Sand Formation of the United States. 287 



ANANCHYTES. Lam. 



This genus is found in fine preservation in the calcareous deposits 

 just mentioned. The species has much resemblance to one from the 

 green sand of England in the collections of the Academy, but of 

 which I do not know the specific name. The American specimens 

 have five pair of ambulacra, one of which is contained in a deep sul- 

 cus. Length from half an inch to an inch and three fourths. 



ECHINUS. Lam. 



Of this genus I have hitherto found only pentagonal, oblong, de- 

 tached plates ; margin granulated, with a central, circular, smooth 

 area, and a tubercle for the attachment of a spine. These remains 

 are well represented by the sections of the mammillated echinus, fig- 

 ured by Parkinson, Vol. III. pi. 1 . fig. 11. 



CLYPEASTEB. LttM. 



The blue marls have furnished a few casts of this genus. 



In the collection of tlie academy are some additional remains of 

 EchinidecB, but too imperfect to justify a classification. In the calca- 

 reous beds of New Jersey, I found granulated echinal spines more 

 than two inches in length, and not to be distinguished from those of 

 the European chalk. I possess similar remains from the blue marls 

 farther north. 



CRUSTACEA. 



ASTACus. Lam. 



A small species, but having nearly all its parts entire, was found 

 in digging the Chesapeake and Delaware canal. 



CANCER. Lin. 



Dr. Van Rensselaer* has described and figured four specimens 

 (cheifly the claws) of this genus, from New Jersey. Three very 

 distinct species are preserved in the academy, but these also are only 

 the claws. From these scanty remains it would be almost impossi- 

 ble to determine even the Lamarckian genera with any degree of ac- 

 curacy. 



Portions of other Crustacea have come under my observation, but 

 I have not yet been able to refer them to any definite place in the 

 systems. 



* xVnnals N. Y. Lyceum, Vol. I. p. 195, &c. 



