jo FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



In the dry season the natives dig basins in the bed of this stream 

 from which they get their drinking water. 



The Rio Ixtla, a tributary of the Rio Amacusac which empties 

 into the Balsas, is a clear stream with sandy and gravelly bottom. 

 Our collections were taken from this stream a short distance 

 above the picturesque old bridge at this place. A few speci- 

 mens were also taken from the Rio Tembernbe, a small tributary 

 of the Rio Ixtla. 



The San Francisco System. 



At La Antigua the Rio San Francisco is a broad stream with 

 a hard bottom. At this point the water was not more than 4 feet 

 deep. La Antigua is just above tide w r ater, and most of the fishes 

 taken here belong to salt or brackish water. 



A tributary of the Rio San Francisco at Jalapa is a small 

 stream. A dam is built at the head of the falls. ' Above the dam 

 the water is deep and the stream fills the narrow valley, forming 

 a sort of lake which is well filled with aquatic vegetation. Sein- 

 ing here was quite impossible. A few fishes were taken above 

 the dam by using the seine as a dip net. 



The small stream below the dam was seined for some distance. 

 It was narrow, with steep muddy banks, and contained a great 

 deal of vegetation. 



The Panuca System. 



At San Juan del Rio we visited the Rio Moctezuma which 

 flows into the Rio Panuca. The water in it was confined to a 

 few deep holes, with none running between them. Collecting 

 here was easy and satisfactory. The bed of the river was rocky, 

 but the shore of the deep holes next the bed of the stream was 

 sandy and with a gentle slope. 



The Verde System. 



The Rio Verde is a small Pacific coast stream which heads a 

 short distance above Oaxaca. It was nearly dry when our collec- 

 tion was made. Its bed at Oaxaca is broad and covered with 

 sand. A few holes in the bed contained a few fishes belonging to 

 two species. 



The Quiotepec System. 



The Rio Quiotepec drains a considerable area directly east of 

 the head waters of the Rio Balsas, and flows into the Gulf of 



