62 PROCEEDINGS OF THE ACADEMY OF [Feb., 
Diam, in mm........ 23 23 23 23 22.8 
Alf, ancmm) wike..3: 14 1355 (h38.d4 13 13.5 
The total variation in diameter in this colony is 3.2 mm. The 
variation in altitude is comparatively greater, owing to the varying 
degree of elevation of the spire. 70 per cent. of the lot are from 24 to 
25 mm. in diameter. Figures 6-9 were drawn from specimens of the 
type lot from this Station. 
Station 4. Cleft in the rocky summit of hill at fork oF Big Emigrant 
Canyon, facing mouth of canyon (pl. I, fig. 10). Ten specimens, two 
alive, measure: 
Diana MM ee... 26 25.5 25.5 25 25 25 24 23.7 23.3 2303 
ult, AM TON Paces, 15 1G lea 61S bp ae haa hoes 
They differ from the type lot in having the aperture barely per- 
ceptibly larger, umbilicus smaller. In a specimen of the type lot 
25 mm. in diam. the aperture measures 11.4x13.1 mm. In one of 
the same diameter from Station 4 it is 12 x 13.4 mm. 
Spirally striate forms.—The shells from Stations 2, 3, 5, 6—Big 
Emigrant Mountain and Cross J Mountain—usually show numerous 
spiral strize on the upper surface of the last whorl, but this character 
is variable; in some shells of each lot no spiral strize can be made out. 
Station 2. Close to the creek in the middle branch of Big Emigrant 
Canyon, under stones. Three dead shells measuring 23.5, 22.3 and 
21.8 mm., and similar to those from Big Emigrant Mountain. This 
place is probably about 1,000 feet lower than the type locality. 
Station 3. Big Emigrant Mountain. This name is given to a 
mountain about four miles above the fork of Big Emigrant Canyon 
on the left side of the east branch. November 11 and 12 it was visited, 
On the side toward the canyon, under a rocky bluff, under stones 
among scrub oaks (Quercus hypoleuca?), in a situation resembling that 
of Sonorella bowiensis, numerous specimens of a small form were 
taken, almost all dead shells. Sixty-five adults taken measure in 
diameter as follows: 
Diana in min 20.5 20 1935 219.3 19°18. 8) Alero etees 
No: of shells.0.0.Gnicus: 1 il 4 1 6 A 7 6 
iam. in MM. 3. 18° W7-8: Asoc L738" 17" TGs wiles 
No. sor shes. Ske if 4 4 5 ee es 4 if 
The shells are in the average more depressed than typical S. optata. 
The largest measures, alt. 10.5, diam. 20.5, aperture 9.2 x 11.2 mm. 
Another, alt. 10.5, diam. 18.5, aperture 8.3x9.9 mm. There are 
