BATOCRINID^. 461 



Arms in pairs, bifurcating on a minute axillary, which occupies the same 

 face with the proximal arm plate ; they are rounded and composed of rather 

 short pieces, of which in the upper portions of the arms every third or 

 fourth plate is extended laterally into a small node or short spine. Iriter- 

 brachials three ; the first twice as large as the others, higher than wide, and 

 with concave sides ; the two of the second row long and narrow. Anal 

 area distinctly rounded, forming a low longitudinal ridge, with a deep groove 

 at each side. The first anal plate is generally a little narrower than the 

 radials, and followed by a vertical row of three or four higher anals, quad- 

 rangular in outline, which support a subcircular mammilloid protuberance 

 containing the anus. Ventral disk highly convex, somewhat inflated ; the 

 posterior oral and the first radial dome plates extended into long, slender 

 spines, the former central, and surrounded in mature specimens by about 

 eleven convex pieces of nearly equal size, among which the smaller orals, if 

 represented at all, cannot be identified. Similar pieces surround the radial 

 spines, which enclose secondary radial plates. Anus at midway between the 

 central spine and the arm regions ; facing laterally. Column moderately 

 small, composed near the calyx of narrow and wide pieces alternately 

 arranged. 



Horizon and Localiti/. — Upper part of the Upper Burlington limestone, 

 Burlington and Pleasant Grove, Iowa. 



Type in the (Worthen) Illinois State collection. 



Dorycriniis intermedius (M. and W.). 

 Plate XLIY. Fig. 1. 



1S68. Dorycrinus qaiaquelobus, var. intermedins — Meek and Worthen ; Proceed, Acad. Nat. Soi. Pliila. 

 p. 346, and Geol. Rep. IlHnois, Vol. V., p. 385, Plate 10, Fig. 4. 



Intermediate between Dorycrinus quinquelohus and D. mississippiensis, dif- 

 fering from the former in its larger size, the more abrupt spreading of the 

 dorsal cup, the different form of the basals, and the much greater length of 

 its spines ; from the latter in having invariably but two arm openings in the 

 antero-lateral rays ; and from both of them in the enormous size of its 

 column. 



Dorsal cup rapidly and uniformly spreading from the bottom of the radi- 

 als to the arms ; base broadly truncated, slightly projecting, and rounded at 

 the lower margin ; the interradial spaces moderately depressed at the arm 



