O70 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
(P) Actinocrinus chouteauensis S. A. Mitter. 
Plate XLVI. Figs. 11a, 6. 
1892. () Actinocrinus chouteauensis —S, A. Minter; Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 18, 
Plate 3, Figs. 9 and 10. 
Of medium size. Calyx as wide as high, the dorsal cup three times as 
high as the disk, pentangular at the arm bases; the sides very slightly con- 
vex to the top of the costals, then rapidly spreading to the arms. Plates 
without ornamentation, convex and a little tumid ; the suture lines depressed. 
Basal cup moderately large, gradually spreading ; the interbasal sutures 
well defined ; axial canal large. Radials as long as wide (one of them in the 
type a little wider than long) ; the lower end of the two heptagonal ones dis- 
tinctly angular. Costals considerably narrower than the radials, nearly as 
wide as long; the first hexangular; the second generally hexangular, and 
partly smaller than the first. Distichals one, small, twice as wide as long. 
Palmars one preserved in the specimen, very short. Arms apparently four, 
the arm openings directed obliquely upwards and arranged in pairs. Regular 
interradials 4 to 5; decreasing gradually in size upwards. Anal plate as 
long as, but narrower than, the radials, supporting 2, 4, and 2 plates. Ven- 
tral disk convex, the plates large and nodose. Orals large, asymmetrically 
arranged, the posterior one smaller than the others, and pushed in deeply 
between them. Ambulacral plates three, large, two of them of a second 
order. Interambulacrals three or four, in contact with the interbrachials. 
Anal tube subcentral, its length unknown. 
Horizon and Locality. — Referred to the Chouteau limestone, near Sedalia, 
Mo.; but the color of the fossil and of the matrix leaves but little doubt that 
it came from the Lower Burlington. 
Type in the collection of F. A. Sampson. 
Remarks. —This species was described from a single specimen, which had 
only the calyx preserved, and the ventral disk was partly covered by matrix. 
On removing this, we found Miller’s ideal figure of the disk (his figure 10) 
to be incorrect, inasmuch as the so-called large plate adjoining the posterior 
oral is only the base of the anal tube, as shown by our figure. 
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