416 PROCEEDINGS OF THE ACADEMY OF [June, 
enlarged, the rest slender. The basal third or less is sheathed, the 
sheath composed of firm, circular muscles. The papilla (fig. 1, pp.) 
is cylindric, with a conic, glandiform end. The retractor muscle is 
inserted on the epiphallus, which is nearly as long as the penis, and 
bears a short flagellum. The vagina is about three-fourths as long 
as the penis. In two individuals the organs measure, in mm.: 
| | | 
Sta- “a : Epiphal- | Flagel- | : Diam. 
Ban Penis. Papilla. | las. pee Vagina. shalt 
| at eee than 
25 12 3 | Tal 0.75 9 Sal 
22 10 DRG | 8.5 0.75 8.2 19 
Baboquivari Mountains, the types No. 111,549, A. N. 8. P., from 
Station 25, in the head of Thomas Canyon about half a mile from 
Baboquivari Peak. Also at Station 23, at the northern bases of 
crags at summit of the spur which divides Thomas Canyon. In 
Sycamore Canyon, at Station 26, in a slide on the ridge of the head 
branch, about 300 feet or more below the summit; Station 27, about 
1,000 feet lower, near bed of canyon; Station 28, still lower, and 
Station 31, further down the canyon, low on the south side. 
In Oro Fino Canyon it was taken at Station 21, at the foot of the 
cliffs on north side of Mount Mildred, a conspicuous butte at the 
southern side of the mouth of the canyon; also Station 22, among 
low crags near the north side of the canyon. 
This is the common species of the Baboquivaris throughout the 
short section of the range which we explored. It is distinguished by 
having a larger aperture than any other Sonorella known. The 
rather long penis with a strong basal sheath and a papilla of very 
peculiar and characteristic shape are diagnostic of the soft anatomy, 
and confirmed in a number of individuals from several stations. 
All of the stations are on the eastern watershed of the range. The 
only collecting station on the western slope (24) had a quite different 
Sonorella, S. vespertina. 
The size is smaller in Oro Fino Canyon. At Station 22 the shells 
are decidedly more solid and more opaque than the types. Height 
12, diam. 18 mm. to height 13, diam. 19.5 mm.; 43 whorls. Soft 
anatomy is typical. 
Specimens from high on the ridge near the head of Sycamore Can- 
yon, Station 26, are also rather small, diam. 18 to 19.3 mm. Near 
the bottom of the canyon, at Station 27, the shells measure 19 to 
