length of the animal is about the same in the two species. 
The elevation is about equal also, but in ealifornica the girdle is 
generally wider at th sides, especially in old specimens. In size, 
individuals of the northern species considerably exceed any of the 
southern I have seen, although the majority of specimens do not 
differ much. 

N. ALTERNATA Sowerby. PI. 54, figs. 25, 26, 27. 

Shell elongated, subdepressed, very minutely granulated ; lightly 
keeled by a central rib ; lateral areas separated by a lateral rib. 
Anterior valve radiately ribbed ; posterior valve small. 

Girdle furnished with minute spines, alternately banded black 
and white. Length 15, breadth 8 mill. 

Narrow, rather flat, minutely granulated; the first valve radiated 
with slightly raised ribs, the intermediate have each three faint 
ribs, one dorsal, the other two lateral ; the last is very small, with 
a nearly terminal apex. The margin is covered with very minute 
spines, in alternate patches of black and white ; general color, dark 
olive-green. (Sowb.) 

Japan (Mus. Cuming). 

Chiton alternatus SOWB., Mag. of Nat. Hist., 1840, p. 288 ; Conch. 
Illustr., f. 141. 



282 NUTTALLINA. 

This form has not been noticed by subsequent authors. It seems 
to agree with the preceding species in the dorsal and lateral ribs, 
and also those upon the anterior valve ; but as the interior is 
unknown, its reference to Nuttallina is provisional. 

Subgenus MIDDENDORFFIA Carpenter, 1882. 

Middendorfia CPR., MS. and in DALL, Proc. U. S. Nat. Mus.,. 
J881, pp. 284, 287, type Chiton polii Phil, non Desh., (Jan. 20, 
182.) Dawsonia CPR. 1873, preoc., same type. Beania CPR. 
MS., not of Johnstone. Beanella DALL, Proc. U. S. Nat. Mus. 
1881, pp. 284, 287, type C. pseudorissoi CPR. ined., in Mus. Cuming 
no. 51. 

Valves exposed, rather square and short, granose outside with 
low ribs at lateral areas and on head- valve. Insertion plates rather 
sharp, not notably rugose, the teeth more or less thickened outside at 
the slit-edges ; slits of hea^-valve corresponding in position to exter- 
nal ribs. Tail valve small witn .nucro behind the center, the teeth 
directed forward, eaves and sinus coarsely spongy. Girdle narrow, 
compactly covered with a pavement of minute striated scales and 
spinose at the edge. Gills extending forward over three-fourths the 
length of the foot. Type Ch. cinereus Poli, not Linn. 

This subgenus agrees with Nuitallina in the markedly porous or 
spongy texture of eaves and sinus, in the external sculpture, and in 
the forms of the insertion-teeth, except that in Middendorffia these 
are thickened at the slit-edges. It differs from Nuttallina in the 
rather flattened scale-like, rather than spine-like girdle appendages 
but the younger spines of Nutallina scabra, when examined under a 
strong power are often seen to be striated, appearing like finely 
fluted ivory pillars ; and in some specimens of the same species 
there is a marked tendency to form a marginal fringe of longer 
spines. The differences between the West American and Med- 
iterranean forms are therefore not great, being confined to (a) the 
girdle covering, which often varies as much in closely allied species, 
such as Ischnoehiton conspieuns and I.acrior, or Chcetopleuraperuvi- 
ana and C. hennahi, and (6) the thickened tooth-edges, which 
varies considerable in Middendorffia and fails as a generic charac- 
ter in Ceratozona and some other groups. 

It should be noted that in Middendorffia the true structure and 
especially the sculpturing of the girdle-scales often cannot be satis- 
factorily observed without a compound microscope ; and a magnifi- 



NUTTALLINA. 283 

cation of from 50 to 100 diameters is necessary to demonstrate it in 
many specimens. 

N. CINEREA Poli. PL 54, figs. 28-33. 

Shell oval, moderately elevated, not carinated, the side slopes 
straight. Surface lusterless, generally encrusted with calcareous 
growths, gray or greenish blotched with black or dark green with 
some light markings or light valves. 

The median valves are beaked when young, but eroded and 
hardly beaked when adult, the lateral areas not raised but marked 
by two low wide rounded ribs with a shallow depression between them ; 
one rib diagonal, the other at the posterior border. Entire surface 
of all valves evenly covered with comparatively coarse granules. 
Anterior valve having 8 or 9 low rounded radiating ribs. Posterior 
valve very small, the mucro somewhat behind the center, the slope 
behind it straight ; posterior margin emarginate (as in Eudoxochiton, 
p. 193.) 

Interior bluish in the middle, olive-greenish at the sides. Sinus 
rather deep and angular, very porous or spongy. A more or less 
distinct laminate triangle extending from sinus to beak. Anterior 
valve having 8 or 9 slits corresponding in position to the external 
ribs ; the slits are very short, but are continued as grooves to the 
eaves outside ; median valves with 1 slit ; the anterior teeth nearly 
smooth, distinctly thickened or " propped " outside at the slits ; pos- 
terior valve having slits, the teeth rather stumpy, short in the mid- 
dle behind, longer and directed forward at the sides. Eaves rather 
wide and coarsely spongy. 

Girdle narrow, alternately dark and light, compactly covered 
with small, subcircular or irregularly polygonal scales, striated on 
the convex outer surface, crowded together ; the margin beset with a 
series of slightly flattened, striated translucent bristles, (figs. 31, 33). 

Length 14, breadth 8 mill. 

Length 20, breadth 12 mill. 

Entire Mediterranean and Adriatic Seas; Atlantic Ocean at 
Cadiz, Spain. Littoral zone. 

Chiton cinereus (+ Lophyrus melphictensis) POLI, Test. utr. 
Sicil. i, multivalvia p. 4, t. 3, f. 1-20, (1791). Not C. cinereus 
Linn. C. caprearm SCACCHI, Cat. Conch. Regni Neapolitan!, p. 9 
(1836) teste Monts. C. caprearum Scac., BUG., DAUTZ. and DOLL- 
PUS, Moll. Mar. Rouss. i, p. 492, t. 61, f. 7-9 ; t. 62, f. 1 (1886). 



284 NUTTALLINA. 

Ch. polii PHILIPPI, Enum. Moll. Sicil. i, p. 106 (1836) ; ii, p. 83 
(1844), and of most subsequent authors ; not Ch. polii Desh. 1832. 
Ch. crenulatus LoOARD, Coq. Mar. des Cote's de France, p. 233. 
(1892), and perhaps C. crenulatus Risso Eur. Merid. p. 267. Chiton 
decipiens TIBERI, Bull. Soc. Mai. Ital. iii, p. 141 (1877). Chiton 
corrugatus REEVE Conch. Icon., t. 28, f. 185 (1848). 

Distinguished from other Mediterranean species by the finely 
granose- scaly sculpture covering the entire surface, with two low 
ribs at the lateral areas and 8 or 9 on the head-valve. The girdle 
is composed of short striated scales crowded together, producing a 
" cobble-stone pavement " surface. The true nature of the scales 
appears only when highly magnified. The nomenclature of the 
species is peculiarly involved, like that of most Mediterranean Chi- 
tons. Poli believed it to be the cinereus of Linnaeus, but Philippi dis- 
tinguished it from that and gave the name Polii, which unfor- 
tunately had been some years before bestowed by Deshayes upon 
another species. Monterosato claims to have identified it with Ch. 
caprearum (" caprearm ") of Scacchi, by examination of a type in 
the Petit collection ; but the description given by Scacchi is 
inadequate. Scacchi says : " Chiton caprearm [sic] Nobis. Clypeis 
8 tuberculatis virescentibus, fascia marginali squamoso-muricata, 
perbelle ciliata. Longus lin. 6, latus lin. 4i. Caprearum scopulos 
incolit. " Locard identifies it with crenulatus Risso, the original 
description of which follows : " C. crenulatus. Dorso segmentis omni- 
bus cinereis crenulatis, Long. 17 mill. Penn. Br. Zool. 4, XXX VI, 
3, Pol., 4, iii, f " Of course this may be the present species, but the 
wretched description, without a figure is quite unacceptable. Tiberi 
proposed the name Ch. decipiens as a substitute for polii Phil, not 
Desh. The locality of Reeve's Ch. corrugatus is not known, but the 
description and figures render its identity reasonably certain, and 
Carpenter declares the types to be young polii Ph. In the midst of 
so many conflicting names and opinions I prefer to retain the name 
given by Poli. His description is infinitely better than any of the 
later ones mentioned above. Indeed Poli's work upon this species is 
wonderful for his time, and with such an example before them it is 
surprising that so many Mediterranean naturalists have left such 
miserable work. 

It is needless to say that the Chiton cinereus of Linne belongs to a 
genus which must be admitted by all naturalists who examine the 
subject, to be perfectly distinct. 



CRASPEDOCHITON. 285 

The representation of the coarse pores of the eaves in fig. 28 
causes the teeth to appear pectinated, which is by no means the case. 

Var. pseudorissoi Cpr. Teeth of insertion hardly thickened at the 
edges ; mucro subraedian ; girdle scales elongated, flattened, 
striated. 

Malta. 

The type is no. 51 of Mus. Cuming. Carpenter, after examining 
more material, decided that this form was specifically identical 
with the Ch. polii Phil. His type specimen is a young shell. Not 
having seen it, I am unable to tell whether all of the scales, or only 
those at the edge are elongated. In either case the subgeneric name 
Beania or Beanella falls as a synonym. 

Genus XXV. CRASPEDOCHITON Shuttleworth, 1853. 

Oraspedochiton SHUTTLEW., Bern. Mittheil. 1853, p. 67. Type 
Ch. laqueatus. 

Valves exposed, slightly immersed, granulated ; with five low ribs 
on the head-valve ; insertion plates sharp-edged ; those of anterior 
valve long, strongly grooved inside and out, having slits at the 
positions of the external ribs ; median valves having the insertion 
plates thin, sharp, 1-slit; posterior valve with subcentral mucro, 
teeth short, grooved. Girdle corneous, very minutely roughened. 

The characters of eaves and sinus are unknown to me. The 
external sculpture reminds one of Nuttallina, which differs in the 
posterior inucro, etc. The sharp-edged insertion plates, and the 
correspondence of slits to external ribs show clearly that this genus 
does not belong in the neigborhood of Chiton, Tonicia, etc., where 
Carpenter placed it, but with the genera here accompanying it 
which share these peculiarities. 

C. LAQUEATUS Sowerby. PI. 39, figs. 42-51 ; pi. 44, fig. 68. 

Shell ovate, depressed, granulated ; pale, tawny or greenish, 
maculated with purple or green ; the dorsal rib purple. 

Anterior valve having five low ribs, median valves squared at 
the ends, and having the sculpture often worn from the median 
ridge, which is wedge-shaped on each valve, the wedge being com- 
posed of about six truncated, somewhat wedged segments, and on 
each side there are oblique, irregular ridges. Posterior valve having 
the mucro central and very little raised. 



286 ANGASIA. 

Interior : Anterior valve (figs. 43, 44, 45) considerably thickened 
within, and shallowly grooved radially ; the insertion plate stout at 
the base, acute at the edge, and furrowed both inside and out, the 
edge consequently being roughly crenulated ; slits 5, corresponding 
in position to the external ribs. Median valves (figs. 46, 47, 48) 
having broad and thin insertion plates, which are smooth-edged, 
and only very finely striated. Posterior valve (figs. 49, 50, 51) 
having the insertion plate very short, thick, moderately sharp-edged 
coarsely grooved within and without, and roughly crenulated on the 
margin. When viewed from above (the valve resting upon a flat 
surface) the teeth are not visible, and all touch the surface, there 
being no upward wave posteriorly. 

Girdle coriaceous (or perhaps better, pithy) and almost smooth. . 

Length 13f, breadth Hi mill. 

Calapan, Island of Mindoro, Philippines, in coarse sand among 
small stones, in 9 fms. (Cuming.) 

Chiton laqueatus SOWB., P. Z. S. 1841, p. 104. REEVE,. Conch. 
Icon., t. 20, f. 135. 

The above description is mainly compiled from details furnished 
by Mr. E. A. Smith of the British Museum, who also drew figures 42 
-51 from one of the original specimens. The scale-like granules are 
said to be represented somewhat too small on the figures. Sowerby 
remarks that the four or five central valves in several specimens are 
nearly covered by a dark purple color, the two last patched with 
green, and the first nearly white, but subject to some variations. 
Shuttle worth describes the girdle " limbus eorneus, minutissime 
asperulus, " but Smith says it is nearly smooth in the British 
Museum specimens, and the insertion plates are visible through it, 
as shown in fig. 42. 

Genus XXVI. ANGASIA Carpenter, 1882. 

Angasia CPR., Table Reg. Chitons 1873 ; and in DALL, Proc. U. 
S. Nat. Mus., 1881, p. 283, 286, 289, 290 (Jan. 20, 1882). Augasia 
SCUDDER, Nomencl. Zool. p. 38 (typog. err). 

Valves outwardly and within like those of Chcetopleura, but the 
eaves small ; girdle minutely scaly-pilose, and furnished with tufts 
of hairs at the sutures. Type A. tetrica Cpr. 

I have seen no specimen of this form, which I believe to be 
related to Craspedochiton. Carpenter writes as follows : 



ANGASIA. 287 

" This genus differs from Callistoplax in having the eaves short, 
the teeth straight (though frequently propped outside, as in Callo- 
vhiton), the mantle crowded with minute horny scales or rudimentary 
bristles and furnished with pore-bunches round the sutures. The 
anterior valves is 5 slit, as in Acanthochites, but that may be only a 
specific peculiarity. The Hanleya variabilis Ad. and Ang. P. Z. S. 
1864, p. 194, probably belongs to this genus, but has not been 
dissected. Angasia is known at once from Hanleya by the presence 
of insertion teeth ; and from Placiphora by the regular articulation 
of the tail plate. If the genera be grouped according to the mantle- 
pores, Angasia will represent Chcetopleura in the tufted series, as 
Callistoplax represents Callistochiton. " 

A. TETRICA Carpenter, n. sp. PI. 61, figs 27-32 (sculpture not 
represented.) 

Shell oval, greenish-ashen, rather elevated, the jugum acute ; 
mucro slightly in front of the middle, slightly elevated ; valves 
squared, beaked ; the terminal ones much flattened. Jugular area 
obscurely tricostate ; lateral areas obscurely defined by a diagonal 
angle ; anterior valve somewhat obsoletely five-angled ; the whole 
surface very closely sculptured with wide, irregular, flattened some- 
times striated pebbles, smaller toward the dorsal ridge. 

Interior : Posterior valve having 9-13 slits, the teeth small, 
radially flattened, rugose outside and propped, generally bilobate ; 
anterior valve having 5 slits, the teeth more acute, roughened out- 
side, slightly propped ; central valves with one slit, the teeth acute, 
rugose outside, conspicuously thickened or propped at the sides of 
the slit ; eaves small ; sinus narrow, short, smooth ; sutural plates 
separated. 

Girdle narrow, leathery, with very close and very minute cor- 
neous scales ; at the sutures and around the end valves there are 
bunches composed of a few short spicules, and there are a few 
scattered spicules also. 

Length 15, breadth 9| mill.; divergence 120 (Q?r.) 

Ceylon (Mus. Cuming, No. 83). 

A. tetrica CPR. MS., and in BALL, Proc. U. S. Nat. Mus., 1881, 
p. 286 (no description). 

A common observer might describe the mantle simply as rough 
and leathery, so minute are its remarkable features. The same 



288 CALLISTOPLAX. 

structure, but without the pores, characterizes some species herein 
referred to Chcetopleura. The posterior valve somewhat resembles 
an irregular Maugerella ; the anterior valve is strictly Acanthochi- 
toid. Both of these are flattened, while the ridge is sharp on the 
central valves. (Cpr.) 

Var. CALCULOSA Cpr. 

Shell externally very similar to A. tetrica, but roseate ; jugal areas 
distinctly tricostate ; anterior valve distinctly five-angled ; pebble- 
sculpture smoother. Interior : posterior valve normal, with 5 slits, 
the teeth all acute, but slightly roughened, hardly propped ; sinus 
narrow, deep, smooth, flat. Bunches of spicules minute, inconspic- 
uous ( Cpr.) 

Philippines (Mus. Cuming no. 79, part.) 

Angasia (f tetrica var.) ealculosa CPR., MS. 

" The insertion plates of this shell offer a marked contrast to the 
Cingalese shell, being strictly like Ischnochiton (with shortened 
eaves) throughout. But one specimen, after an anterior fracture, 
has mended it with distinctly rugulose teeth, and made its posterior 
teeth propped and lobed, showing a close connexion between the 
two forms. It is probable that Mr. Cuming's specimens from the 
two localities had been intermixed. The tufts could scarcely be 
detected in shriveled specimens " ( Cpr.) 

Genus XXVII. CALLISTOPLAX Carpenter, 1882. 

Callistoplax CPE., Table of Regular Chitons, 1873. Ball, Proc. 
U. S. Nat. Mus. 1881, p. 283, 286 (Jan. 20, 1882). TRYON, Struct, 
and Syst. Conch, ii, p. 342. 

Valves outwardly and within as in Callistochiton. Girdle naked 
except for a series of bristle-bearing pores. 

The present genus is one of the very few which rest entirely upon 
characters of the girdle ; but so different is this from that of Callis- 
tochiton, not only in the presence of pores, but in the entire absence 
of scales, that no course seems open but to treat the group as of 
generic value. 

C. RETUSUS Sowerby. PI. 61, figs. 17-26. 

Shell small, subelongate, slightly elevated, the jugum acute; 
mucro median, very obtuse, elevated in adult specimens. Jugal 
area smoothish, granulose, in the adult having a few acute longitu- 



CALLISTOPLAX. , 289 

dinal lirulse ; central areas with about 10 rugulose-granose lirse on 
each side, perpendicular to the diagonal line, the interstices cancel- 
lated. Lateral areas having two very strong rounded ribs, the 
front one stronger, separated by a narrow sulcus, and concentrically 
wrinkle-granose and very minutely granulose ; sutures with a series 
of imbricating granules. Anterior valve having 7 ribs, of 
which the posterior ones (as in the median valves), bifurcate, and are 
imbricated along the sutures ; posterior valve in the young shell 
having 6 ribs, all of these bifurcate, and the anterior ones split 
twice, making 14 delicate, flattened ribs, which tend forward some- 
what. 

Interior: the posterior valve, in a young specimen has about 11 
slits, the teeth curved in harmony with the external ribs, and 
directed radially outward ; in the adult there are about 12 slits, the 
teeth solid, directed somewhat forward, rugose- costate at the mar- 
gins, concave in the middle, the eaves very heavily callous. Ante- 
rior valve having 7-8 slits, situated in the middle of the ribs, the 
teeth following the curvature of the outer margin, acute. Central 
valves with 1 slit, teeth excurved, eaves wide, pectinated, spongy. 
Sinus narrow, deep, narrowly slit on each side of the lamina, and 
sometimes denticulated by the external sculpture. 

Girdle narrow, smooth, thin, having 40-53 bunches of long, cor- 
neous hairs around the margin, hardly sutural (figs. 23, 24). 

Length 14, breadth 8 mill.; divergence 120. 

Guacomayo and Puerto Portrero (Cuming) ; China Seas (Cum- 
ing.) 

Chiton retusus SOWB. P. Z. S. 1832, p. 28, Conch. Illustr. f. 22. 
REEVE, Conch. Icon., t. 17, f. 99. Plaxiphora retusa H. & A. Ad. 
Genera Rec. Moll, i, p. 481. Callistoplax retusa CPR. MS. and in 
Ball, Proc. U. S. Nat. Mus. 1881, p. 286. 

The locality " China Seas " given by Cuming to Carpenter, is 
probably wrong, that originally given by Sowerby being much more 
worthy of confidence. The above description is from Carpenter's 
MS. 

Figures 17-23 represent a young specimen ; in the adult the ribs 
become more numerous and the tail-plate more " Acanthoid " in 
appearance (figs. 25, 26). 



19 



290 CERATOZONA. 

Genus XXVIII. CERATOZONA Dall, 1882. 

Ceratophorus CPR., Table of Regular Chitons, 1878, type C. 
guildingi Rve. Not of Diesing, 1850. Ceratozona DALL, Proc. U. 
S. Nat. Mus. 1881, p. 283, 286 (Jan. 20, l&SZ).Newcombia CPR., 
MS., type C. setosus Sowb. Not Newcombia Pfr., Malak. Bl. i, p. 
117, 1854. 

Valves strong, exposed. Insertion plates of anterior valve long, 
sharp, rugose outside, thickened at the slits, which correspond in 
position to the external ribs ; median valves with similar propped 
teeth ; tail valve having the teeth thick, shorter, rugose, sinus 
solid. Girdle tough, bearing peculiar corneous spines, similar in 
substance to itself, generally sparsely bunched, at the sutures. The 
gills extend the entire length of the foot. Type C. guildingi Reeve 
= C. rugosa Sowb. 

Shuttleworth may readily be excused for grouping the type of this 
genus in Chcetopleura. Compared with Ch. hennahi it is seen that 
both have the teeth sharp, and rugose outside ; both have the eaves 
solid or occasionally with a row of minute pores along the outer 
bases of the teeth ; and finally both have horny spinelets on the 
girdle. But in Ceratozona the insertion teeth are thickened at the 
slits which correspond in position to the riblets of the exterior ; the 
valves are much more firmly held in the tough girdle, and the 
appendages of the latter are much more deeply inserted in its sub- 
stance. If we examine an alcoholic example of Chcetopleura 
hennahi we find that the cuticle of the girdle peels off readily, bringing 
with it all the spinelets, which leave shallow pits in the fleshy sub- 
stance of the girdle; but in Ceratozona, only the smaller hairs are 
thus readily removed, the larger ones being deeply and very 
intimately attached. Moreover, in most specimens, a pair, or a 
small bunch of spines, may be detected near each of the sutures ; 
but this character is often obscure or even wholly obsolete. From 
Nuttallina this group differs in the solidity of the sinus, the less pos- 
terior mucro, generally rugose and " propped " teeth, and the 
peculiar girdle-spines. 

C. RUGOSA Sowerby. PI. 61, figs. 33-37, 41-45. 

Shell oblong, rather convex, the back broadly arched. Surface 
generally much eroded, green, olive or slate-blackish on the sides, 
the central areas whitish along the middle, flamed with blackish at 
the sides, or green there ; tail valve having a broad pink ray 
behind. 



CERATOZONA. 291 

The valves are strong, and when not eroded they are somewhat 
leaked. Lateral areas hardly raised, but defined by a strong . 
rounded rib, sometimes with a lower wide rib behind ; having a 
sculpture of irregular wavy wrinkles over ribs and interval, and 
also upon the sides of the central areas. Head-valve having about 
11 low radiating ribs and superficially waved concentrically. Tail 
valve rather depressed with a subcentral, slightly projecting mucro, 
the area behind it obsoletely radiated. 

Interior blue-green, varying in intensity. Sutural plates moder- 
ate, separated by a rather wide smooth sinus. Anterior valve 
having 7-10 slits, the teeth long, acute, slightly rugose outside and 
denticulate at the edge, generally thickened or propped very strongly 
along the slits ; central valves with 1 slit, the teeth much thickened 
at the edges of the slit ; posterior valve having 8-10 slits, the teeth 
much shorter and blunter than in front, wedge-shaped, denticulate 
at the edge, not perceptibly propped or thickened along the slits, 
Eaves very narrow, having a single series of pores along the bases 
of the teeth. 

Girdle very tenacious, rather wide, yellowish, armed with numer- 
ous corneous, yellow rather long and pointed spines, most numerous 
around the edge, and in most specimens showing a bunch of several 
at each suture ; among these larger spines, slender flexible beards 
are scattered (fig. 35). 

Length 40, breadth 25 mill. ; generally smaller. 

Jupiter Inlet, east coast of Florida (G. W. Webster et al.) to 
.Jamaica (C. B. Ad., Johnson & Fox) ; Porto Rico (Blauner) ; St. 
Vincent and Trinidad (Guilding). 

Chiton rugosus (Gray) SOWERBY, Conchol. Illustr. no. 6, fig. 49, 
(1841 ?). REEVE, Conch. Icon., t. 18, f. 115 (April 1847). CMow- 
(Chcetopleura) rugosa Sowb, SHUTTL., Bern. Mittheil. 1853, p. 78. 
Chiton squalidus C. B. Ad., Proc. Bost. Soc. Nat. Hist., ii, p. 8, 
(Jan. 1845). Chiton guildingii REEVE, Conch. Icon., t. 21, f. 138 
(May, 1847). Ceratophorus guildingi CPR. Ceratozona guildingi 
DALL, Catal. Mar. Moll., S. E. U. S. p. 172. Ch. bicolor (C. B. Ad.) 
GRAY, P. Z. S. 1847, p. 67. 

This species is not likely to be confused with any except the next. 
The valves are rather strong and blue-green inside, sometimes very 
pale. The girdle is of a conspicuous horny yellow color when 
scrubbed as in most cabinet specimens, but is dull and dark in the 
natural condition. The horny, curved bristles are both fine and 



292 CERATOZONA. 

coarse, but the more delicate ones are easily lost. The pore-bunches 
at the sutures are rarely conspicuous, and often cannot be made out 
without the aid of a lens and a lively imagination ; and this fact 
somewhat impairs their value as a generic character. Nearly all of 
the adult specimens I have seen are very much eroded. 

Some recent authors have used the name guildingi Reeve, for 
this species ; it is not easy to see why, for Sowerby and Adams both 
preceded the author of the Iconica. The original figure of guildingi 
is copied on my plate, fig. 37. The sculpture varies a good deal. 
Fig. 36 is drawn from one of the most strongly sculptured speci- 
mens I have seen, from Jupiter Inlet, Fla. Fig. 34 is from Sta. 
Cruz., of the Virgin group, being drawn from a specimen colored, 
exactly like Sowerby's original figure of rugosus (fig. 33). In this 
shell the teeth are less propped and the eaves narrower than in the 
Florida examples. Fig. 35 is from a Jamaica specimen. 

I have seen no specimen with the mucro so posterior as it is shown 
in Carpenter's figure (fig. 41) ; all I have seen resemble fig. 39. 

C. SETOSA Sowerby. PI. 61, figs. 40, 38, 39. 

Shell oblong-oval, ashy-greenish, scabrous; front valve, lateral 
areas and posterior valve radially sulcate. Marginal ligament 
setose, the setae rather short and close. 

Length 32i, breadth 15 mill. (Sowb). 

Guacomayo, Central America (Cuming). 

Chiton setosus SOWB., P. Z. S. 1832, p. 27 ; Conch. Illustr. f. 19. 
REEVE, Conch. Icon., f. 100. Not C. setosus Beechey's Voy. 
' Blossom ' t. 41. f. 17,=Mopalia. Not Ch. setosus Tiles, Mem. Ac. 
S. Pet. ix, p. 484 (1824). 

This species is very distinct from C. setiger King, which it in some 
degree resembles. The bristles around the edge are much shorter,, 
thicker and more closely set. (Sowb). 

Carpenter has had figures of the interior and tail valve prepared^ 
and I have copied them in my figs. 38, 39. I have seen no species 
of this sort from the Pacific side of the isthmus, and I am therefore 
not prepared to say what relation setosa sustains toward rugosa, the 
West Indian form. Fig. 40 is a copy of Sowerby's original figure 
of setosus. 



MOPALIIDJE. 293 

Family MOPALIID.E Pilsbry. 

Placiphoroidea (part) and Mopaloidea (part) CPU. 

Chitons in which the valves are divided in the normal manner 
into lateral and central areas; the teeth of insertion are not pectina- 
ted ; and the posterior valve has a posterior-median sinus, with one 
slit on each side or none. The girdle is more or less hairy, never 
scaly. Gill row as long as the foot. 

The normal number of slits in the anterior valve is 8 ; but this is 
often increased or diminished by splitting or' fusion of one or two 
teeth. The slits correspond in position to external ribs, as in the 
last subfamily. In certain forms (Placiphorella, Placophoropsis) 
the number of anterior slits is abnormally multiplied. The inter- 
mediate and posterior valves have not more than 1 welt developed 
slit on each side, and even this is lacking in the tail valve of Plaxi- 
phora. 

The girdle clings more tenaciously to the teeth than in most 
chitons, being like that of Ceratozona. It is frequently provided 
with pores at the sutures, each pore generally bearing two or several 
bristles or hairs ; but the presence or absence of these pores is in no 
case of more than specific value, and in some cases I have found it to 
be a mutable feature among individuals of the same species. 

The present family is in no manner identical with that so named 
by Dall, or with Carpenter's division of similar name ; nor is it in 
any sense equal to the Placophoridce of Dall, Placiphoroidea Cpr. 
These Carpenterian divisions of the " Irregular Chitons " are very 
artificial, just as the primary division of the group into " Regular" 
and " Irregular " forms is artificial. 

The ancestors of Mopaliidse were Callistoplacince, probably not 
^very different from the recent genus Ceratozona. 

Key to the genera of Moiialiidce. 

a. Posterior valve having a slit on each side of the median sinus. 
b. Shell oblong ; girdle narrower in front than at the sides, 
its hairs smooth ; teeth of insertion not lobed. MOPALIA. 
bb. Shell rounded-oval ; girdle expanded and broadest in front, 
its hairs scaly ; teeth of insertion more or less lobed. 

PLACIPHORELLA. 
<ta. Posterior valve having a median tail-sinus but no slits. 

PLAXIPHORA. 



294 MOPALIA. 

Genus XXIX. MOPALIA Gray, 1847. 

Mopalia GRAY, P. Z. 8. 1847, pp. 65, 69, 169, (exclusive of sec- 
tion * *). Type Ch. hindsii. CARPENTER MS. and in Dall, Proe. 
U. S. Nat. Mus., 1878, p. 3Q3.Molpalia GRAY, Guide Syst. Dist. 
Moll. B. M., p. 184 (err.typ.), 1857. GOULU, Otia, p. 118. 
Osteochiton DALL, Proc. U. S. Nat. Mus. 1886, p. 211. Type M. 
sinuata Cpr. 

Valves normally proportioned, transverse, not beaked, exposed, 
the girdle somewhat encroaching at the sutures. Sinus small ; inser- 
tion-plate of anterior valve rather long, sharp, slit into nearly 
smooth teeth which are somewhat thickened at the edges of the slits, 
the latter being normally 8 in number and corresponding in position 
to external ribs. Median valves having similar 1-slit insertion- 
plates. Posterior valve depressed, the mucro post-median, insertion 
plate rather sharp, smooth or roughened, having an oblique slit on 
each side (rarely doubled) and a larger sinus in the middle behind. 
Girdle wider at the sides than in front, leathery, more or less hairy, 
the hairs simple ; with or without sutural pores. 

This gen us is known only from the shores of the northern Pacific, 
extending from Lower California to Alaska and Japan. It may be 
regarded as the most primitive of the existing genera of Mopaliidce; 
Pladphorella, and Plaxiphora being special modifications of the 
Mopalia type. The small additional slits occurring in some forms, 
such as M. acuta, are cases of partial reversion to the multifissate 
ancestral form which gave rise to the family. 

Two species of Mopalia were placed by Carpenter in Pladphorella 
on account of their possessing sutural pores. Dall justly remarks 
that they differ from the true Placiphorellas, and he proposes Osteo- 
chiton as a section of that group for their reception. It is my belief 
that these species have no near alliance with Pladphorella, but that 
they are merely modified Mopalise. The gathering of a few hairs or 
spicules into a pore at the sutures is no uncommon occurrence, and 
in some cases (such as Ceratozona) it is not constant even as a speci- 
fic character. In Mopalia this modification will probably be found 
to occur in all the forms in which the girdle is nearly naked. In a 
small form of M. muscosa from Bolinas Bay the pores are sometimes 
present at all of the sutures, and sometimes at only two or three on 
one side, entirely absent on the other side. Sometimes they bear 
each a large hair, sometimes none. It is therefore obvious that we 
can make no disposition of Osteochiton except to consider it aiL 
absolute synonym of Mopalia. 



MOPALIA. 295 

M. MUSCOSA Gould. PL 63, figs. 46-48 (typical), figs. 49-63 (varr). 

Shell oval, elevated or depressed, the dorsal ridge more or lesa_ 
angular. Valves strong. Surface lusterless, finely sculptured with 
wavy, crenulated logitudinal riblets, often more or less obsolete. 
Color generally dull brown, blackish-olive or grayish, but sometimes 
bright orange, scarlet or vivid green. 

Median valves hardly beaked, the lateral areas slightly raised, 
granose, limited by a raised granose riblet. Central areas having 
close fine longitudinal riblets, with crenulated or latticed interstices, 
the riblets finer and converging on the ridge of the last 6 valves, 
diverging on the second valve, or strongly diverging on the ridge of 
all valves, like a series of superimposed v's. Anterior valves having 
about 10 narrow radiating granose riblets, the intervals granose. 
Tail valve depressed with posterior mucro, the posterior slope very 
short, emarginate behind. 

Interior bluish-green, stained with lilac on the central callus. 
Anterior valve having 8, median 1 short slit, the teeth long, deeply 
striated outside and thickened or propped outside at the sides of the 
slits. Posterior valve having a rounded sinus behind, with one 
oblique slit on each side, the plate roughened outside near the slits. 
Sutural plates broad, the sinus extremely shallow and small. 

Girdle rather narrow, densely covered with round, curved or 
curled hairs. Gill row as long as the foot (pi. 64, fig. 74). 

Length 52, breadth 38 mill. 

Length 25-60, breadth 15-40 mill. ; divergence 120-140. 

Shumagin Is. (rare) to San Diego, California, between tide marks 
and at lowest water. 

Ch. muscosus GLD., Proc. Bost. Soc. N. H. ii, p. 145, July, 1846 ; 
Exped. Moll., p. 313, f. 436 ; Otia, p. 6. Chiton ciliatus REEVE 
Conch. Icon., t. 19, f. 124. Mopalia ciliata H. & A. AD. Gen. Rec. 
Moll., i, p. 478. DALL, Proc. U. S. Nat. Mus., 1878, p. 303 (syn- 
onymy and variation) ; p. 298, f. 35, 35a (dentition). NOT Ch. 
ciliatus Sowerby ! Chiton setosus SOWB. in Beechey's Voy. 'Blos- 
som' p. 150, t. 41, f. 17 (not C. setosus Sowb. 1832). Ch. collei 
REEVE, Conch. Icon., t. 21, f. 136 (1847). Ch. wosnessenskii 
MIDD. Mai. Ross, i, p. 101 (part of diagnosis). Chiton armatus 
NUTT., JAY'S Catalogue, 1839, no. 2678 (not described) ; Ch. aren- 
atus NUTT., in Mus. Acad. Nat. Sci. Philadelphia. C. ornatus 
NUTT. MS. CPU., P. Z. S. 1855, p. 232. and C. consimilis NUTTALL, 
MS. in Brit. Mus. 



296 MOPALIA. 

In its typical state (pi. 63, fig. 46), this species may be known by 
the strong though variable sculpture, dull brown or blackish-olive 
color, the small sinus, the girdle being thickly set with round hairs 
varying from strong bristles to soft hairs. A variation in color is 
seen in some southern specimens (Tomales Bay) which are orange 
or scarlet (pi. 63, fig. 48), or yellowish maculated with orange and 
vermilion. Others from the same locality are vivid blue-green or 
green (pi. 63, fig. 47). 

In his work on the Chitons of Alaska, Dr. W. H. Dall discusses 
the synonymy and variation of this species, concluding that M. 
lignosa Old. should be regarded as an extreme form, connected by 
intermediate examples with the typical muscosa. He writes as fol- 
lows : " This species can be distinguished from all varieties of 
ivossnessenskii by its blackish and proportionately much narrower 
girdle, and by a sort of prolongation of the external layer of the 
shell forward under the apex of the next anterior valve in the 
median line, forming a sort of anterior false apex, which is hidden 
until the valves are separated. In ivossnessenskii this part is 
squared off, the girdle is yellowish (when alive), and the valves are 
much less transverse. It will be surprising if those who have only 
observed these animals by a few dry specimens in collections are 
willing to accept the synonymy above given, I confess that not long 
since I would have been unwilling to believe that the rough, bristly, 
typical muscosa and the dark, smooth hindsii could be properly com- 
bined under one name with each other or with the finely reticulated 
and painted lignosa ; but the study of a large multitude of speci- 
mens has convinced me no arbitrary line can be drawn anywhere in 
a fully representative series, beginning with coarsest ciliata \_muscosa~] 
and ending with a practically smooth hindsii. The characters of 
girdle, sculpture and form are not only variable in themselves, but 
are found variably combined, except that it is rarer to find coarsest 
sculpture with a downy than with a bristly girdle. However, even 
this occurs. On the other hand, out of such a series a dozen forms 
might be selected which, if only the characters were constant, every 
one would acknowledge as good species. " 

Var. HINDSII (Sowb.) Reeve. PL 62, figs. 99, 100; pi. 63, fig. 
57. 

Shell elongated and much depressed, (the angle of divergence 
about 140), the girdle encroaching at the sutures. External color 
a light or dark shade of olive. Surface smoother than in typical 



MOPALIA. 297 

r muscosa; the granose-corrugation being more or less zig-zag or criss- 
cross on the central areas, obliquely corrugated-granose on the- 
lateral areas. Interior white, rvith short crimson rays' under the 
beaks ; tail sinus visible outside. Girdle with few and short hairs. 

Chiton hindsii (Sowb. in Mus. Cuming) REEVE, Conch. Icon., t. 
12, f. 67a, b (IS^.Mopalia hindsii GRAY, P. Z. S. 1847, pp. 69, 
169. H. & A. AD., Genera Rec. Moll, i, p. 478, iii, t. 54, f. 7. 
Mopalia ciliata var. hindsii DALL, Proc. U. S. Nat. Mus. 1878, p. 
304. 

The specimens described are from San Francisco Bay. The teg- 
mentum or outer layer of the valves projects forward somewhat at 
the sinus, as in typical muscosa ; but this can be seen only in the 
detached valves. 

Var. PORIFERA Pilsbry. PI. 62, figs. 93, 94. 

Another form of muscosa, which if constant in its peculiar features 
would make an excellent new species of the section Osteochiton, is 
before me from Bolinas Bay. It is perhaps deserving of a varietal 
name. The shell is rather small, thin and high, but not to as great 
an extent as M. acuta. It is sculptured as in M. hindsii, but the 
diagonal and sutural ribs are more prominent, and sculptured with 
strong, transverse beads exactly as in M. imporcata, the suture being 
dentated by them. Color of valves olivaceous, clouded obscurely 
with smoky, and having a black stripe each side of the dorsal 
lighter stripe. The posterior valve has a depressed mucro near the 
posterior margin, which is very slightly waved inward. Girdle 
firm and leathery, minutely and evenly papillose all over, blackish 
with spots of orange ; having a small pit or pore at each suture, with 
a series of pores alternating with these a little outside of the middle 
of the girdle (pi. 62, fig. 93). Sometimes some of the sutural pores 
bear large hairs, curling outward ; and sometimes some or many of 
the pores are completely absent. 

Length 23, breadth 13 mill; divergence 105-115. 

The interior is a deep blue-green, or gray-blue with a purple-pink 
blush. 

Var. ACUTA Carpenter. PL 64, figs. 75-81. 

Shell rather small, strongly elevated, the dorsal ridge acute ; 
valves thin; sculpture minute and delicate, varying between a 
minute granulation and a fine pitting; the sutures delicately dentic- 



298 MOPALIA. 

ulate; diagonal riblets obsolete or delicately raised. Color oliva- 
ceous obscurely mottled with dusky, the tail valve having a light 
ray behind. 

Interior blue-green. Tail valve slightly waved upward in the 
middle behind, and having either a simple narrow caudal slit, or a 
slit with a small tooth set in its apex. Lateral slits of the tail valve 
generally double on one side. Girdle narrow, sparsely hairy. 

Length 22*, breadth 12J mill.; divergence 105 (Carpenter's 
type). 

Length 22, breadth 13 mill. ; divergence 105 (San Diego spec.). 

Length 23, breadth 15 mill.; divergence 98 (Sta. Barbara 
spec). 

Santa Barbara (Canfield, Gabb.) ; San Diego (Hemphill). 

Chiton acutus CPR., P. Z. S. 1855, p. 232. Mopalia acuta CPR., 
Brit. Asso. Rep. 1863, p. 648. Mopalia plumosa and M. (f var.} 
fissa CPR., MS. (? Not Ch.plumosus Gld). 

The comparative tenuity of the highly angled valves, their deli- 
cate sculpturing over the whole surface, the fine denticulation of the 
sutures and the narrow, often toothed caudal sinus, all give an 
aspect of individuality to this form, and cause me to rank it with 
hindsii and lignosa as a well-differentiated subspecies. 

Carpenter, working from very few specimens, made three species 
of the forms of this. The occasional bi-slitting of the tail plate on 
one side is found also in some specimens of the elevated variety of 
lignosa from Olympia, Wash. It seems to me to be a very variable 
and trifling character. The caudal sinus seems to be indifferently 
narrowly slit or with a little denticle in the apex of the slit, and this 
little denticle also occurs sometimes in M. lignosa. The posterior 
valve has a narrow light triangle behind in all the specimens I have 
seen. 

I have no hesitation in pronouncing plumosa and fissa absolute 
synonyms of acuta, but give here Carpenter's descriptions. 

M. plumosa Carpenter. (PL 64, figs. 80, 81.) Shell oval, regu- 
lar, thin, elevated, the dorsal ridge acute, mucro behind the middle, 
depressed. Valves subquadrate, slightly beaked behind, hardly so 
in front. Olivaceous-ashen maculated with darker ; central areas 
(with the scarcely defined jugal tracts) reticulated-porous, being 
sculptured with interlacing riblets forming quincuncially arranged 
impressed pits. Lateral areas defined but hardly elevated, sculp- 



MOPALIA. 299 

tured with plume-like radii, granose at the sutures, the diagonal ribs 
and the radiating riblets of the head-valve ; the grains elongated, 
subspinose, elegantly serrating the sutures. 

Interior pale blue. Tail valve having the posterior sinus hardly 
indicated externally, small, with a minute tooth set in at the apex; 
at one side it has 2, at the other 3 slits ; slit-rays inconspicuous. 
Central valves having 1, anterior valve 8 slits, the slit-rays con- 
spicuous; teeth acute, small. Eaves small, very spongy. Sinus 
small, deep, flat, the sutural plates separated. 

Girdle thin, narrow, smooth, sparsely and irregularly beset with 
subtranslucent, larger and smaller tubular bristles. 

Length 16i, width 11 mill. ; divergence 112. 

Habitat unknown. 

The above description, from Carpenter's MS., was drawn from a 
single specimen in the collection of Dr. Wesley Newcomb (now of 
Cornell College). The figures 80, 81 represent the same specimen. 

Var. fissa Cpr. Sculpture between that of M. acuta and M. plu- 
mosa ; the granules at the suture and diagonal rib hardly claw- 
shaped ; color and form also intermediate. Interior : posterior 
valve having two slits on one side, one on the other, the median 
caudal sinus minute, acutely slit ; otherwise normal. Girdle smooth 
with sparse, small spines. 

Length 15, breath 10 mill. ; divergence 115. 

This form was described by Carpenter from a single specimen 
from Monterey. It differs from acuta and plumosa in lacking the 
" key-stone " like structure of the caudal sinus ; but the series 
examined by me proves that this character has no constancy. 

Subspecies M. LIGNOSA Gould. PI. 63, figs. 58, 59 (typical) ; 60, 
61, 62, 63. 

Shell oval, elevated, carinated or angular at the dorsal ridge, the 
side-slopes straight. Surface lusterless, apparently smooth ; grayish, 
greenish or bluish with radiating streaks, lines and flammules of 
brown or purple-brown. 

Under a lens the lateral areas appear nearly smooth ; the central 
areas being closely and finely pitted all over. Girdle narrow, 
sparsely hairy. 

Interior white and light blue. Length 60, breadth 35 mill.; 
divergence 120. 

Vancouver I. to Monterey, California. 



300 MOPALIA. 

Chiton lignosus GLD., Proc. Boston Soc. N. H. ii, p. 142, (July, 
1846) ; Otia Conch, p. 3 ; U. S. Expl. Exped., p. 330, f. 424. 
Chcetopleura lignosa GLD., Otia, p. 248. Mopalia lignosa CPR., 
Kep. Br. Asso. 1863, p. 648. Chiton merekii MIDD., Bull. Imp. 
Acad. Sci. St. Petersb. vi, p. 20, 1846 ; Mai. Ross., i, p. 115, 1. 11, f. 
5-6. Ch. eschseholtzii'MiDi>., Bull. 1. c. p. 118, Mai. Ross., i, p. 114, 
t. 11, f. 4 (young shell). Chiton montereyensis CPU., P. Z. S. 1855, 
p. 231. Chiton vespertinus GLD., U. S. Expl. Exped. Moll. p. 323, 
t. 426, 426a (1852). Chcstopleura vespertina GLD., Otia, p. 230, 
242. Mopalia vespertina H. & A. AD., Gen. Rec. Moll, i, p. 479. 
Mopalia simpsoni GRAY, P. Z. S. 1847, p. 69 ; H. & A. AD., Gen. 
p. 479 ; and Brit. Mus. Coll. (name only ; never described. Type 
examined by Cpr). Mopalia ciliata subsp. lignosa Gld., DALL, 
Proc. U. S. Nat. Mus. 1878, p. 304. 

Typically the M. lignosa is extremely unlike M. muscosa, but I am 
compelled to agree with Dall that there exist specimens completely 
uniting the two. A number of published names are above added to 
the long list of synonyms given by Dall (/. c.) ; and Ch. californicus 
(Nutt.) Reeve, which Dall includes, is removed, as it belongs to the 
genus Nuttallina. 

The typical lignosa (figs. 58, 59) is exactly equal to merckii, to 
montereyensis, and to the unpublished insignis Newc. (fig. 63). It 
differs from the following form in the even puncturing of the sur- 
face (obsolete on lateral areas), the peculiar painting, and white 
interior. 

The principal mutations of this type of Mopalia are (1). Toward 
still smoother forms entirely lacking pitted or reticulated sculpture, 
having only a few subobsolete longitudinal wrinkles on the ridge, 
the painting in concentric streaks (following growth marks) on each 
valve. This is shown in figs. 60, 61, of pi. 63, the specimen illus- 
trated being from Olympia, Washington. The C. vespertinus of 
Gould is closely connected with this form, but is represented as 
typically much pitted (fig. 62). It is stained with crimson within. 

(2). Form elevata (pi. 64, figs. 82, 83). More elevated, acutely 
carinated, more or less pitted superficially, and either painted with 
the pattern of typical lignos on a white, creamy or green ground, 
or having concentric zig-zag blackish streaks (fig. 82). Divergence 
about 90. The interior is bright green or blue. 

(3). Forms connecting with M. muscosa var. hindsii, having the 
color pattern of lignosa, but the sculpture intermediate in char- 



MOP ALIA. 301 

acter or quite like that of hindsii. 

M. MIDDENDORFFII Schreuck. PI. 62, figs. 88, 89, 90, 91, 92. 

Shell elevated. Coloration : a broad whitish area along the mid- 
dle, with transverse flammules and lines of red-brown on the ridge ; 
at the sides concentrically and longitudinally painted with red- 
brown and whitish. 

Median valves having the apex indistinct, the lateral areas dis- 
tinct. Entire surface radially closely pitted, the pits very distinct 
over the whole of the central areas, and in the middle of the lateral 
areas, but obsolete on the front and back edges of the latter. 
Anterior valve having 8 radiating riblets. Posterior valve slightly 
emarginate behind. 

Interior roseate in the middle ; lateral slits distinct ; sinus shal- 
low. Anterior valve having 8, central 1, posterior two slits. 

Girdle of moderate width, brown-red, setose, the setae irregularly 
and sparsely scattered, whitish, and about 3 mill, in length. 
Branchiae median, with about 36 branchial lamellae. 

Length 14 mill. ; divergence about 115. 

Bay of Castries in 25 ft. 

Chiton middendorffii SCHRENCK, Bull, de PAcad. des Sci. St. 
Petersb. iv, p. 408 ; Mel. Biol. iv, p. 89 ; Reisen und Forsch. in 
Amur-Lande, ii, Zool., p. 278, t. 12, f. 1-8 (1867). 

A single specimen of this species was dredged by Schrenck, from 
whose account the above description is compiled. The sculpture 
strongly reminds one of some forms of Mopalia lignosa Gld., but the 
coloring differs markedly, and the habitats of the two are widely 
sundered. 

M. IMPORCATA Carpenter. PL 62, fig. 98. 

Shell small, oblong, strongly elevated and acutely carinated, the 
side-slopes straight. Buff-white, slightly stained with rust-brown. 

The median valves are acute at the umbo, but there is no project- 
ing beak; lateral areas bounded by a strongly elevated, narrow, 
crenulated diagonal rib, and having a wider rib at the sutural mar- 
gin, also crenulated, thus denticulating the suture ; the space 
between the two lateral ribs being finely corrugated-granose. Cen- 
tral areas sculptured with strong, curved longitudinal ribs, which 
converge forward somewhat, toward the median keel ; the intervals 
between these ribs being closely and finely latticed across by 



302 MOP ALIA. 

threads radiating from the beaks. Anterior valve having 8 strong, 
narrow, raised ribs, with one wider rib at each sutural edge. 
Posterior valve depressed, the mucro situated at the posterior end. 

Interior white ; sinus very small and shallow. Anterior valve 
having 8, median 1 slit ; teeth but little thickened along the slits. 
Posterior valve having a rather wide moderately deep rounded tail 
sinus, and a single slit on each side. 

Girdle leathery, dusty, with a hair-pore at each suture, and 
some scattered or alternating hairs. 

Length 10, breadth 6 mill. ; divergence 95. 

Puget Sound (Kennerley) ; Sta. Barbara (Cooper). 

fMopalia imporcata CPU., Proc. Acad. Nat. Sci. Phila., 1865, p. 
59. Placiphorella imporcata CPR., in Dall, Proc. U. S. Nat. Mus. 
1878, p. BQQ. Osteochiton imporcatus DALL, 1. c. 1886, p. 211. 

This species closely resembles M. sinuata in size and sculpture. 
The two species differ in the following details : (a) M. imporcata is 
unicolored, while the other is elegantly marbled with blue and 
tawny ; (6) imporcata has the sutural ribs more developed and very 
distinctly serrated, whilst in sinuata the serration is hardly appar- 
ent ; (c) imporcata has the longitudinal riblets of the central areas 
larger and the radiating threads which lattice their interstices much 
smaller and much closer ; and finally, (d) the tail valve in imporcata 
has an entirely posterior mucro, and a much shallower posterior 
sinus. 

The girdles are the same in both species, being leathery, generally 
" dusty " in appearance in dried specimens, although scales are 
quite absent. 

This species might be considered a subspecies of M. muscosa were 
it not that it is smaller and more highly angled, of a uniform light 
color, and has the mucro farther to the rear. The girdle-pores at 
the sutures, and the entire sculpture are exactly like the pore-bear- 
ing variety of muscosa which I have above described from Bolinas 
Bay. It is very likely that the intervening links required to com- 
plete this chain of forms will be found. 

The description and figures are drawn from Carpenter's type 
specimen, now in the U. S. National Museum. 

The length is estimated in this and the following species, as the 
specimens are somewhat curled. 



MOPALIA. 303 

M. SINUATA Carpenter. PL 62, figs. 95, 96, 97. 

Shell oblong, elevated and strongly carinated, the side-slopes, 
straight. Color whitish, clouded with delicate blue-green and macu- 
lated with rich tawny brown. 

Median valves hardly beaked, the lateral areas not raised, but 
strongly defined by an elevated diagonal rib ; sculptured with two 
oblique series of fine riblets forming a latticed pattern. Central 
areas having a series of longitudinal curved riblets converging 
toward the median keel, crossed by curved radiating threads a 
little finer and less prominent (fig. 97). Anterior valve having 8 
(not counting the posterior sutural borders) strong radiating ribs 
narrower than the latticed intervals. Posterior valve depressed, the 
mucro being at the posterior third. 

Interior bluish-white. Sinus very small and narrow. Anterior 
valve having 8 slits, median 1 slit ; teeth thickened outside at the 
edges of the slits. Posterior valve (fig. 96) having a deep rounded 
median sinus behind (which is continued upward in a superficial 
excavation to the mucro), and a single slit on each side. 

Girdle rather narrow, leathery, " dusty " bearing a few hairs, with 
.a rounded pore at each suture (fig. 95). 

Length 11 J, breadth 7 mill.; divergence 105. 

Puget Sound (Kennerley) ; San Francisco Bay (Newcomb). 

f Mopalia sinuata CPU., Proc. Acad. Nat. Sci. Phila., 1865, p. 59. 
Placiphorella sinuata CPU., MS. and in DALL, Proc. U. S. Nat. 
Mus. 1878, p. 303, 3Q6. Osteochiton sinuatus BALL, I.e. 1886, p. 
211. 

This little species has the form and sculpture of the true Mopalias, 
but it differs from them in the posssesion of a bristle or hair-bearing 
pore at each of the sutures, the girdle elsewhere bearing sparsely 
scattered hairs on the leathery, minutely roughened surface. It 
resembles M. imporcata but is sufficiently different in sculpture. 

My description and figures are from Carpenter's type specimen, 
now in the Smithsonian collection. 

M. CILIATA Sowerby. PL 64, figs. 64-73. 

Shell oblong, rather depressed, the dorsal ridge carinated (some- 
times rounded), side-slopes straight or somewhat convex. Surface 
lusterless, finely sculptured, variously colored, usually either (1, 
typical coloring) verdigris green maculated with black or black- 
brown, the girdle yellow (fig. 65) or (2) maculated with maroon 
and sometimes touched with rich chestnut on the ridge, or having 



304 MOPALIA. 

some valves or parts of valves vivid scarlet (fig. 64), or scarlet 
mixed with olive and snow-white, or entirely white ; or (3) light 
olive-buff with brownish girdle (fig. 67). 

Valves somewhat beaked, the lateral areas bounded by a riblet, 
rather coarsely granulated, with larger granules along the posterior 
margin. Central areas sculptured with longitudinal, curving rib- 
lets somewhat granulated, much closer and finer on the dorsal 
ridge. Anterior valve having granose narrow radii, the intervals 
granulated. Posterior valve small, with posterior mucro, broadly 
emarginate or waved at the hinder margin. 

Interior bluish-white or light blue-green. Sinus broad and rather 
rounded, spongy or roughened. Sutural plates arcuate. Anterior 
valve having 8 slits, median valves 1 slit. Posterior valve having a 
broad deep, rounded caudal sinus, and a single slit on each side. 

Girdle wide, yellow or brown, generally notched behind, more or 
less sparsely clothed with curling strap-like brown hairs, which bear near 
their bases a bunch of minute, white, acute spines. (fig. 66; the line 
below is 1 mill. long). 

Length 46-50, breadth 25 mill.; divergence 125. 
Unalashka, Aleutian Is. (small and rare) to SitJca, and southeast- 
ward to Monterey, California ; low water to 20 fms. on stones and 
shells. 

Chiton ciliatm SOWERBY, Ann. and Mag. Nat. Hist. 1840, p. 
289 ; Conch Illustr., f. 79 (1840). Not Chiton ciliatus Reeve, nor 
Mopalia ciliata Dall. Chiton wosnessenskii MIDD. Bull Acad. Imp. 
Sci. St. Petersb. iv, p. 119, 1847. Chiton (Hamachiton, Platysemus) 
wosnessenskii MIDD., Mai. Ross., i, p. 34, 101, t. 11, f. 1-2. Mopalia 
kennerleyi CPR., Suppl. Rep. Brit. Asso. Adv. Sci. 1863, p. 648 ; 
Proc. Acad. Nat. Sci. Phila., 1865, p. 59. M. (kennerleyi var.) 
Swannii CPR., Ann. Mag. N. H. xiv, p. 426, 1864 ; Suppl. Rep. B. 
A. p. 648. Mopalia grayi CPR., 1. c. p. 603 (name only). Mopalia 
ivossnessenskii Midd., DALL, Proc. U. S. Nat. Mus. 1878, p. 305 
(1879). 

This species is distinguised from M. muscosa and its immediate 
allies by its color ; by the lack of that narrow anterior projection 
of the outer layer at the sinus, so conspicuous in the detached 
valves of the typical muscosa; by the encroachment of the wide gir- 
dle at the sutures, the deeper caudal wave of the tail valve, and 
especially by the broad, rounded sinus between the sutural plates. 



PLACIPHORELLA. 305 

This last seems to be a constant character, and the peculiarity of 
the tail valve noticed above is also reliable ; but the encroachment 
of the girdle at the sutures is seen also in M. hindsii ; the lack of air- 
anterior projection or " false beak " is characteristic of many varie- 
ties of muscosa, such as the elevated var. of lignosa found at Olym- 
pia, Washington, and the var. acuta Cpr. from southern California. 
The girdle covering presents a peculiarity not hitherto noticed; 
near the base of each of the curled brown hairs, there is a bunch of 
tiny white thorns or spines. These are also numerous at the edge 
of the girdle, which is seen slightly rolled upward in fig. 66. 

Dr. Carpenter studied the specimens of " C. ciliatus " in Cuming's 
collection, and found them to be genuine muscosus ; and therefore 
Dall in his report on the Chitons of Alaska, as well as other Ameri- 
can writers, accepted the name ciliata in place of muscosa. Unfor- 
tunately, the Cumingian specimens are not the true ciliatus of 
Sowerby, although described and figured as such by Reeve. The 
original C. ciliatus is identical with the small, green black-mottled 
form of " wosnessenskii " found at Monterey, etc. 

An excessively rare monstrosity is shown in fig. 67, representing 
a seven-valved specimen, in which the reduced number is not due to 
injury or coalescence of valves, each valve being completely normal 
both outside and within. This figure, and figs. 64, 65, are drawn 
from Monterey Bay specimens. The sculpture (fig. 68) is stronger 
and sharper in typical ciliata than in the var. wosnessenskii (fig. 72). 

Var. WOSNESSENSKII Midd. PI. 64, figs. 69-73. 

Shell elongated, the back roundly arched not carinated ; dull 
colored, varying from light olive or green to drab, generally with 
blackish patches on each side of the middle, and more or less mot- 
tled throughout with dusky. Sculpture much fainter than in typical 
ciliata. Girdle apparently lacking the white spictiles described 
above. 

Sitka (Wosnessenski, figs. 69-71) ; Olympia, Washington (Hemp- 
hill, figs. 72, 73). 

This seems to be recognizably distinct from the typical ciliata 
from Monterey, etc. American authors have hitherto given Wos- 
nessenski an s too many. 

Genus XXX. PLACIPHORELLA Carpenter. 

Placiphorella CPR., MS. in Dall, Proc. U. S. Nat. Mus. 1878, p. 
303, 306. Type P. velata Cpr. 
20 



306 PLACIPHORELLA. 

Valves very broad and short, the middle ones much broader than 
those toward the ends ; head valve narrowly crescentic, tail valve 
still smaller, with posterior mucro. Sinus small ; insertion-plates 
short and thick, the teeth lobed or rugose. Slits 8 or more in the 
anterior, 1 in the median, 2 in the posterior valve, which has also a 
shallow posterior sinus. Eaves spongy. Girdle widest, often very 
wide, in front, bearing sparsely scattered, scaled hairs. 

This genus differs from Mopalia in the rotund contour of the 
valves taken together, and their extreme shortness individually, as 
if the shell had been crowded together from the ends. The slits are 
practically as in Mopalia, being normally (or at least originally) 8 
in the head valve ; but this number is frequently increased by the 
splitting of some teeth. The mantle-edge is produced in front and 
fringed with long fleshy finger-like processes. The larger hairs of 
the girdle are extremely peculiar, being covered with imbricating 
scales like a snake skin, on a corneous core. Nothing of the sort 
has been found in any other group of Chitons. 

Carpenter originally intended this genus to include forms having 
hair-pores at the sutures, regardless of the other characters of valves 
and girdle ; but the presence of pores is not, in PlacipJiorella and 
Mopalia, even a constant specific character. 

The species are separated by rather slight characters and owing 
to the rarity of specimens in collections, we are not yet prepared to 
say to what extent the characters will hold good. 

P. VELATA Carpenter, n. sp. PI. 66, figs. 6-12. 

Shell roundly oval, broad, rather depressed, quite obtusely angled. 
Surface lusterless. Light colored along the middle, mainly oliva- 
ceous on the sides, especially the lateral areas; the central areas 
variously streaked longitudinally with buff, blue, chestnut and 
pink. 

Median valves not beaked, marked by growth lines ; the lateral 
areas somewhat raised, having a rounded wide diagonal rib and 
another at the sutural margin, the space between them more or less 
excavated. Central areas having a " false beak " or narrow pro- 
jection forward at the dorsal ridge (only visible when the valves are 
separated.) Anterior valve crescent shaped, sculptured with light 
concentric growth-lines only. Posterior valve small, slightly 
waved inward behind, the mucro far backward, recurved and elevated, 
the slope in front of it concave in profile, unless the mucro is eroded. 



PLACIPHORELLA. 307 

Interior white, slightly blue tinted. Sinus in valves i to vi repre- 
sented by a very shallow wave, the sutural plates continuous, being 
connected by aplate which fills the sinus like a key-stone; in valves 
vii to viii the sinus is deeper and more distinctly angular. Anterior 
valve having 8 slits, the teeth obtuse, short, often bilobed or con- 
spicuously rugose. Central valves having 1 slit, teeth wedge-shaped, 
thicker at the edges of the slit. Posterior valve having a very 
heavy callus supporting the short, rugose insertion-plate, which is 
interrupted posteriorly by a broad, shallow sinus, and has 1 slit on 
each side (occasionally two on one side). 

Girdle very broad in front, reddish, fading to yellow toward the 
outer edge, irregularly and sparsely beset with scaly hairs (fig. 13), 
of which one or two are generally to be seen in each suture ; a close 
fringe of short (broken) hairs adorns the girdle-edge. 

Length 50, breadth 38 mill. ; divergence 135. 

Length 30, breadth 24 mill. ; divergence 130. 

Humboldt Bay (Newcomb) and Monterey Bay (Canfield, Hemp- 
hill, et. al.), California; Todos Santos Bay, Lower California (Hemp- 
hill). 

Placiphorella velata CPR., MS. DALL, Proc. U. S. Nat. Mus. 
1878, p. 303, 307 (description of animal) ; p. 298, t. 2, f. 36, a 
(dentition). 

This species is distinguished from the the next by its differently 
formed posterior valve, by the connection of the sutural plates 
across the sinus, and the anterior projection of the tegmentum at 
the sinus. The largest specimens I have seen were collected by 
Hemphill at Todos Santos Bay. 

Fig. 12 represents the insertion-plates of an intermediate valve 
seen from their summits, showing the subtriangular form of the 
posterior insertion-tooth, the non-thickened edges of the slit, etc. 

P. STIMPSONII Gould. PI. 62, figs. 84, 85, 86, 87. 

Shell broadly oval, depressed, subangular, with straight side- 
slopes. Color whitish along the middle, the sides mottled and 
streaked with greenish-yellow, olive and blue, the colors so blended 
as to give a general effect of dark olivaceous. 

Valves not beaked, sculptured with unequal growth-lines. 
Lateral areas having a moderately prominent diagonal rib, with an 
inconspicuous wider, lower, sutural rib, the space between excavated. 
Anterior valve narrowly crescentic, concentrically striated, but 



308 PLACIPHORELLA. 

lacking all radiating sculpture. Posterior valve (figs. 84, 85) 
depressed, the mucronear the posterior margin, which is slightly and 
rather broadly waved inward. 

Interior delicately blue-green tinted. Sinus a rather shallow 
rounded wave in the earlier valves, becoming deeper, narrower and 
angular in the eighth valve. Anterior valve having 8 slits, median 
valves having 1 slit on each side ; the eaves narrow, tenaciously 
adhering to the girdle. 

Posterior valve small, its greatest width, including insertion and 
sutural-plates, measuring hardly more than one-half the width of the 
widest median valves ; the short posterior insertion-plate rising from 
a very heavy callous rim ; having one oblique slit on each side, and an 
almost imperceptible wave where the posterior sinus should be. 

Girdle rather narrow, brown, leathery, sparsely beset with spinu- 
les (the stumps only remaining in the specimen before me), of which 
there is one at each suture and a marginal fringe. 

Length 17, breadth 123 mill; divergence 140. 

Hakodadi Bay, Japan (Stimpson), in 25 fms. 

Chiton (Mopalia) stimpsoni GOULD, Proc. Bost. Soc. N. Hist., 
vii, p. 165 (1859) ; Otia Conch, p. 118. Conf. BALL, U. S. Nat. 
Mus. 1886, p. 210. 

The above description is from the type in the U. S. National 
Museum (no. 1646). It will be seen that the species differs from P. 
borealis in the smooth, not radially sculptured anterior valve, in 
the strongly calloused interior of the posterior valve, its shallower 
tail sinus, etc. The P. velata Cpr. of California has the valves very 
similar to this species in form ; both differing widely from P. bore- 
alis in the solid, not spongy, sinus, partly filled by a short lamina 
connecting the sutural plates ; in the more calloused interior of the 
posterior valve and its smaller size ; the non-radiated anterior valve, 
etc. 

Carpenter has given the following notes in his MS. on a fine 
specimen from Japan, in the Jeffreys collection. "As curled up 
and dried it measures, length 23, breadth 21 mill. ; divergence 120. 
It is olivaceous and orange-ash variegated. Anterior valve smooth. 
Posterior valve having the mucro raised, at the posterior third, the 
sinus continued upward to it outside. Central valves with two 
obsolete but swollen ribs, one sutural, the other diagonal, with a 
broad depression between them. The girdle is very much shrivelled 



PLACIPHORELLA. 309 

and the head expansion doubled up, but the hairs are very well 
preserved. Over the whole of the marginal part are very short 
crowded deciduous whitish hairs. Over the greater portion of the 
surface are scattered distant large tubular, horny hairs, which seem 
to arise deep in the girdle. These hairs are not scaly as in P. blain- 
villii, but present when perfect the aspect of Aspergillum vaginiferum 
in miniature. I cannot say with confidence that all the hairs are 
so sculptured, for some which look perfect do not show it. " 

A. sketch made by Dr. Carpenter from a hair of this specimen is 
copied on pi. 62, fig. 86. The hairs on Gould's type are broken to 
Tery short stumps, not long enough to show their structure. 

P. BOREALIS Pilsbry, n. sp. PI. 66, figs. 14, 15, 16, 17. 

Shell similar in general characters to P. velata. Brown at the 
sides, light along the middle. Surface dull, showing growth- 
lines. 

Valves not beaked, having a slight forward bend in the middle 
at the sinus, but not " false beaked " there as P. velata is. Lateral 
areas more strongly 2 ribbed. Anterior valve sculptured with numer- 
ous very low, wide radiating riblets. Posterior valve having the 
mucro near the posterior margin, depressed, the slope in front of it 
rising, convex rather than concave ; posterior margin waved 
inward. 

Interior light blue-green. Sutural plates separated in all the 
valves by an angular, spongy sinus. Anterior valve having 11 slits, 
the teeth unequal, lobed or. roughened. Median valves having one 
slit, the teeth being peculiarly curved outward at its edges. Posterior 
valve much less callous inside than that of P. velata, the insertion- 
plate uneven, roughened, but having a single well developed slit on 
each side; the median tail-notch deep and wide. Eaves very 
spongy. Girdle unknown to me. 

Breadth of anterior valve 16, length of front slope, including 
teeth 4i mill. 

Breadth of a median valve 22, length from sinus to beak 4 mill. 

Breadth of posterior valve 15, length direct from sinus to sinus 
5 mill. 

Divergence 135. Measurements of breadth include the inser- 
tion-plates. 

Bering Island, Bering Sea (Grebritzki). 

Placiphorella stimpsoni DALL, (part), Proc. U. S. Nat. Mus. 1886 



310 PLACIPHORELLA. 

p. 210. Not of Gould. 

This form is known to me by the valves of a single individual, no.- 
106,922 of the Smithsonian register. It differs from P. velata in 
the greater prominence of the lateral ribs, the curiously excurved 
teeth of the side insertion-plates (fig. 15), the less calloused interior 
of the posterior valve, and its very different form. Compare fig. 9 
with fig. 16, the former representing the tail valve of P. velata, the 
latter that of P. borealis. Some other differences are indicated in 
the descriptions. In this specimen the slit on one side of the pos- 
terior valve is nearly obsolete. 

P. BLAINVILLII Broderip. PL 66, figs. 26-32. 

Shell ovate, very broad, depressed ; variously clouded, streaked: 
and maculated with rosaceous and olivaceous or red-brown, gener- 
ally tessellated at the sutures. 

Median valves hardly beaked. Jugal areas sometimes defined by 
an obsolete v-shaped sulcus. Central areas appearing a trifle and 
most minutely granulate under a lens, otherwise smooth and shining. 
Lateral areas slightly swollen, concentrically marked by ribs of 
growth ; margins of valves rounded, the sutures not very deep 
except in young specimens. Posterior valve having the mucro pos- 
terior, almost terminal ; the posterior sinus of the valve wide and 
shallow. 

Interior : anterior valve having 8 slits, the teeth rather short and 1 
roughened or crenulated outside. Posterior valve having a single 
slit on each side. Median valves with 1 slit; the sutural-plates 
rather straight and narrow, sinus a shallow wave. 

Girdle thin, very broadly expanded, in front, narrow and not 
sinuous behind. Surface having sparse, comparatively short hairs, 
which in drying become appressed on the girdle, each hair appearing 
scaly under the microscope, like a snake's skin (fig. 28). The hairs 
are not especially sutural in position, suture-pores being absent in 
adult examples ; nor do hairs occur in bunches anywhere. Besides 
these scaly hairs, there are scattered chaffy hairlets (which in one 
specimen more contracted than the rest are gathered into little 
bunches.) 

Length 50, breadth 36 mill. ; divergence 147. 

Inner Lobos Island (Lobos de Tierra), Peru, on stone in 17 fins. 
(Cuming.) 

Chiton blainvillii BROD., P. Z. S. 1832, p. 27. SOWERBY, Conch. 



PLACIPHORELLA-PLAXIPHORA. 311 

Illustr., f. 6. REEVE, Conch. Icon., t. 3, f. 13. Mopalia blain- 
mllii GRAY, P. Z. S. 1847, p. 69. Mopalia blainvillei CARPENTER, 
MS. and in DALL, Proc. U. S. Nat. Mus. 1878, p. 303. Placiphor- 
ella blainvillii DALL, 1. c. 1886, p. 210, 211. 

This large species is nearly allied to P. velata of California, but it 
differs in having the lateral areas simply somewhat swollen, and not 
excavated in the middle. The sinus between the sutural plates is a 
shallow wave, but it deepens on the two or three backward valves, 
as in the Californian species. The description given above is com- 
piled from Carpenter's notes on the type specimens. 

P. PETASUS Reeve. PI. 66, fig. 25 (enlarged.) 

Shell small, somewhat abbreviately ovate. Valves with a polished, 
slightly beaked triangular area in the center, roughly granulated on 
each side. Bright scarlet. Ligament very broad, especially in front, 
also bright scarlet, beset here and there with short hairs and bristles. 

Length 1, breadth f inch. (Eve.) 

Cape Rivers, Celebes (Belcher.) 

Chiton petasus REEVE, P. Z. S. 1847, p. 25 ; Conch. Icon., t. 26, 
no. 114, fig. 112, (not 112 on plate of details, nor 114) ; July, 1847. 
ADAMS & REEVE, Zool. of the Voy. H. M. S. ' Samarang,' Moll., 
1. 15, f. 11. 

Referred to this genus on account of the peculiar girdle. A single 
specimen was collected. The characters of the interior have not 
been made known. 

Genus XXXI. PLAXIPHORA Gray, 1847. 

Plaxiphora GRAY, P. Z. S. 1847, pp. 65, 68, 169. SHUTTLEW., 
Bern. Mittheil. 1853, p. 69. H. & A. ADAMS, Gen. Rec. Moll, i, 
p. 481. Placiphora CPR., MS. and in DALL, Proc. U. S. Nat. Mus. 
1881, p. 284. Placophora DALL, Cat. Mar. Moll. S.-E. U. S., p. 174 ; 
not Placophorus Mulsant, 1873 (Trochilidce). Euplaxiphora SHUT- 
TLEW., 1. c., (proposed for biramosus and petholatus). Euplacipliora 
CPR., 1. c., (type P. petholata'). Chcetopleura (part) ROCHEBRUNE, 
Miss. Sci. du Cap Horn, 1882-1883, vi, Zool., Polyplacophores, p. 
135 (1889), not Chcetopleura Shuttlew. ! 

Valves mostly exposed, all having insertion-plates developed, that 
of the anterior valve normally with 8 (sometimes 7-9) slits (except 
in the subgenus Placophoropsis which has many slits). Median 
valves 1 slit. Posterior valve having the insertion-plate smooth, 



312 PLAXIPHORA. 

unslit, interrupted behind by a median, rounded sinus, which does 
not generally emarginate the tegmeutum ; mucro posterior. Girdle 
bearing simple bristles or hairs, scattered or gathered into pores or 
tufts at the sutures. Type Chiton setiger King. 

This genus is most nearly allied to Mopalia and Placiphorclla, from 
both of which it differs in the unslit insertion-plate of the tail valve. 
The peculiar girdle-bristles of Pladphorella are an additional char- 
acter separating the genera. 

In Plaxiphora, as in Mopalia and Placiphorella, the bristles of the 
girdle are indifferently scattered or gathered into sutural bunches. 
This character is of specific value only when strongly developed ; 
and each of the three genera contain species which in occasional 
individuals develop pores, or species usually poriferous, but varying 
to poreless. This distinction, which Blainville, Gray and the Adams 
brothers considered fundamental, is therefore of comparatively tri- 
vial importance. 

Plaxiphora is divisible into a number of minor groups, as follows : 

Subgenus PLAXIPHORA (restricted.) 

Slits of anterior valve normally 8 (sometimes 7 or 9 by coales- 
cence or splitting), coresponding in position to external ribs ; the 
teeth long outside. Girdle widest at the sides. Mantle not fringed 
in front of the head. Distribution, Southern extremities of the 
southern continents ; living in the littoral zone. 

This subgenus although rather homogeneous, may conveniently be 
divided into three sections, as follows : 
Section I. Plaxiphora, restricted (=Euplariphora Bhuttl. not Cpr.). 

Valves exposed. Entire shell normal in form ; posterior valve 

not greatly reduced in size or altered in form. 
Section II. Guildingia Cpr. Valves partially immersed in the 

girdle, which encroaches at the sutures. 
Section III. Fremblya H. Ad. Valves exposed. Shell short and 

broad ; the posterior valve reduced to a narrow crescentic form, 

and seen to be strongly arched upward if viewed from behind. 

Subgenus PLACOPHOROPSIS Pilsbry. 

Slits of anterior valve numerous (about 20) ; teeth very short. 
Girdle widest and much dilated in front. Mantle produced into 
several long finger-like processes in front of the head. Distribution, 
Northwest Atlantic ; living in deep water. 



PLAXIPHORA. 313 

Subgenus PLACOPHOROPSIS Pilsbry, 1893 (n. s.-g.) 

Shell short, obovate, the valves short and wide ; having very short, 
almost obsolete insertion-plates, that of the anterior valve having 
many (about 20) shallow notches ; posterior valve with callous ridges 
at the sides and a shallow rounded caudal sinus. Girdle enormously 
broadened in front, narrow behind. 

This section is intermediate between Placiphorella and Plaxiphora, 
differing from both and from and all Mopaliidce, in the multiplica- 
tion of anterior slits, although some specimens of Placiphorella show 
the same tendency. It must be understood that although in many 
groups of Chitons, such as all Ischnochitonince and Chitonince, the 
number of anterior slits is a character of merely specific importance, 
the case is far otherwise in those groups in which the slits correspond 
in number and position with external ribs, such as Nuttallina and its 
allies, and the Mopaliida:, Acanthochitidce, etc. In these groups the 
number of slits in the anterior insertion-plate is a highly constant 
generic character, apparent exceptions being generally readily trace- 
able to the splitting of one or more primary teeth. 

Besides the character just discussed, Placophoropsis resembles 
Placophorella in the form of the girdle ; but it differs in lacking 
Mopaloid slits in the posterior insertion plates. Placophoropsis 
resembles Plaxiphora in the non-slit posterior insertion-plate, but it 
differs in the obsolescence and multiple slitting of the anterior inser- 
tion plate, and in the anterior dilation of the girdle. 

The obsolescence or shortness of the insertion-plates in this form 
is evidently due to degeneration from disuse. Deep sea Chitons not 
being subjected to the constantly recurring impacts and stresses 
which affect littoral forms, have no need of elaborate structures for 
binding the valves in their places. Consequently the primitive 
forms, such as Lepidopleurus, have been able to survive unaltered 
under these conditions. In the case of Placiphoropsis, which is 
descended from littoral forms having long, well-developed insertion 
plates, especially in the anterior and median valves, the shortness of 
the plates is to be ascribed to the absence of the external stimuli 
which act constantly upon the littoral Mopaliidce. 

P. ATLANTICA Verrill & Smith. PI. 66, figs. 18-24 ; pi. 65, figs, 73, 
74, 75. 

Shell obovate, wider in front, tapering toward the small posterior 
valve, which is only about half as wide as the anterior valve. Rather 



314 PLAXIPHORA. 

depressed, roof-shaped, the dorsal ridge angular, side slopes slightly 
convex. Color pale brown, whitish along the middle and at the- 
edge. Girdle extremely wide in front, narrow behind, dark brown 
in alcoholic specimens. 

Median valves very wide and short, a trifle beaked in the middle* 
Lateral areas strongly elevated, the diagonal slope abrupt ; slightly 
excavated in the middle, obsoletely granulated. Central areas hav- 
ing rather inconspicuous growth-lines and an obsolete or nearly 
effaced granulation. Anterior valve very short and broad, having 
many faint radiating riblets and obsoletely granulated throughout. 
Posterior valve small, with posterior, slightly elevated mucro, and 
elevated postero-lateral ribs. 

Interior white. Sinus very narrow, square. Insertion-plates very 
short, almost subobsolete, that of the anterior valve wide, calloused, 
having about 20 irregular and excessively shallow notches (hardly 
slits), obsolete toward the ends ; median valves with 1 slit. Poste- 
rior valve having a low wide callous ridge, slightly rugose, and in 
the middle interrupted by a shallow rounded sinus (pi. 65, figs. 73- 
75.) 

Girdle " very broad anteriorly and narrow posteriorly. It increases 
gradually from the posterior end to a point opposite the fifth plate, 
where it suddenly expands into a broad round front, with the 
breadth one-third greater than the greatest breadth of the shell. It 
is thick, leathery and scabrous, everywhere closely covered with 
minute spinules ; the lower surface anteriorly shows many radiating 
grooves (not distinct in the smaller examples) ; *between these are 
rows of slightly raised small verrucse, covered with small spinules. 
The inner edge, or mantle-border, is sharply defined, enclosing an 
elliptical area around the head and gills, with a well marked poste- 
rior sinus ; its front edge is divided into about seven digitations, the 
anterior ones rather long, tapering, and tentacle-like but coriaceous- 
and covered with fine spinules, like the rest of the marginal mem- 
brane. Cephalic hood large, broad-lunate; foot relatively small, 
ovate. Gills numerous (in the largest about sixteen on each side), 
extending nearly the whole length (more than two-thirds) of the 
foot, but reaching neither end of it." 

Length of largest specimen (alcholic) 32, breadth 26 mill. ; length 
of shell 21, breadth 18 mill. Divergence 130. 

N. lot. 40 Or, W. long. 68 54', in 610 fms., of Nantucket Island, 
and in N. tat. 42 15' 25", W. long. 65 48' 40", in 122 fms., off New 



PLAXIPHORA. 315 

England. (U. S. Fish Commission Steamer 'Albatross', 1883.) 

Placophora (Euplacophora) atlantica V. & S., Amer. Journ. of 
Science xxiv, Nov., 1882, p. 365 (footnote) ; Trans, of the Connecti- 
cut Academy of Natural Sciences, vi, p. 206, t. 30, f. 1, la, 16. (May, 
1884). Placophora atlantica V. & S., BALL, Bull. 37, U. S. Nat. 
Mus., p. 174, t. 45, f. la, b; t. 63, f. 102, 102a (reproduced from 
Verrill & Smith.) 

A very peculiar species. The figures of the tail and head plates 
given by Verrill and copied on plate 66 are not very good, and I 
have therefore drawn others from one of the original specimens, on 
pi. 65. 

The only specimen of this species which I have examined has a 
deep cleft in the posterior margin of the tegmentum of the tail valve, 
parallel to the lower border of the valve. Whether this is or is not 
abnormal must be decided by the examination of more material. 
It is well shown in fig. 74, of plate 65. 



Subgenus PLAXIPHORA Gray. 
Under this subgenus three sections, defined above, are placed. 

Section Plaxiphora Gray. 

This section as here restricted corresponds to Gray's original 
genus, except that he was ignorant of the fact that sutuial pores or 
tufts are absent in some species. It is absolutely equivalent to 
Shuttleworth's section Euplaxiphora, but Carpenter restricted this 
last name to species of the P. petholata type, having no pores or 
tufts at the sutures. The mutability of this character has been dis- 
cussed under Mopalia; therefore it is necessary in this place merely 
to state that the presence of pores at the sutures is not even a con- 
stant specific character in Plaxiphora, except when the tufts are 
strongly developed. There are several species in which the pores 
are visible in some specimens, but quite absent in others preserved 
in the same way. 

The corrugated Plaxiphoras are in great need of revision ; but the 
material now in museums is insufficient. Great latitude may be 
expected in the range of specific variation, as in the genus Mopalia* 

Partial key to species of Plaxiphora. 
a. Central areas unsculptured save for growth-lines. 



316 PLAXIPHORA. 

b. Sutural pores or tufts distinctly developed ; sinus shallow, 
c. Anterior valve distinctly ribbed ; lateral areas dis- 
tinct, setiger, biramosa. 
cc. Anterior valve smooth ; lateral areas indistinct. 
Dark brown, banded with paler at the ridge, 

simplex, 
bb. Sutural tufts or pores absent. 

c. Lateral areas undefined, not sculptured. 

d. Sinus deep, narrow, denticulate ; brown, with 
a yellow-bordered dorsal band of chestnut, 

wahlbergi. 

dd. Sinus wide, smooth; black, with a green- 
bordered dorsal black triangle, glauca. 
cc. Lateral areas defined by a beaded rib, concentric- 
ally wrinkled. 

d. Colors bright and variegated ; size small, 

carpenteri. 
aa. Central areas corrugated, at least at the sides, 

Group of P. petholata. 
Group of P. terminalis. 



Group of P. setiger. 

Shell smoothish ; girdle with distinct sutural pore-bunches. 
P. SETIGER King. PI. 65, figs. 76, 77, 78, 79. 

Shell elliptical, low roof-shaped, the ridge carinated, side-slopes 
straight. Surface lusterless, smooth except for delicate growth-lines. 
Color ashy-olive or bluish, with concentric dark streaks, and gener- 
ally having unequal stripes radiating from the beak of each valve, 
these markings varying from indistinct to conspicuous. 

The median valves are not beaked. Lateral areas not raised, but 
clearly defined by a narrow, raised diagonal rib let, and perceptibly 
swollen or ribbed toward the posterior margin, giving the young a 
bicostate appearance ; the two ribs being more or less nodose, especially 
in young specimens, and toward the beaks in adults ; and there are 
also a few extremely indistinct radiating riblets in the slightly 
excavated middle portion of the lateral areas. Central areas smooth. 
Anterior valve having about 8 narrow radiating riblets, becoming 
obsolete as they near the peripheral margin, but each ending in a 



PLAXIPHORA. 317 

slight projection there ; the intervals bearing some indistinct radii. 
Posterior valve depressed, the mucro inconspicuous and about at the 
posterior fourth ; posterior area obsoletely radiately ribbed. 

Interior light blue-green. Sinus small and shallow. Sutural 
plates low. Anterior valve having 8, central valves 1 slit; the slits 
short, continued in grooves to the eaves; teeth long, irregularly- 
striated outside, thickest along the slits, sharp edged. Posterior 
v* alve having the insertion-plate long and stout at the sides, inter- 
rupted by a rounded sinus in the middle behind ; its edge smooth, 
unslit. Eaves very narrow and very spongy. 

Girdle rather wide, leathery, having at each suture a small pore 
bearing several long corneous bristles, and with one or two more or 
less irregular series of bristle-bearing pores on the surface of the 
girdle, and a more or less dense clothing of small soft hairs over its 
outer part. 

Length 50, breadth 35 mill.; divergence 125-135. 

Chiton setiger KING, Zoological Journal v, p. 338 (1831). Sow- 
ERBY, Conch. Illustr., f. 17 ; Zool. Beechey's Voy., pi. 40, f. 7 (bad). 
REEVE, Conch. Icon. t. ix, f. 48a, t. xiv, f. 48c. GOULD, U. S. 
Expl. Exped., Moll., p. 330, f. 425. Plaxiphora carmichaelis GRAY, 
P. Z. S. 1847, p. 68, and subsequent writings, probably not Chiton 
carmichaelis GRAY, Spic. Zool. 1828. Plaxiphora carmichaelis 
HADDON, Challenger Report, Polyplac., p. 32. H. & A. AD., Gen. 
Rec. Moll, i, p. 481 ; iii, t. 55, f. 3. Chcetopleura savatieri ROCHE- 
BRUNE, Bull. Soc. Philomathique de Paris, 1880-1881, p. 119; 
Miss. Sci. du Cap Horn, Polyplacophores, p. 135, t. 9, f. 3a, 3b. 
Chcetopleura frigida ROCHEBR,, Miss. Sci. du Cap Horn, p. 137, t. 9, 
f. 5a, 5b. (young shell.) 

This is the only well-established species known to inhabit the 
extremity of South America. It will be readily recognized by the 
smoothness of the surface, strong diagonal rib, and generally well- 
defined sutural pores, each bearing several bristles. The variation 
in color is well-shown on the plate. The C. savatieri (pi. 67, figs. 
41, 42), and C. frigida (pi. 67, figs. 39, 40) of Rochebrune are 
merely, it seems to me, individual mutations of setiger the last being 
a young shell. It will not escape the observant zoologist that the 
artist who drew the plate of Chitons illustrating Rochebrune's paper, 
did not see the lateral slits in the valves. One is likely to infer that 
the other characters may be equally erroneously represented. 

Some authors have given Gray's name carmichaelis to this species ; 



318 PLAXIPHORA. 

but this identification rests only upon the synonymy given in Gray's 
several lists. Waiving for the moment the question as to the 
identity of the original carmichaelis with setiger, we notice that the 
rest of Gray's synonymy of this species is in several respects incor- 
rect. C. biramosus Quoy for instance, is not the same as setiger ; 
and his list of Chitons shows a number of other errors of synonymy. 
It is not safe therefore to trust Gray's dictum in such matters ; and 
it may fairly be doubted whether the original carmichaelis, which is 
described as being " scarcely keeled," one-half an inch long, etc., 
etc., is the same as the large, strongly carinated Ch. setiger. In 
any case, Gray's name should be ruled out on the score of faulty 
definition. The name setiger was acceptably defined ; the species 
was correctly located by King ; and it was sheer piracy on Gray's 
part to shift his name from some poor little half-inch Cape of Good 
Hope specimen to this fine large form from Cape Horn. The 
original description of carmichaelis is as follows : 

Chiton carmichaelis Gray. Shell oblong, convex, scarcely keeled, 
smooth, bluish-brown streaked and lined with white ; front valves 
with distant rather broad radiating nodulose ribs ; front and back 
margins of the lateral arese of the middle valves with a single similar 
rib ; hinder valve smooth. Margin scabrous, brown. Length J an 
inch, breadth f. Icon. Wood, Cat. Suppl., 1. 1, f. 10. Inhab. Cape 
of Good Hope. Capt. Carmichael, Brit. Mus. 

Chiton carmichaelis GRAY, Spicil. Zool. pt. 1, p. 6 (July 1, 1828). 
Not Plaxiphora carmichaelis GRAY, P. Z. S. 1847, pp. 68, 169. P. 
vannichaelis GRAY, Guide Syst. Dist. Moll. B. M., p. 186. 

Var. FREMBLYI Broderip. PI. 67, figs. 37, 38. 

Shell oblong, flattened, olivaceous-brown, varied with whitish- 
green lines ; anterior valve with elevated subgranose rays ; inter- 
mediate valves angular at the sides, the lateral areas biradiate, rays 
subgranose, intervals longitudinally subsulcate. Girdle set with 
numerous short bristles. 

Length If, breadth 1 inch. (Brod.~) 

Bay of Valparaiso (Cuming). 

Chiton frembleii BROD., P. Z. S. 1832, p. 28. (7. setiger var. 
Jremblii SOWB., Conch. Illustr., p. 7, f. 4. Chcetopleura hahni 
ROCHEBRUNE, Miss. Cap Horn, Polyplac., p. 136, t. 9, f. 4 (1889.) 

This differs from P. setiger in being somewhat wrinkled concentric- 
ally. I have not seen specimens. Broderip inserted an e in Frem- 



PLAXIPHORA. 319 

Wy's name, evidently by inadvertence. 

The figures represent C. hahni Rochebr., which I believe to be 
identical. It is thus described : 

Chcetopleura hahni [pi. 67, figs. 37, 38]. Shell broad-ovate, flat- 
tened, obtusely carinated, violaceous-bluish, with spots and lines of 
brown irregularly distributed. Anterior valve rounded, with 10 
radiating ribs. Posterior valve very small, elliptical, feebly beaked. 
Lateral areas of the median valves narrow, bounded by a beaded 
rib ; central areas covered with deep concentric striae, and very 
minutely striated transversely. Girdle wide, brown, covered with 
tawny hairs. Length 48, breadth 35 mill. (Rochebrune.} 

P. BIRAMOSA Quoy & Gaimard. PI. 68, figs. 51-54. 

Animal ovoid, elongated, flattened, valves very transverse, little 
elevated, forming a low arch, not carinated ; striated transversely in 
front. White or green with a circle of red-brown on each valve. 
The anterior valve has 9 teeth on its edge, the posterior valve none. 
The sutural laminae are not wide, and are separated only by a very 
obtuse sinus. The insertion plates are slit at the sides at usual. Inte- 
rior dull white. 

Girdle nude, vivid red-brown, having two spaced series of rough, 
sparse and bifurcating hairs, the inner series contiguous to the 
valves, the other near the periphery of the girdle, which is also 
hairy. (.&.) 

Length 45, breadth 31 mill. 

Chiton biramosus Q. & G., Voy. de FAstrol. Zool. iii, p. 378, 
t. 74, f. 12-16. Plaxiphora biramosa Q. & G., HUTTON, Man. N. Z. 
Moll. 1880, p. 116 (translation of Quoy's diagnosis). Acanthoehcetes 
biramosus HUTTON, Trans. N. Z. Inst. iv, p. 181 (incorrect descrip- 
tion, from Deshayes). Placiphora super ba CPR. MS. 

The external form is noticeably different behind in the two 
individuals which we possess ; but the red color of this species and 
its two series of bifurcating spines will readily distinguish it. ( Q. 
& G.} 

I believe the form which Carpenter described in MS. as P. superba, 
is the same as Quoy and Gaimard's C. biramosus. Carpenter's 
description is as follows : 

P. superba (pi. 68, figs. 55-61). Shell large, oval, elevated, the 
dorsal ridge acute ; mucro subposterior, little elevated. Reddish- 
olive, maculated with darker and paler. Valves nearly rectangular, 



320 PLAXIPHORA. 

but well indented at the sutures, having a " false apex " in front. 
Lateral areas having indistinct, subobsolete radiating riblets. Ante- 
rior valve subangled by 8 radii, which slightly undulate the- 
peripheral margin ; otherwise nearly smooth except for growth- 
lines. Interior : posterior valve having the insertion-plate elevated,, 
rounded, interrupted in the middle behind by a very narrow, deep 
sinus. Anterior valve having 8, central valves 1 slit ; teeth long, 
slightly striated and slightly thickened at the edges of the slits out- 
side. Sinus narrow, short. Sutural laminae continuous over the ante- 
rior false apex. Girdle (fig. 61) tough ; black, leathery, hardly 
sinuated behind, smooth, with a few bristles at the sutures and 
around the margin. 

Length 60, breadth 40 mill. ; divergence 110. 

New Zealand (Mus. Cum., no. 2.) 

This very fine but unsculptured species was marked as new in Dr 
Gould's collection, but not described by him. It is abnormal in the 
nearly smooth aspect of the tough girdle, in which however the 
binary pores (of which five surround the head valve) are distinctly 
marked. The shape of the valves is nearly as in Mopalia ivosness- 
enskii. ( Cpr.} 

Professor Hutton has considered his Tonicia corticata a synonym 
of biramosa, in his Manual of New Zealand Mollusca, 1880 ; but the 
description (copied below) would hardly lead me to the same 
conclusion, although Button's species is undoubtedly a Plaxiphora. 
In sculpture it must resemble P. terminalis. 

Tonicia corticata. Oval ; margin naked ; valves much depressed ; 
posterior margins slightly concave ; lateral areas bounded on each 
side by a flatly nodulose ridge, the space between being obliquely 
striated, the striae running outward and backward ; median areas 
rugose, without either distinct lines or granules. Length 1*25, 
breadth 1*13 inch. Color: margin black when dry; valves grey; 
inside white, covered over with white, coralline growth and small 
marine algae. Founded on a specimen in the Colonial Museum, 
locality not stated. (Hutton, in Trans. N. Z. Inst. iv, p. 180, May, 
1872.) 

P. SIMPLEX Carpenter. PI. 67, figs. 43, 44, 45, 46. 

Shell similar to P. modesta, but more elevated, longer ; valves 
rude, maculated with brown-purple ; dorsal ridge rounded ; mucro 
posterior, flattened ; lateral areas scarcely defined ; valves rounded, 



PLAXIPHORA. 321 

with large sutures. Entire surface smooth, generally eroded, sub- 
spongy. Interior ; posterior valve with a moderately elevated 
insertion-plate, moderately sinuated behind. Anterior valve with 8, 
median valves 1 slit ; teeth acute, scarcely thickened at the edges of 
the slits. Eaves short, spongy. Sinus very narrow, smooth, straight. 
Girdle spongy, having very close, small hairlets, and longer corneous 
hairs scattered and at the sutures. (Qor.) 

Length T35, breadth '7 inch, divergence 120. 

Var. : length I'l, breadth '65 inch, divergence 100. 

Tristan Island, Tristan da Cunha, on the shore, and off Nighten- 
gale Island, Tristan da Cunha, 100-150 fms. (' Challenger.') 

Euplaeiphora simplex CPR., MS. Plaxiphora simplex CPR., in 
Haddon's Keport on the Polyplacophora of the Challenger Expedi- 
tion, p. 33. Also described by HADDON, I. c., p. 34, t. 3, f. 13, 
13a-c. 

This species I have not seen. The P. modesta alluded to by Car- 
penter is a form of P. petholata. 

Haddon describes P. simplex as follows : 

Shell smooth, simply marked with line of growth, flat sides meet- 
ing at a variable angle. Anterior valve small, surface smooth. 
Under surface with eight slits, teeth fairly long, smooth and sharp ;; 
eaves short. Intermediate valve : Central area ; smooth, flat. 
Lateral areas inconspicuous, with two or three very faint radiating 
ridges. Under surface with a median horizontal rib-like swelling ; 
sutural laminse broad, but not deep ; jugal sinus wide and shallow ; 
one lateral slit ; eaves short. Posterior valve very small and flat, 
greatly corroded; umbo apparently flat and terminal; posterior 
border thickened. Under surface : sutural laminae as in intermediate 
valves, but the jugal sinus is comparatively narrow and deep ; slits 
and teeth absent ; posterior border much swollen. 

Girdle very thick and fleshy, upper surface having a spongy 
appearance, owing to being beset with very short horny spines, 
which are scarcely raised above the surface; there are tufts of longer 
spines, three to nine in each tuft, opposite the sutures of the valves; 
these have no definite position round the anterior valve. Situated 
outside these are numerous scattered similar tufts, usually somewhat 
smaller in size, which pass into an imperfect peripheral fringe of 
spines, (pi. 67, figs. 44, 46). Color : all the valves of a uniform 
dark brown, with a pale (lilac) narrow triangular band along the 

21 




322 PLAXIPHORA. 

jugum of the intermediate valves (and anterior area of the posterior 
valve). Under surface of all the valves of a bluish-green color ; 
laminae of insertion paler. Girdle, upper surface dark brown ; 
under surface dusky orange. 

Length 40, breadth 25, height 10 mill. ; angle of divergence 125 
to 135 (two specimens from 100 to 150 fathoms.) 

Length 25 to 35, breadth 14 to 17, height 8 to 9 mill. ; angle 90. 
to 110 (two shore specimens.) 

Group of P. wahlbergi. 

No sculpture except some concentric lines; sinus deep, dentic- 
ulate ; girdle without sutural tufts. 

P. WAHLBERGI Krauss. PI. 55, figs. 17, 18. 

Shell ovate-oblong, slightly convex ; brown with a chestnut-brown 
median band and two yellowish longitudinal bands. Concentrically 
sulcate. Interior white, brownish-violet in the middle. Anterior 
valve semilunar ; posterior valve subtriangular, depressed ; inter- 
mediate valves subreniform, having distant concentric grooves on 
the front part of the central areas, and on the lateral areas. Girdle 
brown, leathery, velvety. Length 15, breadth 9 lines. 

This species has rather thick, little convex valves, rounded on 
their outer ends, and having the older or posterior half of each 
eroded, and deprived of color and sculpture. Lateral areas not 
differentiated. The forward part and the sides of each valve have 
6 or 7 separated, sometimes finely granulated furrows, parallel with 
the margins. The posterior margin is eroded, probably beaked in 
the middle. The insertion-plates are narrow, roughened outside. 
Anterior valve excavated behind, having 8 slits. Posterior valve 
lacking teeth. The valves have in the middle a chestnut-brown 
shining band, 2 mill, wide, on each side of which a yellow streak of 
greater or lesser width generally lies ; but usually they are eroded 
and gray. (Krauss.) 

Table Bay, Cape of Good Hope. 

Chiton wahlbergi KRAUSS, Die Siidafrik. Moll., p. 36, t. 3, f. 1 
(1848). Euplaciphora wahlbergi CPR., MS. 

May be known by the separated concentric grooves of lateral and 
central areas, parallel with the valve-margins, and also by the sinus, 
which is deep, narrow and denticulate, the last being an unusual 
character in this genus. The girdle has irregular setae. 



PLAXIPHORA. 323 

Group of P. petholata. 

Shell somewhat sculptured. Girdle covered with crisp hairs, not 
forming bunches at the sutures, nor having pores there. 

P. PETHOLATA Sowerby. PI. 68, figs. 62, 63, 64, 65, 66, 67. 

Shell elliptical or oblong, rather depressed, the dorsal angle 
rounded but side-slopes rather straight. Surface finely corrugated at 
the sides, nearly smooth in the middle. Color black or blue-black, 
with pink, creamy or greenish-white angular markings at the sides, 
and a wide triangle of the same light tint on the ridge of each valve, 
generally enclosing a dark, ill-defined dorsal stripe. 

The median valves are slightly beaked. Lateral areas hardly 
raised, defined by a narrow, inconspicuous and slightly curved 
diagonal riblet, the surface finely corrugated in zig-zag or vermic- 
ulate pattern. Central areas corrugated zigzagly at the sides, in front 
of the diagonal rib, the corrugation becoming finer toward the middle, 
and giving place to a microscopic pattern resembling a dense punctula- 
tion united with a minute zigzag or vermiculate wrinkling. Anterior 
valve having about 9 narrow radiating riblets, the intervals densely 
and finely zigzag-punctate. Posterior valve depressed, wide and 
short, the mucro at the posterior edge, slightly acute and a little 
elevated ; posterior area of the valve very narrow, ill-defined. 

Interior dark blue-green. Sinus deep, wide, angular, its edge light 
brown and very spongy. Anterior valve having 8 slits, correspond- 
ing to external riblets, central valves 1 slit ; the teeth acute, some- 
what thickened at the edges of the slits. Posterior valve having a 
rather blunt, smooth insertion plate, interrupted by a shallow sinus 
in the middle behind. Eaves very narrow, spongy. 

Girdle rather wide, black-brown and brown alternately, rather 
densely clothed with corneous or dark brown bristles, large and 
small, not in the least arranged in series or issuing from sutural 
pores. 

Length 40, breadth 27 mill.; divergence 125. 

Length 32, breadth 18 mill. ; divergence 130. 

Length 45, breadth 25 mill. 

Australia (Sowb.) ; Tasmania (Cuming.) 

Chiton petholatus SOWB., Mag. of Nat. Hist. New Series, iv, p. 
289 (May, 1840) ; Conchol. Illustr., f. 64, 65, and var. porphyrius, 
f. 59. REEVE, Conch. Icon., f. 74. Euplaciphora petholata CPU., 
MS. Not Plaxiphora petholata ANGAS, P. Z.'S. 1865, p. 187 and 



324 PLAXIPHORA. 

1867, p. 224. Euplaciphora modesta CPR., MS. 

The sinus is squared, and the internal layer is bevelled off expos- 
ing the very porous outer layer as in Nuttallina. Back of this 
porous area, the width of which varies, the surface shows transverse 
cuts or puncture-slits. The hairs of the girdle show no trace what- 
ever of arrangement in tufts or pores. The exterior is finely sculpt- 
ured with zigzag wrinkles, and the diagonal riblets on each valve, 
as well as the radii on the head valve, may be either nearly smooth 
or closely granose. The pattern of coloring is characteristic but 
still quite variable. 

Var. CONSPERSA Adams & Angas. 

Shell oval, little elevated, with obtuse dorsal ridge. Ashy, with 
a few scattered clouds of dark and olivaceous. 

Valves squared, thin ; apices not conspicuous, jugal areas marked 
off by slight indentations which are slightly divergent; but other- 
wise finely sculptured like the rest of the middle part of the central 
areas ; pleura having about 20 irregularly roughened line on each 
side, the lirse mainly forming right angles with the diagonal rib, but 
branching and minutely undulating ; becoming very fine toward and 
upon the jugum ; interstices very small. Lateral areas with the 
diagonal rib much elevated, rendered nodulous by the wrinkles pass- 
ing over it ; the same sculpture extending across the lateral areas 
and becoming more nodulous at the suture. Anterior valve having 
8 ribs, besides those at the sutures. Posterior valve having the 
mucro at the posterior fourth, and with two diagonal ribs. 

Interior : anterior valve having 8 slits, median valves 1 slit, corre- 
sponding to the external ribs ; the teeth slightly thickened at the 
edges of the slits. The posterior valve has well developed, sharp 
insertion-plates on each side. 

Girdle pale brown, maculated with black-brown ; bearing fine, 
sparsely scattered soft corneous hairs. 

Length 21-22, breadth 12-14 mill., divergence 117. 

Port Lincoln, South Australia, under rocks (Angas.) 

Chcetopleura conspersa AD. & ANG., P. Z. S. 1864, p. 193. 
ANGAS, P. Z. S. 1865, p. 187. Placiphora conspersa CPR., MS. 

I have seen no specimens of this form, which Carpenter believed 
to be a variety of P. petholata. The above description is from Car- 
penter's MS., and was drawn from Angas' type. 



PLAXIPHORA. 325 

P. CAEPENTERI Haddon. PL 67, figs. 33, 34, 35, 36. 

Shell smooth, the sides meeting at an angle of 105. Anterior 
valve with eight radiating ridges, not counting the swollen posterior 
borders. Numerous concentric minor ridges cause these ridges to be 
rugose. Under surface with nine slits, two being very close together ; 
eaves short. 

Intermediate valves: central area smooth, with fine lines of 
growth ; no distinct keel. Lateral areas prominent, concentrically 
rugose, with a beaded ridge along the anterior border, and, to a less 
extent, along the posterior border. Under surface with a median hori- 
zontal rib-like swelling; sutural laminae broad, but not deep ; jugal 
sinus shallow ; one lateral slit ; eaves short. Posterior : valve anterior 
area so large as to reduce the posterior area to a minimum ; smooth ; 
umbo minute, nearly terminal. Posterior area merely forms a con- 
centrically grooved thickening of the posterior border of the valve- 
Under surface : sutural laminae as before, but the jugal sinus is com- 
paratively narrow and deep ; slits and teeth absent ; the posterior 
border is greatly swollen. 

Girdle closely beset with very minute horny spines. The specimen 
had been dried when I received it, and none of the longer spines, 
characteristic of other species, are observable ; but I think I can 
discern traces of small sutural tufts. 

Color : anterior valve with a median triangular area, with the 
apex at the umbo, is of a kind of chocolate color, which is variegated 
with minute zigzag grey lines ; the lateral spaces are of a dark slate 
color. Intermediate valves: central area: jugum pink; greenish 
toward the umbo when worn down. Pleura dark greenish-brown, 
with irregular longitudinal green bands. Lateral areas madder 
brown, blotched with brown. Posterior valve : anterior area resem- 
bling the central areas ; posterior border pinkish. Under surface of 
all the valves pale bluish green ; laminae of insertion white. Girdle 
reddish-brown. 

Length 14, breadth 9 mill. ; height 4 mill. (Haddon.') 

Tristan da Cunha. 

Plaxiphora carpenteri HADDON, Challenger Rep. Polyplac., p. 34, 
t. 1, f. 8; t. 3, f. Sa-g. 

The sculpture of the shell, slight as it is, is sufficient to character- 
ize this species. (Haddon.*) 

P. GLAUCA Quoy & Gaimard. PI. 68, figs. 68-72. 

Animal oval, widened at the sides. Valves wide, rounded, little 



326 PLAXIPHORA. 

elevated, subtriangular. uniform and smooth except toward the 
anterior margins where they are marked with three or four mar- 
ginal striae; they are black toward the lateral margins, with a tri- 
angle of the same color in the middle, bordered with yellowish or 
greenish. 

Inside they are of a beautiful emerald green, the sutural laminae 
being of the same color and separated by a wide sinus. The anterior 
valve has its margin cut into 9 smooth teeth. Posterior valve hav- 
ing a semi-circular ridge in place of the teeth. The valves taken 
together form an elongated oval. All of the intermediate valves 
have one slit and two transverse striae on the apophyses. 

Girdle of a beautiful light green, covered with rigid but not acute 
bristles of the same color. ( Q. & G.) 

Length 50, breadth 37 mill. 

d' Entrecasteaux Channel, Tasmania. 

Chiton glaucus Q. & G., Voy. de 1'Astrol. Zool. iii, p. 376, t. 74, 
f. 7-11 (1834). Not Chiton glaucus GRAY, an undetermined species, 
see p. 172.lPlaxiphordciliata ANGAS, P. Z. S. 1865, p. 187, not 
Chiton ciliatus SOWB. 

This species is evidently allied to P. petholata. It is probably the 
form Angas collected at Guichen Bay, South Australia, and listed 
as " P. ciliata." He found it on rocks at low water, and remarks 
that it is the largest of the South-Australian Chitonidae. 

Group of P. terminalis. 

Sculpture stronger than in P. petholata. Girdle generally with 
more or less distinct sutural pores. Distribution, New Zealand. 

P. TERMINALIS (Cpr.) Smith. PI. 51, fig. 14. 

Shell resembling P. petholata in sculpture, but more elevated, 
longer, the mucro entirely terminal, produced. Dorsal ridge striped 
with white. Sculpture much more distinct, consisting of irregularly 
zigzag wrinkles all over, coarser at the sides. 

Interior having 8 slits in the anterior, 1 in the median valves. 
Posterior valve with subplanate insertion plate ; the subjugal area 
punctate, teeth, sinus and eaves as in P. petholata. Girdle having 
bunches of long horny hairs at the sutures and around the margin, 
elsewhere smoother. 

Length 25, breadth 12? mill. ; divergence 120. (<7/>r.) 

New Zealand (Cuming.) 



PLAXIPHORA. 327 

Plaxiphora terminalis CPR., MS. in Mus. Cuming. Chiton (Plaxi- 
phora) terminalis E. A. SMITH, Voy. Erebus and Terror, Moll., p. 4 
t. 1, f. 13 (1874). Plaxiphora terminalis Smith, HUTTON, Man. N. 
Z. Moll. 1880, p. 116 (reprinted from Smith.) 

Smith has described this species in detail, as follows: "Shell 
elongately ovate, rather elevated, roundly angled along the top of 
the valves, black or bluish-black, with a white wedge-shaped stripe 
with a black one within it down the centre of the valves, forming a 
continuous white stripe divided by the black one along the center of 
the shell, in some specimens with a few short white dashes diverg- 
ing from the radiating ridges. The intermediate valves mucronated, 
bisected on each side by one raised radiating rib, the posterior mar- 
gins sinuated and thickened by coarse concentric lamellae ; the 
entire surface is covered with minute striate-wrinkling, those near 
the ridge being coarser than the rest and radiating from it like the 
webs from the shaft of a feather. The posterior terminal valve has 
the mucro quite terminal. The anterior valve radiately eight-ribbed 
(at times one or two additional minor ones are present) with diverging 
oblique striations on each side of them. Interior of valves greenish- 
blue ; valve lobes whitish, the sinus between them deep ; the hairs 
or bristles on the mantle-margin are short, few and horny, those 
arising from the nine pores being thicker than the rest. 

" Largest specimen (in a contracted state) 42 mill, long ; width of 
valves, 20 mill. ; an average specimen, length 25 mill.; width 11 
mill. 

New Zealand (Col. Bolton and Capt. Stokes.) 

" Terminalis " appears to be but a manscript name attached to 
some specimens in the Cumingian collection. As I understand that 
Dr. P. P. Carpenter is engaged on a work on Chitonidcel retain the 
characteristic name he imposes; The central white stripe with the 
black one within it appears to be very constant." 

Carpenter gave the varietal name zigzag, (in MS.) to specimens in 
the Cuming collection (no. 31) having stronger sculpture, one more 
anterior riblet, etc. It seems to be merely an individual variation. 

P. EXCURVATA Carpenter, n. sp. 

Shell elongated, elevated, the dorsal ridge rounded, valves angled 
at the sides, obtusely beaked, the sutures indented. Irregularly 
maculated with coppery green and black. 

Lateral areas defined by an obtuse curved rib ; toward the rib on 



328 PLAXIPHORA. 

each side closely concentrically sulculate. Anterior valve having 
about 7 or 8 ribs, sometimes with some intercalated subobsolete 
riblets. Posterior valve small, the mucro subposterior, swollen. 

Interior blue. Anterior valve having 7-8, median valves 1 slit ; 
teeth long, acute, scarcely thickened at edges of the slits. Posterior 
valve having an obtuse insertion plate, a little sinuated in the middle 
behind. Sinus broad, straight, spongy. 

Girdle wide, thin, hardly sinuated behind, tessellated with brown 
and ashy, beset all over with sparse, delicate, short setae, longer at 
the sutures. 

Length 70, breadth 39 mill. ; divergence about 110. 

Australia? (Haines Coll., and Coll. McGill University, Mon- 
treal.) 

Euplaciphora excurvata CPU., MS. 

This shell has a general external resemblance in size and shape to 
P. cuprea, from which it is known at once by the color and sculpture 
outside, by having no posterior slit in the girdle, and inside by the 
smoothness and sharpness of the insertion-plates. It also resembles 
P. superba, but is entirely destitute of sutural pores. 

P. C^LATA Reeve. PL 58, figs. 21, 22. 

Shell oblong-ovate, somewhat attenuated anteriorly, terminal 
valves (the posterior of which is small and slanting) and lateral 
areas of the rest broad-ribbed and neatly carved with close-set waved 
laminse ; central areas very minutely reticulated. Beautifully orna- 
mented with green and pink. Ligament horny, here and there 
bristly. (Reeve.) 

New Zealand (Earl, Cuming.) 

Chiton ccelatus Kv., Conch. Icon., t. 17, f. 101 (1847). Strepto- 
chiton cupreus CPR., MS., olim. ? Tonicia zigzag HUTTON, Trans. 
N. Z. Inst. iv, p. 181 (1872.) 

The verdigris green and peculiar pink color-pattern is character- 
istic and singularly beautiful. 

Von Martens has stated that Tonicia zigzag Hutton is a synonym of 
" Aeanthopleura " ccelata Rv. (Crit. Cat., p. 49) ; a conclusion 
accepted by Hutton (Man. N. Z. Moll., p. 115, 1880). As in other 
cases of alleged identity, the original type of zigzag should be 
re-examined. Hutton's description is as follows : 

Tonicia zigzag Hutton. Oblong; mantle slightly tomentose; 
valves slightly flattened on each side, but not keeled; posterior 



PLAXIPHORA. 329 

margins sloping backwards into a point, crenulated on the sides ; 
anterior valve with 9 radiating ridges crossed by fine concentric 
zig-zag striae ; lateral areas with two, on each side, radiating ridges 
crossed by fine zig-zag strise ; posterior and median areas with very 
fine oblique striae diverging from the dorsal line outward and forward 
crossed by others diverging outward and backward forming an 
engine-turned pattern. Length 88 inch. ; breadth 31 inch. 

Color, mantle white ; valves greyish-black with a white stripe on 
each side of the dorsal line ; interior greenish-blue. 

A single specimen'is in the Colonial Museum, locality not stated. 
(Hutton.) 



The following species probably belongs here, but I have seen no 
specimen, and it has not been figured. 

CHITON (CHJETOPLEURA) PLUMOSUS Gould. 

Shell brown-ashy, valves concave scarcely beaked ; anterior valve 
ornamented with plumose radiating lirse ; posterior valve small, the 
apex marginal and having a submarginal rib on each side. Central 
area large, ornamented with divaricating strise, and lateral plumosely 
co-united strise. Lateral areas small, bounded by asutural rib, strise 
denticulated, interspaces clathrate. Girdle broad, leathery, furnished 
with (bristly?) tubules. 

Length 1-5, breadth '75 inch. (Gld.*) 

Habitat unknown. 

Allied to C. ecelatus Rv., which is said to be highly ornamented 
with green and pink. C. collei and C. muscosus G. belong to the 
same group. (Old., in Proc. Bost. Soc. Nat. Hist, vii, p. 165.) 

Section Guildingia Cpr., 1893, n. sect. 

Guildingia CPR., MS., and in Dall, Proc. U. S. Nat. Mus. 1881, 
pp. 284, 288 (type G. obtecta Cpr. MS.) 

Shell and girdle like Plaxiphora, except that the valves are partly 
immersed by the encroachment of the girdle. 

This section, like Fannettia in the genus Tonicia, rests upon a 
character of very little taxonomic value ; but as it is useful in break- 
ing up a large genus for convenience in identifying, it has been 
retained. 



330 PLAXIPHORA. 

P. OBTECTA Carpenter, n. sp. 

Shell large, broad, partly covered. Valves smooth, most minutely 
punctulate angulate in front ; sutural sinus large, produced forward 
over the jugum ; lateral areas scarcely defined except by an angle 
at the forward outer margin of the valves ; dorsal ridge rounded. 
Intense olivaceous, paler on the dorsal ridge. Mucro of posterior 
valve terminal hardly produced. 

Interior : posterior valve with flattened insertion-plates. Anterior 
valve with 8, central valves 1 slit ; teeth very acute, long, smooth, 
a little thickened at the slit-edges ; eaves narrow, spongy. Sinus 
deep, very obtusely angular, with a spongy area. Sutural laminae 
long, separated. Girdle very broad, sinuated behind, with bundles 
of about three large, horn-like hairs at the sutures, and having 
smaller ones sparsely scattered all over more or less closely. (Qpr.) 

Length 50, breadth 32 mill. ; divergence 120. 

New Zealand (Mus. Cum., no. 45.) 

This very interesting shell differs from the typical Plaxiphorce as 
Fannettia does from Tonicia. It is, however, simply an exaggera- 
tion of P. terminalis. 

Section Fremblya H. Adams, 1866. 

Frembleya H. AD., P. Z. S. 1866, p. 445. Type F. egregia H. 
AD. Fremblya CPU., MS. and in Proc. U. S. Nat. Mus. 1881, p. 284. 
Streptochiton CPU., MS. olim. 

Shell and girdle like Plaxiphora except that the former is short and 
broad, the tail valve very much reduced in size, strongly arched 
upward in the middle behind. Slits in intermediate valves poste- 
riorly situated. Girdle having more or less obvious sutural pores. 

The sculpture of these forms is like that of the more elaborately 
carved Plaxiphoras of the same regions ; but the considerable 
modification in the general form of the tail valve may be held to be 
sufficient ground for the retention of Adams' generic name in a sec- 
tional sense. The organization throughout is otherwise very similar 
to that of Plaxiphora. Two species only are known : P. egregia, in 
which the shell is of a peculiar egg shape, wider behind the middle, 
and the insertion plates are much thickened outside at the edges of 
the slits, and P. ovata, in which the shell is widest at the fourth 
valve, rapidly narrowing toward both ends. 

The following description of his new genus is given by H. Adams : 



BLAXIPHORA. 331 

" Frembleya, gen. nov. Testa ovalis, convexa. Valvse transversse, 
latse, carinatse ; apex posterioris valvse terminalis, producta, fissa. 
Limbus angustus, postice fissus, setis cornels dense obsitus. The 
covering of the mantle, the form of the visible portions of the valves, 
and the peculiarity of the terminal valve, render this species distinct 
from any form of Chitonidse yet described. It has the appearance 
of a Lorica with the mantle covered with long bristles instead of 
imbricate scales." 

There seems to be no reasonable objection to the correction of the 
etymology of Frembly's name, which in H. Adams' article was 
incorrectly spelled through inadvertence or typographical error. 

P. EGREGIA H. Adams. PI. 65, figs. 80, 81, 82. 

Shell ovate, a little narrower in front, green-brown, paler at the 
sides. Anterior valve radially ribbed, the ribs pustulose, interstices 
obliquely lirate ; posterior valve and median valves subcarinate, the 
dorsal areas densely longitudinally lirate; lateral areas radially rib- 
bed, the ribs pustulose. Girdle moderate, furnished with short, 
corneous spicules. (H. Ad.) 

Length 15, breadth 9 mill. 

"Habitat unknown" (Ad.); Newcastle, Australia (Dieffenbach, 
teste Cpr.) 

Frembleya egregia H. AD., P. Z. S. 1866, p. 445, t. 38, f. 9. 
Streptochiton tortuosus CPR., MS., olim. 

Of this species I have seen a single mutilated specimen, no. 36,638 
of the Smithsonian Institution register. It is yellowish along the 
middle and at the side margins of the valves, pale green on the side- 
slopes. The species differs from P. ovata in being widest behind the 
middle. Carpenter describes the type as follows : Shell olivaceous, 
maculated with more or less intense ; ovate, broad, elevated ; dorsal 
ridge rather acute, much elevated, the side-slopes straight. Valves 
strongly beaked, each one eroded in front from the attrition of the 
next valve forward. The central areas have about 16 lirse on each 
side, about equalling the interspaces in width. Lateral areas elevated, 
bicostate, the ribs strongly granose, granules larger at the sutures, 
intermediate space obliquely costate or v-costate. Anterior 
valve having 10 radiating ribs, the interstices sculptured with 
v-shaped sulci, the v'-s meeting over the ribs and rendering them 
somewhat nodulous. Posterior valve with posterior elevated mucro 
and a single posterior rib on each side ; posterior area very narrow 



332 PLAXIPHORA. 

and smooth. The girdle has soft hairs, and a few larger, and there 
is some trace of pores. The posterior slit in the girdle mentioned by 
Adams seems to be an accidental tear ; H. Adams believes the 
same. 

Length 15, breadth 10 mill; divergence 133. 

P. OVATA Button. PI. 54, figs. 34-40. 

Shell short-oval, very wide in the middle, rapidly narrowing toward 
the ends ; moderately elevated, the dorsal ridge carinated, side slopes 
slightly convex. Surface lusterless, sculptured in "herring-bone 1 " 
pattern. Color buff along the ridge, pale olive-green on the side- 
slopes, with a small curved dark spot or two on each valve. 

Median valves broadly v-shaped, the apices of the valves elevated 
and acute. Lateral areas narrow, a little raised, the diagonal rib 
sculptured with a series of closely super-imposed v's, their apices 
directed toward the beak of the valve, one limb of each v direc- 
ted outward, curving, and forming the sculpture of the pleura, 
the other limb forming an oblique corrugation of the lateral area 
(fig. 40). Sutural margin of each lateral area obliquely, coarsely 
granose. Central areas having a nearly smooth band along the 
dorsal ridge, and numerous slightly curving and diverging riblets on 
each side. Anterior valve small, its width about that of one side- 
slope of the fourth valve, its apex elevated and slightly recurved ; 
surface having 8 strong ribs, besides those at the sutural margins, 
the anterior ribs strongest and wider apart; ribs nodose, intervals 
obliquely corrugated. Posterior valve (figs. 36-39) small, forming an 
extremely narrow crescent, strongly curved upward at the acute pos- 
terior mucro, the front ("central") area narrow, concave ; viewed 
from behind (fig. 37) it presents the appearance of a wide inverted 
v. 

Interior bluish-white. Sinus exceedingly broad, rounded, the 
sutural-plates widely separated. Insertion plates long, having the 
slit near the posterior edge of the plate. Anterior valve having 8, 
median valves 1 slit. Posterior valve (fig. 39) having a keel-like 
insertion-plate without slits on each side, and a broad sinus in the 
middle behind. 

Girdle rather narrow, yellowish, bearing a pore-tuft of hyaline 
white bristles at each suture and a fringe of bristles at the edge. 

Length 15, breadth 13 mill.; divergence 112. 

Cook Strait; Dunedin, New Zealand ; on seaweed. 

Acanthochcdes ovatus HUTTON, Trans. N. Z. Inst. iv, p. 182 (1872). 



PLAXIPHORA. 333 

Acanthoehites ovatus BUTTON, Man. N. Z. Moll., p. 177 (1880.) 

This species differs from P. egregia in contour, the fourth valve_ 
being the widest, the sixth much narrower, whilst in the other 
species the fifth and sixth valves are as wide as the fourth ; more- 
over the side teeth of ovata do not seem to be thickened at the edges 
of the slits as they are in egregia. The specimen described and 
figured was sent by Professor Hutton. 



ERRATA. 

Page 75, dele the word ISCHNOCHITON, in 8th line. 

Page 97, I. CURTISIANUS is not an Ischnochtton but a Liolophura, 

see p. 242. 

Page 110, For " L regulatus" read "I. rugulatus." 
Page 133, " I. PUSIO" is probably not an Ischnochiton, but a true 

Chiton, and it is likely to prove identical with Chiton 

murrayi Haddon, described on p. 161. 

Page 151, line 11, for " indentification " read "identification." 
Page 182, last line, remove " C. scytoderma " from the synonymy 

of C. rubicundus. 
Page 191. The authority for C. SULCATUS shouldbe " Wood," not 

" Sowerby." 

Page 204, line 14, for "indentification" read "identification." 
Page 206, fifth line from bottom ; the reference to Savigny should 

read " t. 3, f. 6, 1-2," instead of " f. 4." 
Page 329. " Chiton (Acanthopleura) piceolus" Shuttlew., included 

under Acanthopleura granulata as a doubtful synonym, 

is probably referable to the genus NUTTALLINA, s. g. 

Middendorffia, and it should be compared with N. 

einerea Poli, p. 283. 

NOTE. 

The Index to Chitons will accompany the conclusion of the mono- 
graph, to be contained in the next part of the MANUAL. 



EXPLANATION OF PLATES. 



NOTE. The drawings credited to Foord, Smith and Emerton were 
prepared under the supervision of Dr. Carpenter, and were loaned 
by the Smithsonian Institution, for reproduction in the MANUAL. 

PLATE 1. 

FIGURE. PAGE. 

1-13. Lepidopleurus benthus Haddon. Challenger, . . 9 
14-22. Lepidopleurus belknapi Dall. Challenger, . . 7 

PLATE 2. 

23-31. Lepidopleurus alveolus Sars. Moll. Arct. Norv., 6 

39, 40. Lepidopleurus pagenstecheri Pffr. Moll. S. Georg., 12 

41, 43-46. Lepidopleurus cajetanus Poli. Ross del., . 15 

42. Lepidopleurus cajetanus Poli. Conch. Icon., . . 15 
47-50. Lepidopleurus granoliratus Cpr. Pilsbry del., . 14 
51-53. Lepidopleurus granoliratus Cpr. Foord del., . 14 

PLATE 3. 

54-57. Lepidopleurus cancellatus Sowb. Moll. Reg. Arct., . 3 
58. Lepidopleurus cancellatus Sowb. Ross del., ... 3 
59-63. Lepidopleurus arcticus Sars. Moll. Reg. Arct., . 5 

64-66. Lepidopleurus asellus Speng. Ross del., . .13 

67-70. Lepidopleurus rugatus Cpr. Pilsbry del., . . .11 
71-79. Hanleya hanleyi Bean. Moll. Reg. Arct., . . 17 

PLATE 4. 

74-77. Hanleya hanleyi var. abyssorum Sars. Moll. Reg. 

Arct 18 

1 78-81. Lepidopleurus curvatus Cpr. Emerton del., . . 16 
82-84, 85. Hanleya mendicaria M. & A. Emerton del., . 18 
83. Hanleya mendicaria M. & A. Inv. Mass., . . .18 

86. Lepidopleurus rarinotus Jeffr. P. Z. S., . See Appendix. 

87. Lepidopleurus catillus Rv. Conch. Icon., . . . 10 

88. Lepidopleurus fuliginatus Ad. & Rv. Conch. Icon., . 10 

PLATE 5. 

89-100. Hemiarthrum setulosum Cpr. Challenger Rep., . 20 

(334) 



EXPLANATION OF PLATES. 335 

1-3. Hemiarthrum setulosum Cpr. Moll. S. Georg., . . 20 
4-8. Hemiarthrum setulosum Cpr. Emerton del., . . 20 

PLATE 6. 

9-14. Microplax grayi Ad. & Ang. E. A. Smith del., . 21 

12-16. Hanleya tropicalis Ball. Emerton del., . . .19 

17, 18. Hanleya tropicalis Ball. 'Blake' Moll., . . ' . 19 

19, 21. Trachydermon steinenii Pffr. Moll. S. Georg., . . 82 

22-24. Trachydermon lividus Midd. Mai. Ross., . . 76 

25-27. Trachydermon cinereus L. Moll. Reg. Arct., . . 68 

28. Trachydermon cinereus L. Ross del., . . . .68 

29, 30. Trachydermon cinereus L. Pilsbry del., . . .68 
31. Trachydermon cinereus L. Hist. Br. Moll., . . .68 
32-34. Trachydermon albus L. (head and tail valves badly 

drawn). Emerton del., 70 

PLATE 7. 

35. Trachydermon albus L. Moll. Reg. Arct., . . .70 

36-38. Trachydermon albus L. Pilsbry del., ... 70 

39-45. Trachydermon exaratus Sars. Moll. Reg. Arct., . 71 

46-49. Trachydermon exaratus Sars. Tr. Conn. Acad., . 71 

50-56. Trachydermon ruber L. Moll. Reg. Arct., . . 80 

57. Trachydermon cinereus L. Pilsbry del., . . 68 

58. Trachydermon cinereus var. variegatus Phil. Moll. Sicil., 69 
59-60. Trachydermon cinereus var. variegatus Phil. Moll. 

Rouss., 69 

PLATE 8. 

61-65. Trachydermon dentiens Gould. Pilsbry del., . . 73 

66-68. Trachydermon scrobiculatus Midd. Mai. Ross., . 76 

69, 70. Trachydermon pusillus Sowb. Conch. Icon., . . 80 

71. Trachydermon stramineus Sowb. Conch. 111., . . 79 

72, 73. Trachydermon virgatus Rv. Conch. Icon., . . 78 
74, 75. Trachydermon virescens Rv. Conch. Icon., . . 78 
76, 77. Trachydermon puniceus Couth. Expl. Exped., , 81 
78, 79. Chsetopleura cullierti Rochebr. Moll. Cap Horn, 

[See Appendix 

80, 82. Callochiton fulgetrum Reeve. Conch. Icon., . . 83 

81. Callochiton fulgetrum Reeve. Cpr. del., . . . .83 
83-85. Callochiton lobatus Cpr. Emerton del., . . .53 

PLATE 9. 

86, 87, 91. Callochiton castaneus Wood. Conch. 111., . . 52 

88, 89, 90. Callochiton castaneus Wood. Pilsbry del., . . 52 

92. Callochiton illuminatus Rve. Emerton del., . . .51 

93, 94. Callochiton illuminatus Rve. Conch. Icon., . . 51 



336 EXPLANATION OF PLATES. 

95, 96. Callochiton laavis Mont. Pilsbry del., . . 49 

97, 98. Callochiton laevis Mont. Hist. Br. Moll., 49 

PLATE 10. 

1, 2. Callochiton platessa Gld. U. S. Exped., ... 49 

3, 4, 5. Callochiton platessa Gld. Emerton del., . . 49 

6. Callochiton versicolor Ad. (^platessa Gld.). P. Z. S., . 50 

7. Callochiton crocinus Eve. (probably distinct from versi- 

color). Conch. Icon., 50 

8. 10-15. Tonicella marmorea Fabr. Moll. Reg. Arct., . 41 
16-21. Tonicella submarmorea Midd. Emerton del., . . 42 
22-24. Tonicella submarmorea Midd. Mai. Ross., . . 42 

PLATE 11. 

25, 27. Tonicella lineata Wood. Ross del., . . . .42 

26. Tonicella lineata Wood. Emerton del., . . . .42 
28. Tonicella lineata Wood. Pilsbry del., . . . .42 
29-31. Tonicella sitchensis Midd. Mai. Ross., ... 44 
32-34. Schizoplax brandti Midd. Sib. Reise, . . .47 
35-37. Schizoplax brandti Midd. Emerton del., . . .47 
38, 39. Leptoplax coarctatus Sowb. Emerton del., . . 25 
40, 41. Ischnochiton interstinctus Gld. U. S. Ex. Exped., . 119 

PLATE 12. 

42. Chsetopleura peruviana Lm. Ross del., . . . .28 

43-46. Chsetopleura peruviana Lm. Emerton del., . . 28 

47. Chsetopleura hennahi Gray. Conch. Icon., . . .29 

48, 49. Chsetopleura hennahi Gray. Ross del., . . .29 

50. Chsetopleura parallela Cpr. Ross del., . . . .34 

51. Chsetopleura columbiensis Sowb. Conch. Illust., . . 34 

52. Chsetopleura columbiensis Sowb. Conch. Icon., . . 34 

53. 54. Chsetopleura lurida Sowb. Conch. Icon., . . .33 
55, 56. Chsetopleura scabriculus Sowb. (=lurida). Conch. 

111., 33, 34 

PLATE 13. 

57, 58. Chsetopleura isabellei Orb. Voy. Amer. Merid., . 35 

59. Chsetopleura janeirensis Gray. Conch. 111., . . .37 

60. Chsetopleura janeirensis Gray. Pilsbry del., . . .37 
61,62. Chiton segmentatus Rv. Conch. Icon.(=Chsetopleura 

janeirensis), 37 

63, 64. Chsetopleura spinulosa Gray. Conch. Icon., . . 38 
65, 66. Chsetopleura dieffenbachi Rve. Conch. Icon., . . 35 
67, 68. Chsetopleura sowerbyana Rve. Conch. Icon., . . 39 
69, 70. Chsetopleura gemmea Cpr. Emerton del., . . 31 
71-74. Chsetopleura gemmea Cpr. Ross del., . . .31 



EXPLANATION OF PLATES. 337 
PLATE 14. 

80. Chsetopleura nobilis Rve. Conch. Icon., . . . 30 

81. Cyanoplax hartwegi Cpr. Original, . . . .45 

82. 83. Cyanoplax hartwegi Cpr. Emerton del., . . .45 
84, 85. Cyanoplax hartwegi Cpr. Ross del., . . .45 
86-89. Ischnochiton acrior Cpr. Ross del., . . .61 

.90. Cyanoplax bipunctatus Sowb. Conch. 111., . . .46 

PLATE 15. 

91, 93. Ischnochiton conspicuns Cpr. Ross del., . . .63 

92, 96. Ischnochiton conspicuus Cpr. Piisbry del., . . 63 
94, 95. Ischnochiton conspicuus Cpr. Emerton del., . . 63 

97. Ischnochiton conspicuus var. solidtis Cpr. Emerton del., 64 

98, 100. Ischnochiton magdalenensis Hds. Ross del., . . 62 

PLATE 16. 

1, 2. Ischnochiton alatus Sowb. Emerton del., . . .60 

3, 4. Ischnochiton alatus Sowb. Piisbry del., . . .60 

5. Ischnochiton alatus Sowb. Ross del., . . .60 

6-8. Ischnochiton juloides Ad. P. Z. S., . . . . 55 

9, 10. Ischnochiton limaciformis Sowb. Ross del., . . 57 

11, 12. Chiton productus Rv. (=1. limaciformis). Conch. 

Icon 57 

13, 14. Chiton sanguineus Rv. (=1. limaciformis). Conch. 

Icon., .......... 57 

15, 16. Ischnochiton limaciformis Sow. Conch. Icon., . . 57 

17, 18. Ischnochiton fallax Cpr. Emerton del., . . .59 

PLATE 17. 

19, 20. Ischnochiton floridanus Pils. Ross del., . . .58 

21, 22. Ischnochiton floridanus Pils. Piisbry del., . . 58 

23, 23. Ischnochiton purpurascens Ad. Ross del., . . 58 

24. Ischnochiton purpurascens Ad. Emerton del., . . 58 
25 26. Ischnochiton pectinatus Sowb. Ross del., . . .64 
27, 28. Ischnochiton pectinatus Sowb. Emerton del., . . 64 

29. Ischnochiton pectinatus Sowb. Piisbry del., . . 64 

30. Chiton acutiliratus Rv. (=1. pectinatus Sowb.). Conch. 

Icon., 64, 65 

32, 33. Ischnochiton viridulus Couth. U. S. Exped., . . 141 

39. Chaitopleura hennahi Gray. Piisbry del., . 29 

PLATE 18. 

35-39. Ischnochiton tridentatus Piisbry. Piisbry del., . 140 

40. Ischnochiton trifidus Cpr. Cpr. del. (see appendix), . 141 
41-46. Ischnochiton regularis Cpr. Emerton del., . .142 

22 



338 EXPLANATION OF PLATES. 

47,48. Ischnochiton dispar Sowb. Conch. Icon., . . . Ill 

49, 50. Ischnochiton inquinatus Rve. Conch. Icon., . . 90 

51-55. Ischuochiton adamsii Cpr. Pilsbry del., . . .I'll 

56, 57, 59. Ischnochiton australis Sow. Pilsbry del., . . 144 
58. Ischnochiton australis Sow. Conch. Icon., . . . 144 

PLATE 19. 

60, 61. Ischnochiton tigrinus Krauss. Sudafrik. Moll., . 143 
62, 63. Ischnochiton tigrinus var. unicolor Pils. Pilsbry 

del., 143, 144 

64-66. Ischnochiton hakodadensis Cpr. Pilsbry del., . 147 

67. Ischnochiton novsehollandist Gray. Pilsbry del., . .145 

68. Ischnochiton novsehollandise Gray. Ross del., . .145 

69. Ischnochitou novsedollaudise Gray. Conch. Icon., . . 145 
70-74. Ischnochiton albrechti Schrenck. Amurl. Moll., . 147 

PLATE 20. 

1-4. Ischnochiton rissoi Payr. Bull. S. Mai. Ital., . .102 
5-7. Ischnochiton rissoi Payr. (young). Bull. S. Mai. Ital., 102 

8-10. Ischnochiton rissoi var. meneghinii. Journ. Conch., . 103 

11. Ischnochiton yerburyi Smith. P. Z. S., . . . . 101 

12, 3, 14, 15. Ischnochiton oniscus Kr. Siidaf. Moll., . 100 
16, 17. Ischnochiton reticulatus Rv. Conch. Icon., . . 101 
18, 19. Ischnochiton pertusus Rv. Conch. Icon., . . . 103 
20. Ischnochiton striolatus Gray. Conch. Icon., . . . 105 
21-24. Ischnochiton striolatus Gray. Ross del., . . .105 
25, 26. Ischnochiton caribseorum (Cpr.) Smith (=1. striola- 
tus). J. Linn. Soc., . . ... . . . 107 

PLATE 21. 

27, 28. Ischnochiton pruinosus Gld. U. S. Expl. Exped., . 109 

29-34. Ischnochiton imitator Smith. P. Z. S., 116 

35, 38. Ischnochiton punctulatissimus Sowb. Conch. 111., . 115 

36, 37. Ischnochiton punctulatissimus Sowb. Pilsbry del., .115 

39. Ischnochiton interstinctus Gld. Pilsbry del., . . 119 

40, 41. Ischnochiton papillosus Ad. Ross del., . . . 114 
42-46. Callistochiton shuttleworthianus Pils. Pilsbry del., . 273 
47, 48. Ischnochiton catenulatus Sowb. Conch. Illust, . 110 

49. Ischnochiton roseus Sowb. Conch. Icon., . . .113 

50. Ischnochiton roseus Sowb. Conch. Illustr., . . .113 

51. 52. Ischnochiton colubrifer Rve. Conch. Icon., . . 95 
53. Ischnochiton rugulatus Sowb. Beech ey's Voy., . .110 
54-56. Ischnochiton rugulatus Sowb. Conch 111., . .110 

57. Ischnochiton rugulatus Sowb. Conch. Icon., . . .110 



EXPLANATION OF PLATES. 339 
PLATE 22. 

58. Ischnochiton longicymba Q. & G. Ross del., . . 87 

59. Ischnochiton longicymba Q. & G. Astrol., . . .87 
60-66. Ischnochiton longicymba Q. & G. Pilsbry del., . 87 

67, 72, 73. Ischnochiton haddoni Pils. Pilsbry del., . .88 

68, 70, 71. C. longicymba Sow. (=1. haddoni Pils.). Conch. 

111., . 88 

69, C. longicymba Rve. (=1. haddoni Pils.). Conch. Icon., . 88 

74. Ischnochiton divergens Rve. Pilsbry del., . . .90 

75, 76. Ischnochiton divergens Rve. Ross del., . . .90 

77. Ischnochiton divergens Rve. Conch. Icon., . . .90 

PLATE 23. 

78. 80. Ischnochiton fruticosus Gld. U. S. Ex. Exped., . 91 

79. Ischnochiton fruticosus Gld. Pilsbry del., . . .91 
81, 82. Ischnochiton contractus Rve. Conch. Icon., . . 93 
83, 84. Ischnochiton decussatus Rve. (= contractus). Conch. 

Icon., . . 93, 94 

85. Ischnochiton exiguus Sowb. Conch. Illustr., . . .98 

86. Ischnochiton exiguus Sowb. Conch. Icon., . . .98 

87. 88. Ischnochiton castus (=contractus). Conch. Icon., 93, 94 
89, 90. Ischnochiton sculptus Sowb. Conch. Illustr. . . 92 
91.. Ischnochiton pallidus Rve. Conch. Icon., . . .89 
92, 93. Ischnochiton petaloides Gld. U. S. Exped., . . 118 
94, 95. Ischnochiton carinulatus Rv. Conch. Icon., . . 96 
96, 97. Ischnochiton pallidulus Rv. Conch. Icon., . . 95 

PLATE 24. 

98, 99. Ischnochiton crispus Rve. Conch. Icon., . . .89 

100, 1-4. Ischnochiton ustulatus Rve. Emerton del., . . 96 

5. Chiton granulosus Frembly. Zool. Journ., . Appendix. 

6. Liolophura curtisiana Smith. 'Alert' Zool., . . . 242 

7. 8. Ischnochiton adeiaidensis Rve. Conch. Icon., . .136 
9, 10. Ischnochiton muscarius Rve. Conch. Icon., . .132 

11, 12. Ischnochiton ustulatus Rve. Conch. Icon., . . 96 

J-15. Ischnochiton tessellatus Q. & G. Astrol., . . 138 

16, 17. Ischnochiton arbutum Rve. Conch. Icon., . . 139 

18, 19. Ischnochiton milleri Gray. Conch. Icon., . . . 137 
20-22. Ischnochiton cariosus Cpr. var. subcariosus Pils. 

Pilsbry del, 65, 67 

23. Ischnochiton cariosus Cpr. typical. Emerton del., . . 65 

PLATE 25. 

1-10. Ischnochiton dalli Haddon. Chall. Rep 133 

11-19. Ischnochiton dorsuosus Haddon.^Chall. Rep., . .135 



340 EXPLANATION OF PLATES. 

PLATE 26. 

20, 21. Ischnochiton mertensii Midd. Ross del., . . . 125 

22, 24-26. Ischnochiton mertensii Midd. Pilsbry del., . 125 

23. Ischnochiton mertensii Midd. Emerton, . . . 125 
27. Ischnochiton cooperi Cpr. Ross del., .... 127 
28-30. Ischnochiton cooperi Cpr. Pilsbry del., . . . 127 
31-33. Ischnochiton clathratus Rve. Pilsbry del., . . 128 
34. Ischnochiton clathratus Rve. Emerton del., . . . 128 

PLATE 27. 

* 

35-39. Ischnochiton lindholmi Schr. Amurl. Moll., . . 85 
40-43. Ischnochiton cyaneopunctatus Kr. (=lentiginosus 

Sowb.) Siidaf.Moll., 135 

44. Ischnochitou lentiginosus Sowb. Conch. 111., . . . 135 

45, 46. Ischnochiton versicolor Sowb. Conch. Illustr., Appendix. 
47, 48. Ischnochiton pulcherrimus Sowb. Conch. Icon., . 130 

49. Ischnochiton constant! Velain. Arch. Z. Exper., Appendix. 

50. Ischnochiton coreanicus A. & R. Conch. Icon., . . 129 

51. Ischnochiton bergoti Velain. Arch. Z. Expe*r., Appendix. 
52-54. Ischnochiton inca Orb. Voy. Amer. Merid., Appendix. 

PLATE 28. 

1-4. Chiton sulcatus Wood. Ross, del., .... 191 
5-8. Chiton goodalli Brod. Ross, del., . . . .191 

PLATE 29. 

9. Chiton goodalli Brod. Conch. Icon., .... 191 

10. Chiton barnesi Sowb. Conch Icon., .... 190 

11, 12. Chiton barnesi Sowb. Pilsbry del., , . . .190 
13, 14. Chiton (?) dimorphus Rochebr. Miss. Cap Horn. 

(See appendix). 
15-21. Chiton murrayi Haddon (?=C. pusio Sowb., p. 133). 

Chall. Rep., 161 

PLATE 30. 

23. Chiton magnificus Desh. Ross del., . . . .160 

24. Chiton magnificus Desh. Emerton del., .... 160 

25. Chiton stokesii Desh. Conch. Icon., .... 165 

26. Chiton stokesii Desh. Original, 165 

27. Chiton granosus Fremb. Pilsbry del., . . . .167 

28. Chiton granosus Fremb. Zool. Journ., .... 167 
29,31. Chiton cumingi Fremb. Conch. Icon., . . . 164 
30. Chiton cumingi Fremb. Ross del., .... 164 



EXPLANATION OF PLATES. 341 

PLATE 31. 

32-34. Chiton rusticus Desh. Moll. Re*un., . . . .186 
35, 36. Chiton lyratus Sowb. Conch. Icon., . . . .184 
37, 38. Chiton angusticostatus Q. Voy. Astrol., . . . 187 
39, 40. Chiton mauritianus Voy. Voy. Astrol., . . .188 
41, 42. Chiton capensis Gray ( nigrovirens Blv.). Conch. 

Icon., 187 

43. Chiton cymbiola Sowb. (tulipa Q.). Conch. Icon., . 185 

44, 45, 47. Chiton tulipa Quoy. Ross del, . . . .185 

46. Chiton tulipa Quoy. Voy. Astrol., 185 

48, 49. Chiton cymbiola Sowb. (^tulipa Q.) ... 185 

PLATE 32. 

50. Chiton patulus Brod. (=stokesii Brod,). Conch. Icon., 165 
51-52. Chiton stokesii Brod. Pilsbry del., . . . .165 

53. Chiton stokesii Brod. (1 sq. mm. of girdle indicated), 

Pilsbry del., 165 

54. Chiton virgulatus Sowb. Conch. Icon., .... 166 

55. 56. Chiton virgulatus Sowb. Pilsbry del., . . . 166 

57. Chiton albolineatus Sowb. Conch. Illustr., . . . 160 

PLATE 33. 

58, 59, 60. Chiton tuberculatus L. Ross del., . . .153 

61. Chiton tuberculatus var. assimilis Rv. Conch. Icon., . 155 

62. Chiton tuberculatus var. assimilis Rv. Ross del., . . 155 

63. Chiton tuberculatus var. assimilis form ater. Ross del., 155 

64. Chiton foveolatus Sowb.) (viridis Spengl.). Conch. 

Icon., ... 156 

65. Chiton viridis Spengl. Ross del., ..... 156 
66 67. Chiton viridis Spengl. Pilsbry del., .... 156 

PLATE 34. 

68. Chiton Isevigatus var. articulatus Sowb., ventral view. 

Emerton del., . .159 

69. Chiton Isevigatus var. articulatus Sowb. Conch. Icon., . 159 

70. Chiton Isevigatus var. articulatus Sowb. interior. Pilsbry 

del., 159 

71. Chiton Isevigatus Sowb., typical. onch. Icon., . . 159 

72. 74. Chiton marmoratus Gmel. Ross del., . . . 158 

73. Chiton marmoratus Gmel. Conch. Illustr., . . . 158 

75. Chiton marmoratus Gmel., interior. Pilsbry del., . .158 

76. Chiton marmoratus Gmel. Conch. Icon., . . . 158 
77-79. Chiton canariensis Orb. Moll. Canar., . . .184 

PLATE 35. 

80. Chiton marmoreus Rv. (squamosus L.). Conch. Icon., 155 

81. Chiton squamosus L., one-half valve. Pilsbry del., .155 



342 EXPLANATION OF PLATES. 

82. Chiton squamosus L. Ross del., . . . . .155 

83, 84. Chiton insularis Rochebr. Nouv. Arch., . . .183 
85, 86. Chiton hamyi Rochebr. Nouv. Arch., . . .183 
87, 88, 90. Chiton olivaceus Speng. Pilsbry del., . . 180 
89, 91, 92. Chiton olivaceus Speng. Ross del., . . .180 
93. Chiton affinis Issel. Savigny, . . . . .181 

PLATE 36. 

91. Chiton jugosus Gould. U. S. Exped., . . .. .178 

92. 94, 95. Chiton jugosus Gould. Pilsbry del., . . .178 

93. Chiton jugosus Gould. Ross del, . . .. ... 178 

96,97. Chiton rcreus Rve. Conch. Icon., . . . .179 

98, 99. Chiton marquesanus Pils. Pilsbry del., . . .170 

100. Chiton marquesanus Pils. Ross del., . ... . 170 

1. Chiton sinclairi Gray. Erebus & Terror, . . . 174 

2, 3. Chiton sinclairi Gray. Pilsbry del., . . . .174 

4. 6. Chiton canaliculatus Q. Pilsbry del., . .177 

5. Chiton insculptus Ad. (==canaliculatus Q'.). P. Z. S., . 177 

PLATE 37. 

6. Chiton quoyi Desh. (color var.). Ross del., . . .172 

7. Chiton quoyi Desh. (sculpture) Pilsbry del., . . . 172 

8. Chiton quoyi Desh. Conch. Icon., . * . . . . 172 

9. 10. Chiton caliginosus Rve. Conch. Icon., . Appendix. 

11. Chiton dissimilis Rve. Conch. Icon., .... 184 

12, 13. Chiton muricatus Ad. P. Z. S., .... 175 
14,15. Chiton pellisserpentis Q. Ross del., . . .173 

16. Chiton pellisserpentis Q. Astrol., . . .173 

17. Chiton pellisserpentis Q. (1 sq. mill, of the girdle indicated). 

Pilsbry del., . . . ... . . . 173 

18. Chiton pellisserpentis Q. Emertou del., . . . .173 

PLATE 38. 

19. Chiton subfuscus Sowb. typical. Conch. Icon., . 162, 163 

20. Chiton subfuscus var. mesoglyptus Pils. Conch. 111., .164 

22. Chiton subfuscus var. mesoglyptus Pils. Ross del., . 164 

21. Chiton subfuscus var. mesoglyptus, valve of same specimen 

as fig. 22. Pilsbry del., 164 

23. Chiton boweuii King. Conch. Illustr., . ... 164 
24-26. Ischnochiton sulcatus Q. & G. Voy. Astrol., . . 138 
27, 28. Chiton tenuistriatus Sowb. Conch. 111., . . . 188 
29, 30. Chiton cingillatus Rve. Conch. Icon., . Appendix. 
31, 32. Chiton luzonicus Rve. Conch. Icon., . Appendix. 
33, 34. Chiton aquatilis Rve. Conch. Icon., . . .169 

PLATE 39. 
35. Tonicia disjuncta Fremb. Conch. Icon., . . .212 



EXPLANATION OF PLATES. 343 

36-41. Tonicia disjuncta Fremb. Emerton del., . . . 212 
42-51. Craspedochiton laqueatus Shutt. Emerton del., . 285 
52. Ischnochiton rugulatus Sowb var. Conch. Icon., . . 110 

PLATE 40. 

1,2. Tonicia truncata Sowb. Conch. Icon., . . . 211 

3, 4. Tonicia fortilirata Sowb. Conch. Icon., . . . 207 

5, 6. Tonicia picta Sowb. Conch. Icon., . . . .211 

7. Tonicia carpenteri Angas. P. Z. S., . . . . 208 

8-11. Tonicia lamellosa Q. & G. Voy. Astrol., . . .209 

12. Tonicia zschaui Pffr. Moll. S. Georg., .... 204 

13-15. Tonicia tehuelchus Orb. Voy. Amer. Merid, . . 205 

16, 17. Tonicia suezensis Rve. Conch. Icon., . . . 206 

PLATE 41. 

19. Tonicia chilensis Fremb. Pilsbry del., . . . .197 

20. Tonicia chilensis Fremb. Conch. Icon., . . . .197 

21. Tonicia fastigiata Sowb. Pilsbry del., . . . .199 

22. Tonicia elegans Fremb. Pilsbry del., .... 196 
Betw. 22 and 24. Tonicia elegans Fremb. (color-pattern only). 

Pilsbry del., 1$6 

24. Tonicia elegans Fremb. (second valve). Pilsbry del., . 196 

25. Tonicia lineolata Fremb. Conch. Icon., . . . .198 

26. Tonicia lineolata Fremb. Zool. Journ., .... 198 

27. Tonicia lineolata (var. connecting with elegans). Ross 

del., . . .198 

28. Tonicia atrata Sowb. Conch. 111., . . . .201 

29. 30. Tonicia atrata Sowb. Conch., Icon., . . .201 

PLATE 42. 

31. Tonicia elegans Fremb. Ross del., . . . .196 

32. Tonicia elegans Fremb. var. Conch. Icon., . . . 196 

33. 34, 35. Tonicia elegans Fremb. (not typical). Emerton, 

del, . .196 

36-39. Tonicia fastigiata Gray. Conch. Icon, . . . 199 

40. Tonicia chikensis (^fastigiata). Conch. Icon., . . 199 

PLATE 43. * 

41. Tonicia swainsoni Sowb. Conch. Icon, .... 201 

42. Tonicia swainsoni Sowb. Pilsbry del., . . . . 201 

43. Tonicia swainsoni Sowb. Ross del, .... 201 

44. 45. Tonicia granifera Sowb. Conch. Icon, . . . 200 
46, 47. Tonicia gravi Sowb. Conch. Icon, .... 200 
48, 49. Tonicia (?) martieli Rochebr. Moll. Cap Horn, . 203 
50, 51. Tonicia horniana Rochebr. Moll. Cap Horn, . . 203 
52, 53. Tonicia lebruni Rochebr. Moll. Cap. Horn, . . 203 



344 



EXPLANATION OF PLATES. 



54, 55. Tonicia schrammi Shuttle w. Pilsbry del., . . 205 

56, Tonicia schrammi Shuttlew. Journ de Conch., . . 205 

PLATE 44. 

57, 60. Chsetopleura watsoni Sowb. Conch. Icon., See appendix. 

58, 59. Chsetopleura watsoni Sowb. Conch. 111., See appendix. 

61. Chsetopleura castanea Q. Voy. Astrol., . See appendix. 

62. Chsetopleura fulva Wood. Ross, del., . . See appendix. 

63. Chsetopleura fulva Wood. Conch. Icon., . See appendix. 

64. Chsetopleura fulva Wood. Pilsbry del., . . See appendix. 

65. 67. Tonicia rubridens Pils. Pilsbry del., . . .202 

66. Tonicia rubridens Pils. Ross del., 202 

68. Craspedochiton laqueatus Sowb. Conch. Icon., . . 285 

PLATE 45. 

69, 70. Tonicia crenulata Sowb. Conch. Icon., . . .195 
71, 72. Tonicia crenulata Sowb. Ross del., .... 195 

73. Chiton rubicundus Costa. Catal., 182 

74,75. Chiton pulchellus Phil. (=rubicundus Costa). Enum., 182 
76, 77. Acanthopleura borbonica Dh. Pilsbry del., . . 230 
78, 79. Acanthopleura borbonica Dh. Moll. Reun., . . 230 
80, 81, 83, 84. Acanthopleura spinosa Brug. (valves i, ii, viii). 

Emerton del., .220 

82, 87. Acanthopleura spinosa Brug. (valve iv). Pilsbry del., 220 

85. Acanthopleura spinosa Brug. Conch. Icon., . . . 220 

86. Acanthopleura spinosa Brug. (girdle spines). Emerton 

del., .220 

PLATE 46. 

88. Eudoxochiton nobilis Gray (type). Erebus & Terror, . 193 

89, 90. Eudoxochiton nobilis Gray (valve vii). Pilsbry del., 193 
91. Eudoxochiton nobilis Gray (interior). Emerton del., . 193 
92-94. Eudoxochiton nobilis Gray (valve viii). Pilsbry del., 193 

95. Eudoxochiton nobilis Gray. Pilsbry del., . . .193 

96, 100. Eudoxochiton huttoni Pils. (valve vii). Pilsbry del., 194 

97. Eudoxochiton huttorii Pils. Ross del., .... 194 

98, 99. Eudoxochiton huttoni Pils. (valve viii). Pilsbry del., 194 
1-5. Chiton miles Cpr. Emerton del., . . . .188 

PLATE 47. 

6-9, 11-14. Acanthopleura echinatum Barnes. Emerton 

del., 218 

10. Acanthopleura echinatum Barnes. Zool. Journ., . . 218 
15-17. Acanthopleura echinatum (young). Emerton del., . 218 
18-20. Acanthopleura brevispinosa Sowb. Emerton del., . 231 
21. Acanthopleura brevispinosa Sowb. Ross del., . . 231 



EXPLANATION OF PLATES. 345 

PLATE 48. 

22. Acanthopleura spiniger Sowb. Charlesworth's Mag. Nat. 

Hist., . . . , . . . . 221 

23. Acanthopleura spiniger Sowb. Conch. Illustr., . . 221 
24-26. Acanthopleura spiniger Sowb. (Interior, and posterior 

valve). Pilsbry del., .221 

27. Acanthopleura spiniger Sowb. Conch. Icon., . . 221 

28. Acanthopleura spiniger var. granata Rv. Pilsbry del., 224, 

[225 

29. 30. Acanthopleura spiniger var. granata Rv. Conch. 

Icon., 224,225 

31. Acanthopleura spiniger var. (Viti Is.) Ross del., . . 223 

32. Acanthopleura spiniger var. (Viti Is.). Pilsbry del., . 223 

PLATE 49. 

33,34. Acanthopleura spiniger var. cunninghami Rve. Conch. 

Icon., 225 

35, 36. Chiton linter (Chemn.) Rve. Conch. Icon., (See 

appendix.) 
37, 38. Chiton piceus Rv. not Linn. (=A. spiniger var. obesa 

Shuttl.) 226 

PLATE 50. 

39. Acanthopleura granulata Gmel. (St. Thomas). Ross del., 227 

40, 41. Acanthopleura granulata Gmel. (group of white and 

of dark spines). Pilsbry del., . . 227 

42. Acanthopleura granulata Gmel. (occidentalis Reeve). 

Conch. Icon., 227 

43. Acanthopleura granulata (Key Vaccas, Fla.). Ross del., 227 
44-47. Acanthopleura granulata Gmel. (St. Domingo). 

Pilsbry del., 227 

48. Acanthopleura granulata Gmel. (St. Thomas). Ross del., 227 

49. Acanthopleura granulata Gmel. Emerton del., . . 227 

PLATE 51. 

1. Schizochiton incisus Sowb. 235 

2. Schizochiton incisus Sowb. (half of head valve). Q. J. 

M. S., 235 

3. Schizochiton incisus Sowb. (eye, x 200). Q. J. M. S., . 235 
4-5. Schizochiton incisus Sowb. (valves i and ii). Emerton 

del., . . . 235 

6-8. Schizochiton incisus Sowb. (valve viii, ventral, profile 

and posterior views). Emerton del., .... 235 
9-12. Lorica angasi Ad. & Ang. Emerton del., . . . 238 



346 EXPLANATION OF PLATES. 

PLATE 52. 

14. Lorica cimolea Rv. (=volvox Rve.). Conch. Icon., . 237 
15. Lorica volvox Rve. Ross del., ..... 237 

16. Lorica volvox Rv. (1 sq. mill, of girdle). Pilsbry del., . 237 

17, 18. Lorica volvox Rv. (posterior valve). Pilsbry del., . 237 

19, Lorica volvox Rv. (anterior valve). Pilsbry del., . . 237 

20, 21. Lorica volvox Rv. (intermediate valve). Pilsbry del., 237 

22, 23. Enoploctiton niger Barnes (posterior valve). Emer- 

ton del., 252 

24, 25. Enoplochiton niger Barnes (intermediate valve). 

Pilsbry del., . 252 

26. Enoplochiton niger Barnes. Ross del., .... 252 

27. Enoplochiton niger (surface). Q. J. M. S., . 252 

28. Enoplochiton niger (surface). Q. J. M. S., . . 252 

29. Enoplochiton niger (girdle of a young specimen). Emer- 

ton del., . . . . ... 252 

PLATE 53. 

30. Liolophura incana Old. ( L. gaimardi Blv.). IT. S. Expl. 

Exped., . 240 

31. Liolophura gaimardi Blv. (girdle spines). Pilsbry del., . 240 

32. Liolophura gaimardi Blv. Ross del., .... 240 
33-35. Liolophura gaimardi Blv. Pilsbry del., . . .240 
36-40. Liolophura georgiana Q. & G. Voy. Astrol., . . 241 

41. Liolophura japonica Lisch. (Girdle spines). Pilsbry del., 242 

42. Liolophura japonica Lisch. Ross del., . . . 242 

43. 44. Liolophura japonica Lisch. Jap. Meeres-Conch., .242 

45. Liolophura japonica var. tessellata Pils. Ross del., 

46. Liolophura japonica var. tessellata Pils. Pilsbry del., .243 

PLATE 54. 

21, 22. Nuttallina scabra Rv. Pilsbry del., . . . .280 

23, 24. Nuttallina californica Nutt. Pilsbry del., . . 279 
25-27. Nuttallina alternata Sowb. Conch. 111., . . .281 
28-30. Nuttallina cinerea Poll. Emerton del., . . . 283 

31. Nuttallina cinerea Poli (edge of girdle x 100). Pilsbry 

del., 283 

32. Nuttalliua cinerea Poli. Test. Utr. Sic., . . . .283 

33. Nuttallina cinerea Poli (girdle x 50 ca.) Pilsbry del., . 283 

34. 35. Plaxiphora ovata Hutt. Pilsbry del., . ' . . 332 
36-39. Plaxiphora ovata Hutt. (profile, posterior, dorsal and 

ventral views of posterior valve). Pilsbry del., . . 332 
40. Plaxiphora ovata Hutt. (sculpture of intermediate valves). 

Pilsbry del., 332 

41-45. O. caliginosus Cpr. (=Liolophura japonica Lisch.) 

Emerton del., . 244 

46. Onithochiton amicorum Bd. Voy. Curacoa, . . . 249 



EXPLANATION OF PLATES. 347 

PLATE 55. 

1. Onithochiton lyellii Sowb. Conch. Illustr., . . . 247 

2. Onithochiton lyellii Sowb. Conch. Icon., . . . 247 
3-7. Onithochiton lyellii Sowb. Emerton del., . . . 247 
8, 9. Onithochiton incii Kv. (=lyellii Sowb.). Conch. Icon., 248 

10, 11. Onithochiton semisculptus Pils. Ross del., . .247 

12, 13. Onithochiton quercinus Old. U. S. Exped., . . 248 

14, 15. Onithochiton undulatus Q. & G. Ross del., . . 245 

16. Onithochiton undulatus Q. & G. Voy. Astrol., . . 245 

17, 18. Plaxiphora wahlbergi Kr. Siidaf. Moll., . . .322 

19. Onithochiton rugulosus Ang. P. Z. S., . . . . 249 

20. Onithochiton maillardi Desh. Moll. Reun., . . .250 
21-23. Onithochiton literatus Kr. Siidafrik. Moll., . . 251 

PLATE 56. 

1, 4, 6. Pallochiton lanuginosus Cpr. Ross del., . . 257 

2, 3. Pallochiton lanuginosus Cpr. Pilsbry del., . . 257 
5, 7-11. Pallochiton lanuginosus Cpr. Emerton del., . . 257 

12-16. Nuttallina californica Nutt. Emerton del., . . 279 
17, 18. Nuttallina californica Nutt. Ross del., . . .279 
19, 20. Nuttallina scabra Rve. Ross del., . . . .280 

PLATE 57. 

21. Dinoplax gigas Gmel. Conch. Icon., .... 255 

22. 27-31. Dinoplax gigas Gmel. Emerton del:, . . . 255 
23-26. Dinoplax gigas Gmel. (young). Siidafrik. Moll., . 255 

32. Dinoplax gigas Gmel. (young). Ross del., . . . 255 

33. 35. Tonicia confossa Gld. Pilsbry del., . . . .210 

34. Tonicia confossa Gld. U. S. Expl. Exped., . . . 210 

PLATE 58. 

1, 2. Callistochiton crassicostatus Pils. Emerton del., . .264 
3-6. Callistochiton crassicostatus Pils. Pilsbry del., . . 264 
Fig. below 1, and 7, 8. Callistochiton palmulatus Cpr. Emerton 

del., 262 

9-11. Callistochiton palmulatus var. mirabilis Pils. Pilsbry 

del., 263 

12. Callistochiton palmulatus (typical). Pilsbry del., . . 262 
13-16. Callistochiton palmulatus (typical). Emerton del., . 262 
17. Callistochiton decoratus Cpr. Ross del., . . . 269 

18-20. Callistochiton decoratus Cpr. Pilsbry del., . . 269 
21, 22. Plaxiphora c^elata Rve. Conch. Icon., . . .328 

PLATE 59 

21-26. Callistochiton pulchrior Cpr. (=pulchellus Gray). 

Foord del., 272 



348 EXPLANATION OF PLATES. 

27, 28. Cailistochiton elenensis Sowb. Conch. Ill, . .267 

29, 34. Cailistochiton antiquus Rv. Pilsbry del., . . . 274 

30-32. Cailistochiton antiquus Rv. Emerton del., . . 274 

35. Cailistochiton antiquus Rv. Conch. Icon., . . . 274 

36. Cailistochiton coppingeri Sm. ' Alert ' Zool., . . . 275 
37-42. Cailistochiton infortunatus Pils. Foord, del., . . 266 
43, 44. Cailistochiton bicostatus Orb. (=pulchellus Gray). 

Voy. Am. Mer., 272 

45. Cailistochiton adenensis Smith. P. Z. S., ... 276 

PLATE 60. 

1. Cailistochiton pulchellus Gray. Spicil. Zool., . . . 271 

2. Cailistochiton pulchellus Gray. Conch. Icon., . .271 
3-6. Cailistochiton pulchellus Gray. Pilsbry del., . . 271 

7-10. Cailistochiton gabbi Pils. Pilsbry del., . . .270 
11-15. Cailistochiton (?) heterodon Pils., .... 276 
16. Cailistochiton (?) heterodon var. savignyi Pils. Savig. 

^Egypt, 277 

PLATE 61. 

17-22. Callistoplax retusus Sowb. Emerton del., . . 288 

23, 24. Calliscoplax retusus Sowb. Emerton del., . . .288 

25. Callistoplax retusus Sowb. Conch. Illustr., . . 288 

26. Callistoplax retusus Sowb. Conch. Icon., . . . 288 
27-32. Angasia tetrica Cpr. Emerton del., .... 287 

33. Ceratozona rugosa Sowb. Conch. 111., .... 290 

34. Ceratozona rugosa Sowb. (Santa Cruz). Pilsbry del., . 290 

35. Ceratozona rugosa Sowb. Pilsbry del.,. .... 290 

36. Ceratozona rugosa Sowb. (Jupiter Inlet). Pilsbry del, . 290 

37. Ceratozona guildingii Rv. (=rugosa Sowb.) Conch. 

Icon., 290 

38. 39. Ceratozona setosa Sowb. Emerton del., . . .292 
40. Ceratozona setosa Sowb. Conch. 111., . , . 292 
41-45. Ceratozoua rugosa Sowb. Emerton del., . . . 290 

PLATE 62. 

84, 85. Placiphorella stimpsoni Gld. (tail valve). Pilsbry del., 307 

86. Placiphorella stimpsoni Gld. (girdle-hair). Carpenter del., 307 

87. Placiphorella stimpsoni Gld. Ross del., . . . 307 
88-92. Mopalia middendorffii Schr. Amurl. Moll., 

93. Mopalia muscosa var. porifera Pils. Pilsbry del., . . 297 

94. Mopalia muscosa var. porifera Pils. Ross del., . . 297 

95. Mopalia sinuata Cpr. (girdle). Emerton del., . . 303 
96 (upper fig.). Mopalia sinuata Cpr. Ross del., . . 303 
96 (lower three figs.). Mopalia sinuata Cpr. (tail valve). 

Emerton del., 303 



EXPLANATION OF PLATES. 349 

97. Mopalia sinuata Cpr. (intermediate valve). Pilsbrydel., 303 

98. Mopalia imporcata Cpr. (intermediate valve). Pilsbry 

del., .... 301: 

99. Mopalia muscosa var. hindsii Bd. Pilsbry del., . . 296 
100. Mopalia muscosa var. hindsii Bd. Ross del., . . . 296 

PLATE 63. 

46. Mopalia muscosa Gld. (typical). U. S. Expl. Exped., . 295 

47, 48. Mopalia muscosa Gld. Ross del., .... 295 
49-56. Mopalia muscosa Gld. Emerton del., . . . 295 

57. Mopalia muscosa var. hindsii Bd. Conch. Icon., . . 296 

58, 59. Mopalia lignosa Gld. Ross del., . . . .299 

60. Mopalia lignosa smooth form. Ross del., . . . 300 

61. Mopalia lignosa smooth form. Pilsbry del., . . . 300 

62. Mopalia lignosa (vespertina Gld.). U. S. Ex. Exped., . 300 

63. Mopalia insignis Newc. (=liguosa Gld.) 300 

PLATE 64. 

64-68. Mopalia ciliata Sowb. (Monterey Bay). Ross & 

Pilsbry del., 303 

69,70,71. Mopalia ciliata var. wosnessenkii Midd. Mai. Ross. 305 

72. Mopalia ciliata var. wosnessenskii Midd. Pilsbry del., . 305 

73. Mopalia ciliata var. wosnessenskii Midd. Ross del., . 305 
, 74. Mopalia muscosa Gld. Emerton del., .... 295 

75. Mopalia acuta Cpr. Ross del., 297 

76-79. Mopalia acuta Cpr. (tail valves). Pilsbry del., . . 297 
80, 81. Mopalia plumosa Cpr. (=acuta Cpr.). Foord del, . 298 
82, 83. Mopalia lignosa form elevata. Ross del., . . . 300 

PLATE 65. 

73-75. Plaxiphora atlantica V. (tail valve). Pilsbry del., . 313 
7H. Plaxiphora setiger King. Conch. Icon., . . .316 

77, 78, 79. Plaxiphora setiger King. Emerton & Ross del., 31 6 
80-82. Plaxiphora egregia Ad. P. Z. S., ... 331 

PLATE 66. 

6, 7. Placiphorella velata Cpr. Emerton del., . . . 306 
8-10. Placiphorella velata Cpr. (posterior valve). Pilsbry 

del., .... ..... 306 

11. Placiphorella velata Cpr. (intermediate valve). Pilsbry 

del., 306 

12. Placiphorella velata (Insertion-plate, seen from end of 

valve). Pilsbry del., 306 

13. Placiphorella velata (girdle-hair). Pilsbry del., . . 306 

14. Placiphorella borealis Pils. (intermed. valve). Pilsbrydel., 309 



350 EXPLANATION OF PLATES. 

15. Placiphorella borealis Pils. (Insertion-plate seen from end 

of valve). Pilsbry del., . 309 

16,17. Placiphorella borealis Pils. (posterior valve). Pilsbry 

del, 309 

18-24. Placophoropsis atlantica V. Tr. Conn. Acad., . .313 

25. Placiphorella petasus Rv. Conch. Icon., . . .311 

26, 27. Placiphorella blainvillii Sowb. Conch. Icon., . . 310 
28-32. Placiphorella blainvillii Sowb. Emerton del., . . 310 

PLATE 67. 

33-36. Plaxiphora carpenteri Had. Chall. Rep., . . 325 

37, 38. Chsetopleura hahni Rochebr. (^Plaxiphora fremblyi) 

Miss. Cap Horn, 318 

39, 40. Chsetopleura frigida Rochebr. (=Plaxiphora setiger, 

young). Miss. Cap Horn, ..... 317 

41, 42. Chsetopleura savatieri Rochebr. (= Plaxiphora setiger) 

Miss. Cap Horn, 317 

43-46. Plaxiphora simplex Cpr. Chall. Rep., . 320 

PLATE 68. 

51-54. Plaxiphora biramosa Q. & G., Voy. Astrol., . .319 
55-61 . Plaxiphora superba Cpr. (=biramosa Q.). Emerton del. 319 

62, 64. Plaxiphora petholata Sowb. Pilsbry del., . . 323 

63,66. Plaxiphora petholata Sowb. Emerton del., . .323 

65. Plaxiphora petholata Sowb. Ross, del., . . .323 

67. Plaxiphora petholata Sowb. Conch. Illustr., . . .323 

68-72. Plaxiphora glauca Q. & G. Voy. Astrol., . . 326 



NOTE. The Parts of Vol. XIV of the MANUAL were issued to 
subscribers upon the following dates : 

Part 53, including pp. 1- 64, plates 1-15, July 25, 1892, 
Part 54, " " 65-128, " 16-30, Nov. 25, 1892. 
Part 55, " " 129-208, " 31-40, Feb. 25, 1893. 
Part 56, " " 209-350, " 41-68, June, 1893. 

The Title page, Preface and Introduction to Polyplaeophora, 
accompany Part 56. 

END OF VOL. XIV. 



POLYPLACOPHORA. 



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