By Dr. Forrest SHREVE. 
The Desert Laboratory, Tucson, Arizona. 
A rapid journey made through an interesting stretch of country 
awakens a constant desire to stop, linger and examine the natural 
phenomena in greater detail. It is often extremely vexing to feel it nee- 
essary to push forward under these circumstances, but in the very 
rapidity of such a trip there is a value which it is impossible to over- 
look. A rapid journey through a diversified region keeps the observer 
from being overwhelmed with new details and leaves his mind free to 
receive the larger impressions. In the excursion made by members of 
the Western Society of Naturalists and the Ecological Society of Amer- 
ica, under the auspices of the San Diego Society of Natural History, 
there was opportunity for a considerable examination of details at the 
same time that the journey of 200 miles, covered in two days, was sut- 
ficiently rapid to give the participants a vivid series of pictures of very 
dissimilar regions. To leave the humid Pacific shores in the morning 
and to witness the sunset on the arid sands of the Colorado desert on 
the same day is an experience which can not fail to linger in the reeol- 
lections of all who have enjoyed it. 
The course of the excursion lay east from San Diego, through the 
complex and crowded foothills to Campo, then through a series of val- 
leys lying between 3500 and 4000 feet, to a rather abrupt edge, from 
which it was possible to overlook the Imperial Valley. From this place 
the route descended rapidly to the edge of the desert, at about 1000 feet. 
In the vicinity of San Diego much of the country has been altered by 
cultivation, but the greater part of the journey lay through virgii 
country. 
From San Diego to the drainage divide of the Cuyamaca Mountains, 
east of Campo, the prevailing vegetation is chaparral, in which Adeno- 
stoma fasciculatum is the predominant plant. This type of vegetation, 
so characteristic of Southern California, here reaches a height of about 
5 to 6 feet, forming dense thickets in some places and low or open stands 
in others. Among the commonest associated plants are Rhus ategri- 
folia, Eriodictyon crassifoliuwm (yerba santa), Audibertia polystachya 
(white sage), and Hriogonum fasciculatwm. In the flood-plains of the 
larger streams are to be seen large trees of Quercus chrysolepis and 
Platanus racemosa, together with species of Sambucus, Salix, Populus 
and the climbing Vitis girdiana. The narrow dales, or valleys devoid 
of streamways, appear to have been originally unoceupied by either 
trees or chaparral, although it is now difficult to be sure of such a matter. 
There is little change in the character of the chaparral until an 
