442 PALEONTOLOGY OF ILLINOIS. 



each, for the reception of the second radials, very shallow, 

 and about half as wide as the upper margin. Anal plate 

 wider below than any of the first radials, but narrowing; 

 upward; provided with a very obscure angle at the middle 

 of the under side, so as to present a subpentagonal outline. 

 (Arms and vault unknown.) 



Surface ornamented with comparatively strong, rounded 

 costa?, wider than the furrows between. On the base these 

 are arranged in three divaricating series, the lateral costa3 

 being parallel to the lateral margins, and the divergence 

 upward. On the radial and anal plates there are 7 or 8 of 

 these costse which run nearly vertically and parallel, the 

 lateral ones, however, converging above, so as to leave 

 Bmall triangular spaces on the superior lateral corners, on 

 which there are a few short costse not properly connected 

 with the others* 



Hight of body, 0.30 inch; breadth, 0.37 inch. Costa? 

 on radial plates, six or seven in the space of 0.20 inch. 



In the coarseness of its costae this species is nearest like I), strittlux, 

 of Owen and Shnmard, but it differs in having its costse rather smaller, 

 more rounded and separated by furrows, distinctly smaller than the 

 costse themselves, which are also without the numerous little asperities 

 seen on those of D. striatus. It is also a smaller, shorter species, with 

 a much more depressed or nearly flat base. 



Locality and position Upper division of the Burlington group, at Bur- 

 lington, Iowa. Mr. WACHSMUTH'S collection. 



GENUS CALCEOCKQs T US, Hall. 



Calceocrinus, Hall, 1852. Palaeontology, N. T., Yol. II, p. 352. 



ICheirocrinus, Hall, 1860. Thirteenth Report Regents University, If. T., (State Cab., N. H.) p. 122 

 (not Cheirocriniis, Eichwald, 1856, Bull. Soc. des Nat. Mosc. Vol. 29. p. 128, and Leth. Ross., Yol. I, p. 

 645, PL xxxii, Fig. 1, a, b., I860.) 



Dr. SHUMARD has suggested, in his catalogue of North American 

 Palaeozoic iTchinodermata ( Trans. Acad. Sci., St. Louis, ii, p. 358, 

 1866), that the curious genus of Crinoids described by Prof. HALL, in 

 the Report of the Regents, cited above, under the name Ckeirocrinw, 

 may be the same type for which Prof. HALL had previously proposed 



