SOME NEW AMERICAN FOSSIL CRINOIDS. 



During somewhat protracted researches upon the fossil Crinoids, there 

 have come into my possession a considerable number of specimens belonging 

 to species hitherto un described, and also much excellent material illustrative 

 of species imperfectly known, or described without figures. Most of these 

 remain to be dealt with in due course of systematic work. The obligation of 

 describing some specimens of a remarkable new species entrusted to me for that 

 purpose, already too long delayed, tempts me to publish along with it some others 

 which are specially notable, either by way of extending the stratigraphic or 

 geographic range of certain groups, illustrating species hitherto unfigured, or 

 throwing light upon unsettled questions of classification. These objects, which 

 appeal to me with more interest than the mere description of new species, and 

 which I am sure are of greater service to science, have induced the present 

 contribution. 



CAMERATA. 



DIMEROCRINIDAE. 

 DiMEROCRiNUS Phillips apud Miu-chison. 



1836. Silurian System, p. 674, PI. XVII, figs. 4, 5. 



1881. Dimerocrinus Wachsmuth and Springer, Revision of the Palaeocrinoidea, II, 197; III, 101. 



1897. Thysanocrinus Id. N. Amer. Crin. Cam., 190. 



This hitherto exclusively Silurian genus was proposed by PhiHips without 

 definition, but upon two species, D. decadactylus and D. icosidactylus, of which 

 he gave a brief description and figures bj' which they can be easily recognized' 

 as familiar forms at Dudley, England; specimens of them are found in the 

 principal museums, under Phillips's names. From these species the generic 

 characters are readily determinable, but were not correctly understood until 



