POTERIOCRINID^. POTERIOCRINUS. 



2. Family. POTERIOCRINID^. 



The genera in this natural group are less numerous than in the preceding. It 

 comprises l^oteriocrinus, Taxocrinus, and Synhathocrinus. 



The different species composing this, and the preceding family are found in a fossil 

 state but none have hitherto been discovered in the recent seas. 



The lower series of plates surrounding the bodies of the Poteriocrinidm appear to rest 

 on, and articulate on to the superior columnar joints, which latter also articulates by 

 radiating strias to the concealed dorso central plates. 



Genus 1. POTERIOCRINUS. (Miller.) 



Etym. noTHPlON (Potherion) a drinking cup, from the supposed resemblance the 

 armless body bears to a common conical wine glass. All the known species of Poterio- 

 crinus occur only in the mountain limestone formation. 



Definition.— Dorso-central plate tripartite ? 1 ; first series of perisomic plates, five, (2;) 

 second series, five (3;) third series, or ray-bearmg plates, five, (4,) with two or three 

 intennediate plates, a, b, c. 



