MAMMALS OF THE MEXICAN BOUNDAEY. 7 



has a party of similar size performed an equally large amount of 

 work, in such a spirit of good fellowship. Our association with the 

 Mexican Commision was one of unbroken friendship, cemented by 

 continued companionship and hardships shared in common. 



MONUMENTS AND BOUNDARY SECTIONS. 



The Mexican Boundary Line consists of seven sections, two of 

 Avhich are formed b}' portions of two rivers — the Rio Grande and 

 Colorado: two are straight oblique or azimuth lines; two are sections 

 of parallels or lines following the earth's curve; and one is a meri- 

 dian or north and south line. 



The longest section of the Boundary is that fonned by the Rio 

 Grande, which rises in Colorado and flows 1,700 miles to the Gulf of 

 Mexico and forms 1,100 miles of the Boundary Line on its lower 

 course. This Rio Grande section was surveyed by a separate Com- 

 mission, consisting of Col. Anson Mills, U. S. Army, and another 

 commissioner appointed by the Mexican Government, 



The boundary sections are shown in fig. 1. 



Fig. 1. — Diagram showing sections of Mexican boundary line (section 1 is omitted.) 



1. The Rio Grande from its mouth to a point about 3 miles above 

 El Paso, Texas. Extent, 1,770.3-1: kilometers or 1,100 miles'." 



2. Parallel 31° -17' north latitude, from the middle of the Rio 

 Grande, at the last point, west to meridian 108° 12' 30" west longi- 

 tude (Monuments Nos. 1 to 40). Extent, 159.38 kilometers, or 99.03 

 miles. 



3. Meridian 108° 12' 30" west longitude, from the last point, south 

 to the parallel 31° 20' {Monuments Nos. 40 to 53). Extent, 49.83 

 kilometers, or 30.96 miles. 



4. Parallel 31° 20', from the last point, to meridian 111° 4' 34,3'' 

 (Monuments Nos. 53 to 127). Extent, 272.94 kilometers, or 169.59 

 miles. 



5. Sonora azinuith line, from the last point to the Colorado River, 

 latitude 32° 29', longitude 114° 46' 48". 7 (Monuments Nos. 127 to 

 205.) Extent, 377.13 kilometers, or 234.33 miles, 



a The Boundary Coniniissioii with which I was connectetl as medical officer 

 and naturalist had nothing to do with the survey of this first section, but con- 

 ducted that of the six remaining sections from the Rio Grande to the Paciflc 

 Ocean. 



