Wachsmuth and Springer—Paleoerinoidea. 367 
Kurland’s Ser. 1), vol. iv, p. 110, who placed only the Cana- 
dian species under Hybocrinus, and proposed for the typical 
Russian form the genus Hoplocrinus, accepting Barocrinus 
distinct therefrom. : 
mp. des Sci, 
knowledged the differences between the Canadian and Rus- 
Carpenter (Quart. Journ. Geol. Soc. London, August, 1882), 
agreed with Schmidt and Volborth that Apiocrinus dipentas 
was a Hybocrinus but only the typical form. He considered 
the simple azygous plate in the Russian species as 25 probab y 
equivalent to the two present in the Canadian s ecies,’ 
Toposed a modification of Billings’ generic definition, so as to 
Include the Russian form; but he considered Berocrinus, as 
defined by Grewingk, to be “an altogether different generic 
t ” 
he differences in the number and arrangement of the plates 
at the azygous side have been very generally regarded as excel- — 
lent characters for distinguishing genera among Palzocrinoidea, 
and in the Cyathocrinide, which show but little variation in 
the general construction of the body, they frequently consti- 
tute, when the arms are unknown, the only means of separa- 
tion. That in the present instance the two types happen to 
reason for making these g 
rule, since all Cyathocrinide are more or less protuberant 
ong the anal regions. : 
Tt has been satisfactorily proved that there exists a structu- 
Tal difference in the azygous plates of the respective types; 
