326 ' PROCEEDINGS OF THE ACADEMY OF [May, 
Dr. Mearns returned to Mesquite Springs along the ridge running ~ 
from Daniels Mt. towards our camp in Sheridan Canyon, and along 
the wash running out of this canyon. 
Dr. Mearns found the following seven species, which were deter- 
mined by Dr. Wm. H. Dall:* 
Patula strigosa Gould, var. concentrata Dall. [Specimens reported — 
from summit of Hacheta Grande =Oreohelix hachetana.] | 
Epiphragmophora hachitana Dall [=Sonorella hachitana}. 
Polygyra mearnsii Dall [= Askmunella mearnsi]. : 
Thysanophora horni Gabb. 
Holospira crossei Dall. 
Holospira bilamellata Dall. 
Holospira mearnsi Dall. =| 
The relationships of the Big Hachet fauna are closest with the 
Florida and Organ ranges. Near related species of Sonorella and 
Ashmunella inhabit these three ranges, and Sonorellas very close to 
hachitana have been found in the Carrazolillo and Peloncillo Moun- — 
tains. The Oreohelices stand nearest to Chiricahua species. The 
Holospiras and Vallonia are special to the range, but the other small 
shells are common to most mountains of southern Arizona. 
Holospira is the most generally distributed snail in these moun- 
tains. Its abstemious nature is evidently satisfied with the scanty 
moisture supplied by the rare rains and light snow, which is said to 
whiten the mountains for brief periods in the winter. No doubt 
a great many colonies and other local races of Holospira remain to 
be found. 
Holospira lives only where there is limestone. We never found — 
but one colony on igneous rock, and this was on a dyke in a limestone ~ 1 | 
region. They are usually found on the hot slopes, east and south, 
where other snails are totally absent or very rare. 
The subgenus Radiocentrum of Oreohelix is represented by two 
new species, making five now known. The new forms agree in 4 
genitalia and sculpture of the embryonic shell with those already 
known. In the large number examined? no embryos were found, 
so that there can be very little doubt that the species of this group 
3 Diagnoses of new mollusks from the survey of the Mexican boundary, Proc. — 
U. S. Nat. Mus., XVIII, 1895; Report on the mollusks collected by the Inter- —__ 
national Boundary Commission of the United States and Mexico, Proc. U.S. | 
Nat. Mus., XIX, 1896. - 
4 Besides dissecting several individuals each of four of the species, we have 
pulled hundreds in cleaning the shells, without finding any embryos. Among 
ordinary Oreohelices it is rather exceptional to find an individual not gravid. 
