FRESH WATER AND LAND SHELLS, 15 
inargin; ligament short and thick; epidermis dark-brown or black, roughly striate on the 
margin, but smooth and highly polished on the sides and towards the beaks; marks of 
growth rather indistinct and distant; umbonial slope rounded; cardinal teeth large, ele- 
vated, crenulated, pointed, single in the right and double in the left valve; lateral teeth 
long, rather thick, somewhat curved and separated from the cardinal tooth; anterior cica- 
trices distinct; posterior cicatrices distinct; dorsal cicatrices placed nearly in the centre 
of the cavity of the beaks; cavity of the shell rather deep; cavity of the beaks shallow 
and rounded; nacre usually salmon coloured, sometimes white. 
Remarks.— Many of this species were sent to me by Mr. White. None of the 
beaks are sufficiently perfect to detect the undulations of the tips. The form and size of 
this species approaches closely to U. confertus and U. Geddingsianus, (Nobis.) It may 
be distinguished from them, however, by the remarkable polish of the superior portion of 
the disk and the beaks, and by the rough strie of the other portion of the epidermis. 
‘The adult specimens are all very dark-brown or black. The younger shells are yellowish, 
with numerous dark-green rays over nearly the whole disk. Some of the adult specimens 
are quite straight on the basal margin, and almost falcate. 
Unio Lazarus. Pl. XIV. Fig. 9. 
Testa levi, arcuatd, valdé transversa, compressa, valdé inxquilaterali, posticé subbiangulata ; valvulis per- 
tenuibus ; natibus undulatis, vix prominentibus; epidermide tenebroso-fusca, rugoso-striatad; dentibus cardi- 
nalibus minimis ; lateralibus longis, acicularis, remotis rectisque; margaritd vel alba vel purpurea et valdé 
iridescente. 
Shell smooth, arcuate, very wide, compressed, very inequilateral; subbiangular behind; valves very thin; 
beaks undulated, scarcely prominent; epidermis dark-brown, roughly striate; cardinal teeth very small; 
teeth long, acicular, remote and straight; nacre white or purple and very iridescent. 
Hab. Abbeville District, S.C. J. P. Barratt, M.D. 
My cabinet and cabinet of Dr. Barratt. 
Diam. .4, Length .9, Breadth 2 inches. 
Shell smooth, emarginate at base, very wide, compressed, very inequilateral, behind 
subbiangular, before rounded; posterior slope wide and flattened; substance of the shell 
very thin, thicker before; beaks placed near to the anterior margin, furnished with very 
minute undulations at the tip, scarcely prominent and very small; ligament long and thin; 
epidermis dark-brown, roughly striate, with obscure marks of growth; umbonial slope 
biangular; cardinal teeth very small, crenulate, double in the left and single in the right 
valve; lateral teeth long, separated from the cardinal tooth, acicular, straight and slightly 
turned up at the extreme posterior point; anterior cicatrices distinct; posterior cicatrices 
confluent; dorsal cicatrices small and placed under the plate posterior to the cardinal 
tooth; cavity of the shell very shallow; cavity of the beaks very shallow and rounded; 
nacre white or purple. 
lateral 
Remarks.—This is a small, very thin and fragile species. The young have very much 
the appearance of the young of the clongate variety of U. complanatus, but the adult 
and middle aged are arcuate, and cannot be mistaken for that species. The young are 
