GENERAL REMARKS. ]3 



The following species of the Pacific region, 8 in number, extend through the Mexican into the Atlantic region : 



Eysenhardtia orthocarpa. Acacia Greggil. Chilopsis saligna. Juniperus occidentalis. 



Prosopis pnbescens. Fraxinus pistaciiBfolia. Juglans mpestris. Juniperus pachyphlcea. 



Juglans rupestris and Juniperus occidentalis reach their greatest development in the Pacific Coast region, and 

 extend through the Pacific-Mexican region into western Texas ; no other species are common to the Pacific Coast 

 forest and the Atlantic-Mexican region. The 6 remaining Pacific-Atlantic species belong to the Pacific-Mexican 

 region, just reaching western Texas. 



The following species of the Southern Pacific region extends into the Atlantic region: 



Salix amygdaloides. 



The following species of the Pacific forest, 12 in number, endemic to the interior arid region, do not extend 

 beyond its limits : 



Acer grandidentatum. Crataegus rivnlaris. Populus angnstifolia. Finns monophylla. 



Robinia Neo-Mexicana. Fraxinus anomala. Finns flexilis. Picea pungens. 



Cercocarpus ledifolins. Quercus undulata. Pinus ednlis. Yucca brevifolia. 



A detailed examination eif the distribution of the arborescent species composing the North American forests 

 shows that 



Magnolia is represented by seven Atlantic species, with the center of its distribution in the southern Alleghany 

 region. 



Liriodendron is represented by a single species, widely-distributed through the eastern and central portions of 

 the Atlantic region. 



Asimina is represented by a single widely-distributed arborescent species and by three frutescent species of 

 the Atlantic region. 



Anona, Capparis, Ganella, and Glusla are represented each by a single semi-tropical species. 



Gordonia is represented by two species of the southern Atlantic region, one of wide distribution, the other 

 rare and local. 



Fremontia, a genus endemic to the Pacific region, is represented by a single species of the southern Pacific 

 Coast region. 



Tilia is represented by two Atlantic species, with its center of distribution in the southern Alleghanj' region. 



Byrsonima is represented by a single semi-tropical species. 



Guaiacum is represented by a single semi-tropical species. 



Porliera is represented by a single species of the Atlantic-Mexican region. 



Xanthoxylum is represented by two species of the Atlantic region, by a semi-tropical species, and by a second 

 semi tropical species which reaches the Atlantic-Mexican region. 



Ptelia is represented by a single arborescent species of wide distribution in the Atlantic, reaching also the 

 Pacific region, where a frutescent species occurs, and by a second frutescent species of the south Atlantic region. 



Canotia, a genus endemic to the Pacific-Mexican region, is represented by a single species. 



Simaruba, Amyris, Swietenia, Ximenia, are each represented by a single semi-tropical species. 



Bursera is represented by a single semi-tropical species and by a second frutescent species of the Pacific- 

 Mexican region. 



Ilex, an Atlantic genus, is represented by four arborescent and several frutescent species, with its center of 

 distribution in the southerp Atlantic region. 



Cyrilla and Gli/tonia are each represented by a single species of the southern Atlantic region. 



Euonymus is represented by a widely-distributed arborescent species in the Atlantic, and by a frutescent species 

 in both the Atlantic and the Pacific regions. 



Myginda, Schcefferia, and Reynosia are each represented by a single semi-tropical species. 



Gondalia is represented by one semi-tropical and by one species of the Atlantic-Mexican reaching the Pacific- 

 Mexican region. 



Rhamnus is represented by one arborescent and by one frutescent species in the Atlantic, by two arborescent 

 and one frutescent species in the Pacific region, and by one frutescent species common to the two regions. 



Geanothus is represented by a single arborescent species in the Pacific Coast region and by several frutescent 

 species widely distributed through the Atlantic and the Pacidc regions. 



Golubrina is represented by a single semi-tropical species. 



JEsculus is represented by two arborescent and by three frutescent species in the Atlantic, and by an arborescent 

 species in the Pacific region. 



Ungnadia, an endemic genus of the Atlantic-Mexican region, and just reaching the Pacific-Mexican region, is 

 represented by a single species. 



Sapindus is represented by one species widely distributed through the southern Atlantic, and reaching the 

 Pacific region, and by one semi-tropical species. '-' 



Acer is represented by five Atlantic and four Pacific species. 



Negundo is represented by one species widely distributed through the Atlantic and the Pacific regions and by 

 second species in the Pacific region. 



