632 UNIO 
Unio ceruscus GouLp, Pr. Bost. Soc. Nat. Hist., I, 1856, p. 15. 
—Simpson, Pr. U. S$. Nat. Mus., XV, 1892, p. 419, pl. 
LX, figs. 1, 7.— Syn., 1900, p. 714. Frierson, Naut., 
XXV 10115 p.zo, pl. Tees el eaase 
Margaron (Umno) coruscus LEA, Syn., 1870, p. 48. 
This is a remarkably variable and puzzling form and inter- 
mediates are abundant leading in the direction of several 
other species. ‘There is a small shell in the Lea collection 
from Dr. Gould with the dimensions given above, which has 
no locality but “Florida” given, which may probably be con- 
sidered typical. It seems to have the characters of maturity 
though it may be a young shell. It is a rather solid, inflated, 
oval, shining shell, the epidermis being clouded tawny, green- 
ish-yellow and green, with a few faint rays, whence its name 
coruscus, no doubt. Nearly all the specimens which I refer to 
this species, are more or less truncated in front and angled at 
the upper anterior part. The shells are usually solid, rather 
inflated and oval in outline, though thinner specimens occur, 
and others, which are narrowed in front. The nacre is purplish 
in all the numerous specimens I have seen, and it is generally 
dull. One or two forms may possibly be worthy of varietal 
names. 
Var. frvanus B. H. Wright. 
Shell not quite so inflated as is usual, subsolid; epidermis 
reddish, orange, red-brown and greenish, often finely raved, 
very brilliant. 
Length 43, height 25, diam. 15 mm. 
Type localitv, Lake Ashby, Volusia County, Florida. 
Unio fryanus B. H. Wricut, Pr. Ac. N. Sei. Phila., 1888, p: 
TIS Ap hehe te 
Unio coruscus var. frvanus SIMPSON, Syn., 1900, p. 714. 
Var. diozensis S. H. Wright. 
Shell subsolid, sometimes almost thin, narrowed at the an- 
terior end and rather high on the dorsal margin at the poste- 
