436 MOLLUSCA. 
shorter, not continuously straight, and forming an abrupt angle above, 
anteriorly ; the posterior extremity is less acute and more nasute ; the 
cavity of the beaks is also somewhat over-arched. Excepting the 
beaks, it is like A. fluviatilis. 
Figures 546, 546 a, 546 4, three views of the shell. 
Anoponta aNGuLATA (Lea). Genus Unio, IL, pl. 16, it, QL 
Mr. Lea’s figure and description give but a very imperfect idea of 
this very remarkable shell. In the first place it is very much larger 
than the valve seen by Mr. Lea,—an inch and seven-tenths by three and 
a half inches; the umbonal carina is very strongly marked ; anterior to 
this the epidermis is bright leaf-green, smooth, with radiating ranges 
of short wrinkles; posterior to it, the epidermis is dusky, and laid in 
loose, foliaceous, concentric folds. The nacre within the pallial im- 
pression is of an oily lustre, and deep peach-blossom colour blending 
with salmon colour. 
Found in the Sacramento River, California. 
ANODONTA FEMINALIS (Gould). 
T. solidula, transversa, ovato-triangularis, anticé acuminata, margine 
postico in margine dorsali desinente, arcuato ; margine ventrali recto ; 
apice rectangulari ; apicibus inconspicuis, erosis, anticis, dechvitate 
posticali obtusé angulato; epidermide lamelloso, piceo: margarita 
purpurascens ; limbo argenteo ; dente cardinali obsoleto. 
Anodon feminalis, GouLp ; Proceed. Boston Soc. Nat. Hist., 111. 293. 
Noy. 1850. Expedition Shells, 87. 
Sue. rude, rather thin, transversely elongated, triangular-ovate, 
inequilateral, somewhat falcate ; anteriorly narrow, and rapidly widen- 
ing backwards; dorsal margin arched, regularly curving into the 
posterior obliquely-curved margin without an angle, and forming a 
right angle with the ventral margin, which is slightly arcuate con- 
vexly ; anterior extremity rounded; valves thin and rude, rather ven- 
