144 ■ SMITHSONIAN INSTITUTION 



PLATE LXIX 



PAGE 



Figs. 1-9. Onychocrinus exsculptus Lyon and Casseday 430 



(Also on Plates LXX and LXXI) 



Figs. 1.2. The principal type specimens, from unpublished drawings made by Col. Sydney S. Lyon. 

 Author's collection. 



3. Another specimen used by Lyon in the description, additionally cleaned ; showing part of 



the tegmen, with ambulacra and perisome preserved. Author's collection. 



4. Posterior view of a specimen with rays broken off, showing form of posterior basal, and 



the strong anal tube with perisome attached to its margin. Note the extreme lateral 

 position of the socket on posterior basal in this and in fig. 8. Author's collection. 



5. Ventral view of a specimen with tegmen preserved; showing perisome, ambulacra, pos- 



terior oral and its supporting plates, and part of the anal tube. The small orals cannot 

 be identified. Author's collection. 



6. Dorsal view of a perfect crown, showing the form and proportions of the calyx and rays 



when extended. The very slender ray divisions and delicate ramules are in marked 

 contrast to those of the preceding species. Author's collection. 



7. The type of Onychocrinus monroensis M. and W., from the Keokuk limestone of Monroe 



County, Illinois — probably a young specimen of O. exsculptus. University of Illinois. 



8. A rather robust specimen of the same type as last, from the same beds at Keokuk, Iowa. 



Remnants of the very small ramules are seen in several places, and those that appear 

 larger are drawn much too large, being poorly defined in the matrix. Author's col- 

 lection. 

 g. The type of O. norzvoodi M. and W., from the Keokuk beds at Nauvoo, Illinois ; a mature 

 specimen probably of this species, having 5 IBr exceptionally in one ray. University 

 of Illinois. 



Keokuk Gr. ; Lower Carboniferous. Crawfordsville, Indiana, except as otherwise 

 stated. 



