Maryland Geological Survey 243 



somewhat shorter. Number of brachioles on one side of each ambuladrum 

 varying with age, there being in the youngest known specimen (no. 1) 

 about 5, in a mature individual (no. 3) about 19, and in the largest ex- 

 ample (no. 4) about 22. Ambulacral grooves narrow in comparison with 

 the large size of the ambulacrals, and covered by very small rectangular 

 ambulacralia which are sliarply elevated into a median ridge. There are 

 usually from 10 to 12 ambulacralia to each ambulacral, but in different 

 specimens the number varies. The branches going to the brachioles at the 

 lateral ends of the plates have the ambulacralia as well developed as the 

 median series. Brachioles slender, composed of rather large, elongate, 

 smooth pieces. Those at the distal ends of the ambulacra have 6 pieces in 





Fig. 12. — Analysis of Pscudocrinites perdeivi Schuchert. 



a column 4 mm. long; seemingly these brachioles did not exceed 12 mm. 

 in length. 



Anal area small, not prominent, and composed of 2 circles of plates. 

 The outer circle has from 7 to 9 pieces of unequal size, and the flat 

 pyramid has 7 or 8 equal triangular pieces. The madreporite is rather 

 large for Pseudocrinites, but the hydropore is minute, and both are placed 

 within a distinct hollow separating the ambulacra of one side. Basal 

 pectinirhomb smallest, that of plates 14 and 15 largest. Column slender, 

 tapering rapidly for a short distance from the theca, and composed oi 

 pieces of equal thickness. Length unknown. 



This splendid large and odd Pseudocrinites is readily distinguished 

 from all other species of the genus by the short, high, and angulated 

 ambulacra. The form of the theca and the plate sculpturing are also 

 characteristic. 



