A NEW FRESH-WATER MOLLUSK FROM INDIANA. 



By Bryant Walker, 



Of Detroit, Michigan. 



Among the collections of Ancylids made in Lake Maxinkuckee, 

 Indiana, by Dr. Paul Bartsch, is a new species of Ferrissia, which is 

 here described and figured. 



FERRISSIA BARTSCHI, new species. 



Shell small, very much depressed, regularly oval, the left margin 

 being only slightly more curved than the right, regularly rounded 

 at both ends; apex prominent, blunt, 

 rounded, situated on the posterior third 

 of the shell, slightly turned to the right; 

 apical striae conspicuous; lines of growth 

 fine and regular; anterior slope nearly 

 straight, but oblique, curving down more 

 rapidly as it approaches the anterior 

 margin. Irregularly radiately striate; 

 posterior slope straight below the swell 

 of the apex; left slope convex, slightly 

 flattened towards the apex; right slope 

 nearly straight. 



Length 2.5, width 1.5, alt. 5 mm. 



Type.—Cat. No. 334709, U.S.N.M., 

 from a marsh at the south end of Lake 

 Maxinkuckee, Indiana. Topotypes in Coll. Walker (No. 47087). 



This diminutive species has only one near relative; namely, Fer- 

 rissia novangliae Walker. It differs from this in its smaller size and 

 more depressed shape, more regularly oval outline, less eccentric 

 apex, which projects more conspicuously above the transverse 

 outline of the shell and in the degree of postulation of the anterior 

 slope. 



Fig. 1.— Fekkissa baktschi, new 



SPECIES. 



Proceedinqs U. S. National Museum, Vol. 57— No. 2321. 



525 



