136 The American Geologist. September, i898 
resented by only one large, subtrigonal piece. Anus excentric. 
Structure of arms and column not known. 
Type: Idiocrinus eloiigatus. 
Distribution: So far as known, restricted to the Niagara group 
of America. 
Remarks. Differing from all other dicyclic Camerata in hav- 
ing a single plate in the anal area, in its central, undivided oral 
pyramid, and in having but one interambulacral plate to each side 
of the disk. 
. Idiocrinus elongatus W. and Sp. (nov. spec.) 
A small species. Calyx obconical; the ventral disk on a level 
with, or below, the upper margins of the dorsal cup ; the cup 
deeply excavated at the bottom, the basals forming a large fun- 
nel-shaped pit. Plates without ornamentation and flat, except 
the radials, which are a little convex, and rise slightly above the 
plane of the cup. Suture lines not grooved. 
Infrabasals minute, constituting the bottom of the basal con- 
cavity. Basals extremely large and elongate, the lower end curv- 
ing abruptly inward, and forming a sharp edge around the bot- 
tom of the calyx ; the exposed part of the plates rising to more 
than one-third the length of the dorsal cup. Radials once and a 
half as wide as high, distinctly angular at their lower faces; the 
two posterior plates hexagonal, being truncated by the interbra- 
chio-anal plate. Costals together less than half the size of the 
radials; the first linear; the second a very little higher, and its 
upper angles quite obtuse. Distichals 2, somewhat higher and 
wider than the costals; the upper semi-free. Interbrachials 
one, those of the four regular sides resting upon the deeply slop- 
ing sides of the radials, the anal one upon the narrowly trun- 
cated basal; all extending to the upper end of the calyx, and all 
much higher than wide. 
The oral pyramid is somewhat weathered in the type, and the 
median part is imperfect, the apparent opening in the center being 
a mere break. The specimen, however, is interesting as showing 
indistinct traces of inter-oral sutures, which are obsolete in other 
specimens of this genus. The pyramid occupies nearly one-third 
the width of the disk, and its upper end, when perfect, formed a 
level with the distal faces of the second distichals. Interam- 
bulacral plates one, forming a triangular area lined by small side- 
pieces, which stand erect and form upon the surface well-defined 
