80 DESCRIPTION OF NEW 



Hab. Newtown Creek, New Jersey, near Philadelphia. Wm. Hyde. 

 Also Schuylkill, at Fair Mount. 



My Cabinet. 

 Cabinet of Mr Hyde. 

 Diam. 2-1, Length 2-3, Breadth 4-6 inches. 



Shell elliptical, inflated, inequilateral ; substance of the shell thick ; 

 beaks somewhat prominent and rather largely undulated at the tip ; liga- 

 ment rather short ; epidermis dark brown, smooth, shining and ap- 

 parently without rays ; anterior cicatrices distinct ; posterior cicatrices 

 confluent ; dorsal cicatrices obsolete ; cavity of the shell deep ; cavity 

 of the beaks very small ; nacre white, sometimes salmon colour. 



Remarks. — The large specimen here figured was found by Mr 

 Hyde in Newtown Creek, nearly opposite to Philadelphia, many 

 years since, and is the only full grown or large one I have seen. 

 Within five or six years, from time to time, I have found near Fair 

 Mount, six individuals, which, although they appeared not to be mature 

 shells, were evidently different from any described Anodonta, and I 

 have not hesitated to refer them to this species observed by Mr Hyde. 

 The specimens from Fair Mount are rather thin in the substance of the 

 shell, while that from Newtown Creek is somewhat thick. This may 

 be referred to difference of age. In all the specimens there is an en- 

 tire absence of rays and the young are possessed of a yellow epidermis. 

 This species differs from the Jin. Jiuviatilis, (cataracia, Say), in being 

 more transverse, in the beaks being more medial and in having the 

 undulations of the beaks larger, while the Jiuviatilis is more granulate. 



Anodonta Oregonensis. Plate XXI. fig 67. 



TestH subalatd, elliptica, subinflata, in(Bquilaterali ; valvulis tenuibus ; natibus vix promi- 

 nentibus, ad apices undulatis ; epidermide subfulgida striataque ; margarild alba. 



Shell subalate, elliptical, somewhat inflated, inequilateral ; valves thin ; beaks scarcely 

 prominent, undulated at the tip ; epidermis rather shining and striate ; nacre white. 



