2o6 



NORTH AMERICAN INDEX FOSSILS. 





Fig. 1474. Exiteloceras jenneyi. 



. and suture, X f- (After Whitfield.) 



359. E. pariense (White). (Fig. 1475.) Cretacic. 



Very loose helicoid spire in young, with whorls separated by 



more or less than their diameter; costse sharply rounded, oblique, 



more than their width apart ; a row of tubercles on each side of 



r^- 



Fig. 1475. Exiteloceras pa?'iense, entire ^hell. >:; -j, and fragment and suture en- 

 larged. (After Stanton.) 



siphuncle, one to a rib, subspinous when well preserved, but vari- 

 able; lobes of sutures all smaller than saddles. 

 Coloradoan of Upper Kanab, Utah. 



CLX. Heteroceras d'Orbigny. 



A more, or less composite group of phylogerontic ammonites, 

 with helicoceran young, but loose, and generally irregularly coiled 



