[EndocerasJ dui)\ex,^^ Wahlenbery et auctt. 



397 



measured the septa are 6 lines apart at a place where the 

 diameter is 16 lines, while thej are only 4 lines distant where 



Fig-. 1. 



Endoceras Wahlenhergi. — a, portion of tlie septate part of the sliell (nearly 

 one third of it), with some of the smooth inner shell-layer remaining, 

 natural size (s, siphuncle) ; h, portion of the test of another specimen, 

 natural size ; c, part of section from fragment of a large specimen, 

 showing siphuncle (s) and sheath (sA), natural size ; d, section and 

 siphuncle of young individual, natural size ; e, diagram to show 

 average rate of tapering of the species. 



