570 THE CRINOIDEA CAJilERATA OF NORTH AlIERICA. 



(?) Actinocrinus chouteauensis S. A. Miller. 

 Plate XLVL Figs. 11a, h. 



1892. (?) Actinocrinus cliouteauemis — S. A. MiiLEK ; Adv. Sheets 18th Rep. Geol. Surr. Indiana, p. 18, 

 Plate 3, Kgs. 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 Uttle 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. Eegular 

 interradials 4 to 5 ; decreasing gradually in size upwards. Anal jjlate 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. Arabulacral plates three, large, two of them of a second 

 order. Interatnbulacrals three or four, in contact with the interbrachials. 

 Anal tube subcentral, its length imknown. 



Horizon and Locality. — Eeferred 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. 



TyjJe 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. 



