The Delta of the Rio Colorado. 9 
Another basin below the sea-level connected with the delta is to be 
found on the farther side of the Cucopa Mountains, which bound the 
delta on the southwest. During floods the waters bathe the entire 
eastern foot of the mountains, and great volumes find a way around 
the southern end of the range to this basin, filling the depression in 
two places known as the Laguna Maquata and Coyote Laguna. 
These are also soon dried up after the supply of water ceases. 
The topographical features described above combine to make the 
Cucopa Mountains, which are to be reckoned as among the most arid 
on the continent, a peninsular ridge at high water connected with dry 
FIG, 5.— ACTIVE MUD- S cauer a NEAR VOLCANO LAKE, CERRO PRIETO, THE LARGEST OF 
TH OUP SEEN IN THE DISTANCE, IS NUW QUIESCE NT. 
land by a narrow strip a few feet only above sea-level, and extending 
northwestward across the international boundary. 
Not unexpectedly to the naturalist, this range affords many ende- 
mic species of plants and animals, and those which range beyond its 
confines bear a more intimate relation with the forms inhabiting the 
mainland of Mexico and Arizona than to the remainder of peninsular 
California. 
Hot springs and other manifestations of volcanic energy are to be 
found all along the geological vault on the eastern side of the penin- 
sula of Baja California, but the most pronounced feature of this char- 
acter is to be found well out in the delta near Volcano Lake. Here on 
