78 PROCEEDINGS OF THE ACADEMY OF [Feb., 



group further differs from the 0. strigosa group in possessing radially 

 costulate apical whorls. 



Snails of both of these groups live immured in the shaded rocks of 

 the mountain "slides," composed of broken rock or spawls tumbled 

 down from the peaks above. 0. clappi lives from 5,000 to 7,000 feet, 

 and O. barbata from 7,000 to 10,000 feet above the sea. The dead 

 shells are seldom found upon the surface. Oreohelix chiricahuana, in 

 the same mountain range, requires but little covering, and is found in 

 dry situations, often with but a single leaf or a small spawl for pro- 

 tection. It agrees with the Oreohelices of other regions in having a 

 very thin cuticle, often wanting. Dead agavas and yuccas furnish 

 a home for these, the Holospiras and Succinea avara; but 0. barbata 

 and O. clappi, the Ashmunellas and Sonorellas require an atmosphere 

 with more moisture, and dwell from one to two feet below the surface. 

 He who finds must dig. 



All Chiricahuan Oreohelices are confined to that range, and none 

 of them are closely related to species found elsewhere. All are con- 

 spicuously variable in each colony and in different colonies, nearly 

 every one of which shows a degree of racial differentiation, so that 

 one acquainted with these shells, even as imperfectly known at 

 present, could locate himself if lost in the Chiricahuas by digging for 

 ( )reohelices ! 



No adequate discussion of these shells can be entered into without 

 more and better illustrations than are possible to us at this time, and 

 long series of measurements. We have merely indicated briefly the 

 salient features of each colony. 



The Oreohelix clappi series. 



The group of local races which for taxonomic purposes is considered 

 to compose the species O. clappi comprises about a dozen colonies, 

 scattered over the range for a distance of about 44 miles. The 

 relationships of the snails of these colonies may be expressed dia- 

 gramatically thus : 



Emigrans — Onion Creek — Reed's Mt. — type Cataracta 



Horseshoe — Shake Gulch — Rucker Box 



The forms toward the left in this diagram are successively more 

 roughly sculptured, toward the right they are smoother. The type 

 happened to be of intermediate character, and near the central point 

 of the range of the species. The upper line forms a variation-series 

 extending from Big Emigrant Canyon {emigrans) to the Falls of 



