Occasional Papers of the Museum of Zoology 3 



at the bottom. Columella not much more than a chalky wash 

 of shell material on the epidermis. 



Operculum very thin, transparent, light yellow, nearly round, 

 with the acute apex as a sort of triangular appendage. On the 

 anterior side, this appendage is, in life, alone free of the animal's 

 foot. Margins firm, but not thickened. Lines of growth few and 

 fine. The nucleus is sunken and is just below the center of the 

 operculum, slightly nearer the left margin than the right. Two 

 whorls, regularly and widely coiled, show within the operculum. 

 In shape and in form of whorls this operculum resembles that of 

 G. cotnalensis Pilsbry, illustrated in Proceedings of the Academy of 

 Natural Sciences (Philadelphia, March, 1906), p. 168. 



Measurements: Altitude, 13 mm.; diameter, 4! mm. Aperture 

 altitude, 4^ mm.; diameter, 2j mm. (Type.) 



Measurements of four paratypes: 



Type locality: Creek below Seminole Springs, Lake County, 

 Florida. T. Van Hyning, collector, May 11, 1918. 



Type: No. 45938, collection of Dr. Bryant Walker. Paratypes 

 in the Museum of Zoology, University of Michigan (No. 10586), 

 and in my own collection. 



Remarks: In some of the specimens of this species, the folds 

 or plicae are sometimes obscure, sometimes very strongly marked 

 and sinuous. In two specimens the columella is refiexed just below 

 the center. No bands are present in any of the material, but a 

 slight difference in color occurs where the dark folds cross the 

 lighter epidermis of the body whorl. G. vanhyningiana is a small 

 local race of the group, the leading representative of which is the 

 well-known G. catenaria Say. Not only is the new species connected 



