. 62 Couthouy's New Species of Mollusca 
also a brown spot occupying the centre, internally, while 
ours is an uniform yellowish white. I have named it 
C. pubéscens from the downy ciliations upon the coste, 
which give it that appearance. Most specimens were 
about half the size here given. 
NucuLA MYALIS. 
Plate HI. fig. 7. 
testå ovata, sub-equilaterali, levi, concentricé zonatà; latere 
stico longiore et latiore, rotundato, antico sub-rostrato ; natibus ap- 
proximatis ; dentibus rectis; epidermide olivaceo-nigricante. 
Long. twenty-two twentieths, lat. seven twentieths 
alt. twelve twentieths of an inch. 
Hab. (whole ?) coast of New England. 
My own Cabinet. 
Cabinet of Bost. Soc. Nat. History. 
* of A. A. Gould, M. D. and D. H. Storer, M. D. 
* of John C. Jay, M. D., N. York. 
Description. ` Shell ovate, nearly equilateral, slightly 
gaping at both extremities, moderately convex, with nu- 
merous ridges of growth; summits antero-dorsal ; pos- 
terior side rather more than half the whole length, pos- 
terior superior margin somewhat depressed, inferior 
rounded ; anteriorly sub-rostrate, not truncated, slightly 
compressed laterally and superiorly, anterior dorsal area 
lanceolate, smooth, shiny, carinated and rectilinear in 
its whole extent from the beaks to the extremity, poste- 
rior dorsal area superficial, elliptical and finely striated ;. 
basal margin regularly curved and entire ; ligamentary fossa 
median, triangular and profound: teeth from 20 to 22, 
posteriorly rectilinear, angulated anteriorly or internally 
