THE NAUTILUS. 51 



and the form of the septum or deck also varies. Besides variation 

 in color and form the Norrisia specimens are more porcellanous 

 than Crepidula rugosa (but not so much so as the form found on 

 Lunatia), and the texture does not run into layers as in the typical 

 C. rugosa. Some years ago this form was often distributed by col- 

 lectors and labeled Crepidula adunca Sby. In notes on the mol- 

 lusks of the vicinity of San Diego, Cal., and Todos Santos Bay, 

 Lower California, by Charles R. Orcutt, he lists Crepidula adunca 

 Sby. as " not rare on Norrisia norrisii." While some of the forms 

 found upon Norrisia have the remote apex of C. adunca, I have 

 never seen one with the "short, deeply sunk and slanting deck, and 

 a hole above it passing up the spire," as described by Philip P. Car- 

 penter in his catalogue of Mazatlan Mollusca in his note on the 

 adunca form. Then again, C. adunca is found upon smalhr uni- 

 valves where the base for it is much contracted ; for instance, I have 

 seen it in situ on Drillia penicillata Cpr., and as one would infer, 

 the shell has its sides closer together than the form found upon 

 Norrisia. For the Norrisia form I would suggest Crepidula rugosa 

 Nutt., variety norrisiarum. 



A NEW SPECIES OF LYMNAEA FROM OHIO, WITH NOTES ON LYMNAEA 



PARVA LEA. 



FRANK COLLINS BAKER. 



Lymnaa sterkii n. sp. 



Shell small, elongated, turreted, rather thin ; color light yellowish- 

 horn ; surface dull to shining, marked by distinct, raised, crowded, 

 growth lines, without spiral lines; protoconch very small, rounded, 

 smooth, wine-colored ; whorls 5^, very convex, the last distinctly 

 shouldered ; spire narrow, rather acute, turreted, a trifle longer than 

 the aperture ; sutures very deeply impressed ; aperture ovate, almost 

 continuous in some specimens; peristome thin, acute; columella 

 almost straight, without a plait but with a faint thickening ; inner 

 lip reflected to form a broad, flat callus which is appressed to the \ ar- 

 ietal wall and projects widely over the umbilical region ; umbilkus 

 rather wide and deep. 



Length 7.75; width 3.50; aperture length 3.50; width 1.75 mm. 



