fo 
PLATYCRINIDZ. 719 f 
Original type said to be in the White collection at Ann Arbor, Mich., but 
not certainly identified. 
fiemarks. — Our description was made from the quite perfect specimen 
figured on Plate LXVI., Fig. 4, which we have identified as belonging to this 
species, although much smaller than Hall’s type, and the specimen figured 
by Miller as the type of P. sulcatus. The specimen figured by Whitfield as | | 
Hall’s type is somewhat imperfect in the basal disk; the very large pentapet- ! 
alous opening in the centre is due to accident, as no Platycrinus in its 
normal condition had an opening in the base for the central canal of any 
such size or shape as the figure shows. The species is interesting as being 4 
the first authentic Platycrinus in America in which a long anal tube has : | 
been observed. It is plainly shown in our specimen, but is broken off just 
within the tips of the arms, and does not appear from the view given in | 
our figure. | 
EKUCLADOCRINUS Mezerx (emended W. and Sp.) | 
1871. Mexrx; U. 8. Geol. Survey of Montana by Hayden, p. 373. | 
1878. W. and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 248, and 1881, Revision, Part IT., p- 76 (Proceed. 
Acad. Nat. Sci. Phila., p. 250). 
1890. S.A. Minter; North Amer. Geol. and Palsont., p. 244. | 
Syn. Platyerinus (in part) Hann 1858; Wurre 1862. i 
Construction of the dorsal cup, ventral disk and column, as in Platycrinus, 
but the brachials extended outward and forming large tubular appendages | \ 
or arm trunks, which pass out from the calyx, and give off the arms alter- | 
nately from opposite sides. These trunks are extensions of the calyx, com- | 
posed of a greater or less number of successive orders of brachials, of two 
plates to each order; they are roofed over by large, rigid, or nearly rigid, 
covering plates throughout their whole length, forming a good sized tubular } 
passage underneath, which communicates with the inner part of the calyx. 
There are generally two such trunks to the ray, which are in contact to near | 
the top of the palmars, and support a single arm from every axillary. Some | | 
species, however, have but one appendage to the ray, and their arms are | 
given off in clusters of four or more from every second brachial. The arms |, 
are of moderate size, biserial and pinnule-bearing, but were apparently short, 
and the lower ones did not rise to the top of the crown. lj 
Distribution. — Restricted, so far as known, to the upper part of the i 
Burlington and the lower beds of the Keokuk groups of America. | 
Type of the genus: Hucladocrinus montanensis Meek. 
