198 PROCEEDINGS OF THE ACADEMY OF [March, 
Trail, below the cross-bed sandstone, and in ‘‘Spectacle Cove,”’ Station 
A, at about the same level. It was not taken north of the Grand 
Canyon. 
LYMN AIDA. 
Lymnea parva Lea. 
Pipe Spring, Ariz. 
Lymnea obrussa Say. 
Deception Lake near Kanab, Utah, small, slender specimens. 
Planorbis tenuis Phil. 
Reservoir back of Williams, Ariz. 
Planorbis deflectus Say. 
Fredonia, Ariz., Station 38, near the Utah boundary. 
- PHYSIDA. 
Physa virgata Gld. 
Reservoir back of Williams; Pipe Springs, Vermilion Cliffs, Station 
39. Physa traskii Lea and Ph. orbignyana Lea are synonymous with 
virgata. 
Physa humerosa Gld. 
Indian Gardens on the Bright Angel Trail in the Grand Canyon 
(C. M. Cooke). A small form, evidently referable to this species. 
Physa gyrina Say. 
The Greens, near Kanab, Utah. Another small Physa of uncertain 
identity was taken in Deception Lake, Utah. 
SPHAIRIIDA. 
Pisidium sp. undet. 
The Greens, Kanab Creek, near Kanab, Utah. 
EXPLANATION OF PLATES XII, XIII, XIV. 
Pirate XII.—Figs. 1-14.—Oreohelix yavapar profundorum P.and F. Cotypes. 
Spectacle Cove. No. 103,234 Acad. Nat. Sci. Phila. 
Figs. 15-17.—Oreohelix yavapai extremitatis P.and F. Station C, Upper 
talus, west of Bass Camp. No. 103,237. 
Figs. 18-21.—0O. y. extremitatis P. and F. Cotypes. 100-400 feet below the 
rim along the trail near Bass Camp. No. 103,236. 
Figs. 22-24.—Oreohelix yavapai angelica P. and F. Cotypes. 100-400 feet 
below the rim. Bright Angel Trail. No. 103,239. 
Fig. 25.—O. y. angelica. Same locality. No. 103,241. 
Figs. 26-28.—Sonorella coloradoensis (Stearns). Whitish, bandless form 
from White Creek, 1 mile above its junction with Shinumo Creek, Grand 
Canyon, north side. No. 103,255. 
Figs. 29, 30.—Sonorella coloradoensis (Stearns). Head of Starvation Tank 
Wash, Grand Canvon, south side. 
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