1915.] NATURAL SCIENCES OF PHILADELPHIA. 367 



The fauna of this small range is strongly individualized, since all 

 of the Holospiras and larger Helices are very distinct from species 

 of other ranges, even the Sonorellas having well-defined conchological 

 features. Like the Huachucas, there is (or was) an Oreohelix of the 

 strigosa group, but hairy forms and the Radiocentrum group are 

 wanting. The minute shells are all species common to the Chiri- 

 cahua, Huachuca and other larger ranges, but the Transition and 

 Canadian Zone species are very sparsely^ represented by Pyramidula 

 cronkhitei, Cochlicopa luhrica and Vertigo coloradensis arizonensis 

 only. Otherwise the fauna is purely Lower Sonoran. 



The collecting stations are as follows: 



Station 1. Slide of heavy, angular rock on west side of cataract 

 branch of Tweed Canyon, below the crags of this side. • 



Station 2. Near the foot of small ravine next west of the granite 

 defile forming the outlet of the Tweed amphitheatre. 



Station 3. Near and at top of ridge above Station 2, 



Station 4. Rim of amphitheatre, western side. 



Station 5. Immediately north of small peak at N. W. of amphi- 

 theatre. 



Station 6. Crag about half way up mountain on east side of cataract 

 branch, overlooking part of Cochise Stronghold. 



Station 6|. West of Station 6. 



Station 7. Limestone ridge at the head of Cataract Branch. 



Station 8. Higher up on the same ridge eastward. 



Station 9. East side of the rocky bed of Cataract Branch, near the 

 foot of the (dry) "falls." 



Station 10. Bottom of eastward ravine in Tweed amphitheatre. 



Station 11. Part way up ridge northwest of 10. 



Station 12. High peak at summit of preceding ridge. 



Station 13. High peak southeast of 12. 



Station 14. ]\Iiddle of ridge running from 13 to mouth of amphi- 

 theatre. 



Station 15. Near bottom of ravine north of 14, and further up than 

 10. 



Station 16. Arroyo in mesa in the mouth of Tweed Canyon. 



Station 17. Third small ravine west of the large granitic spur in 

 Tweed Canyon. 



Station 18. Above Station 17, and separated from it by granitic 

 dyke about 50 yards wide. 



Station 19. Below Station 17. 



Stations 20-22. Second ravine from large granitic spur in Tweed 

 Canyon. 



Station 22a. Second ravine west from Station 2, lower part of 

 mountain. 



Station 23. Second ravine west from Station 2, near summit of 

 ridge. This station and the preceding one were not visited by 



