ECHINOCARIS. 



PPP. 5 



Oeological Range. 



The following table gives the distribution of the de- 

 scribed species of the genera Echinocaeis, Elymocaris 

 and Tropidocaris. It is seen that the number of species 

 reached its maximum in the Chemung group, which would 

 naturally be expected from the almost total disappearance 

 of the order Trilobita at the close of the deposition of the 

 Hamilton group. 



Besides the species of the list here given, I have seen two 

 undescribed species of Echinocaris, from the Chemung 

 group, of New York ; also a large form belonging to the 

 genus Elymocaris, from the Hamilton group of western 

 N. Y. ; and another species, probably belonging to the 

 latter genus, from the same horizon in the central i)art of 

 the State. 



Echinocaris, Whitfield. 



punctata. Hall, . . . 

 lonfiicauda. Hall, . . 

 sublevis, Whitfield, . . 

 pustulosa, Whitfield, . 

 multinodosa, Whitfield, 

 aocialis, Beecher, . . . 



Elymocaris, Beecher. 

 siliqua, Beecher, 



Tropidocaris, Beecher. 



bicarinata, Beeoher, 

 interrupta, Beecher, 

 alternata, Beecher, . 



XXX 

 XXX 

 XXX 

 X 



