578 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
first, and two in the second row. Ventral disk highly elevated and bulging 
at the outer margins, where the plates stand erect. Orals nodose, pushed 
over to the anterior side, and in the larger specimens separated by accessory 
pieces. Radial dome plates as large as the orals, strongly nodose and some- 
times subspinous, The mterambulacral plates in contact with the inter- ¥ 
brachials. Anal tube subcentral, rather large at the base. 
Horizon and Locality. — Chouteau limestone ; Sedalia, Mo. 
Z'ypes in the collection of F. A. Sampson, Sedalia. 
fvemarks. — This species is closely related to Actinocrinus (Blairocrinus) 
tryuges, if not identical with it. Miller claims the latter species has eight 
arms to the ray, and the other but four, neither of which is clearly shown 
by the specimens. However, there can be no doubt that Miller’s “ Blairo- 
crinus”’ bullatus is identical with this species. We examined a number of 
specimens from the collection of Mr. Sampson, some of which were labeled 
by Miller B. arrosus, others B. bullatus, and found that he had described the 
plumper specimens as B. bullatus and the crushed ones as B. arrosus. We 
also became convinced that the anus of this species is not so excentric as it 
appears in Miller’s figures, which represent it when pushed out of place | 
by oblique pressure, but that its position is almost central. This is clearly 
shown by Mr. Sampson’s beautiful specimen, of which we give three figures 
on Plate LV., Figs. 8a, 0, ec. 
STEGANOCRINUS Meex and Worrtuen. 
1866. Manx and Wortnen; Geol. Rep. Illinois, Vol. IL., p. 195, also ibid. Vol. TIL, p. 474. | 
1879. Zire. (subgenus of Actinocrinus); Handb. d. Paleont., Vol. I., p. 370. 
1881. W.and Sp.; Revision Paleocr., Part II., p. 149 (Proceed. Acad. Nat. Sci. Phila., p. 328). 
1889. 8S. A. Minter; N. Amer. Geol. and Paleont., p. 282. 
Syn. Actinocrinus ; SHumARD, 1855; Haun, 1860; Muzx and Wortnen, 1860. 
In its general structure resembling Actinocrinus, but the rays, instead of 
being produced into mere lobes, are formed into arm-like, tubular extensions 
or trunks, which rise to the full length of the crown, giving off armlets alter- 
nately from opposite sides. There are either one or two of these brachial 
trunks to the ray, according to species, depending on whether they take 
their origin from the costals or distichals; they were apparently rigid, and 
movable, if at all, only asa whole. The dorsal side of these appendages is 
formed by a longitudinal row of axillaries, or by a succession of syzygies, in 
which latter case the second plate of the various orders is arm-bearing. 
