716 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
ftemarks. — This species is of the type of P. discoideus, but the dorsal cup 
is deeper, the facets shorter, semi-circular instead of lyre-shaped, and the 
limbs do not extend above the height of the facets. It also departs from 
that species in the’ ornamentation, and comes from a higher horizon.: The 
description is made from the type specimen shown in the Iowa Report, Plate 
8, Fig. la, which is somewhat crushed at the base; figure 1d, on the same 
plate, is from a different specimen, which may be of another species. 
Platycrinus Gorbyi S. A. Mituzr. 
Plate LX VILL. Fig. 15. 
1891. S.A. Mitter; Geological Survey of Missouri, Bull. 4, p. 15, Plate I, Fig. 14, 
In the form of the dorsal cup and the proportions of the plates closely 
resembling P. cavus ; but the ornamentation is coarser, and the radial facets 
smaller, more projecting, and their faces flat instead of concave. 
Dorsal cup decagonal in a dorsal aspect; the basal disk projecting dis- 
tinctly below the lower margins of the radials; the sides of the latter ex- 
panding rapidly so as to form a flat, spreading cup. The plates moderately 
strong; their surface covered with two irregular rows of rather large nodes, 
of which the outer ones are frequently confluent, and form an undulated 
ridge around the beveled edges of the plates. The basi-radial and inter- 
radial sutures deeply channeled. Basal disk regularly pentagonal, flat around 
the margin, with a slight funnel-shaped depression in the middle; the proxi- 
mal stem joint circular; interbasal sutures obsolete. Radials one third 
wider than long; the ends of their limbs almost on a level with the upper 
ends of the facets. The facets semi-ovate, and but slightly notched at the 
upper end; they occupy about a third of the width of the plates, and not 
quite one half their length. All other parts of the species unknown. 
Horizon and Locality. — Lower Burlington limestone, Burlington, Iowa, 
and Sedalia, Mo. 
Type in the collection of Mr. R. A. Blair of Sedalia. 
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