GEOLOGICAL SOCIETY. 



97 



sions of the upper part of these rotatory feet, five arti- 

 culations are visible, of which the second is furnished 

 on its anterior edge with two slight spines, and the last 

 terminates in an oval plate, as in the genus Portunus. 

 The abdomen consists of eleven distinct articulations 

 tapering gradually to the tail, a small part of which only 

 remains. The abdomen presents no trace of a division 

 into longitudinal lobes." 



Dr. Dekay has indicated the genera Jlpm, Binoculus 

 and Lepidurus, as most nearly allied to his new genus. 



The highly interesting specimen which forms the 

 subject of the above notice , is at present in the cabinet 

 of the Lyceum of Nat. Hist, of N. York ; it was origi- 

 nally described in the American Monthly Magazine, 

 vol. iii. p. 291, by the late Dr. Mitchell, who consi- 

 dered it a fossil fish of the genus Siluriis. 



Locality. Westmoreland, Oneida county, New York. 



Place in the Geological series*- — There is some doubt 

 as to the precise nature of the rock in which this fossil 

 occurs ; in the memoir above noticed it is stated : — 

 " The rock containing the impression, is called by the 

 country people bastard limestone, and has been de- 

 scribed under many different names : it is said to be 

 clay-slate, by Dr. Mitchell ; graywacke slate, calcife- 

 rous sand rock, transition sand rock &c, by others. It 

 is of a bluish color, with a conchoidal fracture, homoge- 

 nous appearance and earthy smell ; it effervesces slightly 

 with acids, contains a few sileceous particles, and gives 

 fire with steel." 



Vol. T—N 



