THE NAUTILUS. 125 



DESCRIPTIONS OF NEW SPECIES OF LYMN.EA. 



BY FRANK C. BAKER. 



Lymnsea dalli n. sp. 



Lymnsea parva Baker, Nautilus, XIX, p. 52, 1905. (Not of 

 Lea.) 



Lymnsea dalli Baker, Bull. Ills. State Lab. N. H., VII, p. 104, 

 1906. 



Shell very small, thin, ovate-conic, turreted ; color greenish or 

 whitish-horn ; surface dull to shining, marked hy heavy, crowded 

 growth-lines, which are elevated into distinct ribs in some specimens ; 

 protoconch very small, flatly rounded, light-horn colored ; whorls 4^ 

 to 5, rounded and distinctly shouldered ; spire generally obtusely 

 conic, turreted, a trifle longer than the aperture ; sutures very deeply 

 impressed ; aperture elongate, ovate or elliptical, the peristome con- 

 tinuous in many specimens ; outer lip acute ; inner lip forming a 

 rather flat extension over the umbilical region, leaving a rather pro- 

 nounced chink ; the lower part of the aperture is somewhat effuse ; the 

 columellar extension of the inner lip is appressed so as to form a 

 pseudo-plait ; the inner edge of the outer lip frequently forms a rib- 

 like ridge in very old specimens. 



Length 3.25, breadth 2, aperture length 1.5, breadth 1 mm. Lake 

 James, Ind. 



Length 4, breadth 2, aperture length 2, breadth 1 mm. Lake 

 James, Ind. 



Length 3, breadth 2, aperture length 1.25, breadth, .9 mm. Lake 

 James, Ind. 



Length 4.25, breadth 2, aperture length 1.75, breadth 1 mm. 

 Lake James, Ind. 



Length 4.5, breadth 2.5, aperture length 2, breadth 1.1 mm. 

 (scalariform). 



Length 3.75, breadth 2.75, aperture length 2, breadth 1.25 mm. 

 Rockford. 



Length 4, breadth 2.1, aperture length 2, breadth 1.1 mm. Rock- 

 ford. 



Types : Chicago Academy of Sciences ; cotypes, Academy of Nat- 

 ural Sciences, Philadelphia ; Smithsonian Institution, Washington. 



Type Locality: Lake James, Steuben Co., Indiana. 



