91 
tion seen previously by the writer in the islands in the harbor at 
Guaymas, 
The alluvial plain of a ee is about as large as the state of 
Massachusetts and suppo wth of mesquite fis 
sopts), willow (Sa/ix) and on ade excant, which 
this time were beginning to show the spring awakening. In a 
upper part of the delta, the newly formed low-lying land sup- 
seth tee plantations of a huge cane (Phragmites Phragntites) 
the lower part is replaced by a cattail So " (Dypha 
ie. A stop of four days was made at Lerdo for the 
purpose of making observations, rigging the on | calking 
the boat. Interesting conditions were encountered along the 
Santa Clara Slough, which is a flowing salt stream winding its 
way through a sandy and gravelly desert plain. 
In order to make a section of the entire delta Professor Forbes 
left the party at this point, and having secured horses rode 
northwestward a distance of eighty miles to the town of Calexico 
on the international boundary. Mr. E. C. Cushman, who was 
stationed at Lerdo on a mission to the Cocopa Indians for the 
Louisiana Purchase expedition joined the expedition and accom- 
panied us to the gulf. 
In descending the river the poplars were left behind a short 
distance below Lerdo, the willows extended some distance 
bearing salt grass (Destichlis spicata), salt bush (A‘rif/ex) and 
mesquite and still nearer the mouth of the river were great 
stretches of mud flats many ie in extent bearing only salt 
grass, and Jaced with ‘a network of salt sloug s. This lower 
course of the river is subject to strong tidal waves, ‘which sweep 
reat expanses of plain and make navigation dangerous for river 
craft, and the record of the occasional attempts made to explore 
this region is a long retail of accident on water and privations on 
land, 
After clearing the mouth of the river our course was laid for 
~ San Felipe Bay on the west coast of the gulf at a distance of 
about fifty miles, which was made without special incident. This 
bay is an indentation of the shore line with a small volcanic hill 
