new Species of Crinoids. 169 



tubercles appears to be smooth. It is a curious circumstance 

 that in several instances in which the spines remain on the 

 calyx-plate they do not lie irregularly crossed over each 

 other, but in one nearly parallel direction, as if their attaching 

 ligaments had simultaneously given way, and some gentle 

 uniform influence had acted on the spines, so that they all 

 fell in the same direction (PI. VI. figs. 6, 7). 



Stem. — Attached to the bases of two of my specimens 

 (PI. VI. figs. 1, 6) there are five or six of the upper joints 

 of the stem, which show its characters and enable the nume- 

 rous detached fragments, which are abundant in the same beds 

 with the crinoids themselves, to be identified. I have col- 

 lected thirty of these fragments, but the longest does not ex- 

 ceed 21 millim. 



The stem is cylindrical, with a moderately large cylindrical 

 central canal (PI. VI. figs. 13, 14). It varies from 3 millim. 

 in diameter in a very small form, to 6*3 millim. in a large 

 one ; in the majority of specimens it is from 4"5 to 5 millim. 

 iti thickness, including the exterior flange. The inner canal 

 of the stem is from 1*5 to 2*8 millim. in width (PI. VI. fig. 15). 

 The constituent joints or rings are of two kinds, with inter- 

 mediate forms. In the larger joints the peripheral margin 

 expands into a flange with thin edges, and the joints are nearly 

 as thick again as the smaller intermediate joints, in which the 

 projecting flange is either entirely absent or but very slightly 

 developed. The larger are between *4 and *7 millim. in 

 thickness, and the smaller from *2 to *5 millim. In some 

 portions of the stem there are three of the smaller rings be- 

 tween each of the larger, which are then about 1*5 millim. 

 apart, and the central of the smaller rings exhibits an inci- 

 pient flange, whilst in others the larger are only about 1 millim. 

 apart, with a single intervening narrow ring. The facets of 

 the rings are even and furnished with numerous, fine, equal, 

 radiating grooves and ridges, which extend from the exterior 

 margin to the inner edge (PI. VI. fig. 15). The number of 

 these varies partly with the size of the ring. In a small 

 ring, 3 millim. in diameter, there were sixty-four ridges, and 

 an equal number were present in a ring 4*25 millim. in 

 width. The face of the ring in another detached stem, 

 3*75 millim. in width, had seventy-five ridges, while there 

 were only seventy-seven with a thickness of 5 millim. As a 

 rule, these minute ridges are simple, but rarely there is a 

 slight bifurcation or notch in them near the outer margin. 

 There is no special delimitation of the inner margin of the 

 stem-joints round the central canal. 



At irregular intervals on the stem, whorls of cirri are 



