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PLATYCRINID&. (eo 
are thickened around the facets, which project considerably and face almost 
horizontally. Facets concave, semicircular, the surface crenulated at the 
margin, their middle portions distinctly granular, the upper end provided 
with shallow fossa; the distal faces directed obliquely outward and support- 
ing a large covering plate at each side of the ambulacral passage. Costals 
depressed pentagonal, five to six times as wide as long, the upper angles 
obtuse. Distichals as long as the costals at the median line, those of the same 
ray interlocking laterally with each other and with the palmars above; the 
axillary rhomboidal, the arm-bearing face directed obliquely to the side, the 
opposite one horizontally. The palmars have the same form as the dis- 
tichals, but are a little shorter.. Plates of the succeeding orders more cuneate 
and less regular in their arrangement; the axillaries upwards from the 
fourth or fifth order decidedly triangular, while -the plate below is but 
little higher at one side than at the other, an arrangement which gives 
to the upper part of the trunks a waving outline. The arms are set deeply 
into the trunks, and their two or three proximal plates actually form part of 
them, being suturally attached to the sides of four or five brachials, which 
are truncated for their reception. The arms are directed obliquely upwards, 
are biserial from the second plate, thicker at the proximal ends than at the 
distal, and they are not very long, the lower ones not rising to the top of 
the crown. ‘The ventral covering of the appendages has not been observed 
in this species, being hidden by the arms, but the transverse section shows 
that it was similar to that of HL. millebrachiatus. 
Ventral disk composed of comparatively few, large, very heavy and con- 
vex plates, among which the posterior oral occupies the central part. This 
is surrounded by eight plates of nearly the same size, viz., the four other 
orals, the proximal covering pieces of the posterior ambulacra, and two 
plates, which, together with two others of equal size, form a protuberance 
enclosing the anal opening. The covering pieces are large, but decrease 
somewhat in size as they approach the appendages. There are but three 
interambulacral plates in this species, transversely arranged, of which the 
middle one, although less convex than the other disk plates, is larger than 
any of them ; it 1s hexagonal, somewhat elongate, concave at the sides, and 
it stands erect, being completely visible in a side view. 
Column similar to that of #. millebrachiatus, but without wtodleire the long 
diameter of the joints proportionally greater, and the twist more Soi than 
in that species. The joints increase in length rather rapidly near the calyx, 
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Sa Sy aes et Se ae ae ee es RE EE ORE. 
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