28 Mr. F. A. Bather on British Fossil Crinoids : 



brachials are probably only the third postpalmars, instead of 

 the sixth as in T. callipygits, a fact that further enhances the 

 graceful slimness of the arms. The arm -ossicles are smooth 

 with a very slight constriction in the middle, and a very slight 

 swelling, hardly to be called a ridge, anteriorly. The height 

 of the ossicles is about equal to their breadth all the way up 

 the arms. Lateral compression is more obvious in the proximal 

 than in the distal region of the arms, and may in this case be 

 due to simple mechanical pressure by the rock. More dis- 

 tally the arms have almost a flat shallow appearance. The 

 ventral surface of the arms is nowhere exposed. 



Costals, in r. post, arm apparently 9. The edges of the 

 proximal costals in each ray are bent upwards parallel to the 

 curved edges of the radial facet. There is no bevelling of 

 the outer edge as in the type species. 



The remainder of the arms is too fragmentary to allow the 

 number of distichals, palmars, &c. to be more than guessed 

 at : the average number in each series was probably about 10. 

 Anal structures : — Eadianal, since it rests on both r. and 1. 

 post. IB., is hexagonal, not pentagonal ; in correlation with 

 this it is higher than wide : in other respects as in type 

 species. 



Brachianal not shield-shaped, but an irregular hexagon, 

 very slightly higher than wide. Normally it was probably 

 situated as in T. calhpi/gus, but in the present specimen it is 

 separated from 1. post. E. by the tegminal plate before 

 alluded to. 



The connexion of the ventral sac with the anal plates is as 

 follows (see PI. I. fig. 5). The Brachianal does not support 

 a second brachianal, but is itself axillary. The first plate of 

 the left-hand distichous series is axillary, and the same appears 

 to be the case with the corresponding plate on the right. 

 Then follow series of folded plates so like those of T. calli- 

 yygus that further description is unnecessary ; the anticlinal 

 lolds, however, are a little broader proportionally than in that 

 species. 



In the present specimen the ventral sac attained a length 

 of at least 24 millim. 



The Tegmen^ beyond a few small plates on either side the 

 origin of the ventral sac, is not seen in this specimen. 



The Stem (PI. I. tig. 5) is smooth in the proximal 

 portion, and this smoothness does not appear to be due to 

 rubbing. There are 23 ossicles preserved, of alternating 

 height but regularly decreasing diameter. The smaller ones 

 are about half the height of the larger, so that approximate 

 measurements are : — heigiit '34: and -17 millim. : diameter 2*7 



