Description of New Genera of Echinodermata. 23 
the upper sloping side of the first azygous plate on the right; the 
higher azygous plates are not shown in our specimen; the column 
is rather small and obscurely pentagonal near the head. 
The surface of the plates of body and arms is strongly granu- 
lated, and this, with the angularity of the arms and the union of the 
granules forming a sharp ridge or keel down all the rays, strongly 
characterize this species, and suggests the specific name. It prob- 
ably belongs to that branch of the genus Poteriocrinus for which 
Wachsmuth suggested the name Pachylocrinus. 
Found in the Keokuk Group, at Crawfordsville, Indiana, and 
now in the collection of Wm. F. E. Gurley. 
POTERIOCRINUS CRAWFORDSVILLENSIS, N. sp. 
Flate LV., Fig. 8, natural size. 
Species large, robust; calyx obconoidal, expanding very grad- 
ually from the large column, longer than wide, and composed of 
smooth rounded plates with well defined sutures; basals large, 
widening but little upward, pentagonal, about as wide as high; sub- 
radials longer than wide, expanding but little upward, those shown 
in our specimen hexagonal, the two on the azygous side probably 
heptagonal; radials pentagonal, very little wider than high, the 
articulating surfaces occupying the entire width of the plates; the 
second radial or brachial plate in the ray opposite the azygous side 
is pentagonal, about as high as wide, rounded, and supports upon 
its two upper sloping sides free arms, one of which bifurcates on 
the third plate above, and the other does not divide; the arms are 
robust, long, very slowly tapering, rounded, and composed of thick 
cuneiform plates; column large, round, composed of thicker and 
thinner plates, the articulating faces of which are marked by radia- 
ting furrows, which show the serrated edges. Proboscis and other 
parts unknown. 
This species belongs to that branch of Poteriocrinus for which 
Wachsmuth proposed the subgeneric name of Scytalocrinus. Its 
characters are very strongly marked, and it resembles P. missou- 
riensis, from the St. Louis Group, about as much as it does any 
other species in the genus. 
It was found in the Keokuk Group, at Crawfordsville, Indiana, 
and belongs to the collection of Wm. F. E. Gurley. 
