MEXICO. 17 
The caves, though of considerable size, were on the whole rather disappointing, 
and the only animals seen were innumerable bats, which tainted the whole atmosphere ; 
as regards other living creatures, even after a diligent search, neither Mr. Flohr nor 
myself succeeded in discovering any traces of insects. A Lepisma and a beetle are, 
however, reported as having been found by other collectors. 
Gadow’s account of the Rio Balsas or Mescala basin informs us that it is bordered 
on the south side, parallel with the Pacific coast, by a long high range of mountains, 
attaining an altitude of 10,000 feet, densely wooded and intersected by deep gorges, 
while the river beds, which form the only available roads, occasionally widen into 
meadows. 
At Chilpancingo there is a wind swept, shallow depression of cretaceous formation, 
surrounded by sparsely wooded hills with meadows on the top of the ridge. ‘To the 
west the slopes of the Sierra Madre del Sur are covered with rich forest growth: oaks, 
dwarf palms, and pines abound, higher up oaks, pines, and arbutus, and, finally, pines 
alone, form dense high forests; while in the gorges, especially within the cloud-belt, 
most luxuriant undergrowth prevails. Omilteme (7100 feet) where many specimens 
were obtained, is situated in these mountains. 
At Cumbre de Los Cajones, a pass of 3500 feet marks the beginning of volcanic 
formation. The typical ‘tierra caliente,’ with an essentially tropical flora and fauna, is 
found on the southern slope of the main ridge, coinciding with what is officially known 
as La Costa. The upper limit may be put at 1000 feet, but the country loses its 
tropical character on the ridges, which rise higher than 1500 feet. 
From Coquillo to Chacalapan (700 feet) there is tropical life, and from thence to the 
coast across lower ridges, the subsoil consists of gneiss and granite in rapid decom- 
position, while wooded ground and open pastures are also found. The rivers during 
the winter season are frequently dry, but near the granite bound coast are lagoons 
mostly containing pure water ; a broad belt of almost impenetrably high forest extends 
in places to the sea. Mangrove swamps are permanent features of the landscape, but 
in the rainy season many parts of the forests are inundated, and over nearly the whole 
of the coastal district a dense mass of tall herbs usurps the place of brushwood in the 
forest belts. 
Throughout the State of Guerrero large collections, chiefly consisting of birds and 
insects, were made for us by Mr. and Mrs. H. H. Smith, who spent a considerable 
time in the district, paying special attention to the fauna during the time I employed 
them in Mexico. ; 
We have no detailed account of the States of Durango, Sinaloa, and Sonora, but the 
general aspect is barren and rocky, and although I sent one or two collectors to 
those districts, I gained no accurate information as to the physical features. 
BIOL. CENTR.-AMER., Introd. Vol., January 1915. D 
