ACTINOCRINID&. — 577 
large and axillary. Of the palmars only one plate is preserved, and so the 
number of arms cannot be accurately ascertained from the specimen; but to 
judge from the size of the arm openings, it is quite probable that it had an 
additional bifurcation, and the species had six arms to the ray, but not eight 
as suggested by Miller. Arm facets directed horizontally. Regular inter- 
brachials: 1, 2, 2; the first very large, rising to the top of the second cos- 
tals; those of the third range meeting the interambulacrals. Anal plate 
smaller than the radials, followed by 2, 2, and 2 plates. Ventral disk con- 
vex, composed of but few plates. The ambulacrals, which are represented 
by three large pieces over each ray, are spinous; while the orals are almost 
flat. Anal tube stout at the base, but rapidly increasing in size upwards. 
Horizon and Locality. — Chouteau limestone ; near Sedalia, Pettis Co., Mo. 
Type in the collection of S. A. Miller. 
Actinocrinus arrosus (8. A. Miter). 
Plate LV. Figs. 7, and &a, 6, e. 
1892. Blairocrinus arrosus——S8. A. Minter; Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 41, Plate 7, 
ies, Peto) os 
Syn. Blairocrinus bullatus 8. A. Mintxr; ibid., p. 41, Plate 7, Figs. 6 and 7. 
Of medium size. Calyx distinctly quinquelobate, its height equal to three 
fourths its width in well preserved specimens. Dorsal cup saucer-shaped, its 
height less than half that of the ventral disk ; the surface deeply sculptured ; 
the radial plates being strongly keel-shaped, the interradial ones provided 
with a sharp central node, leaving deep, pit-like depressions between the 
nodes and the ridges. Suture lines indistinct. 
Basal cup small, projecting but little beyond the column, and only the 
angles of the plates bending upwards; it is notched at the sutures, and tri- 
lobate in outline. Radials a little wider than long, covered with a transverse 
node. Costals as wide as the radials, but only half as long; the first quad- 
rangular ; the second pentangular and generally a little larger than the first. 
Distichals one, small, axillary, supporting apparently a single palmar. Arm 
openings twenty, arranged in pairs, and directed horizontally or slightly 
downward. The number of arms unknown. Interradial spaces subovate, 
composed at the regular sides of three plates, of which the two upper are 
quite small, and placed level with the arm openings. The anal plate as 
large as the radials, and similarly sculptured ; it supports two plates in the 
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