New Missouri Crinoids, Etc. — Rozvley. yi 
Strybalocystis? elongatus, (nov. sp.) 
Fig. 39. Side view of the body and part of tfie column, natural size. 
Basal plates longer than wide, apparently four in number. 
The plates of the second ring are larger than those of the first, 
from six to eight sided, and longer than wide. The plates of 
the third ring are smaller than those of the first, length and 
breadth about equal. The still smaller plates of the fourth 
ring complete the calyx. The vault or ventral plates are very 
small. 
The column is large and made up of joints of equal length. 
As the only two specimens of this little cystoid, collected by 
the writer, are imbeded in hard limestone matrix and show the 
same side of the body, the description is necessarily incom- 
plete and the generic reference may be wrong. 
The types were collected from the Delthyris Shaly lime- 
stone (Lower Helderberg group), at Red Rock landing. Perry 
county, Mo., and found associated with Dalmanites tridenti- 
fera, Spirifer perlamellosus and Platyceras pyramidatum. 
Strybalocystis missouriensis, (nov. sp.) 
Figs. 40-41. Lateral and basal views oi the type specimen, natural 
size. 
Basal plates four, of nearly equal size and excavated below 
the column. The six plates of the second ring are larger and 
from five to seven sided. Length and breadth about equal. 
The plates of the third ring are eight in number and of 
irregular sizes and shapes. The vault plates are eleven or 
twelve in number and small. One small, round opening near 
the edge of the vault is the only apparent hole through the 
test. 
All of the calyx plates are not only very convex but have 
sharply elevated ridges from the center to the angles of the 
plates. 
This cystoid probably had no arms and is closely related 
to Miller's S. tumidus and S. gorbyi. It occurs in the Nia- 
gara limestone of St. Genevieve county. Mo., near St. Marys, 
and is associated with two or three species of Pisocrinus. 
Orthis clcgantula and a Nucleospira. With one exception, 
these are the only cystoids ever described from Silurian rocks 
of the state and are therefore very interesting. 
