90 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



seen in the mountains during the summers of 1892 and 1893. For 

 this reason, as well as on account of the absence of water and the 

 difficulty of transportation, I did not attempt to establish a perma- 

 nent collecting station at the summit of the San Luis Mountains. 

 Stations No. 17, at the lower timber line on the east side, and No. 20 

 (at Monument No. 66) (Plate III, fig. 2), just below timber line on 

 the west side, were'occupied ; and Station No. 18, in the cypress zone on 

 the east, and a camp at the spring in Turkey Canyon, at a correspond- 

 ing altitude on the west side, were centers of collecting activity for 

 several weeks. During July, 1892, the writer, with the assistance of 

 Lieut. Francis G. Irwin, explored the Animas and San Luis ridges 

 from the San Luis Pass north to the second Animas Peak (altitude, 

 2,505 meters) and south to the heads of Cajon Bonito Creek, in Mex- 

 ico. In addition to this, I made collections in the moimtains on the 

 following dates: May 31, 1892, crossed range at Cook Pass; June 

 2 and 29, 1892, crossed range at Irwin Pass, near the Boundary Line ; 

 June 1, 1892, explored Turkey Canyon to about 1 mile above the 

 second spring; June 2, 17, and 29, 1892, eastern base, near the Bound- 

 ary; June 18 to 19 and 22 to 27, 1892, San Francisco Canyon and 

 adjacent portions of east slope from base to summit; July 5 and 19, 

 1892, west slope from base to summit; several visits were made 

 during July, 1892, to Mr. Holzner's camp at the lower spring in 

 Turkey Canyon; September 11, 1893, San Francisco Canyon, east 

 side, from base to summit; September 24, 1893, Irwin Pass from 

 Monument 64 to Monument 66; August 31 and September 1, 4, 5, 6, 

 and 7, 1893, west side from base to summit, in the vicinity of Turkey 

 Canyon; September 25, 26, 29, 30, and October 1 and 2, 1893, west 

 slope of San Luis Mountains, sometimes touching the summit. Mr. 

 Holzner collected birds and mammals on the east side of the San 

 Luis Mountains, in San Francisco Canyon and its vicinity, June 22 

 to 27, 1892. From July 11 to 23 he camped at the lower spring in 

 Turkey Canyon, on the west side of the range. 



Flora of San Luis Mountains. — Many important plants are found 

 in the vicinity of this station, as will be seen from the lists below. 



These mountains are largely of calcareous rock, and are steep and 

 much eroded. Where the rock is covered with soil they are wooded, 

 from a well-marked lower timber line at about 1,600 meters, or 5,250 

 feet altitude, to the summit (altitude 2,400 meters, or 7,874 feet). A 

 list of the trees is given below, their vertical range and relative 

 abundance having been sufficiently commented on : 



Pinus atrobiformis Engelmann. 

 Pinus cem'broides Zuccarini. 

 Pinus ponderosa Lawson. 

 Pinus mayriana Sudworth. 

 Pinus chihuahuana Engelmann. 



Pseudotsiiga mvcronata (Rafinesque) 



Sudworth. 

 Cupressus arizonica Greene. 

 Juniperus monosperma (Engelmann) 



Sargent. 



