62 



abundance and luxuriance of the half-dozen species of trees, 

 the ocotilla, larger shrubs, and cacti. The lower, flatter parts 

 of the slope, where the altitude is only slightly greater than 

 that of the Laguna Salada and its flood-plain, are covered 

 with scattering clumps of mesquite similar to the one at the 

 Tres Pozos. Interspersed among the mesquites are patches 

 of an Atriplex, probably the quail-brush, A. lentiformis (PI. VI, 

 Fig. 1.), and between the clumps is a sparse growth of bunch- 

 grass. Mesquites are by no means confined to this lower 

 belt, however, for they form rows, sometimes veritable hedges, 

 along the innumerable arroyos that reach for a distance of 

 eight or ten miles up the slope to the abrupt face of the Tina j as. 

 Indeed, the size and vigor of the mesquites in this dry expanse 

 does not conform to the general opinion that the species is 

 unable to flourish on the desert proper. Beyond question, 

 the largest trees that we saw were along the upper washes. 



At the southeastern extremity of the basin, near the foot 

 of the Pinto Range and bordering the delta flood-plain, is an 

 extensive dune area where acres of '' antelope weed" (Abronia 

 villosa) were in blossom at the time of our visit. Southwest- 

 ward from here, and uphill, this type of terrane is succeeded 

 by stretches in which saltbush {Atriplex polycarpa) and creo- 

 sote prevail, although there are also a number of wind-formed 

 mounds, twelve or fifteen feet high, still covered by the pro- 

 jecting limbs of large, moribund mesquites. At least one 

 such mesquite dune was used as a roosting place by a small 

 flock of ravens, in April, 1915. 



Beginning in the sandy area just described, and extending 

 for several miles up the long slope, is a broad belt of creosote 

 bushes in which there is a considerable mingling of gramineous 

 plants and annuals. Pebbly tracts, practically bare of vegeta- 

 tion, are common among the creosotes, and in such places we 

 frequently found horned larks feeding. 



Running in more or less parallel lines across the creosote 

 belt, and extending with sporadic interruptions from the face 

 of the Tina j as to the very floor of Pattie Basin, are the long 

 gulches or arroyos previously mentioned. These are usually 

 gouged out to a depth of from two to eight feet below the 



