Plate XI. 



EXAMPLES OF STATE QUARRY SYNTHETODONT DEN- 

 TAL PLATES. 



All figures reduced slightly less than the natural size. 



The smaller plates with more or less distinct sulci, such as 

 the originals of Figs. 6, 8, 10, 15, 22, 23, 25, etc., are determinable 

 as belonging to Synthetodus trisulcatus, the larger ones, which 

 are apparently simple, as somewhat imperfect examples of S. 

 calvini; all from the State Quarry beds near North Liberty, in 

 Johnson county, Iowa. 



Originals preserved in the Museum of Iowa State University. 

 Pages 231 and 233 



336 



