414 PROCEEDINGS OF THE ACADEMY OF [June, 
Station 22. Low crags in the northern part of Oro Fino Canyon. 
Station 23. Crags on the southern rim of the northern branch of 
Thomas Canyon. 
Station 24. West side of the main ridge near summit, south of 
Baboquivari Peak. Vitrea indentata wmbilicata and _ Sonorella 
vespertina. 
Station 25. East side of ridge, about half a mile from the peak. 
Station 26. Near the southwestern head of Sycamore Canyon, 
between one and two hundred yards below the summit of the Thomas- 
Sycamore ridge, in a rock “‘slide.”’ 
Station 27. About 1,000 feet below Station 26, near the bottom 
of the canyon. 
Station 28. Not far below Station 27. 
Station 29. Bed of upper Sycamore Canyon, about a mile above 
the foresters’ cabin, and not far above the dam. 
Station 30. Creek in Sycamore Canyon (a small Physa, not 
determined with certainty, was the only fresh-water. shell found at 
this station). 
Station 31. Sycamore Canyon, about 3 miles up its bed, and 
3 mile up a southwestern branch ravine. Succinea avara Say and 
Sonorella baboquivariensis only. 
Sonorella vespertina n. sp. PI. X, figs. 5, 5a, 5b. 
The shell is umbilicate (width of umbilicus contained 9 or 10 
times in diameter of the shell); cinnamon, fading to whitish around 
the umbilicus, and with white bands above and below the chestnut- 
brown shoulder band. Surface glossy, the initial half-whorl having 
some radial wrinkles, the rest of the embryonic shell without any 
distinct sculpture, though there is some extremely indistinct radial 
roughness, stronger near the suture. In fresh young shells of 23 
whorls the surface of the last embryonic and first neanic whorls 
is densely set with very short hairs, extending also over the base. 
These are fugacious, lost with further growth. The later whorls 
are marked with the usual growth lines. Whorls 43, the last rapidly 
widening, rather steeply descending close to the aperture. Peristome 
narrowly expanded on the outer and basal margins, dilated and 
reflexed at the columellar insertion. 
Height 11, diam. 19.8 mm. (type). 
a9 11.3, 73 20 a9 
yo es ares 18 ‘ 4% whorls. 
Genitalia (Pl. XIII, fig. 9)—The penis is very small and tapers 
distally to the epiphallus, the long penial retractor being inserted 
on the latter. The flagellum ({l.) is represented by a minute bud or a 
slight swelling. The penis-papilla (fig. 9, pp.) is slender, tapering, 
