eg 1907. NEw CRINOIDS — SLOCOM. 283 
height of the calyx. Radials five, equal, sides slightly converging 
towards the base; moderately convex longitudinally, so that the ven- 
tral view of the calyx is subpentangular. A semicircular excavation 
occupies nearly the entire distal edge of the radials, and the processes 
thus formed are rather short for the genus. The costals are not pre- 
served in the type or any of the. specimens at hand. The inter- 
radials or orals are large and are not visible in a side view; they 
comprise the greater part of the ventral disc. They extend to the top 
of the radial processes, and rest against their inner faces. Laterally 
they connect with each other, but leave a comparatively large round 
opening for the peristome in the center of the disc. The deflected 
lateral edges form the ambulacral groove extending from the arm 
bases to the central opening. The anal opening is situated at the 
juncture of the posterior interradial with the processes of the two 
posterior radials. None of the plates which covered the peristome, 
ambulacral grooves or anal opening is preserved. 
The natural casts are similar in form to the exteriors, but shghtly 
constricted at the arm bases and somewhat shorter in proportion to 
their diameter. The interradial processes are indicated by five rather 
stout protuberances between which the dorsal cup curves gradually 
into the convex ventral disc. A large circular protuberance in the 
center of the disc indicates the size and position of the peristome, and 
a small one rising out of the posterior interradial process indicates the 
anal opening. 
Dimensions of the type are as follows: 
Natural mold Natural cast 
Height of calyx, 6.7mm. Height of calyx, ALS ti 
Height of basals, Ore ION bol basals: Means 
Height of radials, 2.4 ‘Height of radials, Dodane: 
Height of processes, Om wl teen, Ol processes, roe Tit 
6 oe 
Diameter at arm bases, 5.0 Diameter at arm bases, 2.9 
Diameter at top of basals, 4.1 Diameter at top of basals, 3.0 
As to size, form and pattern of ornamentation, this species ap- 
proaches S. hammelli 5S. A. M. * and from the original description and 
figures it would hardly be safe to separate them. Upon comparison, 
however, with the types of S. hammell1, which are in the paleontological 
collections of the University of Chicago, the ornamentation of the 
plates was found to be so much more prominent in the specimens here 
described as to warrant specific distinction. The striations in both 
species-are so grouped as to form geometric figures. For instance, the 
longitudinal striae on the right posterior radial and the basal on which 
* 17th Rept. Geol. Ind., p. 635, Pl. VI, Figs. 7-9. 
6c # 6 
