2 University of Michigan 



stant advice and assistance is the reason behind its production. 

 The writer did the detailed work and the drawing, and any 

 inaccuracies or errors of judgment that may appear can safely 

 be laid to him. The drawing and photography were done at 



the zoological laboratory of the University of Pennsylvania. 



As a detailed study of the environment of the region has 

 already been published/ it is only necessary, in this paper, to 

 present again the location of the region and to summarize 

 briefly the ecological habitats. 



Location 

 All of the collection was made on or within a few miles of 

 the Hacienda de Cuatotolapam, except one day's work at the 

 Laguna de Catemaco, about twenty miles away. The hacienda 

 (map in Ruthven's paper; /. c.) lies between the Rio San Juan 

 and the Arroyo Hueyapam, a tributary, in the Canton of Aca- 

 yucan, southern \"era Cruz. This is approximately i8° N. 

 Latitude and 95^ W. Longitude, and about 50 feet above sea- 

 level. The country is quite typical of the tropical lowlands, 

 and the collections were made during what is known as the 

 wet season. 



The Laguna de Catemaco is a few miles to the north in the 

 heart of the coastal San Andreas Tuxtla range, and not far 

 from the city of San Andreas Tuxtla. This lake also drains 

 into the San Juan River system. The range and the lake 

 basin appear to be of volcanic formation. The altitude of the 

 latter is not definitely known to me, but is probably not more 

 than 2000 feet above sea-level. From the appearance of this 

 region, a considerable difference in the molluscan population 



1 Ruthven, A. G., 1912. The Amphibians and Reptiles Collected 

 by the University of Michigan-Walker Expedition in Southern Vera 

 Cruz, Mexico; Zool. Jahrb., XXXII, abt. f. Syst. ; pp. 295-330; pi. vi-xi. 



