44 PROCEEDINGS OF THE ACADEMY OF [Feb., 



mollusca of the southwestern states: iv. the chiricahua 



mountains, arizona. 



by h. a. pilsbry and j. h. ferriss. 

 Contents. 



Introduction. 

 I. Conditions determining the isolation of snail colonies, p. 46. 

 II. Influence of environment on the shell, p. 47. 



III. Factors in the formation of species and races, p. 49. 



IV. Distribution of Chiricahuan mollusks, p. 50. 

 V. Systematic descriptions of species, p. 53. 



The Chiricahua Mountains stand near the southeastern angle of 

 Arizona, extending for about fifty miles from northwest to southeast, 

 being one of the numerous short roughly parallel ranges of that part 

 of New Mexico and Arizona. The Peloncillo range, lower and very 

 arid, sharply limits the horizon eastward, distant about twenty miles. 

 The next range westward is the Dragoon Mountains, fully thirty 

 miles away. These ranges are separated by mesa having an elevation 

 of about 5,000 feet, but lower in the middle. 



The northwestern end of the range is known as the Dos Cabezas 

 Mountains, being separated from the main range by a depression 

 to 5,500 feet near Fort Bowie. The mountains as far south as White 

 Tail Canyon are rather arid, the trees stunted oaks and pinons, with 

 small beech, walnut, willow, buttonwood, etc., in the canyons. The 

 Cave Creek region is much more verdant and at elevations of 8,000 

 feet and over there are fine pine and spruce forests. 1 The mountains are 

 rugged, almost everywhere cut into sharp ridges and peaks, the slopes 

 steep and stony or rocky, often broken by cliffs. The accompanying 

 map gives a general idea of the positions of the various valleys or 

 canyons mentioned herein. Various maps of single canyons give the 

 locations of collecting stations. 2 



1 For an account of the flora of the Chiricahuas see J. C. Blumer, The Plant 

 Geography of the Chiricahua Mountains, Science, XXX, p. 720, November 19, 

 1909. 



2 The general map of the range and that of Cave Creek Canyon were drawn 

 from sketches made by both authors, with some few additions to the general 

 map from a map of the Chiricahua Forest Reserve, published by the Forest 

 Service, U. S. Department of Agriculture, 1906. This map is very inaccurate 

 in many details, yet useful in the absence of anything better. The other maps 

 of canyons are from the note-book of one of the authors. Elevations where 

 given herein are in part from the Forest Reserve map, in part estimated; and 

 all must be accepted as only approximate. 



