AND OTHER FAMILIES. 45 



Anodonta Ferussaciana. Plate VI. fig. 15. 



Testa siibcylindraced, inxquilaterali, inflatd ; margine dorsali sub natium 

 apices curvd ; valvulis icmiibus; epiderrnidcfidgidtl, obsolete radiaid, olivx colorem 

 tenebrosum habente ; natibus prominulls, biiiis ternisve unduUs exiguis ad apices ; 

 cicatricibus conspicuis ; margaritd cceruleoalbu et iridescente. 



Shell subcylindrical, inequilateral, inflated ; dorsal margin curved immediately 

 under the point of the beak ; valves thin ; epidermis dark olive, shining, with obsolete 

 rays ; beaks somewhat prominent with two or three small undulations at tip ; cicatrices 

 perceptible ; nacre bluish white and iridescent. 



Hab. Ohio River, near Cincinnati. T. G. Lea. 



My Cabinet. 

 Cabinet of the Academy of Natural Sciences of Philadelphia. 

 Cabinet of Mr Nicklin. 

 Cabinet of Professor Vanuxem. 

 Cabinet of the American Philosophical Society of Philadelphia. 

 Diam. 1-4, Length 1-8, Breadth 3-5 inches. 



Shell subcylindrical, inequilateral, much inflated, more angular 

 behind than before; dorsal margin curved immediately under the 

 point of the beak ; basal margin disposed to be emarginate ; substance 

 of the shell thin; epidermis dark olive, shining, with numerous obso- 

 lete rays, near the beaks lighter and destitute of rays ; ligament rather 

 short and thin ; beaks somewhat prominent with two or three small 

 undulations at tip; cicatrices perceptible; cavity of the beaks shallow; 

 cavity of the disk deep and rounded ; nacre bluish white and iridescent. 



Remarks. — This species was received with the Jl. incerta, here- 

 in described, from the Ohio river. It differs from that species in 

 having prominent beaks, in being more cylindrical, in its dark colour, 

 and in the curve which exists immediately under the beaks, in which 

 it resembles the A. areoliin (Swainson). In the latter this curve is so 

 strong and thick as to resemble an incipient tooth. In young speci- 

 mens the epidermis is more on the yellow, and the rays greenish and 

 bright.* 



* Since the above description was made and the figure printed, I am in possession of sev- 

 eral specimens from Illinois, beautifully and very distinctly rayed. 

 VOL. V. M 



