1901] VEGETATION OF WESTERN TEXAS 217 
On the sand hills of the lower Staked plains region one of 
the western mountain oaks (Q. undulata or Q. Gambelit) occurs 
in low thickets. To this region and the buttes and mesas east- 
ward the trans-Pecos chaparral formation extends, and such 
reduced growths of Quercus and Juniperus as occur here become 
identified with the chaparral. 
[ Zo be concluded. | 
UNIVERSITY OF TEXAS. 
