FOSSIL CRINOIDS. 123 



the character of its ponderous arms, and without any accurate knowledge of 

 the structure of its calyx. It was said to have small infrabasals (afterwards 

 stated by Wachsmuth and Springer, Rev. Pal., I, 94, as five), and a single anal 

 plate resting upon the truncated posterior basal; and for these reasons it has 

 always been ranked among the Cyathocrinidae. Wachsmuth and Springer 

 (Rev. Pal., I, 94) described two additional species from the equivalent rocks 

 near Louisville, Kentucky, in one of which they observed a lateral opening 

 directly above the posterior basal, and between two adjoining radials; but this 

 fact attracted no special attention. Nothing was then known of any unusual 

 features of the column or axial opening. 



Investigation of the original specimens upon which these several species were 

 described, and of a considerable quantity of additional material since obtained 

 from the typical localities in New York and near Louisville, has disclosed with 

 perfect clearness the characters of the calyx; leading to the interesting result 

 that the remarkable arms of the American species belong to a calyx in no way 

 distinguishable from certain Eifel species described under the name Gasterocoma. 

 Some of the New York material above mentioned is in the American Museum 

 of Natural History, including one of the types of C. hulbosus, and some in the 

 State Museum at Albany. For the opportunity to use it in this work I am 

 indebted to the courtesy of Prof. R. P. Whitfield, since deceased, and Dr. J. M. 

 Clark, State Palaeontologist. The remainder is in my own collection. 



The genus Gasterocoma was proposed by Goldfuss (and its synonyms, Cera- 

 mocrinus and Epadocrinus, by Johannes Miiller), and afterwards fully described, 

 illustrated and discussed by Schultze (Mon. Echin. Eifelk., 95 et seq.), without 

 definite information as to the character of its arms. It belongs to the very 

 peculiar Crinoid fauna characteristic of the Middle Devonian of the Eifel Moun- 

 tains and adjacent region, which has been so ably studied, and thoroughly 

 described, in the works of Roemer, Miiller, and Schultze; and it has not hitherto, 

 to my knowledge, been recognized elsewhere. The leading characters of this 

 genus, and of the little group of peculiar Crinoids associated with it, are, (1) 

 the anus passing out through the dorsal cup below the level of the arm bases; 

 (2) horseshoe-shaped radial facets, with a dorsal canal extending throughout 

 radials and arms ; and (3) in most of them an undivided infrabasal disk, usually 

 pierced by a central axial, and four peripheral, canals. 



Comparing the calyx of the above mentioned American specimens with this, 

 it now appears that it has an anal opening lateral through the dorsal cup, below 

 the level of the arm bases, between the posterior basal and the two posterior 



