72 PK0CEEDING8 OP THE ACADEMY OF 



Locality and position. Lower division of the Burlington group, at Burling- 

 ton, Iowa. Lower Carboniferous. Mr. Wachsmuth's collection. 



Erisocrincs Whitei, M. and W. 

 Body of moderate size, very much depressed, or almost dish-shape, below 

 the top of the first radials, being about three times as wide as high. Base 

 very small, and entirely hidden by the slender, round column, when it is at- 

 tached. Subradials small, forming together a nearly flat pentagonal disc. 

 First radials comparatively large, thick and presenting a general quadrangular 

 outline, there being scarcely any visible angle at the middle of the under side, 

 which is distinctly shorter than the straight transverse upper edge, and about 

 as long as the divergiuglateral margins. Second radial pieces as large as the 

 first, which they equal in breadth ; broadly rounded on the outer or dorsal 

 side, pentagonal in form, and each supporting on its superior sloping sides 

 two arms, thus making ten to the whole series. Arms simple from their ori- 

 gin, flat on the outside, and composed of quadrangular pieces, the first of which 

 is nearly as long as wide, and the others about half as long as wide, with 

 scarcely any tendency to assume a wedge shape. Surface merely finely gran- 

 ular. 



Height of body to the top of first radial pieces, measuring to their inner 

 edges, 0-14 inch; breadth, 0-.40 inch; breadth of column, 0'G8 inch. 



This species will be distinguished from the last by its more depressed body, 

 which has its under side between the top of the first radial pieces and the 

 column, slightly convex in outline, instead of concave, which results from the 

 greater prominence of the basal and subradial pieces of the latter. The spe- 

 cies under consideration likewise has its radial pieces proportionally wider, 

 particularly the second radials, which also differ in being broadly rounded 

 instead of angular on the dorsal side, and not constricted on their lateral 

 margins. Its arm pieces are also flat, instead of convex, on their outer 

 side. 



Owing to the fact that the column entirely hides the very small base of this 

 species, and the sutures between the subradials, or first range of pieces around 

 the summit of the column, are rather obscure, and really look as if there were 

 only three instead of five of these pieces, we were led to suspect that these 

 might be the basal pieces, which would remove the species entirely from the 

 genus Erisocriiius. On removing the column, however, we have been able to see 

 what we believe to be five minute basal pieces within the first series surround- 

 ing the end of the column, which would necessarily have to be succeeded by 

 five pieces in the next range. Hence, we think we can scarcely be mistaken 

 in supposing the appearance of only three suture lines between the plates we 

 regard as the subradials, as merely an abnormal condition, resulting from two of 

 the suture lines being anchylosed, or accidentally obliterated. This supposi- 

 tion is also strengthened by the near specific relations between this and the 

 last described species, in which all the basal, subradial and other plates are 

 clearly and distinctly seen. 



In case our genus Erisocrinus is not distinct from Fhilocrinus, with which we 

 have already suggested it may be identical, then the names of the species here 

 described will have to be written Philocriniis antiquus and P. Whitei. 



The specific name of this species is given in honor of Dr. C. A. White, the 

 able State Geologist of Iowa. 



LocalUy and position. Upper division of the Burlington Group, at Burling- 

 ton, Iowa. Lower Carboniferous. Mr. Wachsmuth's collection. 



Genus CALCEOCRINUS, Hall. 



Calceocrinus, Hall, 1852. Palaeontology N. Y. Vol. 11, p. 352. 



? Clieirocrinus, Hall, 1860. Thirteenth Report Regents University N. Y. (State 



Cab. N. H.), p. 122 ; (not Clieirocrinus, Eichwald 185G, Bull. Soc. des Nat. 



Mosc. vol. 29, p. 123, and Leth. Ross. vol. 1, p. 645, pi. xxxii, fig. 1, a, b., 



1860). 



[April, 



