296 Alexandkr G. Eüthven, 



obtained, but the oiilj^ otlier group tliat was collected at all 

 extensively was the Crustacea, the specimeiis of which have been 

 studied and reported lipon by Dr. Pearse. ^) 



The region chosen for investigation was in the Canton of Acayucau 

 in soiithern Vera Cruz. Headquarters were established on the 

 hacienda of the Cuatotolapam Sugar Company, which lies between 

 the San Juan River and the San Andreas Tuxtla Range, northeast 

 of the Station of Rives on the Vera Cruz al Istmo R. R. The 

 immediate region of the hacienda (viz., between the San Juan River, 

 Arroyo Negra, Laguna de Chacalapa and the San Andreas Tuxtla 

 Range, see PI. 6) was worked in as much detail as possible in tlie 

 six weeks (July 10 to August 20) spent in the field, and a few days 

 were spent in a reconnaissance in the mountains about Lake 

 Catemaco. 



T p g r a p h y. 



The country lying between the San Juan River and the San 

 Andreas Tuxtla Mountains, which received most of our attention, 

 is a gently roUing piain. The altitude of this piain is low. Mr. 

 H. B. Reese, Assistant Chief Engineer of Construction of the National 

 Railroads of Mexico, informs me that the elevation of the banks of 

 the San Juan River at the proposed crossing near the hacienda is 

 15 meters above sea-level. The most conspicuous elevations on this 

 piain are the groups of Indian mounds along the streams. Of the 

 streams traversing the region, Arroyo Negra, La Laja Creek, Hueyapam 

 and San Juan Rivers, the first three ai*e tributaries of the latter. Owing 

 to the level nature of the topography the drainage is rather poor. 

 The streams all have a low gradient soon after leaving the moun- 

 tains and flow sluggishly through beds of alluvium. There are 

 numerous shallow ponds , some of which are doubtless dry except 

 during tlie rainy season. They were all filled with water during 

 the Summer. These ponds are mostly small, but one, the Laguna 

 de Chacalapa, is about a mile in length, altho apparently not over 

 one meter deep. 



East of the flood piain of the Hueyapam River the land rises 

 rapidly to the foot hüls of the mountains. The latter appear to be 



1) Report on the Crustacea collected by the TJniversity of Michigan- 

 Walker Expedition in the State of Vera Cruz, Mexico, in: 13. Ann. Rep. 

 Michigan Acad. Sc, p. 108. 



