GASTROPODA— SIPHON ARIIDJE. 



8i3 



662. A. subovatus M. and H. (Fig. 1198.) Cretacic. 



Somewhat more elongate than preceding; sides somewhat par- 



FlG. 1 197. Anisomyon patel- 

 liformi% var. (After Meek. ) 



Anisomyon subovatus. (After Meek. ) 



allel ; beak more anterior ; apical angle larger, slopes gently convex. 



Pierre of Yellowstone River and of Black Hills. 

 663. A. sexsulcatus (M. and H.). (Fig. 1 199.) Cretacic. 



Fig, 1 199. Anisomyon sexsulcatus. (After Meek.) 



Large ; beak in anterior third ; surface with six radiating grooves. 



Pierre of Yellowstone River and of Colorado. 

 664. A. borealis (Morton). (Figs. 1200-1201.) Cretacic. 



Very large ; beak excentric, sometimes almost anterior ; a regular 

 rounded fold from beak to posterior end. 



"b 



Fig. 1200. 



iyon dorealis, side and anterior view of Fig. 1 20 1, a. 



Meek.) 



(After 



