Pores m Pistillate Criiioids. — Springer. 145 
ly thin, so that no aid can be had by grinding on any of the 
specimens I have. I have a specimen, however, in which the 
ventral sac, crushed flat, is free on both sides. The fissures 
seem to have been filled with a matrix the same color as the 
test. At the depressions toward the sides of the plates the sac 
is as thin as tissue paper, and when seen by transmitted light 
the fissures show as bright lines, as if they were actually open 
slits. 
Scytaloaijuts hoveyi. from the Keokuk limestone of Craw- 
fordsville, has a sac of hexagonal plates which are crossed by 
fissures similar to those of Scapliiocrimis missouriensis, only 
in this species the plates are somewhat thicker. In one of my 
specimens, near the distal end of the sac, the edges ot sev- 
eral plates are turned up and exposed to view. These show 
with the greatest distinctness that the fissures pass over the 
edge of the plates and run to the interior. Fig. 8 of PI. XVI, 
which is an enlarged view of some of these plates, shows this 
perfectly. The fissures cross at the middle of the sides, not 
at the angles. 
It is not upon these specimens with elongate fissures, 
however, that I place the chief reliance, but upon specimens 
of additional species in which the ventral sac is either per- 
fectly smooth, or can be made so by grinding ol^ the surface, 
and which have well defined pores passing through the test, 
on the radial lines. 
The first of these is Scytalocrimis van Jiornei Worthen, 
from the St. -Louis hmestone (PI. XVI, figs. 13, 14). In this 
the surface of the sac is perfectly smooth, unmarked by ridges 
or depressions of any kind. The pores are darker colored 
than the substance of the test, and appear distinct on the 
radial lines at the middle of the sides of the hexagonal plates, 
as shown in the enlarged figure (14) of one of the plates. The 
pores are small in this species, but their position on the su- 
tures is readilv observable, and cannot be mistaken. 
Parisocriniis snbramosus M. & G. PI. XVI, figs, i, 2, 
3- 4- 
This is a rare species from the Keokuk limestone at Craw- 
fordsville and Indian Creek, Indiana, of which I possess three 
specimens from the latter locality, showing the pores in the 
ventral sac. Figure i represents a nearly entire specimen, 
