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4. Description of new species of the genus Cumingia, 
WITH SOME ADDITIONAL GENERIC CHARACTERS. 
By Arthur Adams, R.N., F.L.S. etc. 
(Mollusca, PI. VIII.) 
Cumingia, G. B. Sowerby. 
Testa bivalvis, incequilateralis, cequivalvis, latere antico rotund at o, 
postico hiante subacuminato; dentibus, cardinally in utrdque 
valvd unico, parvo antico, lateralibus in alterd valva ad utrum- 
que latus uno, valido, in alterd nullo ; ligamento interno foveolce 
subcochleariformi affixo; impressionibus muscularibus duabus 
lateralibus distantibus, anticd irregulari oblongdy posticd sub- 
rotundatd ; impressione musculari pallii sinu maximo. 
Shell ovate, inequilateral, equivalve; a shallow spoon-shaped car¬ 
dinal tooth and a single small tooth by its side in each valve, a strong 
lateral tooth on both sides in one valve only ; palleal impression with 
a large sinus, posteriorly gaping. 
All the species of this genus gape more or less posteriorly, are 
more or less lamellose, and the cavity for the cartilage is spoon¬ 
shaped and projects into the cavity of the valves, differing in this re¬ 
spect from Amphidesma or Semele. 
Cumingia similis, A. Adams. C. testd subtrigonali-ovatd de¬ 
cussate striatd, lineis transversis concentricis, lamelld unicd 
prope marginem ventralem antice latiore rotundato supra angu- 
lato postice angustiore subrostratd, ared posticd clausd, lunula 
lanceolato-ovatd, margine ventrali postice coarctatd. 
Hab. in Borea-Occidentali Ora Americae. (Mollusca, PI. VIII. 
tig. 4.) 
Shell triangularly ovate, decussately striated, lines of growth trans¬ 
verse and concentric, rather strongly marked, a single lamella near 
the ventral margin, anterior side the widest, rounded in front and 
angulated above, posterior side narrower, somewhat beaked poste¬ 
riorly, area closed, lunule lanceolately oval, ventral margin posteriorly 
contracted. 
Hab. N.W. coast of America. (Mus. Cuming.) 
Cumingia Clerii, A. Adams. C. testd ovatd compressd subce- 
quilaterali, albd, opacd, sublcevi, nitidd, striis transversis con¬ 
centricis alveolisque irregularibus, latere antico angustiore ro¬ 
tundato, postico latiore, margine ventrali integro arcuato. 
Hab. ad Talcuhano, Chili. (Mollusca, PI. VIII. fig. 3.) 
Shell ovate, compressed, subequilateral, white, opake, rather smooth 
and shining, marked with faint transverse concentric striae, and nu¬ 
merous pits irregularly disposed, anterior side narrower and rounded, 
posterior side wider; ventral margin entire, arcuated. 
Hab. Found at Talcuhano, Chili, by Capt. Clery, French Marine, 
attached to fuci in shallow water. (Mus. Cum.) 
Cumingia antillarum, A. Adams. C. testd ovato-trigonali, 
concentnce lamellosd; lamellis sub distantibus, interstitiis valde 
