MAMMALS or TIIK M KM CAN IJOUNDARY. 



77 



(Elaps fulvius) and rattlesnakes (Orotalus adamanteus atrox a ) are 

 abundant ; and numerous other species were collected. 

 The following is a li^t of the land and fresh-water mollusks collected 



in the vicinity of Fori (Mark, Texas: '• 



1. Polygyra texasiana Moricand. 



2. Limax campestris Binney. 

 :'». Bulimulus dealbatus Say. 



4. Bulimulus dealbatus ragsdalei 



Pilsbry. 



5. Bulimulus alternatus tnariw Al 



Iters. 



0. Grlandina texasiana Pfeiffer. 



7. Pupa fallax Say. 



s. I'lijxi contracta Say. 



'.). Succinea lineata W. <;. Binney. 

 in. Succinea avara Say. 

 11. Succinea luteola Could. 

 ill. Helicina orbiculata Say. 



13. Zonitoides radiatula Alder. 



14. Linuiaa columella Say. 



15. Limnwa humilis Say. 



16. Physa osculans Haldeman. 



17. Planorbis liebmanni Dunker. 



is. Planorbis tumidus Pfeiffer. 

 19. Planorbis trivolvis Say. 

 l'ii. Planorbis bicarinatus Say. 



21. Valvata guatemalensis Morelet. 



22. Amnicola peracuta Walker. 

 •j::. Amnicola sp. 



24. SpJiwrium elevatum Haldeman. 



25. Sphcerium solidulum Prime. 



26. Pisidium compressum Prime 



27. Lampsilis anodontoides Lea. 



28. Lampsilis texasensis Lea. 



29. Lampsilis texasensis compressus 



Simpson. 



30. Lampsilis berlandieri Lea. 



31. Lampsilis mearnsi Simpson. 



.".2. A notion I it im h< Ci II is Say. 



:;:;. Vnio popeii Lea. 



34. Quad'rula undulata Barnes. 



35. Qua drill a COUChiana Lea. 



Station No. 3. — Fort Hancock, El Paso County, Texas. Altitude, 

 7G0 meters (2,500 feet). Post built on bottom land beside the Rio 

 Grande. Lines of cottonwood and willow mark the shifting 

 courses of the river, which dries up at certain seasons. The river 

 flats are occupied by dense patches of arrowwood, flanked by the 

 tornilld or screwbean and mesquite. Still farther back is an arid 

 waste of sandhills and desert country, forming one of the lower basins 

 of the Eastern Desert Tract, with the characteristic desert flora in 

 which the Kg berlinia and a coarse Senecio are conspicuous. 



This region is sparsely inhabited, not irrigated, nor under culti- 

 vation. 



This important station was occupied by me from June 7 to July 2, 

 L893. Large collections of animals and plants were made. The 

 birds and mammals were of special interest, particularly the former, 

 as they were almost all breeding specimens, frequently taken with 

 theii nests and eggs, and all typical of the Eastern Desert; 



«For convenience the determinations and nomenclature of Edward l>. Cope 

 in the work entitled The Crocodilians, Lizards, and Snakes of North America, 

 printed in the Report of the I", s. National Museum for 1898, are bere adopted. 



'j The greater part of these were collected after the publication of Dr. Wil- 

 liam Ilealey Dall's report on the niollnsks collected by the Biological Section 

 of the International Boundary Commission, printed in the Proceedings of the 

 United States National Museum, XIX, 1896. I am indebted to Doctor Hall and 

 Mr. Charles Torrey Simpson for assistance in determining these species, 



