PLATE 10 



Fig. 1. Portion of mesa at 3500 feet altitude near Dos Palmos Spring 

 on the desert slope of the Santa Rosa Mountains close to the upper 

 edge of the LoweT Sonoran Zone; photograph taken May 27, 1908. In the 

 background, on the shaded slopes, are such Upper Sonoran shrubs as 

 juniper, Rhamnus, scrub-oak, and with them such birds as Aphelocoma c. 

 californica, Thryomanes h. charienturus, and Pipilo c. senicula. In the fore- 

 ground Lower Sonoran vegetation predominates, with such birds as 

 Amphispiza b. deserticola, and Heleodytes b. couesi. Crossing this exact 

 place was the line of traps which produced in a single night (May 30 

 31) the following mammals: Perodipus a. agilis, Dipodomys m. xiniitilus 

 Neotoma i. desertorum, Perogtmthus p. bangsi, Perognathus f. pallidm 

 Peromyscus e. eremicus, Ammospermophilus I. leururus, and Notiosorex craw 

 fordi. Other mammals taken in the vicinity were Sylvilagus b. cineras 

 cens and Peromyscus h. rowleyi, thus showing the peculiar zonal overlap 

 ping at this point. 



Fig. 2. Female Vireo vicinior on nest located 850 millimeters above the 

 ground in bush of Adenostinna fuscicuhitiiin. The nest is seen to be sup- 

 ported not only at several points in the rim, but by the stiff twigs at 

 sides and bottom. This was a species of extraordinarily limited range 

 (see p. 291). 



[406] 



