53 



The vault is convex, most veiiticose on the side opposite tlie 

 azygous area. It is fully as large as tbe calyx and bears a very 

 small subcentral proboscis. It is covered with rather lari;e, polyg- 

 onal, convex plates, and is slightly depressfd in the interi-adial 

 reas. 



This species somewhat resembles in form, B. spcr<j('iieiish, but 

 differs in the interradial and azygous ai-eas, beside that is a 

 twenty armed species while this has only eighteen. It will not be 

 mistaken for any hitherto described. 



Found in the Warsaw group, in Washington county, Indiana, 

 and now in the collection of Wm. F. E. Gurley. 



