DESCRIPTIONS OF NEW SPECIES. H9 



spire by numerous small longitudinal folds, parallel with the slightly 

 oblique direction of the lines of growth. These folds appear upon the distal 

 portion only of the last volution. 



Length of the largest example obtained, twenty-five millimeters; diam- 

 eter of the body volution, twelve millimeters. 



This species differs from R. priscus Meek, with which it is associated 

 in the less robust and more elongate form of the shell, its proportionally 

 longer spire, niore delicate and finer markings, and the less abrupt convexity 

 of the volutions upon the proximal side of the suture. 



The specific name is given in honor of the author of the genus. 



Position and locality. Point of Rocks Group ; Bear River Valley, near 

 Mellis Station, Wyoming. 



Genus PLANORBIS Guettard. 

 Subgenus BATHYOMPHALUS Agassiz. 



Planorlls (BatUyomplialus) Kanabensis (sp. nov.). Shell rather small ; 

 spire flat or nearly so, suture impressed ; volutions five or six, narrow, 

 regularly increasing in size to the aperture, broadly convex upon the upper 

 side ; periphery abrubtly rounded to the broadly convex under side, the 

 latter extending obliquely downward and inward to the well defined, mod- 

 erately broad, and deep umbilicus. 



Surface marked by ordinary lines of growth. 



Diameter of coil, twelve millimeters. 



Position and locality. Point of Rocks Group; Upper Kanab, Utah. 



Genus PHYSA Draparnaud. 



PJiysa Kanabensis (sp. nov.). Shell rather under the average size; very 

 elongate ; spire extended ; volutions about six, broadly convex ; aperture 

 very narrow, ending sharply at its distal end and abruptly rounded at the 

 proximal end. 



The specimens of the collection are all imperfect, but the species is 

 peculiarly distinguished by its very slender elongate form, its extended spire, 

 spire, and its very narrow elongate aperture. 



Position and locality. Point of Rocks Group ; Upper Kanab, Utah. 



