4 CALIFORNIA ACADEMY OF SCIENCES. 



privilege of studying this material, and for the use of 

 the museum libraries, and to Mr. Samuel Garman for 

 aid in making the collection available for study. We 

 wish to express our thanks to Miss Frances M. Slack of 

 the museum library, and to Mr. Thomas J. Kiernaii of 

 the Harvard University library, for many favors. 



To Dr. G. A. Boulenger of the British Museum, to 

 Dr. E. D. Cope of Philadelphia, and to Mr. Alexander 

 Thominot of the Jardin des Plantes, we are indebted for 

 the examination of types. To Dr. David S. Jordan we 

 are indebted for advice concerning some of the questions 

 of nomenclature and other favors. 



The species are numbered consecutively. Varieties 

 have the letters "a," "b," "c," etc. attached to the 

 number of their respective species. Doubtful species 

 have the decimals ".1," ".2," ".3," etc., attached to the 

 number of the valid species preceding. 



In the descriptions the usual formulas have been em- 

 ployed. The length of the head is measured from the 

 tip of the snout to the end of the bony opercle in all fam- 

 ilies but the Loricariidae, in which it is measured from 

 the tip of the snout to the end of the temporal plate. 

 The length is measured from the tip of the snout to the 

 base of the middle caudal rays. The " interocular " is 

 measured between the nearest edges of the eyes, the " in- 

 terorbital " between the nearest edges of the bony orbits. 

 Unless otherwise stated, the color descriptions have been 

 taken from alcoholic specimens. 



In the matter of nomenclature we have followed the 

 canons of the A. 0. U. Code as far as possible and prac- 

 ticable. 



CARL H. EIGENMANN, 

 KOSA S. EIGENMANN. 



