138 
Cyclas transversa. — Transversely oblong subovate, snb- 
i nsequilateral : anterior margin decidedly more widely rounded than 
tlie posterior margin : beak obviously elevated above the general 
curvature : cardinal teetb double, distinct. 
Length, over one-fourth of an inch ; breadth, nine-twentieths of 
an inch. Inhabits Kentucky. 
This shell is more transverse than even the similis, nob. 
Cyclas triangularius. — Transversely oval, subtriangular, sub- 
equilateral : disk with transverse, rather raised lines : beak some- 
what prominent; elevated much beyond the general curvature : 
teeth, viewed in profile, distinct and elevated. 
Length, two-fifths of an inch ; breadth, half an inch. Inhabits 
Mexico. 
The apex of this species is not so acutely elevated as that of 
the calyciilata, Drap., but the shell is more drawn up to an angle 
in that part. 
Anodonta IMPLICATA.—Transversely oblong-oval, subcylin- 
dric, yellowish olive : disk convex, the wrinkles not very promi- 
nent ; umbonial slope hardly presenting a very obtuse angle or 
curve : beak but little elevated, obsoletely undulated : hinge mar- 
gin nearly parallel to the base, diverging a little from it anterior" 
ly, and terminating in a slight, obtuse angle : within deeply con- 
cave. 
Length, one inch and a half ; breadth, three inches and a fifth ; 
convexity, one inch and three-twentieths. Inhabits a pond in 
Danvers, Massachusetts. 
For this species, I am indebted to Dr. Harris, of Milton. It is 
more cylindrically convex than any I have met with. 
As respects the proportions of length and breadth, it resembles, 
A. elongatus, Swains. ; but the umbones are less elevated and not 
placed so far back as in that species. It is also a thinner shell, 
and the dorsal view is altogether different, exhibiting a regular 
curvature. 
Anodonta lugubris.- — Transversely oblong-oval, subovate, 
blackish-brown : disk convex, acutely wrinkled : umbonial slope, 
with a distinct elevation or line: beak, slightly elevated, with 
two or three sinuous undulations : within, white : margin, parti- 
cularly before, livid : hinge margin somewhat parallel to the 
