160 



ruMK IV 



Pa Re. 



liatostoma variahiU- Tliicli 150 



1. Cross section, sliowiiifr an nnnsiial (It'li-vdiinicnt of cystoid 



diaphragms, x IS. Ballstown, Ind. 

 la. Longitudinal section of a specimen liaving an unu.sually deep 



mature region, x 18. Weisburg, Ind. 



