282 Field Columbian Museum — Geology, Vol. II. 



altogether before the center of the plate is reached. Sutures obscure, 

 not marked by grooves. 



Basal plates three, about equal in size. Two are pentangular and 

 one is quadrangular. Together they form an obconical cup comprising 

 about half the height of the calyx, triangular at the base and circular 

 at the top. There is a slight circular depression in the center of the 

 base for the reception of the column. Radial plates five, equal in 

 size with the lateral edges produced into interradial processes. Height, 

 aside from the processes, about equal to that of the basals. The 

 characters of the vault are quite obscure, but appear to correspond 

 with the description of the genus. 



This species is based on a single silicified specimen (Mus. No. P 8416) 

 in a fairly good state of preservation. Its obconical form renders it so 

 unlike all other species of the genus that comparison with them seems 

 to be superfluous. The following measurements, in millimeters, taken 

 from the type specimen, may be of use for comparison in case other 

 specimens are found. 



Diameter at base, 2.3 mm 



Diameter at top of basals, 5.5 



Diameter at top of calyx, 6.4 



Height of radials aside from spines, 4.6 



Height of basals, 5.0 



Height of calyx, 9.6 



Length of spines, 1.6 



Locality: Collected by the writer in the fall of 1905 in the clay 

 pockets of the Niagaran limestone at Romeo, Illinois. 



Stephanocrinus skiffi, sp. nov. Plate LXXXIV, Figures 16-20. 



The calyx has a small triangular base. It expands rapidly to the 

 top of the basals and moderately from that point on. The distal edges 

 of the radial plates are excavated for the reception of the arms, thus 

 forming five interradial processes. The plates of the dorsal cup are 

 ornamented with a series of acute prominent striae. These striae are 

 oblique at and below the upper lateral angles of the radials, longitudinal 

 on the middle of the radials and basals and transverse on the lower 

 part of the basals. Sutures are obscure and do not interrupt the 

 striae. 



Basal plates three, about equal in size, one quadrangular, two pent- 

 angular. Together they form a funnel-shaped cup, triangular at the 

 base and expanding very rapidly to the top. An acute angular ridge 

 extends from the base to the center of each plate where it becomes 

 lost in the longitudinal striae. The basal cup comprises about half the 



