ACTINOCRINID &. 989 
arm plates. Only the first palmars are in contact laterally, the others being 
free. In the three anterior rays only one of the distichals is axillary; the 
opposite one, being truncated, supports two or three more moderately large 
cuneate distichals, which are followed by the regular arm plates. Some- 
times, but exceptionally, both distichals are truncate, and the ray has but 
two primary arms, while the other rays have three or four. The first branch- 
ing of the arms generally takes place from the ninth to tenth double row of 
joints, the second and third from the tenth to fifteenth above. ‘The bifurca- 
tions are given off at one side of the main arm, which generally has three 
bifurcations, sometimes, however, but two; they are widely divergent, and 
the side-branches rarely bifurcate again. Arms heavy throughout, tapering 
very little upward; at each bifurcation there is a small node, and the arms 
themselves are slightly inflated — a peculiarity by which they are readily 
recognized. Pinnules apparently small, their two or three proximal joints 
provided with small hooks. Anal plate considerably narrower than the radi- 
als. Interbrachials in two ranges; there being one and five at the regular 
sides, and three or two followed by five or six at the anal side. When there 
are three plates in the first row, the middle one is narrow and wedged in 
between the two at the sides, often barely touching the anal piece. The two 
outer plates of the second row at each side of the area curve outward in the 
direction of the free rays, and are largely interambulacral, touching but 
slightly the costals; the extended upper part resting against the covering 
plates of the ambulacra. Ventral disk from the top of the free rays to the 
base of the orals obconical, leaning a little to the anterior side ; broadly coni- 
eal above; the plates irregularly arranged, slightly convex, about equal in 
size. The orals occupy the truncated upper face of the disk; the posterior 
one is located in the centre between the orals at one side and the anal tube 
at the other; it is strongly nodose or subspinous; the other four orals are 
produced into long, very heavy spines, which either gradually taper to their 
extremities, or widen upward and fork at the top. Anal tube very short and 
stout, directed obliquely upward; the opening lateral, and surrounded by 
four or five acute spines of fully one half the length of those surmounting 
the orals. Ambulacra hidden by superimposed plates to the bases of the free 
rays, where those of the first and second order are represented by a single, 
strongly nodose plate. Column moderately strong, the nodal joints consid- 
erably widest, and angular at their margins; while the intervening ones are 
very short. 
