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PLATYCRINID^. CYATHOCRINUS. 



Genus V. CYATHOCRINUS. (Miller.) 

 Etym. KYAeos (Cyathos,) a Cup. 



Definition. — Dorso-central plate quinque-partite, (1); on which rest the first series 

 of perisomic plates, five in number (2); second series six, five of which bear the rays (3); 

 with one intermediate or non-ray-bearing plate (a). 



The ray-bearing plates in the figure of the dissected skeleton are those of the 

 C. geometricus, and are more elongated above the ray articulations than in the typical 

 species. 



All the species of Cyathocrinus are of small size, and none of them appear to have 

 been abundant in the localities in which they are found. 



1. Species. Cyathocrinus planus. {Miller.) 

 PI. VII. fig. 4, a, b, c, d, e. 



Definition. — Dorso-central plate quinque-partite, forming a saucer-shaped concavity, 

 on the edges of which rest the first series of perisomic plates five, four of which are 

 pentagonal, and one hexagonal ; second series six, five of which bear the rays. The 

 non-ray-bearing plate is hexagonal, and invariably occurs on the hexagonal plate of 

 the first series. 



