Descriptions of Xew Species and New Varieties 



223 



crenatum. Aperture ovately rounded, the li)) riiu thickened and broadly 

 reflected. A callus on the parietal wall renders the aperture continuous. 

 There is usually. a border of dark chestnut or reddish brown within the 

 aperture. The aperture may be rounded above or there may be a sharp 

 V-shaped angle, depenfling upon whether the dorsal carina is sharp or 

 rounded. There is normally an indication of angulation at this point. The 

 basal part of the aperture is flatly rounded. Several old lip expansions may 

 show on the body whorl back of the aperture. Color whitish, tinged with 

 chestnut in some specimens. 



♦Measurement taken behind the expanded lip. 



Type Locality. Lac La Hache, Cariboo District, British Columbia. 



Type Material. Fifteen specimens, collected by H. and R. D. Svihla, 

 are deposited in the Museum of Comparative Zoology of Harvard Uni- 

 versity, Accession no. 93710. The individual selected as holotype is shown 

 on plate 119 as fig. 16; paratypes as figs. 17-21. 



Helisoma columbiense shows relationship to the binneyi group in its 

 sculpture and the carination of its whorls. It differs from the members of 

 that grou}) in that it is of smaller size, has less relative axial height, its rib 

 striae are less widely spaced and the whorls are usually more angulate. 



It differs from the subcrenatum group in having more regular and less 

 widely spaced rib striae, in its angulated base and spire depression, and in 

 the shape of the aperture. 



Helisoma hennicotti, New Species 



Plate 89, figs. 13-17 



Shell in four whorls, rapidly increasing in diameter. Body whorl axially 

 very high. Sculpture of evenly spaced, rather heavy, rib-like growth lines 

 becoming more widely spaced on the last half of the body whorls. Spire 

 depression concave, widely cone-shaped, flat-sided, bordered by a strong, 

 sharp carina, extending to the aperture. Base showing three whorls, the 

 umbilicus deep, with a small perforation; only slight indication of a carina 

 in adult, but distinct and sharp in immature specimens. Aperture auriform, 

 sharply angled above, flatly rounded and effuse below, the outer lip ex- 

 panded. Parietal wall with a thin wash of callus which connects the ex- 

 tremes of the lip. Color light, yellowing horn, brownish or bluish in some 



