ACTINOCRINID 2. 621 
Cactocrinus ornatissimus W. and Sp. 
Plate LVILT. Fig. 3. 
1887. Actinocrinus ornatissimus —W. and Sv.; Geol. Rep. Illinois (1890), Vol. VIII., p. 163, Plate 16, 
Fig. 9 (not Plate 17, Fig. 3). 
1890. Actinocrinus ornatissimus —S. A. Mitten; N. Amer. Geol. and Pal., p. 219. 
Of medium size, specimens of light color. Dorsal cup depressed, 
semiglobose; height equal to half its width; plates delicate and highly 
ornamented, but not convex; suture lines difficult to see. The surface is 
marked by a system of sharply elevated, very prominent rounded ridges, 
passing from plate to plate, and meeting in large stellate clusters in the 
interbrachial spaces; those following the middle of the radial series are 
widest, and pass from the basi-radial suture into the arms; they increase in 
width toward the arm bases, and divide the surface into five well defined 
pentangular fields. Scattered between the ridges there are bead-like nodes, 
and the ridges are more or less undulating. | 
Basals short; forming a small rim, which is slightly notched at the 
sutures. Radials and costals decreasing in size in ascending order, all wider 
than long; the first costals quadrangular with convex sides; the second 
generally heptangular. Distichals and palmars one, except in the outer 
divisions of the rays, in which the first palmar is succeeded by two to three 
cuneate plates, which support an arm; while the inner ones are axillary, 
and followed by two post-palmars with two arms; there being normally 
three arms to each main division, and six to the ray. Arms long, moderately 
stout, rounded on the back, their tips curved and folded inward; they are 
composed at their bases of cuneate pieces, which interlock and gradually 
become biserial, every second to fourth joint of both series being long, and 
bearing a conspicuous, tooth-like node. The intervening joints are much 
shorter, and connected longitudinally by waving sutures. Pinnules closely 
packed and contiguous; composed of short joints, and each one armed with 
a short hook. Interbrachials comparatively large, occupying fully one half 
of the whole interbrachial space, and rising to the middle of the second 
costals; there are two plates in the two succeeding ranges, which are fol- 
lowed by the interambulacrals. First anal plate as wide as the radials, 
and often higher, supporting 2, 3, and 2 plates. Interdistichals generally 
three, with frequently a small interpalmar. Ventral disk short hemispheri- 
