160 



PI.A.TK IV. 



Page. 



Uatostotna rariubilr Ulricli 150 



1. Cross section, showing an unusual (It'levopnient of cystoid 



diaphragms, x IS. Ballstown, Ind. 

 la. Longitudinal section of a specimen having an unusually deep 



mature region, x IS. Weisburg, Ind. 



