IBIS. 1920. PL.VH. 



The "Barrens," i.e. one of the two types of border-zone between 

 the Forest and the "flateau." Middle-Atlas (5700 ft.) 





The Crest-mounds," i.e. the other tvpe of border zone 

 between the Forest and the "Plateau." Middle-Atlas 



(5700ft.) 



