378 PROCEEDINGS OF THE ACADEMY OF [1898. 



ate and more constant than that of the City of Mexico, or of the 

 Hacienda de Eslava, where a meteorological station has been estab- 

 lished. In consequence of the meteorological conditions, the ped- 

 regal supports a flora made up of many representatives of the tierra 

 fria, tierra templada and tierra caliente. 



The Serrania de las Cruces is a continuation northwestward of 

 the Sierra del Ajusco. It is an elevated region, and by reason of 

 that elevation and exposure to the winds of the north and west pre- 

 sents a very distinct flora. One part of the region, that on the west 

 flanks of the Serrania del Ajusco, is very humid ; the central por- 

 tion is more dry. Large forests of fir, Abies religiosa, once covered 

 the western side, but these are fast disappearing before the axe of 

 Mexican wood choppers. The higher elevations present a charac- 

 teristic alpine flora. Many of the places with an eastern exposure 

 are quite sterile, as to the abundance of plants found in such locali- 

 ties. 



CATALOGUE OF SPECIES FROM THE VALLEY OF MEXICO.* 



A. Lots. City of Mexico. 

 FICOIDEiE. 



1. Sesuvium portulacastrum Linn. Syst. ed X, 1,058; Jacq. Amer., t. 95, Biol. 



Centr. Amer., I, 556. 



North Mexico, South Mexico, Nicaragua. Common on the sea- 

 shores within the tropics. " Verdolaga de Costa," (Cuba). Aug. 12 



(1). 



ONAGRACEiE. 



2. GEnothera rosea [Soland in] Ait. Hort. Kew. ed. I, ii, 3; DC. Prodr., Ill, 51 ; 



Biol. Centr. Amer. Bot., I, 454. 



Widely distributed through Mexico, extending into Texas ; also 

 in Colombia and some of the West Indian Islands. Naturalized in 

 tropical Africa, India and the Canary Islands. Aug. 12 (3). 



COMPOSITJE. 



8. Aster Potosinus A. Gray in Proc. Amer. Acad., XV, (1880), 32 ; Biol. Centr. Amer. 

 Bot., II, 122. 



North Mexico, mountains of San Luis Potosi, 6,000 to 8,000 feet 

 (Parry & Palmer, 384). Aug. 12 (4). 



4 The natural orders are arranged according to the Engler and Prantl sys- 

 tem. The species are according to the Index Kewensis with the aid of 

 Hemsley's Biologia Centrali Americana (Botany). See for a description of 

 the ecological plant regions of the Valley of Mexico an article by the writer : 

 " A Botanical Excursion to Mexico." Amer. Journ. Pharm., 68, p. 588, and 

 the translation Una Excursion botanica a Mexico, El Tiempo Diario Catolico, 

 Dec. 4, 1896. 



