V. Botryocnniifi. 399 



the outer side of the second distichal. This first pinnule is 

 usually stouter than the preceding ones, and is not seldom 

 branched, in which case it should strictly be called an armlet, 

 e. g. a/495 Cambridge (PL XIII. fig. 13) and 136 Holcroft. 

 The ossicle next this axillary distichal, /. e. the third ossicle 

 of the main branch, does not as a rule bear a pinnule, and 

 then the second pinnule arises on the inner side of the fourtli 

 ossicle. After this the pinnules follow regularly on the alter- 

 nate sides of each successive ossicle. Variations from this 

 normal plan may occur; thus in E 1419 B. M. the first 

 pinnule of the left-hand branch of the right posterior arm 

 springs from the outer side of the third distichal. 



The pinnules in ordinary specimens are about 9 millim. 

 long, but usually appear shorter owing to loss of the distal 

 ossicles. They have rounded backs, with a width of about 

 •9 millim., gradually tapering. They are somewhat com- 

 pressed laterally, so that the depth is greater than the width. 

 Their ossicles are half again as long as wide. Considerable 

 variations, however, occur ; thus pinnules of ordinary thick- 

 ness may attain a length of 14 millim. ; others, more thick, 

 are from 17 to 20 millim. long (e. g. 149 Mason Coll.j. In 

 some specimens where the pinnules lie rather closely together 

 they are flattened on the side and have almost the square look 

 of an Encrinus pinnule (PI. XIII. fig. 14). The pinnule 

 ossicles have sometimes a slight ridge at either end (e. g. 

 349 Holcroft). 



The covering-plates of both arms and pinnules are very 

 small ; they appear to have been shield-shaped, from three to 

 four on each side of an ossicle, alternating in the middle with 

 those of the other side (PI. XIII. figs. 8 and 9). 



Anal structures : — Kadianal small, four- sided, and often 

 rectangular ; does not differ from that of other species of the 

 genus. The following are some measurements : — in E 1328 

 from X to r. post. B. 1-75 millim. and from r. post. R. to post. 

 B. 1*4 millim. ; in E 5130 the corresponding measurements 

 are 2'1 millim. and 1'9 millim. ; in E 1419 they are both 1-2 

 millim. 



The Anal x (or Brachianal) has an average height and 

 width of 3 millim., being rather smaller every way than a 

 radial. It is somewhat rounded. On its upper margin it 

 supports three plates, a large middle plate and a smaller one 

 on either side partly resting on the adjacent radials (fig. 1, 

 p. 408). 



This middle plate, which corresponds with that spoken of 

 as the second brachianal in Paper 111. on Thenarocrinus, is 

 shaped like the anal Xj but is half again as wide as high. 



