60 SMITHSONIAN INSTITUTION 



PLATE XXVII 

 (All figures natural size except where otherwise gtated) 



PAGE 



Figs. 1-8. Forbesiocrinus wortheni Hall 253 



Fig. I. The type, dorsal view; drawn after additional preparation exposing outline of basal plates 

 not shown in original figure ; inf rabasals broken away and axial opening obscured by 

 matrix. The specimen is vertically compressed, and shows the broad, flat rays and 

 abundant interbrachials of the species. It is a very mature individual, with maximum 

 development of interbrachials. University of Illinois. 



2. Similar view of another specimen with a few proximal stem joints attached, and showing 



tendency of anal plates to form a median series. Author's collection. 



3. Mature specimen, laterally compressed ; showing stem beyond the enlargement, and arms 



infolding beyond fifth division; anterior view. Author's collection. 



4. Less mature specimen, vertically compressed; dorso-anterior view. Author's collection. 



5. Posterior view of similar specimen, showing anal plates. Author's collection. 



6. Specimen from Nauvoo, Illinois ; right posterior view. Author's collection. 



7. Young specimen from Niota, Illinois ; left posterior view. Author's collection. 



8. Mature specimen from Jersey County, Illinois ; posterior view ; showing profuse develop- 



ment of interbrachials. Type of Forbesiocriinis viacadamsi Miller and Gurley. 

 Their figure in Bull, g. 111. St. Mus., PI. V, fig. i, is not correct as to the basal plates. 

 University of Chicago. 



Keokuk limestone; Lower Carboniferous. Keokuk, Iowa, and various localities on 

 Mississippi River. 



