103 
IX. 
L. A. M. Ritey. 
The State of Sinaloa is situated on the Pacific littoral of 
Northern Mexico, and is bounded on the north by Sonora and 
Chihuahua, on the east by Durango and on the south by Tepic, 
the Gulf of California forming its western limit. The greater 
part of Sinaloa lies north of the Tropic of Cancer. Its area is 
33,671 sq. m., and the population in 1910 was estimated at 
323,642 persons, of whom a large proportion consisted of Indians. 
Three climatic zones may be distinguished : “‘a narrow coastal 
zone where tropical conditions prevail, a broad belt of mountainous 
country covered by the ranges of the Sierra Madre Occidental and~ 
their intervening valleys where oak and pine forests are to be 
found, and an intervening zone among the foothills of the Sierra 
Madre up to an elevation of 2,000 ft., where the conditions are 
subtropical.’’* 
There are two distinct seasons in most parts of Mexico, the 
dry (October to May) and the rainy (June to September). The 
warmest month is generally July, and the coolest December or 
January. The following data for the seaport of Mazatlan give 
some idea of the climate of the southern part of the coastal zone : 
total annual rainfall, 32 in.; mean monthly temperature of 
sti month (January), 67° F., of warmest month (July), 
° F.+ More detailed meteorological data for Mazatlan are. 
eek by Harshberger.t Rain is plentiful everywhere in Sinaloa 
except in the extreme north, where the conditions are arid.§ 
Phytogeographically speaking, the north of the coastal zone 
is included i in the Sinaloa district of the Sonoran Desert Region, 
ile the remainder of the coastal zone falls within the Jaliscan 
Radiant The tract of mountainous country in the interior 
belongs, on the other hand, to the Western Sierra Madre Region.|} 
Our knowledge of the flora of Sinaloa may be said to commence 
with the publication of Seemann’s Flora of North-Western Mexico 
(Bot. Herald, 257-346; 1856). The “Herald” anchored in 
the port of Mazatlan on Nov. 26, 1848, and remained there until 
Dec. 4. Seemann left the port without delay for San Sebastian, 
a small town about 1,000 ft. above sea-level, and on the following 
day proceeded to the Hacienda de las Naranjas, a farm on the 
foot of the Cerro de Pinal, where he “ stayed two days, and found 
in the neighbourhood a fine mountain vegetation—pines and 
oaks in the greatest profusion.” He returned by the same route, 
passing the villages of Santa Catarina and Nanches, and the 
town. of San Sebastian and El Presidio de Mazatlan. 
* Encyel. Brit., ed. 11, xxv. 140 (1911). 
T nae a Intelligence Division, Handbook of Mexico, 35-38 (1919). 
t Phytogeo gr. Surv. N. Am., 150, 151 (1911). 
§ Encycl. Brit., ed. 11, 140. 
ll Hathbérger, ‘ke. 636, 640, 657, 
