On the shells collected by the United States Exploring Expedition, commanded by Charles Wilkes, U.S.N

141

of the jaw, corresponding to the situation of Professor Owen's
sketch of the premolar, Dr. Jackson had made a large and deep
excavation, exposing the fangs of the second tooth, removing
some of the bone from between them, and opening freely into
the dental canal, but without finding any appearance of the
tooth which Professor Owen considers as characteristic of the
Mastodon. Dr. Hays, also, in his paper upon the “ Inferior
Maxillary Bones of Mastodons,” &c., (‘Transactions of the Ame-
rican Philosophical Society, Vol. IV. p. 319,) speaks of having
examined about forty lower jaws, but says nothing of such a
tooth.

Dr. Jackson then alluded, for explanation, to that part of his
former Report upon the Cambridge Collection, (Proceedings of
the Society, October, 1845,) in which he speaks of six as the
true number of the molar teeth in M. giganteum, at least in the
lower jaw, and in which he inferred, from a statement of Pro-
fessor Owen, (Annals of Natural History, Vol. XI. p. 330,)
that he considered five as the number ; the inference was cer-
tainly a fair one. He now finds that in the Odontography,
which he had not seen when his Report was made, Professor
Owen describes seven molars, generally so called, on each side
and in each jaw, but with the saving clause above quoted in
regard to the lower. Dr. Jackson's observation, then, as to the
number of the molar teeth in the lower jaw, corresponds with
that of Professor Owen, except for the * small premolar,” of
the existence of which no proof has yet been given.

Dr. Gould announced that, being employed in the exam-
ination of the Shells collected by the United States Explor-
ing Expedition, commanded by Charles Wilkes, U. S. N.,
he proposed to read before the Society, from time to time,
as they might be prepared, descriptions of the new species,
in anticipation of their future publication, in a more ex-
tended form, and fully illustrated by figures, as one of the
volumes of the great work on the Expedition, issued by
Congress.

He commenced with the following species of the genus
Chiton.

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CHITON LIGNOSUS. ‘Testa solidula, ovata, tectiformis, cæsia,
lineolis fuscis inequalibus subradiantibus marmorata, systemate
duplici punctorum majorum et punctorum minorum impressa;
valvis planulatis, angulatis, sine rostris; areis lateralibus haud
elevatis, vix distinctis; valvá anteriori parva; valva posteriori
vix umbonatá: intus zruginosa. Long. 12, lat. Z poll. Hab.
Puget Sound.

Has the form of C. setiser, and somewhat the coloring of
C. fulvus, Wood. It is also allied to C. tulipa, Quoy.

CHITON QUERCINUS. ‘Testa depressa, ovalis, vix carinata, quer-
cina, maculis olivaceis nubeculata; valvis subrostratis; areis late-
ralibus vix elevatis, longitudinaliter sulcatis, sulcis incumbentibus
et sulco radiante bisectis; areis centralibus ad latera lineis rugosis
longitudinaliter sculptis, ad dorsum punctatis ; valvá anteriori sulcis
concentricis et sulcis radiantibus remotioribus decussatá ; valvá
posteriori prope marginem umbonatá ; margine lato, pruinoso,
flavescente. Long. 4, lat. 2 poll. Hab. New South Wales.

Allied to C. foveolatus, Sowerby.

CuiroN jJucosus. Testa ovalis, carinata, tectiformis, nitida,
coloribus pallidé et saturaté herbeis variegata ; valvis planulatis, ad
apices adunco-acuminatis ; areis lateralibus prominentibus, et lineo-
lis confertis parallelis viridibus longitudinaliter notatis; areis cen-
tralibus sulcis acutis parallelis longitudinaliter aratis, sed ad ver-
ticem simplicibus et minutissimé punctatis ; valvá anteriori con-
centricé lineolatá ; valvá posteriori umbonatá, prope marginem
concentricé lineolatá, przter aream terminalem triangularem
luteolam ; margine granulato, fasciis czeruleis et viridibus limbato :
intus pallidé virescens. Long. 1, lat. 2 poll. Hab. New South
Wales.

Resembles C. Sieulus, which, however, has radiating lines on
the lateral areas.

CHITON FRUTICOSUS. Testa ovalis, valdé elongata, transversim
arcuata, omnino textiliter punctata, olivacea, maculis minutis
saturatioribus fulgurantibus variegata ; valvis haud rostratis ; areis
lateralibus prominentibus, et lineis elevatis interruptis ramosis ra-
diatis; areis centralibus lineis longitudinalibus rugosis, ad latera
profundis, ad dorsum evanidis et arcuatis sculptis ; area posteriori
magna, umbonata, lineis inconspicuis, interdum divaricatis, radi-

143

ata: intus flavo-olivacea : ligamentum latum, pallidum, minutis-
simé granulatum. Long. 13, lat. & poll. Hab. New South
Wales.

Resembles fig. 61 of Sowerby's Conch. Illustr., which is said
to be a variety of C. Indicus, but which has no ramose sculpture
on the lateral areas.

CHITON PLATESSA. ‘Testa parva, tenuis, elongato-ovalis, trans-
versim arcuata, citrino-olivacea, ubique minutissimé punctata ;
areis lateralibus parvis, vix elevatis, lineis 2—3 inconspicuis striatis ;
areis centralibus lineis confertis acutis granulatis arcuatim decus-
satis; valvá posticá magna, obscuré radiatá; margine virente,
fusco tessellato, minutissimé granulato: intus ceruleo-virescens.
Long. 4, lat. 5% poll. Hab. New South Wales.

Similar in its general aspect to C. fruticosus, but smaller,
smoother, and the sculpture of the lateral areas and terminal
valves entirely different. It is almost exactly like fig. 67 of the
** Conchological Illustrations."

CHITON JASPIDEUS. ‘Testa ovata, tenuis, carinata, ubique mi-
nutissimé punctata, coloribus rosaceis plus minusve saturatis
picta ; areis centralibus lineis minutis granosis confertissimé stri-
atis ; areis lateralibus indistinctis, et lineis 3 ad 4 sparse granu-
osis radiatim notatis ; valvis terminalibus granoso-striatis, posticá
excavatá; margine coriaceo, pruinoso. Long. 1, lat. 7 poll.
Hab. Callao.

Resembles, in size, shape, and sculpture, C. apiculatus, Say ;
but the sculpture is more delicate, and the color, resembling
some varieties of jasper, is quite distinctive.

CHITON PuNICEUS, (CovrHovy MS.) Testa parva, oblongo-
elliptica, elevata, ad dorsum carinata, punctatissima, punicea,
gradibus ztatis conspicuis obtusis signata : areis lateralibus præ-
rupté elevatis, et sparsim granulatis; areis centralibus costulis
longitudinalibus parallelis ad 6, plerumque ad medium dislocatis,
clathratis ; valva posteriori rostro parvulo acuto et septo transver-
sali notato: ligamentum minutissimé imbricatum, adversum su-
turas albido fasciatum. Long. 3, lat. 33; poll. Had. Orange
Harbor.

Very much resembles C. ruber, Lowe.

CHITON conFossus. Testa parva, ovata, fastigiata, pallida,

144

roseo et incarnato concinné variegata ; valvis rostratis; areis
lateralibus elevatis, serie posticá squamárum et serie obliquá
squamárum majorum ad apicem spectantium finitis ; intervallo
leevigato, et granulis paucis annulatis sparso ; areis centralibus
plerumque levibus sed punctis sparsis triangularibus retrospec-
tantibus confossis ; valvá posteriori valdé gibbosá, umbone feré
terminali, dentibus insertionis 9, et ad valvam anteriorem 25, pec-
tinatis: margine fusco, carnoso. Long. $,lat. $ poll. Hab. Fee-
jee Islands.

Allied to C. sculptus, Sowb., which has three lateral rays and
the central areas smooth.

CnuiroN PRUINOSUS. ‘Testa parva, oblongo-elliptica, convexo-
elevata, subcarinata, coloribus variis olivaceis, cinereis, et fusco-
rubris irrorata et maculata; areis centralibus sub lente omnino
quincuncialiter punctatis; areis lateralibus longitudinaliter im-
bricato-striatis : intus virescens : margo minutissimé granulatus,
coloribus fuscis et cinereis tessellatus. Long. 7, lat. 3% poll.
Hab. Rio Janeiro.

The sculpture of this very variably-colored species is suffi-
ciently characteristic. — Between the striz are usually found
minute pores, probably produced by some parasite.

CHITON vIRIDULUS, (Cournovy MS.) ‘Testa tenuis, oblongo-
ovata, dilutissimé olivacea, ad dorsum sub-carinata, utrinque sub-
canaliculata, ubique sub lente quincuncialiter insculpta ; areis
centralibus et lateralibus parum distinctis; lineis incrementi prope
marginem conspicuis ; valvis terminalibus leviter radiatis: margo

minutissimé squamatus. Long. 2, lat. 5% poll. Hab. Orange
Harbor.

CHITON PETALOIDES. ‘Testa parva, tenuis, ovalis, arcuatim
elevata, subcarinata, diluté citrina ; areis lateralibus elevatis, ru-
gosé granulatis, et striis radiantibus ad 4 insculptis ; areis centra-
libus longitudinaliter rugosé granulato-punetatis, et lineolis tenu-
issimis angulatis diluté violaceis pictis ; valva posteriori acuté
umbonatá et costa transversali divisá: margo stramineus, minutis-
simé granulato-imbricatus. Long. 3, lat. 2 poll. Hab. Sand-
wich Islands.

A very beautiful and peculiar shell, its markings resembling
the venated petals of some flowers.

145

CHITON DENTIENS. Testa minima, ovata, carinata, olivacea,
ad dorsum albido fulminata, omninò minutissimè granulata ; areis
vix distinctis ; valvis rostratis postice subdenticulatis, dentibus albi-
dis: margo pruinosus. Long. 4, lat. 5% poll. Hab. Puget
Sound.

Resembles C. alternatus, Sowb., which, however, has radiating
ribs upon its lateral areas and terminal valves.

Cuiton INCANUS. Testa solida, oblongo-ovalis, valdé convexa,
cinereo et nigro variegata, concentricé undulato-striata, granulis
sparsis nigris aspersa, ad dorsum subcarinata et longitudinaliter
nigro bifasciata; areis lateralibus vix distinctis : margo aculeis
inequalibus curtis curvatis nigris ct canescentibus indutus. Leng.
l, lat. 2 poll. Hab. New South Wales.

Like C. piceus, Gray, in general appearance, and still more
like C. petholatus, which has a hairy margin.

Cuiton muscosus. ‘Testa ovalis, depressa, scabra, ad dorsum
obtusa, cinereo bifasciata et plumosé striata ; valvis magnis, latera-
liter disjunctis ; areis lateralibus parvis, granulis subquadratis radi-
antibus arcuatim tessellatis ; areis centralibus sulcis acutis confertis
flexuosis subparallelis longitudinaliter aratis ; valvá anticá magná,
semicirculari, decemcostata et granulis subquadratis insculpta ;
valvá posteriori parva, costa transversali inconspicuá subtermi-
nali: margo latus, filis corneis inequalibus muscosis indutus.
Long. 2, lat. 11 poll. Had. Puget Sound.

Allied to C. brevispinosus, but its sculpture and margin are
quite distinct.

Extracts from a letter from Zadock Thompson were read,
announcing the discovery, in the State of Vermont, of Try-
onyx ferox and Cotlus gobio.

Dr. D. H. Storer exhibited a drawing of Gasterosteus
biaculeatus, made from a specimen taken at Nahant.

DONATIONS TO THE MUSEUM.

A jaw of Carcharias obscurus. From Dr. D. H. Storer.

ADDITIONS TO THE LIBRARY.

Thesaurus Conchyliorum. By G. B. Sowerby. Nos. 3 to 6.
8vo. London: 1843 to 1846. Courtis Fund.