222 PALAEONTOLOGY OF ILLINOIS. 



and merely published figures on a separate supplementary plate, with the name 

 OUacrinus printed upon it, but in addition to this he did not, in his little work, 

 consistently follow the binomial system of nomenclature. Some of his names 

 are binomial, it is true, while in other instances he has such names as " Mitra 

 rugoso qwinque perforata," " Genus Sitnlaria triangulariformis," etc. Hence 

 the rule of priority should probably not be regarded as applicable in his case. 



The proposed genus Acanthocrinus of Roemer, seems to be related to Gil- 

 bertsocrinus,. but if we have correctly understood the arrangement of the arms 

 of the former, it is distinct, and more nearly allied to Rhodocrinus. 



So far as we know, the group under consideration seems to be almost entirely 

 confined to the Subcarboniferous rocks, both in this country and England. 

 We know of but a single species (Trematoc7-inus spw/igerus, Hall, found in the 

 Hamilton group of New York) from any other horizon, and it is worthy of note 

 that this species departs in some respects from the other known species of this 

 group, and may belong to another genus. 



Subgenus GONIASTEROIDOCRINUS, L. and C. (See p. 219.) 



GlLBERTSOCRINUS FISCELLUS, M. and W. 



PI. 15, Fig. 5. 



Trematocrinus fiscellus, Meek and Worthen, Sept., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 383. 



Gilbertsocrinus (Goniasteroidocrinus) fiscellus, M. and W., Aug., 18C5. lb., p. 167. 



Body short subcylindrical, longer than wide, rounded and 

 concave below, and nearly flat above; sides rising almost ver- 

 tically to near the summit, where they curve outward. Plates 

 subgranulose, and all convex, those of the subovate interradial 

 spaces less prominent than the rays, and showing a very slight 

 tendency to develope obscure radiating ridges near the edges; 

 sutures distinct. Base small, somewhat concave, obscurely 

 pentagonal, and included within the concavity of the under 

 side ; columnar facet comparatively large, or occupying nearly 

 the whole area of the base, obscurely marked by radiating 

 striae, and provided with a small, pentagonal, star-shaped cen- 

 tral opening. Subradial pieces nearly as wide as long, trun- 

 cated, and narrower above than below, subquadrangular in 



