1911.] NATURAL SCIENCES OF PHILADELPHIA. 197 



Pupilla hebes (Anc). 



Pupa hebes Anc, Pils. and Van., Proc. Acad. Nat. Sci. Phila., 1900, p. 589, 

 pi. 22, figs. 9, 10. 



Bill Williams Mountain. 



Pupilla hebes kaibabensis n. subsp. 



The shell is constantly much shorter than the typical form, length 

 2.7 to 2.8, diam 1.5 mm., whorls 5^. Kaibab Saddle, Station 100, 

 types No. 103,283 A. N. S. P., collected by Ferriss and Daniels, 1909. 

 Also Station 105 in the same region. 

 Bifidaria quadridentata Sterki. 



Bill Williams Mountain. 

 Bifidaria pellucida hordeacella (Pils.). 



Near the Mystic Spring Trail at Station A, on the Oreohelix talus, 

 Spectacle Cove. 



Bifidaria pilsbryana Sterki. 



Bill Williams Mountain. Grand Canyon at the Bright Angel Trail 

 about 100 feet below the rim; Mystic Spring Trail, Station A. Also 

 north of the Grand Canyon at Stations 7, 12, 100 in the region of the 

 Powell-Kaibab Saddle; Station 66, north of Warm Spring Canyon; 

 and at a spring on the northwestern side of Mt. Trumbull. 



Bifidaria ashmuni Sterki. 



Bright Angel Trail, about 100 feet below rim. North of the Grand 

 Canyon at Stations 7 and 12, Kaibab-Powell Saddle; Station 100, 

 near Oak Springs; and at Mt. Trumbull. These places are all far 

 north of its previously known range. 

 Vertigo concinnula Ckll. 



Bill Williams Mountain. 



Vertigo coloradoensis arizonensis Pils. and Van. 



Bill Williams Mountain. 



VALLONIID^]. 

 Vallonia cyclophorella Anc. 



Bill Williams Mountain. Grand Canyon about 200 feet below the 

 rim and at the Indian Gardens, Bright Angel Trail. North of the 

 Grand Canyon at Stations 1, 12, 106 and Oak Springs on the Kaibab- 

 Powell Saddle; Quaking Asp Canyon; Rigg's Springs, Snake Gulch; 

 Warm Spring Canyon ; spring on the northwest side of Mt. Trumbull. 

 A common shell in Arizona north of the Grand Canyon. 



Vallonia perspectiva Sterki. 



Grand Canyon at Seep Spring two miles west of the Mystic Spring 



