138 The American Geologist.' September, 1892 
Horizon and Locality: Upper part of Niagara group; near St 
Paul. Ind. 
Type in the collection of Wachsmuth and Springer. 
Remarks. The oral pyramid of this species, which is found 
occasionally detached from the body, was regarded by Miller, 
Benedict and ourselves to represent probably the ventral struc- 
ture of some Pisocrinus. This appeared the more plausible as it 
was expected from analogy that in Pisocrtnns^ as in the allied 
Symhathocrinus and HapJocrinns^ the ventral disk consisted of 
orals only, and the plate fitted approximately upon the cup of one 
of the species, which occurs in the same bed. 
Hyptiocrinus W. and Sp. (nov. gen.) 
'thTIOS bending back, KPINON a lily.) 
Name applying to the character of the arms which hang down- 
ward. Calyx depressed, wheel-shaped. Infrabasals 5, small. 
Basals 5, four of them equal, angular at the upper end; the pos- 
terior one truncated by the anal plate. Radials comparatively 
small, all hexagonal. Costals 2. Fixed brachials rather large, 
except the first costals, which are quite short and quadrangular. 
First distichals one, the distal face broadly truncated; followed 
by several sharply cuneate pieces, which interlock, and of which 
the two or three proximal ones (in the type) take part in the 
calyx. Arms stout, probably biserial, and pendent, to judge from 
the arm openings, which are directed obliquely downward. First 
interbrachials of the regular sides very large; succeeded by sev- 
eral rows of smaller pieces. Anal plate touching the basals, and 
higher than the radials; supporting three much smaller plates in 
the next row,, and others above. Ventral disk depressed; the 
posterior oral and the radial dome plates spinous ; the anus ex- 
centric, and at the top of a large protuberance. 
Distribution: So far as known, restricted to the Niagara group 
of Indiana. 
Remarks. The genus has its closest relations with Thysanoc- 
rinus, from which it differs in the flatness of the calyx, in the 
pendent arms, and in the spine-bearing disk. 
Hyptiocrinus typus W. and Sp. (nov. spec.) 
Specimens of medium size. Calyx wheel-shaped, nearly once 
and a half as wide as high. Dorsal cup broadly obconical to the 
top of the costals, then flanging outward and somewhat down- 
ward, Arm regions not lobed, but the upper margins of the in- 
