Geol.— Vol. I.] SMITH— LYTOCERAS AND PHYLLOCERAS. -145 



Table of Stages of Growth. 



Measurements of Cross-section. 



Diameter . 



Epkebic. 



4/8 

 coils 



mm. 



8.60 



Genus Phylloceras Suess. 



Phyllocevas, as defined and restricted by Zittel and Steinmann, comprises 

 involute, compressed, high-whorled species, with smooth sides, rounded 

 abdomen, and narrow umbilicus. The septa are branching, leaf-like, have 

 three or four lateral, and at least as many more external auxiliary lobes. 



2 August 31, 189S. 



