160 GEOLOGICAL SURVEY OF THE TERRITORIES. 
or four double corallites. In each of the double calyces there are two 
columelle, from which the rays diverge as usual, the border of the calyx 
being elongate or suboblong, and havin gonly a slight constriction at the 
middle to indicate its double character. Upon the calycular side of the 
corallum these double corallites appear to have been cases of spon- 
taneous fission, and they possibly were such; but the under side of the 
example (which contains about 60 millimeters length of the distal por- 
tion of the corallites and not the earliest or basal portions) shows them 
to have possessed the same general character at that stage of their 
growth which they do at their termination. In other words, they seem 
to have made no progress in separation into two distinct corallites 
while they were growing 60 millimeters in length. Figs. 6a and 6b 
show the upper and under sides, respectively, of that portion of tbe 
example in question which contains the three double corallites. 
“ECHINODERMATA. 
Genus PLATYCRINUS Miller. 
PLATYCRINUS BONOENSIS White. 
Plate 40, fig. 5a. 
Platycrinus bonoensis White, 1878, Proc. Acad. Nat. Sci. Philad., p. 30. 
Body of the ordinary cup-shape, moderately deep; base shallow basin- 
shaped, concave at the middle of the under side, or appearing to be 
so in consequence of the presence of a moderately broad and strong 
circular ridge which surrounds the central portion of the base, but 
which does not extend outward quite to the borders of the base. First 
radial pieces about as long as wide, having the shape and character- 
istics of outline usual in cup-shaped bodies of this genus, scarcely more 
convex than the general convexity of the body; facet for the articula- 
tion of the second radial pieces shallow; second radial pieces very 
small, and transversely subrhombic in outline. Upon the second radial 
pieces the rays divide into two secondary rays, the first piece of each sec- 
ondary ray articulating upon the second radial, but also abutting in part 
upon the upper border of the first radial. Thesecondary rays consist of 
two pieces each, upen the upper one of which they again divide, the outer 
arms of each division from that point upward continuing simple to the 
end, while the two minor subdivisions of the ray again divide into two 
arms each upon the second piece above the first division, beyond which all 
the arms of the whole ray, six in number, aresimple, making thirty arms 
for the whole body. The arms are moderately slender, comparatively 
short, and for the first two or three pieces above the last bifurcation they 
consist of single wedge-shaped pieces. The only examples yet discovered 
have their arms so closely folded together that the pinnules are hidden 
from view. With the arms thus folded the whole animal had an obovate 
form. The stem, near the body, is moderately strong and slightly ellip- 
tical in outline of transverse section; surface nearly smooth, or faintly 
corrugated; the part of the body above the calyx and within the arms 
unknown. 
Height of calyx to the top of the first radial pieces, 8 millimeters ; 
greatest breadth of the same, 10 millimeters ; height from the base of 
the calyx to the top of the arms, 26 millimeters. 
This species resembles P. cequalis Hall, as figured by Meek & Worthen 
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