24 



Family POROCEINID^, n. fam. 



This family has five basals; five subradials; one by five radials; 

 no regular interraclials; small arms; and deep pits and pectinated 

 riiombs, at the angles of the plates. It resembles, in its general 

 structure, the Cijulhocrinidir, and Potcriocrhmhr, but the azygous 

 area is not like that of any other known genus and the pectinated 

 rhombs are like those belonging to Cysiideaus. 



rOROCRINUS KENTUCKIENSIS, n. Sp. 



Plate I], Fig. I'J, side view slwwina deep pits or pectinated 

 rhombs and part of the arms, azygoiis side on the right. 



Calyx obpyramidal, pentagonal, in outline, with the angles at 

 the center of the subradials and again at the arm bases. Height 

 equal to the greatest diameter. Surface radiately sculptured from 

 the center of each plate to the center of each adjoining one. The 

 base of our specimen is slightly broken away so that the true 

 length of the basal plates is not shown in the illustration. Tlie 

 subradials are the largest plates in the calyx aud occupy more 

 than one-third of the length. The first radials are next in size 

 and a single, small, round arn^, occupying about one-third the 

 width, arises from the superior central part. Only three short 

 plates in three of the arms are preserved in our specimen, but 

 the ambulacral furrows may Ije seen extending to the central part 

 of the vault. The third plate is not axillary and hence the 

 arms do not bifurcate on that plate if at all. There are two azy- 

 gous interradials that seem to be arranged as in the type of the 

 genus, but our specimen is silicified aud the sutures are very in- 

 distinct. The vault is quite convex in this species. There is a 

 very large pectinated rhomb at each angle of every plate in the 

 calyx and smaller ones on the vault. Twenty-eight can be dis- 

 tinguished in our specimen. 



The general form, surface ornamentation and exceedingly large 

 pectinated rhombs at once distinguish this species. 



Found in the Trenton Group, in Mercer county, Kentucky, and 

 now in the collection of Wm. F. E. Gurley. 



