^4 S E. O. t'LRICH CORRELATIONS OF CHESTER FORMATIONS 



Tahlc indicating Composition and geologic Dstribution of the 



Ohara Crinoid Fauna 



Huntsville Owen County Burksville 



Dizygocrinus superstes Ulrlch x x x 



Dizygocrinus ( Globocrinus) unionensis 



i Worthen) x x x 



Platycrinus huntsvillw W. and Sp x x 



Onychocrinus distensus M. and W x x x 



Tarocrinus huntsvUUe Springer x x 



Catillocrinus carpenteri (Waehsnmth) x x x 



Vasocrinus sp x x 



Pachylocrinus propinquus (Worthen) x x 



Pachylocrinus salteri (Worthen) x x 



Pachylocrinus scoparius (Hall) x x x 



Pachylocrinus sculpt us l Worthen J x x x 



Pachylocrinus spinobrachiatus (Worthen) x x x 



Pachylocrinus renustus (Worthen) x x 



Scytalocrmus decahrachiatus (Hall) x x 



Scytalocrinus, small species (? new) x x 



Decadocrinus, large species (? new) x x 



Culmicrinus ait*, missouriensis (Shumard) x x 



Cumptocrinus cirri fcr "NY. and Sp x x 



I have never seen an)' specimens of Platycrinus from rocks older than 

 the Sainte Genevieve limestone that I could not at once distinguish from 

 the several varieties commonly united under the name P. huntsvillce. 

 Accordingly, then. I regard this Platycrinus as a characteristic Lower 

 Chester fossil, and I apply the same designation to the other crinoids 

 with which it is associated in the Upper Ohara of Alabama and Indiana 

 and in part already in the lower, or Fredonia, member of the Sainte 

 Genevieve limestone in western Kentucky. 



Age of the crinoid bed near Burksville, Illinois. — To paleontologists 

 who hold views like mine, the extraordinary similarity that obtains, as 

 shown in the foregoing table, between the crinoid fauna of the beds at 

 Huntsville, Alabama, in Owen Comity, Indiana, and in the typical Upper 

 Ohara in Caldwell County. Kentucky, and that which is found near 

 Burksville, Illinois, in beds hitherto credited to the Renault formation is 

 highly suggestive of some error in the age assignment of the latter. If 

 the facts in the case are actually as reported, I can view the resulting 

 condition only as highly disappointing. I have maintained, namely, that 

 in the evolution of organisms of multipartite composition and generally 

 complex structure, even relatively short periods, geologically speaking, 

 intervening between the first and second and between each of the suc- 

 ceeding appearances of such types in the sequence of accessible sedimen- 

 tary marine deposits must be indicated by more or less clearly recogniz- 



