398 MOLLUSCA. 
ting, raised wrinkles, to which a coating of fine sand adheres. Hinge 
too imperfect for description. 
Length three-fourths of an inch; height three-eighths of an inch. 
Inhabits Puget Sound, Oregon. 
It is with some little doubt that I venture to separate this from O. 
hyalina ; but considering its locality, and the fact that the species of 
this genus vary but little, 1 have regarded it as an analogous species. 
Indeed, if the four characters, viz., the gilded nacre, the dusky coloured 
epidermis, and the more numerously wrinkled epidermis, and the 
ventricose pouched form of the posterior basal portion, prove as con- 
stant as in the specimens I have examined, there can be no doubt. 
Figures 509, 509a, exterior and dorsal views of the shell; 509 3, 
the interior. 
OsTEopESMA BRasILIENSE (Couthouy MS.) Gould. 
Testa fragilis, elongato-ovata, anticé ventricosa et truncata, posticé com- 
pressa, concentricé undulata, epidermide fiavicante induta ; umbonibus 
ante-medianis, tumidis, approximatis; margine dorsali feré rectil- 
neart ; margine ventral arcuato: interior margaritacea: ossiculum 
parvum, oblongum. 
Osteodesma Brasiliensis (Couthouy MS.); Proceed. Boston Soc. 
Nat. Hist., 11. 218. May 1850. Expedition Shells, 78. 
SHELL fragile, elongated-oval, widely gaping posteriorly, sub-equi- 
valve, very inequilateral; beaks anterior, protuberant, contiguous ; 
posterior half compressed; anterior half ventricose, its extremity 
abruptly truncated ; lunule depressed, large, cordiform ; dorsal margin 
nearly rectilinear, basal one curving regularly outwards; epidermis 
strong, dirty yellow, projecting some distance beyond the margins. 
Strie of growth coarse and unequal. Interior silvery white; mus- 
cular impressions small, superficial; pallial impression angularly 
sinuated posteriorly. Ossiculum small, oblong, the posterior end 
rounded, the anterior square. [J. P. c.] 
