THE NAUTILUS. 7 



The little brook, only a few hundred feet long, in which the 

 species lives, is also the type locality for Physa walkeri Crandall. 



Lymnsea cyclostoma n. sp. PI. II, fig. 4. 



Shell ovate conic, turreted, umbilicate, light yellowish horn- 

 colored, shining ; lines of growth fine, irregular, subobsolete on the 

 body whorl, stronger on the apical whorls, reticulated by indistinct 

 revolving, impressed spiral lines. Spire elongated, apex subacute ; 

 whorls 5, very convex, those of the spire somewhat shouldered, 

 suture deeply impressed ; body whorl large, inflated, very convex. 

 Aperture broad oval, subcircular, rounded above and below. Colu- 

 mella broadly reflected over the round, deep umbilicus, convex, 

 smooth with no fold, parietal wall with a thin transparent callus. 

 Lip sharp, but thickened within by a heavy white callus. 



Alt. 7.5, diam. 3.25 mm. 



Types (No. 13599 Coll. Walker) from Indian Creek, Kent County, 

 Mich. Also from Alma, Gratiot County, Mich. 



This very distinct little species was first collected by Dr. R. J. 

 Kirkland, of Grand Rapids, Mich., and was listed as L. cubensis Pfr. 

 (umbilicata C. B. Ads.) in my Review of the Moll. Fauna of Michi- 

 gan (1894). Through the courtesy of Mr. E. A. Burt, curator of 

 the Museum of Middlebury College, I have been able to examine the 

 specimen of L. umbilicata deposited in that museum by Adams, and 

 for comparison have figured it (fig. 1). The two species are so 

 obviously distinct that verbal comparison is hardly necessary. L. 

 cyclostoma differs in its more elevated, turreted spire, more broadly 

 reflected columella and thickened white lip. It resembles umbilicata, 

 however, in the sculpture, and is no doubt derived from the same 

 stock. 



In this connection it may not be out of place to add that the 

 inspection of the authentic specimen of L. umbilicata confirms Dr. 

 Pilsbry's reference of that species to L. cubensis Pfr. It is evidently 

 distinct from L. caperata Say, and its reference to that species as a 

 synonym by Haldeman, Tryon, Binney and others is quite erroneous. 



The Middlebury specimen is not quite mature. It has 4^ whorls 

 and measures 6 mm. in height and 4 mm. in diameter. For further 

 comparison I have figured (Fig. 2) a Rhode Island specimen, which 

 is apparently typical ; the dimensions (6.5 x 4.25) agreeing almost 

 precisely with those given by Adams. It is however, somewhat 



