1883. ] and the region farther East. 1017 
Estacado of the Spanish, a nearly barren waste whose general 
level is from 3000 to 4000 feet above that of the sea, its main 
features otherwise being like those of the great interior desert to 
the north-west, and that of the Colorado basin! in California. 
Physa virgata Gld., is attributed by Binney? to Los Angeles, 
where I found it abundant in the basin of the fountain in the 
plaza near the Pico House, opposite the old parish church ; also 
near San Diego and in the Gila river in Arizona, exact locality 
not stated. 
Cooper’ also gives its range as “ Mojavé river to Gila river,” 
on what authority as to Mojavé river and region I do not know. 
As above suggested a glance at the map is necessary to obtain 
a clear idea of the extent of the area incidental to this discussion. 
San Diego county alone includes an area of over 15,000 square 
miles, and extends from the Pacific ocean to the Colorado river, 
its southerly boundary extending easterly along the Mexican 
line 175 miles to Fort Yuma, on the Colorado. 
1 The drainage area of the various basins, within which either of the West Amer- 
ican forms of fresh-water Mollusca occur, to which reference has been made in this 
or previous papers of mine relating to the distribution of such forms, may be briefly 
(in square miles) as follows: 
Columbia river, 298,000 
Colorado « , 257,000. s 
MOGE ee 240,COO 
This of course includes that of its tributary the Rio Pecos, the same as the Colorado 
includes the Gila, etc, 
Of the lesser basins the Sacramento is figured at 31,503, and the San Joaquin at 
24,710 square miles, including the mountain slopes which descend to and merge in 
meget these are the figures kindly furnished me by Wm. H. Hall, Esq., the 
which added together make a total cf over 56,000 square miles west of the crest 
ine of the Sierra Nevada range, and if this total be added to the drainage areas of 
the exterior basing or regions above recited, show a grand total of 851,000 square — 
Miles, to Say nothing of the vast area farther to the north not included within the 
figures or limits of the Columbia River basin. 
_ Omitting the Rio Grande area, which may be considered by some as at present 
table ground, we have left 611,000 square miles, an area so vast as to require 
the examination of a map in order to be appreciated. 
ŽL. and F. W. Shells of N. A., p. 93: 
* Geographical Catalogue. 
. 
