REPORT ON THE CRINOIDEA. 11 



immediately beneath the articular ridge (PI. X. figs. 1-4 ; PI. XX. fig. 7 ; PI. XXXa. 

 fig. 11a; PL XXXII. figs. 6, 8-11, 15), and corresponding to the single pit which 

 lodo-es the third ligamentous bundle in the trifascial articulations of Bathycrinas 

 (PI. Vila. figs. 16, 20, 22, Id'). In Millericrinus, and more especially in Apiocriniis, the 

 portion of the dorsal fossa outside this central pit is enormously expanded ; and the true 

 articular surface becomes relatively insignificant. 



The pairs of fossse are symmetrical on the two sides of each articular face in the 

 first and second radials (PI. Vila. fig. 15 ; PI. XII. figs. 20, 23 ; PI. XXI. figs. 5c, Qd); 

 but in the ordinary arm-joints, which have more or less oblique terminal faces and bear 

 pinnules at their sides (PL Vila. fig. 21 ; PL XXI. figs, ih, 4c), there is a disturbance 

 of the symmetrical arrangement of ridges and fossae which is so very evident in the 

 calyx of all Neocrinoids (PL Vllb. fig. 5 ; PL Villa, fig. 7; PL X. figs. 1, 4 ; PL XII. 

 fig. 15; PL XVIII. fig. 4 ; PL XXX. fig. 3 ; PL XXXIV. fig. 7), with the exception of 

 HolopiLS and its allies (PL III. figs. 1, 2 ; PL V. fig. 1). 



