109 PALEONTOLOGY OF NEW- YORK. 



' Oexiis lIonoi'RL\us. 



Pal$Bontology of New- York, Vol. ii, p. 185. 



The differences indicated between this genus and Poteriocrinus are 

 constant in all the Silurian species examined ; while the general habits 

 of the animals, form of body, etc. are in all resjjects similar to the* 

 carboniferous forms of Poteriocrinus. 



The generic description of the latter genus, having been framed for 

 the Carboniferous species, would require a modifiation of the terms to 

 include the Silurian species which I have indicated by the name of Ho- 

 mocrinus, and which appear sufficiently distinct to constitute a separate 

 genus. In the present state of our knowledge, there is about the same 

 degree of difference between the species of Homocrinus and those of Po- 

 teriocrinus, as exists between some species of the latter genus and those 

 of Cyathocrinus. 



Iloiiiocriiins scoparins (n.s.\ 



Plate L Fig. 1. 



Body elongate-conical, subpentagonal above ; base comparatively large. 

 Surface granulate or granulate-stria te. Basal plates five, pentagonal, 

 longer than wide, cuneiform above. Subradial or costal plates longer 

 than wide, three hexagonal, the other two heptagonal, truncate above, 

 and supporting on the upper lateral margins a small intercalated qua- 

 drangular anal plate. First radial or scapular plates five, pentagonal, 

 wider than long ; four resting upon the upper lateral margins of the 

 contiguous subradial plates ; the fifth resting upon the subradial plate 

 on one side, and upon the intercalated anal plate on the other : its 

 vertical side adjoins the second anal plate, and the upper l^thand angle 

 is truncated by the third anal plate, giving it an irregular hexagonal 

 form with one extremely short side. The succeeding radial plates, to 

 the number of three or four below the first bifurcating plate, are qua- 

 drangular": first bifurcations equilateral. 



