fontiphila Gregg was found where there was an abundance of moisture, 

 north of the dam in Little Rock Creek Canyon, though this snail is related 

 to the desert species of this genus. I was not surprised to find it later over 

 more than 10 miles of arid, sage-covered hills to the east where it seeks 

 shelter beneath dead yuccas. H. Isabella Berry also occurs on hillsides 

 beneath dead yuccas. 



In southern California Sonorella micrometalleus (Berry) is found in 

 extensive rockslides in a canyon 3|/2 miles south of the "Petrified Forest" 

 in Kern County, or 1.7 miles north of the Red Hill-Handsburg highway. 

 The Southern California molluscan subprovince includes a portion of 

 western Arizona, as indicated by the presence of Micrarionta and the 

 absence of those genera which characterize the Southwestern Molluscan 

 Province. 



Before leaving the subject of California deserts, we should not fail to 

 mention Coachella Valley. Here a handful of sand, picked up at random, 

 will contain from a dozen to a hundred tiny fossil snails, including from 

 2 to 6 species. These are freshwater snails that lived here when this area 

 was covered by ancient Lake Cohuilla, at a time when there was abundant 

 rainfall to feed this freshwater lake, which at one time covered an area 

 of 2,200 square miles. 



To the east is the Southwestern Molluscan Province which includes 

 the greater part of Arizona and New Mexico and extends southward into 

 Mexico and perhaps a small portion of western Texas. It is characterized 

 by the presence of Sonorella, Ashmunella, Orephelix of the subgenus Radio- 

 centrum, and Holospira. Much of this province is typical desert, interrupted 

 at intervals by mountain ranges. Snails of the genera Sonorella and 

 Ashmunella are found from humid forests in the mountain ranges down to 

 typical desert habitats in the foothills. Look for snails here in rocky hill- 

 sides and particularly in rockslides. Holospira is to be found on hillsides 

 where limestone is present. At some times of the year it is out in the open, 

 clinging to rocky surfaces, particularly on ledges of limestone. In places it 

 lives under bear-grass and sotol. In dry, hot weather, it is generally found 

 beneath rocks or desert vegetation. 



We should not fail to mention the snails found in river drift. Flash 

 floods caused by cloud-bursts in mountain and foothill country send 

 torrents raging through the river channels. These torrents carry with 

 them much organic debris, a large part of which is cast up at the stream's 

 edge. The debris frequently contains numerous snail shells, most of them 

 of tiny species, which have been brought down from hillsides and some- 

 times carried for a considerable distance. Dr. Pilsbry lists 34 species taken 

 in drift along the San Pedro River near Benson, Arizona. We found 14 

 species here and many more from a locality along this river a few miles 

 south of Benson. 



Recent finds indicate that there are still undiscovered desert dwellers 

 in this great area, passed by when the earlier collectors spent their time in 

 the seemingly more promising locations in higher and more humid habitats. 



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