58 PROCEEDINGS OF THE ACADEMY OF 



first, wider than long, and quadrangular in outline.^ Third 

 radials about as large as the second, from the curved-up edges of 

 which they rise vertically, wider than long, and pentagonal in 

 form ; bearing on each of their superior sloping sides a smaller 

 secondary radial, each of which supports another smaller, more 

 or less cuneiform piece, from which the arms arise ; thus making 

 two arms from each ray, unless the number is increased by bifur- 

 cations after they become free ; arms unknown, but apparently 

 composed, at their origin, of a double series of alternating pieces. 



First interradial pieces, somewhat larger than the first radials, 

 about as wide above the middle as their length, eight or nine 

 sided, with the lower part of eacli curving under to connect witli 

 the first radials, while they curve upward vertically from near or 

 below the middle ; each supporting on the upper side a much 

 smaller hexagonal piece, which rises vertically, and usually bears 

 on its short superior lateral edges two smaller pieces connecting 

 with the secondary radials or first arm-pieces, while its short 

 truncated upper side is not surmounted by any succeeding piece, 

 but connects on its inner surface with the vault. 



Sutures between all the plates channelled. Surface of bodj'- 

 plates ornamented with raised lines or very small radiating costae, 

 that cross the sutures parallel to each other at the sides of the 

 plates, but soon become bent about and connected in various 

 waj^s, so that very few of them extend directly to the middle of 

 any of the plates, the arrangement being such as to produce a 

 kind of vermicular style of ornamentation, especially over all the 

 central part of the plates, like that often seen on the body-plates 

 in AmphoracrinuH. A small rather sharp ridge also extends up 

 the middle of each radial series of plates, more or less interrupted 

 at the sutures, and showing a slight tendency to form a pinched 

 node on the middle of the first and second radials ; while it is 

 sometimes seen to bifurcate on the third radial, to send branches 

 to the secondary radials, but these are generally so small as 

 scarcel}' to be distinguished from the other little ridges ornament- 

 ing all of the body-pieces. 



Ventral tube unknown, but, judging from the spiniferous cha- 



' In one ray of the typical specimen the second radial is abnormally want- 

 ing, while the third is larger than usual. 



[June 6, 



