THE 
AMERICAN GEOLOGIST 
Vol. X. SEPTEMBER, 1892. No. 3 
DESCRIPTION OF TWO NEW GENERA AND EIGHT 
SPECIES OF CAMERATE CRINOIDS FROM 
THE NIAGARA GROUP.* 
By Charles Wachsmuth and Frank Springer, Burlington, Iowa. 
Idiocrinus W. and Sp. (nov. gen.) 
' (lAlOS peculiar, KPINON a lily.) 
Infrabasals apparently 5, extremely small; placed at the bot- 
tom of a more or less deep concavity, and completely hidden by 
the column. Basals 5, very large; the posterior one truncated 
by the interbrachio-anal plate. Badials very large; four of 
them heptagonal; the two adjoining the anal side hexagonal. 
Costals 2, almost linear and considerably narrower than the radi- 
als; the first quadrangular, and three or four times as wide as 
high; the second pentangular, the sides of its upper angle almost 
straight. Distichals 2 in the calyx ; short. Interradial area on 
all sides composed of a single, large plate, which rises to the 
top of the dorsal cup. That of the anal side resting upon the 
basals, the four others upon the sloping upper faces of the 
radials. Ventral disk quite variable in form ; covered by a large, 
undivided oral pyramid. The ambulacra tegminal, and in the 
typical species lined by small side plates. Interambulacrals rep 
*The species will be finely illustrated in our forthcoming Monograph 
on the Crinoidea Camerata of North America. 
