264 BULLETIN 77, UNITED STATES NATIONAL MUSEUM. 



Fia. 156.— ESTHONIOPOEA CXmVATA. O AHB 6, SIDE AND BASAL VIEWS OP A NORMAL EXAMPLE, KATUEAL 

 size; C, TANGENTIAL SECTION, X20, SHOWING THE SMALL OPENING LEFT BY THE INCOMPLETE DIAPHRAGM; 

 d, VERTICAL SECTION, X8, THEOUGH POBTIONS OF TWO LAYERS, ILLTJSTEATING THE CYSTIPHEAGMLIKE 

 INCOMPLETE DIAPHRAGM; 6, ANOTHER VERTICAL SECTION, X20. ECHINOSPHERITES LIMESTONE (CI), 

 DUBOVIKI, GOVERNMENT OF ST. PETESSBUBQ, 



