FOSSILS OF THE NIAGARA GROUP. 361 



Formation and Locality. — In the' Racine limestone of the Niagara group, 

 Racine, Wisconsin. 



The two following species I place among the Cystidse with some hesita- 

 tion, notwithstanding the unsymmetrical form and peculiar character of 

 one of them, which closely resembles in its general features the Holo- 



CYSTITES. 



In many of the Crinoidea proper, we find the plates arranged in suc- 

 cessive order of one, two or three following each other directly in what 

 are termed the radial series ; while between these rays are interradial 

 plates in the usual order of a larger one below, which supports two plates 

 in the second range, followed by a like or greater number in the third 

 range. 



In the Cystideans of the described genera the plates do not follow this 

 order of arrangement, and cannot be separated into radial and interradial 

 series, according to the usual mode in Crinoidea. In the Cystideans, 

 where there are a considerable number of plates, they are arranged in 

 alternating order, so that each succeeding range above the second have 

 their lower margins more or less pointed and inserted partially between 

 and resting upon the sloping upper faces of those of the preceding range. 

 This feature is seen conspicuously in Holocystites, where the plates are 

 numerous. It sometimes happens, that owing to a curving form the 

 plates follow each other in direct order. 



Among the specimens which I had provisionally placed among the 

 Holocystites is a small species of unsymmetrical, sub-clavate form, having 

 the two lower ranges of plates alternating as in that genus, while above 

 these the plates are arranged in consecutive order, until we reach the 

 last range, where every alternate one is omitted, thus producing a con- 

 traction of this part. 



Since this form cannot be consistently referred to any described genus, 

 I propose the name Crinocystites. 



GENUS CRINOCYSTITES, n. g. 



Body elongate, composed of plates of sub-equal size. The number of 

 basal plates undetermined. These support five hexagonal or hep- 

 tagonal plates in the second range, and upon the upper edges of 

 these, three plates of similar form follow in direct succession; and 

 upon the third is a fourth plate supporting one or two arms. 



Between the upper sloping faces of the plates of the second range, 



Cab. Nat. 46 



