668 



NORTH AMERICAN INDEX FOSSILS. 



Few and coarser spirals ; strong transverse sculpture. 

 Guelph of New York and Canada. 



Fig. 924. a, Polenmita crenulata ; b, P. scamnata (right). (After Clarke and 

 Ruedemann, Guelph Fauna.) 



LXIII. Cyclonema Hall. 

 Shell of ventricose whorls, turbinate or conical, with numerous 

 spirals, an oblique aperture, and a thickened, reflected, and flat^ 

 tened or excavated columellar lip and no umbilicus. Ordovicic— 

 Devonic. 

 197. C. bilix Conrad. (Fig. 925, a, b.) Ordovicic. 



FlG. 925. a, b, Cyclonema bilix; c,d, C. mediate; e-g, C. humerosum ; h,i, C. vari- 

 cosum; j, C. subluve. (After Ulrich & Scofield, Pal. Minn.) 



