﻿UNITED STATES. 217 



Remarks. — Three specimens only were received from Mr. Downie, two of which, in 

 alcohol, were males. One of them was quite young, the epidermis of which was 

 yellowish and rayed. This species is nearly allied to Lecontianus (nobis), but it is 

 not so thick a shell, and the epidermis is black and striate, while that shell is smooth, 

 bright brown and rayed. It is perhaps more nearly allied to Downiei in outline, but 

 it is not so thick as that shell, which differs also in having a brown epidermis and the 

 latter is also more inflated than Salillaensis. The three belong to a natural group, 

 the type of which is Lecontianus. 



Unio corvus. PI. 27, fig. 97. 



Testa laevi, subtriangulari, subcompressa, inaequilaterali, postice obtuse biangulata; valvulis crassis, antice 

 crassioribus ; natibus subprominentibus ; epidermide nigricante, superne 1 glabra, polita, inferne striata, ; 

 dentibus cardinalibus subgrandibus, subconicis striatisque ; lateralibus longis curvisque ; niargarita, 

 alba et iridescente. 



Shell smooth, subtriangular, rather compressed, inequilateral, obtusely biangular 

 behind; valves thick, thicker before; beaks somewhat prominent; epidermis black- 

 ish, smooth and polished above, striate below ; cardinal teeth rather large, subcorneal 

 and striate ; lateral teeth long and curved ; nacre white and iridescent. 

 Proc. Acad. Nat. Sci., 1859, p. 112. 



Hah. — Buckhead Creek, Burke County, Georgia, Bishop Elliott, and Ogeechee 

 River, Georgia, Prof. Hanley. 



My cabinet and cabinets of Bishop Elliott and Prof. Hanley. 

 Diam. 1, Length 25, Breadth 2-5 inches. 



Shell smooth, subtriangular, rather compressed, inequilateral, obtusely biangular 

 behind, regularly rounded before; substance of the shell thick, thicker before; beaks 

 somewhat prominent ; ligament short and Very thick ; epidermis blackish inclining 

 to deep brown, smooth and polished above, transversely striate below, with obscure 

 and rather distant marks of growth ; umbonial slope raised into an obtuse angle ; 

 cardinal teeth rather large, subconical and striate; lateral teeth long, rather stout 

 and curved ; anterior cicatrices distinct and well impressed ; posterior cicatrices 

 confluent and well impressed ; dorsal cicatrices placed on the under side of the plate 

 posterior to the cardinal teeth ; cavity of the shell rather shallow and wide ; cavity of 

 the beaks rather shallow and rounded ; nacre white and iridescent. 



Remarks. — Some time since I received a single specimen of this species from 

 Bishop Elliott, about two and one-half inches wide, and more recently a smaller 

 specimen from Professor Hanley, of Oxford, about two inches wide. These are the 

 only individuals I have seen, and they are both very much eroded and imperfect at the 

 beaks, which of course precludes any notice of the form of the tips. There are some 

 small wrinkles on the posterior slope of each of them. In outline this species is 

 between incrassatus (nobis) and Forbesianus (nobis). It is not quite so triangular as 



