GASTROPODA— A URICULIDJE—PHYSID2E. 



815 



Bear River formation of Wyoming. 



668. R. priscus Meek. (Fig. 1203, e.) Cretacic. 

 Obovate, about once and a half as long as wide; shoulder some- 

 what pronounced and slightly angulated. 



Bear River formation of Utah and Wyoming. 



CCX. Alexia Leach. 

 Differs from Melampus in its higher spire of round whorls em- 

 bracing to above the ambitus, the absence of a shoulder, and in 

 cvoid aperture. Protoconch erect. Cretacic-Recent. 



669. A. antiqua (Meek). (Fig. 1203, a-c.) Cretacic. 



FlG. 1203. a-c, Alexia antiqua, with enlargement; d, Rhytophorus nieeki ; e, J?, 

 priscus ; f, g, Limnaa altivuncula ; h, L. consortis ; i, L. nilidula ; /, k, L. tenui- 

 costata ; I, L. meeki ; m, L, shumardi. (After White, U. S. G. S. ) 



Smooth, with whorls gently convex and four columellar plica- 

 tions, the median one strong. 



Colorado formation of Coalville, Utah. 



Family Physhle Dall. 

 CCXI. Physa Drap. 

 Shell thin, reversed (sinistral) ; aperture large; columella twisted 

 or simple; surface smooth. Jurassic-Recent (fresh-water). 

 670. P. carltoni Meek. (Fig. 1205,0.) Cretacic. 



Of moderate size, last whorl with pronounced shoulder. 

 Belly River beds of Utah. 



