4 University of Michigan 



B. Aquatic Habitats. 



V. Lowland forest ponds. Swamps and pools, mainly tem- 

 porary, in the forest itself and in the cleared regions. The 

 two main classes studied are: (a) pool-swamps in the low 

 jungle along La Laja; and (b) the pools in the burnt-over 

 region and cleared land. 



VL Savannah ponds. Established ponds in the savannahs. 

 Although the Laguna de Chacalapa is about a mile in length, 

 it is not over a meter deep at the height of the wet season. 

 Only one shell was obtained. 



Vn. Rivers and lakes, a. La Laja. This is what is known 

 in many Spanish-American countries as a camo (literally, a 

 sewer). It is a sluggish stream and black-water channel oflf 

 of the Arroyo Hueyapam, and does credit to its Spanish 

 designation. 



b. Sand-bars of the Arroyo Hueyapam. At the hacienda, 

 the Hueyapam consists of a steep-banked channel about fifty 

 yards by twenty to thirty feet deep, which, dependent upon 

 the weather, may contain anything from a sizable creek, with 

 pools, little rapids and sand-bars, to a raging torrent that com- 

 pletely fills or overflows it. It is quite typical of the scoured, 

 sandy creeks so common in the tropics. 



c. Rio San Juan. A quite large river, which was in flood at 

 the time visited, and in some places over-reached its banks for 

 almost half a mile. Its bottom is probably sandy. 



d. Laguna de Catemaco. A deep-basined crater ( ?) lake, 

 several miles in diameter. Most of the shore is of volcanic 

 rock and it contained several rocky islands, but near the out- 

 let and in some other places this is covered by a deposit of 

 humus-material. The latter developed, in some parts, a mag- 

 nificent border of water-hyacinths, a hundred yards wide or 

 more. Collecting was also done in a small, but very deep, body 



