74 DESCRIPTION OF NEW 



posterior cicatrices confluent; dorsal cicatrices numerous, deep, and placed in the centre 

 of the cavity of the beaks; cavity of the shell rather shallow; cavity of the beaks shallow 

 and angular: nacre white. 



Remarks. — Three specimens of this species have been recently sent to me by Dr. Hale. 

 It belongs to the group of which Mr. Say's camptodon may be considered as the type, and 

 which includes his declivis and tetralasmus — if the latter be a true species, of which I am 

 unable to decide, never having seen a specimen of it. In all the three specimens before 

 me the outline is remarkably regular and uniform, and very closely resembles the declivis, 

 but the angle is less acute. In the three there is no appearance of rays — one of them is 

 inclined to yellow. The margin of the interior surface is rather broad and dark. The 

 two impressed lines, from the beak to the posterior margin which exist in so many species, 

 are rather more marked than usual. A specimen in Dr. Griffith's cabinet, supposed to be 

 Mr. Conrad's U. excultus, approaches very closely to this species, and it may prove, when 

 more perfect individuals are found and compared, to be only a variety. 



Unio unicolor. PI. IV. Fig. 12. 



Testa Isevi, subrolundd, snbcompressd ; vnlvulis crassis; nalibus siibpromincntibus ; epidermide fused; 

 fontibw cardinalibus parvis ; laleralibus longis sabrectisque; margaritd alba et. iridescente. 



Shell smooth, nearly round, rather compressed; valves thick; beaks slightly prominent; epidermis browD; 

 cardinal teeth small; lateral teeth long and nearly straight; nacre white and iridescent. 



Hab. Tuscaloosa, Alabama. B. W. Budd, M. D. 



Cabinet of Dr. Budd. 

 Diam. .5, Length .8, Breadth 1.1 inches. 



Shell smooth, nearly round, rather compressed and somewhat lenticular; substance of 

 the shell thick, thinner behind; beaks but slightly prominent; ligament short and thin; 

 epidermis rather dark-brown, with very fine, shining strias; cardinal teeth small, single in 

 the right and double in the left valve; lateral teeth long and nearly straight; anterior 

 cicatrices confluent; posterior cicatrices confluent; dorsal cicatrices on the under side of 

 the plate near the cardinal tooth; cavity of the shell rather shallow and regularly rounded; 

 cavity of the beaks small and slightly angular; nacre very white and iridescent. 



Remarks. — This is a very small species, with characteristics more nearly resembling 

 U. lens, (Nobis,) than any other with which I am acquainted. One specimen only was 

 sent to me by Dr. Budd. 



Unio approximus. PI. V. Fig. 13. 



Testa Ixvi, elliplied, inflata; valvulis subcrassis; natibus promimdis; epidermide luted, radiatd ; dentibus 

 rurdinalibus parvin, acuminutis ; luteratibus longis, subrectisque; murgarild alba el iridescente. 



Shell smooth, elliptical, inflated; valves rather thick; beaks somewhat prominent; epidermis yellow, radiated; 

 cardinal teeth small, pointed; lateral teeth Ion" and nearly straight; nacre while and iridescent. 



Hab. Red River, at Alexandria, Louisiana. J. Hale, M. D. 

 My cabinet and cabinet of Dr. Hale. 

 Diam. .1, Length 1.3, Breadth 2.2 inches. 



