Plate VIII. 



EXAMPLES OF STATE QUARRY CTENODIPTERINE 



DENTAL PLATES. 



All figures very nearly of the natural size. 



The greater number of specimens selected for illustration in 

 this Plate (all except Figs. 16, 20, 29, 34) are determined as 

 belonging to Concho dus variabilis, sp. nov., and form a repre- 

 sentative series, showing the wide range of variation exhibited 

 by the detached dental structures, and with evanescent traces 

 of coronal plications (seen especially at the bottom of Figs. 

 13, 15, 28, 33, etc.). The four exceptional figures are probably 

 worn or otherwise imperfect specimens of Synthetodus calvini, 

 all from the State Quarry beds near North Liberty in Johnson 

 county, Iowa. 



Originals preserved in the Museum of Iowa State University. 

 Pages 230 and 233 



324 



