142 APPENDIX. 



timber, consisting of Pinus chihuahuana and Pseudotmga douglasii. The smaller 

 woody plants here include several Californian species, such as Cercocarpus parvifolius 

 and Arctostaphylos tomentosus. The vegetation of the upper valleys of San Bernardino, 

 San Pedro, and Santa Cruz contains a large number of endemic types associated with 

 an intermixture of Californian and Texan species. Proceeding to the lower Santa Cruz 

 valley and the desert of Tucson, a distinct botanical district is entered, where again 

 plants characteristic of a dry region are met with. Here Prosopis and Larrea are con- 

 spicuous, and Cactaceae abound, and include such remarkable forms as the massive 

 Echinocactus mslizenii and the lofty Cereus giganteus. An Agave inhabits the crevices 

 of the neighbouring mountains, where also Franseria deltoidea, Encelia farinosa, and 

 Perityle nuda are found. After the rains the open plains are carpeted with a profusion' 

 of brightly-coloured evanescent annuals, among the most conspicuous of which are 

 Vesicaria and Eschscholtzia. 



The flora of the canons of the Rio Grande differs but little from that of the mountain 

 ravines already alluded to. On the abrupt walls, whether of limestone or of igneous 

 rock, grow Laphamia dissecta and L. bisetosa, Perityle aglossa and P. parryi, Eucnide 

 lobata, Cowania ericifolia, and the monotypic Emorya. In open places the charac- 

 teristic tableland vegetation appears. The flora of the extensive basin of Presidio del 

 Norte is more Mexican in character. Here grow Kallstroemia grandiflora, Martynia 

 violacea, M. arenaria, Talinopsis frutescens, Nicolettia edwardsii, and several species 

 of Boerhaama. Cereus greggii is common, and the delicious-fruited C. straminem 

 flourishes in its greatest perfection. 



Thus far a very much condensed epitome of Dr. Parry's sketch. 



For a picture of western and some parts of central North Mexico we cannot do 

 better than reproduce a portion of Seemann's ' Introduction to the Flora of North- 

 western Mexico ' *, and a few additional particulars will be found in the quotations 

 from Hartweg's narrative of his journeys in Mexico (see page 126). We give Seemann's 

 own words. 



" The district [visited by Seemann] is not defined by any political or natural limits, 

 but by an imaginary line extending from Acapulco north-eastward to Durango, thence 

 to Chihuahua, from that city to the mouth of the river Colorado, in the Gulf of Cali- 

 fornia, and along the western coast of Mexico to Acapulco. Generally speaking, it may 

 be said that a narrow strip of flat land runs along the whole coast, immediately followed 

 by a chain of mountains which on their eastern side join the tableland of Mexico, the 

 plains of Anahuac. Such a district situated partly within the boundary of the tropics, 

 partly without it, and possessing lowlands, high, mountains, and elevated plains, has a 

 great diversity of climate — is subject to great extremes of temperature. On the coast 

 from Acapulco to Mazatlan there are the usual tropical seasons, the wet and the dry, 

 the former commencing about the end of May and ending towards the end of August* 

 * Botany of the Voyage of H.M.S. < Herald,' pp. 262-265. 



