GASTROPODA— SIPHON 'ARIIDM. 8 1 1 



654. C. scitula M. and H. (Fig. 1 194.) Cretacic. 

 Oval, widest in the middle, summit truncated with large depres- 

 sion ; aperture narrow ; a small, indistinct fold near the base of 

 the inner lip; surface with spirals cancellated by growth lines. 



Upper Cretacic of Nebraska, South Dakota and Colorado. 



655. C. galba Conrad. Eocenic. 

 Cylindrical except for slight contraction near the middle; pro- 



Fig. 1 194. Cylichna scitula, X 3- (After Meek.) 



portionally larger and more slender than the other species; inner 

 lip reflected at base; obsolete spirals near anterior (basal) end. 

 Claibornian of Alabama. 



656. C. calvertensis Martin. (Fig. 1 193, c.) Miocenic. 

 Minute; apical end with sunken spire nearly flat. 

 Chesapeakean of Maryland, etc. 



PULMONATA. 



(Air-breathing Snails.) 



Family Siphonariim: Gray. 



CCVI. Hercynella Keyser. 



Non-spiral, more or less cap- or bowl-shaped, unsymmetrical, 



somewhat patelliform shells; often truncated at one end and usually 



with an umbonal angulation. Siluric-Devonic. 



657. H. canadensis Grabau. Siluric. 

 Beak curved towards truncated end, which is asymmetrical;. 



angulation regularly curved. 

 Upper Monroe of Canada. 



CCVII. Anisomyon Meek and Hayden. 

 Shell patelliform with oval or circular (rarely ovoid) aperture,, 

 centren, or between center and anterior end; beak pointed, more 

 or less strongly recurved, but not spiral, generally broken away. 



