PLATE XVIII. 



Page 

 Ptychocrinus pabvus (Hall) - ; 199 



Fig. la. View of the specimen described by S. A. Miller as Glyptocrinus angularis 



(?). (Coll. S. A. Miller.) 

 1/;. Another specimen with the arms better preserved (i). (Same collection.) 

 2. The specimen described by Wetherby as Glyjitocrinus (Meteocrinus) gracilis 



(f). (Coll. Mr. Vaupel.) 



Ptychocrinus splendens (IMiller) 198 



3:{. The type specimen (J). (Coll. S.A. Miller.) 

 3h. Another specimen (J). (Same collection.) 



Thysaxocrinus liliiformis Hall 192 



4. The type specimen. (Museum of Cornell University.) 



Thysanocrinus occidentalis (Hall) 194 



5a. Side view of calyx (|). (After Hall.) 

 ob. Posterior view of calyx. (After Hall.) 

 5c. Dorsal aspect of calyx (f ). (After Hall.) 



Thysanocrinus inornatus (Hall) 193 



6'i. Anterior view of calyx. (Coll. W. F. E. Gurley.) 



6''. Posterior view of same specimen. 



(ip. Ventral aspect of same (^). 



Qd. A young specimen, probably of this species. (Same collection.) 



Thysanocrinus brachiatus (Hall) 195 



7. Dorsal aspect of the type specimen ; the matrix removed so as to show the 

 pinnules and the arrangement of the plates. (Am. Mus. Nat. Hist. N. Y.) 



Idiocrinus elongatus W. and Sp 203 



8a. The type specimen; side view. (Coll. W. and Sp.) 

 8/'. Ventral aspect of same (|*). 



8c. Another view of the ventral disk (f). (Anal side to the right. Coll. W. 

 and Sp.) 



Idiocrtxus ventricosus W. and Sp 205 



9a. The type specimen ; side view. (Same collection.) 



96. Dorsal aspect of the dorsal cup. (Anal side to the left. Same collection.) 



Idiocrinus immaturus (Hall) . , 206 



lOirj. The type specimen; anterior view. (Am. Mus. Nat. Hist. N. Y.) 



lOi. Posterior view of same. 



10c. Dorsal aspect of same. (After Hall.) 



Idiocrinus tennesseensis (Worthen) 206 



11. The type specimen. (Illinois State Collection.) 



