171 



Atlodontaf Iridina, and Hyria, as well as many genera in other 

 families, which the same principles of arrangement would abolish. 

 Ferussac, however, in his " Tableaux Syst.," 1822, has concluded 

 to admit four of the genera; viz. Anodonta, IJyria, Unio and 

 Castalia. 



Alasmodonta confragosa. — Disks with short, oblique un- 

 dulations, and tuberculated beaks. 



Alasmodonta confragosa^ nobis. Disseminator of Useful Know- 

 ledge, vol 2, p. 339. 



Desc. Shell transversely suboval, very dark or blackish ; disk 

 convex, with oblique, irregular, abbreviated undulations, not di- 

 rected towards the beak ; and numerous, more or less abbreviated, 

 slightly elevated lines from the umbo, becoming obsolete towards 

 the base, those before divaricating towards the hinge margin ; 

 beak with a groove and double series of three or four tubercles • 

 lunule, or cavity of the hinge membranes somewhat arquated; 

 within white, margined with opake whitish, or violaceous. 



Obs. This species was first obtained by Mr. 0. Evans in a side 

 stream of the Wabash, called Fox river ; several specimens have 

 been since obtained, but it is rather rare. The teeth resemble 

 A. rugosa, Barnes, but are much less prominent. On a passing 

 glance it might almost be mistaken for Unio pUcatus, nob. 



The tuberculated beaks are somewhat like those of the figure 9, 

 plate 248, of the Encyclopedic Methodique, but that is represented 

 to have the lamelliform teeth. The largest individual I have seen 

 measures three inches and a half long, by five and six-tenths broad 

 and two and a half inches in convexity. In a particular, oblique, 

 reflected light, the surface exhibits a tinge of dark green. 



I have recently received specimens from Mr. Barabino of New 

 Orleans, near which city he obtained them, and where they are 

 probably not uncommon. He did not state the precise locality, 

 but I presume they inhabit the sluggish waters in the rear of the 

 city, and not in the Mississippi. PI. 21. 



Unio phaseolus, Hild. — Specificcharacter. Umbo compressed; 

 cardinal plate very thick ; lateral tooth short ; surface radiated ; 

 beaks simple. 



Unio phaseolus, Hildreth. Journal of Science, vol. 14, p. 

 283. Short and Eaton, Transylvania Journ. of Medicine, for 

 February, 1831. 



