1/2 NORTH AMERICAN INDEX FOSSILS. 



Nanaimo group of Vancouver and in California, and also from 

 India, Japan, South Africa, etc. 



CXXVIII. Gabbioceras Hyatt. 



Discoidal, umbilicate; the young whorls transverse, wider than 

 high; smooth and angulated around the umbilical margin, the 

 impressed zone very shallow and the venter flatly rounded; adult 

 whorls rounded, somewhat higher than wide ; adult suture with a 

 long, narrow, and scarcely crenulated siphonal saddle and deeply 

 incised lateral and dorsal saddles. Comanchic. 



288. G. batesi (Gabb). (Fig. 1420.) " Comanchic. 



Fig. 1420. Gabbioceras batesi, with cross section, X Vi 5 suture enlarged. 

 (After Gabb.) 



Adult whorls nearly circular ; surface with few, narrow, distant 

 costae and numerous fine striae. 

 Horsetown of California. 



CXXIX. Pleuropachydiscus Hyatt. 



Whorls more compressed laterally than preceding; abruptly in- 

 turned at the umbilicus; suture with narrow but not pointed si- 

 phonal saddle, and broad lateral saddles, much less deeply incised 

 than in Gabbioceras; first lateral lobe longer than the ventral lobe. 

 Comanchic-Cretacic. 

 289. P. hoffmani (Gabb). (Fig. 1421.) Comanchic-Cretacic. 



With moderately large umbilicus, and numerous slightly sinuous 



