TABLE OF CONTENTS. VII 



List of trees of the Mexican Boundary Line — Continued. Page. 



Holacantha emoryi (Holacantha) 62 



Koeberlinia spinosa (Koeberlinia; junco) 63 



Fremontodendron oalifornicum ( Fremont tree ) 63 



Rhus integrifolia (Western sumach) 63 



Acer saccharum grandidentatum ( Largetooth maple ) 63 



Acer negundo (Boxelder) 63 



Ungnadia speciosa (Texas buckeye; Mexican buckeye) 63 



Sapindus marginatus (Wild China tree) 64 



Rhamnus crocea (Evergreen buckthorn) 64 



Rhamnus purshiana (Bearberry ) 64 



Zizyphus obtusifolius (Obtuseleaf zizyphus) 64 



Cereus giganteus (Gianl cactus) 64 



Oereus thurberi (Thurber cactus) 66 



Cereus schottii (Schott cactus) ' 66 



Opuntia fulgida (Ghoya) 66 



Opuntia versicolor (Tree cactus) 66 



Opuntia spinosior (Sigura) 66 



Arbutus arizonica (Arizona madrona) 66 



ArcEbstaphylos pungens (Manzanita) 67 



Bumelia rigida (Shittimwood) 67 



Brayodendron texanum (Mexican persimmon) 67 



Fraxinua cuapidata (Fringe ash) 67 



Fraxinus velutina (Leatherleaf ash) 68 



Ohilopsis linearis (Desert willow) 68 



Sambucus mexicana (Mexican elder) 68 



Sambucus glauca (Pale elder; sanco) 69 



Introduced species of trees, now growing without cultivation on the Mexican 



Border of the United States 69 



Ohamaecyparis (Cedar) 69 



Ficus (Fig) 69 



Melia azedarach (China tree; Pride of India) 69 



Schinus molle (Pepper tree) 69 



Eucalyptus '. 69 



Nicotiana glauca (Coneton; Trouadora; Tobacco) 70 



Life Areas of the Mexican Boundary Region 70 



Differentiation tracts 73 



Descriptions of principal collecting stations 74 



Summary of collecting stations 143 



Mammals of the Mexican Boundary Region 149 



Order Marsupialia 150 



Family Didelphiidse 150 



Genus Didelphia 150 



Key to the Species of Didelphis found on the Boundary Line. 150 



Didelphis mesamericana texensis 150 



virginiana 153 



Order Edentata 156 



Family Dasypodidse 156 



Genus Tatu 157 



riovemcinctum 157 



Order tJngulata 158 



Family Tayassuidse 159 



Genus Tayassu 159 



angulatum 160 



sonoriense 162 



