FRESH WATER AND LAND SHELLS. 273 



in reo-ard to undulations, cannot be ascertained. In genera] outline and characteristics, 

 it is allied to U. luteolus, Lam. It is, however, thinner and lighter in the substance of 

 the shell, and the rays are not so broad. The teeth, too, are smaller, and the lateral are 

 much more removed from the cardinal ones. In the two specimens before me the division 

 of the lateral teeth is remarkably short, not reaching more than half the length of the 

 tooth. 



I dedicate this species to Lovell Reeve, Esq., the able author of "Conchologia 

 Iconica." 



Unio luridus. PI. XX. Fig. 29. 



Testa Uevi, eUipticd, compressd, valde insequilaterali, postiee subbiangvlala ; valvulis subcrassis} nalilms 

 parvis, vix prominulis } epidermide tenebrosobruma, striata, eradiata; dentibus cardinalibus parvis, acumi- 

 nata: lateralibus longis curvisque; margaritd vel cseruled-albd vel salmonis colore tinctd. 



Shell smooth, elliptical, compressed, very inequilateral, subbiangular behind; valves somewhat thick; beaks 

 small, scarcely prominent; epidermis dark-brown, striate, without rays; cardinal teeth small, acuminate; lateral 

 teeth long and curved; nacre bluish-white or salmon-coloured. 



llab. Coosawattee river, Murray county, Georgia, Dr. Boykin. 

 My cabinet. 

 Diam. .G, Length I, Breadth 2 inches. 



Shell smooth, elliptical, compressed, very inequilateral, subbiangular behind; substance 

 of the shell somewhat thick; beaks small, scarcely prominent, placed towards the anterior 

 margin; ligament rather long and thin; epidermis dark-brown, striate, without any appa- 

 rent rays, with rather distant marks of growth; posterior slope rather compressed; um- 

 bonial slope very slightly raised into a scarcely visible angle; cardinal teeth small, acumi- 

 nate, double in the left and single in the right valve; lateral teeth long, curved and 

 enlarged at the posterior end; anterior cicatrices distinct; posterior cicatrices confluent; 

 dorsal cicatrices placed above the centre of the cavity of the beaks; pallcal cicatrices 

 slightly impressed; cavity of the shell very shallow; cavity of the beaks exceedingly shal- 

 low and rounded; nacre bluish-white and salmon coloured. 



Remarks. — Some half dozen of this small, unattractive species I owe to the kindness of 

 my late friend, Dr. Boykin. Two of them are slightly salmon coloured, the others are 

 bluish-white. It is somewhat like V. complanaius ; but, in outline, it is more like occullus, 

 (Nobis,) the beak is more terminal than in either, and the whole appearance of the shell 

 reminds one of U. nrctior, (Nobis,) but it is not so wide a shell. Several of the speci- 

 mens are not so dark a brown as the others, but are inclined to dark-olive. 



Unio Clarkianus. PI. XXI. Fig. 30. 



'/'. in Uevi, rl/i/ii! a, ad umbonis inflatd, inequilaterali, postiee angulatd; valvulis missis; nalibus 



subprominentibus, subrotundis; epidermide rufo-fuscd, nilidd; dentibus cardinalibus subcrassis, acuminatis, 

 granulalis} lateralibus subbrevibus, crassis, arcuatis; margarild eel albd vel salmonis colore tincld et 

 iridescente. 



Shell smooth, elliptical, convex, on the umbones inflated, inequilateral, angular behind; valves thick; beaks 

 rather prominent, subrotund; epidermis reddish-brown, shining; cardinal teeth rather thick, acuminate, granular; 

 lateral leeth rather short, thick and arched; nacre while "r salmon coloured and iridescent. 



