630 



NORTH AMERICAN INDEX FOSSILS. 



drawn out into a thin flat carina, which may be very broad and 



entire or broken up into rude spines. Siluric. 



86. E. Valerius (Billings). (Figs. 851, hj\ 852.) Siluric. 



Shoulder angle drawn out into a broad hollow flange with com- 

 paratively smooth edge, and smooth base without revolving ridge 

 around the umbilicus. 



Niagara of Waldron, Indiana, Guelph of Canada, Ohio, and 



Fig. 852. Euomphalopteris Valeria, 

 umbilical view. (After Whiteaves, Pal. 

 Foss., III.) 



Fig. 853. Euomphalopteris elora , 

 apical view. (After Whiteaves, Pal. 

 Foss., III.) 



New York, and Upper Monroe of Michigan. 



87. E. elora (Billings). (Fig. 853.) Siluric. 



Similar to preceding, but smaller and with the shoulder angle 

 drawn out into a series of flat spines. 



Guelph of Ontario. 



XXIX. Scalites Emmons. 



Spirally coiled, with whorls embracing more or less strongly, 

 shoulder flat and horizontal, base of whorl drawn out into a short 

 anterior notch. Ordovicic. 

 88. S. angulatus Conrad. (Fig. 854, a.) Ordovicic. 



Spire forming about one half of the length of the shell, sutures 

 canaliculated, angle slightly acute, sides of whorl nearly perpen- 

 dicular ; shoulder with obliquely backward bending striae. 



Chazy limestone of New York, etc. 



