58 Trans. Acad. Sci. of St. Loxds. 



CiDAROBLASTUS PARVUS n. S. 

 Plate v., Fig. 1. 



Body ovoidal, a little wider at the summit than at the base. 

 Base very small and depressed, but not as much as in the 

 typical specimen of this genus. Ambulacrum narrow and 

 linear, running almost over the whole surface of the body. 

 Fork pieces broad, occupying a little more than half the 

 vertical height of the calyx, with an elongated depression in 

 the center of the interambulacrum where two of them join. 

 Deltoid very broad, occupying nearly half the interambulac- 

 rum, covered with small granules, arranged in regular trans- 

 verse rows, for the reception of little spines. Genital 

 openings very small, not confluent. 



Of this unique species I have several silicious casts, as well 

 as the surrounding molds, which show distinctly the fine 

 spines adhering to them. All the specimens are of a cherty 

 nature and on the whole not as well preserved as most other 

 specimens, but, nevertheless, showing all the above described 

 characters very distinctly. 



Geological formation and locality : In cherty rock of the 

 St. Louis age, in southwestern Missouri. 



Cribroblastus verrucosus n. s. 



Plate v., Fig. 3. 



General form of body globose, vertical and transverse 

 diameters equal. Basals very small and almost concealed by 

 the column, or extending very little beyond it. Ambulacra 

 narrow and linear, running almost over the whole surface of 

 the body. Fork pieces very short occupying hardly one- 

 fourth of the vertical diameter of the body with a very dis- 

 tinctly depressed suture. Deltoids very broad, occupying 

 fully three-fourths of the vertical length of the body, separa- 

 ted from the upper fork piece suture by a double linear de- 

 pression. The whole interambulacral space is rounded and 

 ornamented by coarse granulation very irregularly arranged. 



