NOTES ON A COLLECTION OE FISHES FROM THE RIVERS OF MEXICO, 
WITH DESCRIPTION OF TWENTY NEW SPECIES. 
By DAVID STARR JORDAN and JOHN O. SNYDER. 
INTRODUCTION. 
The writers spent part of the winter of 1898-99 in Mexico, devoting their spare time 
to the study of the fishes in the regions visited. The collection made is not large, 
but it contains a surprisingly large proportion of new forms, 20 of the 42 species 
having not been hitherto described, a fact which indicates that the river fauna of 
Mexico is much richer and more characteristic than has been supposed. The speci- 
mens are in the museum of the Leland Stanford Jr. University, series more or less 
complete having been also sent to the United States Fish Commission, the United 
States National Museum, the British Museum, and the museum at Vienna. The most 
unexpected fact disclosed is that of the large number of very closely related species of 
Ghirostoma or “pescado bianco” inhabiting the great Lake of Chapala. 
We would especially acknowledge the assistance of the following gentlemen: Mr. 
J. E. Page and his son, for assistance in collecting near Tampico ; Messrs. W. P. Mellen 
and W. J. Thompson, of Aguas Calientes; Mr. A. V. Temple, manager of bureau of 
information, Mexican Central Railroad, City of Mexico; Senor Joaquin Cuesta, of 
Atequiza, near Guadalajara. We are also under obligation to officials of the Mexican 
Central and Southern Pacific railways-, and to Wells, Fargo and Company’s Express. 
The following is a description of the localities in which collections were made, 
most of the work with the seiue being performed or directed by Mr. Snyder: 
Rio Lerma . — The Rio Grande de Santiago, locally known as Rio Lerrna, was first 
visited at the “Barranca” near Guadalajara, Jalisco. Here the river flows through a 
canon of volcanic rock at least 2,000 feet below the surface of the surrounding table- 
land. The river (December 23) was swollen and muddy, the water plunging along at 
such a rapid rate that small seines could not be used, and no collecting was done. 
Rio Lerma was next examined at Ocotlan, above the great falls of Juanacatlan, near 
the outlet of Lake Chapala. The same high, muddy water was found, but instead of 
the canon a comparatively shallow river bed which gradually spread over cornfields, 
marshes, and tule lands as the lake was approached. The flooded condition of the 
river and the consequent absence of good seining-places made collecting at the time 
we visited the region very unsatisfactory. To make a thorough study of the ichthyic 
fauna of the lake, which is a magnificent body of water, surrounded by mountains and 
containing several islands, one would have to be equipped with good collecting appa- 
ratus and be prepared to spend some time in the vicinity. 
Rio Verde de Aguas Calientes . — At Aguas Calientes the Rio Verde, a tributary of 
the Lerma, which flows into Lake Chapala, was an ideal collecting-place. The clear, 
cool water, shaded by trees and shrubs along the banks, winds here and there over a 
bed of fine gravel and sand. There are ripples and shallows, frequented by smaller 
fishes, aud many deep pools where the larger ones live. 
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