1899.] NATURAL SCIENCES OF PHILADELPHIA. 401 



Succinea tlalpamensis n. sp. 



Shell pointed-oblong fragile, honey yellow or reddish, somewhat 

 translucent ; stronglij, finely and rather irregularly, closely ivrinkled. 

 Spire slender, acuminate; whorls 2^, very obliquely convoluted, 

 the last scarcely convex above. Aperture very large, ovate, some- 

 what effuse at the base ; columella with a white thread-like edge. 



Alt. 15, diam. 8, longest axis of aperture 11.8, greatest width 

 7 mm. 



Alt. 14^, diam. Sh, longest axis of aperture 12, greatest width 

 7i mm. 



Near Tlalpam, State of Mexico, Mexico. 



Allied to S. retasa Lea (^ovalis Gld. non Say) and S. mlleana 

 Pfr. Compared with the former, S. tlalpamensis has a decidedly 

 larger aperture in proportion to the last whorl, as viewed from the 

 front. The spire is longer and more slender than in S. salleana. 



At Lake Cuitseo, near Huingo, State of ]\Iichoacan, a much 

 smaller form was collected, in Avhich the aperture is not so ample, 

 and less effuse below. Two specimens measure : 



Alt. 10.8, diam. 5.5, longest axis of aperture 8, greatest width 

 4.7 mm. 



Alt. 9.6, diam. 5.8, longest axis of aperture 7.7, greatest 

 width 4.3 mm. 



This may be called var. cuitseana. It has the same number of 

 whorls as the type. 

 Physa osculans rhyssa n. var. 



Smaller than typical P. osculans, pale yellow corneous, trans- 

 parent and fragile, with numerous slight longitudinal folds on the 

 last whorl. 



Saltillo, State of Coahuila, Mexico. 

 Sphaerium martensi n. sp. 



A moderately large, thin species, showing no distinct prodis- 

 soconch at the beaks; ovate, moderately convex, with median, 

 slightly prominent beaks, the surface lusterless, yellowish corneous, 

 finely and irregularly striated, nearly smooth toward the beaks; 

 anterior end narrower, symmetrically rounded ; posterior end wider, 

 obscurely truncated obliquely ; hinge line slightly convex ; basal 

 margin moderately convex. Interior whitish in clean shells; 

 hinge delicate, the left valve with a small, erect, compi-essed car- 

 et; 



