Spirifer raricosta (Conrad) Billings 



Page i8i 



2 2, 23 Views of Billings's original specimens 



Grande Grevc limestone. Grande Greve 



Spirifer sp. 



Page 183 



24, 25 Ventral and dorsal valves of an implicated species with well defined 

 fold and sinus 

 Grande Grlve limestone. Grande Greve 



317 



