24 AMERICAN JOUKJJAL 



DESCRIPTION OF A NEW HELIX FROM UTAH. 



BY WM. M. GABB. 



H. Haydenii, Gabb.— PL 8, fig. 1. 



Shell of moderate size, orbicular ; spire slightly elevated ; 

 whorls 5|, rounded ; suture well marked ; last whorl descending 

 very slightly above to the aperture ; umbilicus funnel-shaped, 

 perspective, occupying about a fourth of the base ; aperture cir- 

 cular, oblique, margins simple or very slightly thickened, con- 

 tinuous, not reflected. Surface covered by prominent, elevated, 

 revolving ribs, acute and with concave interspaces. These ribs 

 vary from nine to ten in number, and, in some specimens, in the 

 interspaces, are faint revolving lines, entirely absent in others. 

 Crossing the revolving sculpture are numerous, irregular, well 

 marked lines of growth. Color unknown. 



Figures. Natural size. 



Locality. Webber Caiion, near Salt Lake City, Utah, where 

 dead specimens were found in abundance associated with S. 

 Cooperii, by Dr. F. V. Hayden. 



Observations. Dr. Hayden collected at the above locality 

 perhaps as many as fifty specimens of this shell, of all ages. 

 The young show that the circular aperture is not a constant 

 character, since, until fully adult, the mouth is of the same 

 shape as in H. Cooperii, which also, in fully mature individuals, 

 not infrequently has a continuous peristome. The apical angle 

 is the same in these specimens as in the unusually flat form of 

 H. Coojjei'ii associated with them. 



