OctT., 1907. New CrINoIDS — SLocom. 291 
is said to have been collected at Joliet, Illinois, and is in the collection 
of the Joliet High School. 
HOMOCRINUS CYLINDRICUS Hall, Plate LXXXIV, Figures 14, 15. 
Pene oylndricus Hall. Pal-“N. Y.,>Vol._Ll, p.186, Pl. -XLI, 
Figs. 2 and 3. 
1859 Potertocrinus cylindricus Hall, Correct List of N. Y. Fossils. 
1879 H. cylindricus W. &. Sp., Revision Paleocrinoidea, Pt. 
Te Aadeney cue intes fh) oe 152 20: 
Calyx subcylindrical, gradually enlarging to the top of the infraba- 
sals and slightly constricted at the arm bases. Surface of the plates 
smooth and conforming to the general curve of the calyx, except the 
radials which are longitudinally convex at the arm facets, giving 
a lobed appearance to the upper part of the calyx; lobes thick. 
Infrabasals five, equal, pentagonal, higher than wide, forming a cup 
whose height and width are about equal. Basals four, higher 
than wide, the largest plates of the calyx. The posterior basal is 
heptagonal, being truncated distally for the support of the anal plate. 
It is somewhat larger than the other four which are hexagonal and 
equal in size. Radials five, wider than high, somewhat smaller than 
the infrabasals. The articulating facets for the arms occupy nearly 
the entire distal edge of the plate. The right posterior radial is smaller 
than the others, on account of the proximal end being displaced by the 
radianal plate. The radial symmetry is disturbed by the presence of 
an anal plate situated between the two posterior radials and resting on 
the posterior basal, anda radianal plate is situated at the right of the 
anal, resting on the posterior and right lateral basal plates and carrying 
on its distal side the right posterior radial. 
The species occurs in this locality in the form of natural casts and 
molds. Owing to the comparative thickness of the plates the casts 
are quite different in shape fromthe molds. The infrabasal cup is in 
the form of a rapidly expanding pyramid. Owing to the convexity 
of the inner surface of the basal plates there is a noticeable constriction 
a little above the middle of the cast and another at the arm bases. 
These features are well shown in Pl. LX XXIV, Fig. 15. Hall’s original 
description* of this species is brief, and, judging from his figures, his 
specimens were not very well preserved. There seems to be little 
doubt, however, that this specimen should be referred to this species. 
The species was described from the Niagaran shale at Lockport, New 
York, and, so far as is known to the writer, has never been reported 
from any other locality. 
# Pal. N. Y., Vol. II, p. 186. 
