MAY, 1902. THE ICHTHYOLOGY OF MEXICO MEEK. 67 



The Lerma System. 



The Rio Lerma is the longest river in Mexico. In its basin 

 are found a large number of lakes. Some of these lakes, as Lago 

 de Chapala, are still connected with the river, while many, as 

 Patzcuaro, Zirahuen and others, have long since become isolated 

 and at present each one forms an independent drainage system. 



The Rio Verde was visited at Aguas Calientes. It contained 

 but little running water. In the bed of the stream were a number 

 of holes from three to five feet in depth. The water, though 

 apparently clear, contained a large amount of algae which so clog- 

 ged the meshes of the seines as to make collecting difficult. The 

 bottom was of sand and gravel. 



A small stream, a tributary of the Rio Verde, flows through 

 the city of Lagos. It contained but a small amount of water. 

 There is a small lake about two miles from Lagos. It is about 

 one-half mile in diameter, and is bordered by a rich growth of 

 cat-tails, tules and other forms of aquatic vegetation. There 

 were no sandy shores and it was quite impossible to use a seine 

 in it. 



In the lake, a small ditch near by, and in the stream at the 

 city, a small collection of fishes was made. Cat-fish, probably 

 Amciurus dugesii, are reported common in the lake, but we were 

 unable to obtain any. 



At La Barca the Rio Lerma is a rather broad, deep river 

 with a very sluggish current. The river was too deep to wade 

 any distance from the shore, and so a few hauls of the seine were 

 made from shore by means of ropes, and with better results than 

 is usually accomplished in this way. The bottom and shores 

 were muddy; occasionally along the margin was considerable 

 aquatic vegetation. 



Lago de Chapala is the largest fresh water lake in Mexico. 

 The Rio Lerma flows into this lake near La Barca at the northeast 

 corner, and flows from it a few miles farther down at Ocotlan. 

 After the river leaves the lake it is known as the Rio Santiago. 



At Ocotlan we collected in the main river and in a few small 

 bayous. The river here is about 200 feet wide and 10 to 15 feet 

 deep. Its banks were steep but less so than at La Barca. 



La Palma is a small village some 20 miles from Ocotlan and 

 on the opposite shore of the lake. Lago de Chapala is from 10 

 to 25 miles wide and about 50 in length. It is surrounded by high 

 hills and mountains. The lake, especially between Ocotlan and 

 La Palma, is shallow. For a mile or so from La Palma it is not 



