COLE : YERTEBRATA FROM YUCATAN. 103 



Further collections were made at Progreso and vicinity from April 

 12 to 17. 



A word should be added as to the general character of the country. 1 

 The northern part of the peninsula is a soft limestone plain, which 

 slopes gently up to the southward from the Gulf. The rock, in many 

 places bare, is at best covered with only a scanty soil, not capable 

 under the existing conditions of supporting a very luxuriant vegeta- 

 tion. There are no surface rivers, at least none of any permanence, 

 the water sinking quickly into the porous limestone rock and finding 

 its way to the sea by underground courses. There are, however, 

 numerous caves and openings down to the water, which, in the north- 

 ern part of the peninsula at least, appears to maintain a fairly constant 

 level but little above that of the sea. These water-holes are known 

 locally as cenotes. 



The western part of the country, in the region of Merida, is largely 

 cleared of the forests and given over to the growing of henequen, the 

 plantations of which sometimes stretch away as far as the eye can reach. 

 To the eastward the land is uniformly forested, except for occasional 

 clearings for the growth of corn or sugar cane. Such is the country 

 about Chichen-Itza, where from the top of one of the ancient ruins which 

 rises above the forest one may look in all directions to the horizon over 

 an almost level and unbroken sea of tree tops. Only here and there is 

 the general level interrupted by a growth of taller trees about a cenote, 

 or where the forest mounts over the crumbled pile of a prehistoric 

 building. 



Owing to the porosity of the rock and the scarcity of surface water, 

 the conditions in northern Yucatan are much more arid than would at 

 first thought be expected, and, as might be supposed, this has a notice- 

 able effect upon the fauna. Many of the birds, for example, are distin- 

 guished as geographical races, and in nearly all cases this distinction is 

 based upon their being smaller in size and paler in coloration than the 

 representatives of the same species which live in the more humid regions 

 of Mexico and the countries to the southward. 



Progreso is situated upon a low-lying strip of sand between the Gulf on 

 one side and an extensive mangrove marsh on the other. This marshy 

 strip, spoken of as la cienaga, el rio, or la laguna, extends along 



1 A good description of the physiographic and climatic conditions of Yucatan 

 may be found in a recent paper by David Casares, A notice of Yucatan, with 

 some remarks on its water supply. Proc. Amer. Antiquarian Soc. for 1905, new 

 ser., 1906, 17, p. 207-230. 



