56 BOTANICAL GAZETTE [JULY 
tum, Yucca, Agave, and Opuntia. So far as might be estimated by 
the instruments at hand, the mountain is probably the one on the 
hydrographic map of 1873-75 designated as a ‘‘sharp white peak 
4288',”” which had not previously been ascended, and still bears no 
name. ; 
METEOROLOGICAL FEATURES. 
Data bearing on the climatic conditions in the delta and of the 
contiguous deserts are very meager. Records have been kept at 
Yuma for a long term of years, and some data obtained at Torres, 
Sonora, quoted in the recent contribution by Mr. Coville and the 
author,’* constitute the only information available. The following 
table taken from the records of the U. S. Weather Bureau’? gives 
the conditions at the head of the delta. 
The transcript of the record was furnished by Hon. Willis L. Moore 
Chief U. S. Weather Bureau. 
4| 3 ali 
1903 16142) 4191) 3)2 iB) si 8i si sis 
Simi Mia t Sl ate eLe ZlalelsZ 
Maxim perature. 6.0%... 76 | 82 | go | 97 |106 |112 [112 [113 |112 | 96 | 87 | 80 . 
Minimum temperature. .....5.. 33 | 29 | 38 | 47 | 50 | 60 | 69 | 72 | 50 | 51 | 42 | 34 o* 
Precipitation... . eis Be ee: SOF fied Pics tos 2.98 
Average precipitation (1876-90).|}.39 |.45 |.18 |.12 |.06 13 |.40 |.13 |.23 |.35 |.64 '|3 . 
MEAN RELATIVE HUMIDITY. 
8 A.M. 
Year Jan. | Feb. —_ April | May | June | July | Aug. | Sept. | Oct. | Nov. Dee. 
Ge ear | ee] ees es | 0 
8 P.M. 
aati a) te ee eee 
It is to be seen that the delta and the contiguous districts have an 
annual precipitation of less than 7°™, and that less than 2°™ was 
** Desert Botanical Laboratory of the Carnegie Institution, p. 23. November 1903- 
"2 GREELY and GLasrorp, Report on the climate of Arizona. Ex. Doc. No. 287: 
Washington. 1891. Climate and Crop service, U. S. Weather Bureau. Report for 
zona Section for 1903. 
