730 



NORTH AMERICAN INDEX FOSSILS. 



About thirty slender whorls, when full grown, embracing nearly 

 or quite to the moderate angulation. Sides (shoulder) flat or 

 gently convex ; primary spirals 6-8, minutely nodose in later 



FlG. 1060. Turritella vertebroides, shell surface, and internal mold. (After 



Whitfield. ) 



whorls and subspinous in adult ; secondary spirals generally 

 present. 



Coloradoan of Utah and Colorado. 

 422. T. vertebroides Morton. (Figs. 1060, 1061.) Cretacic. 



FlG. 1 06 1. TurriUlla vertebroi- 

 des, enlargement of part of surface 

 of the type. (After Whitfield.) 



Fig. 1062. Turritella encrinoides, frag- 

 ment of shell, and enlargement of surface. 

 (After Whitfield.) 



Slender, long, apical angle about 12 degrees ; volutions gently 





