BIOLOGIA CENTPvALI-AMERICANA. 



ZOOLOGIA. 



Class PISCES. 

 Sub-class I. TELEOSTOMI. 



Order I. TELEOSTEI. 



Sub-order I. ACANTHOPTERYGII. 



It has been found convenient to commence an account of the Fresh-water Fishes of 

 Mexico and Central America with the Acanthopterygii, which maj' be recognized by 

 the thoracic or jugular position of the ventral fins, the pelvic bones being directly 

 attached to the clavicles. 



The Acanthopterygian fresh-water fishes of Mexico and Central America may be 

 referred to their families by means of the following key : — 



T. Head asymmetrical, ■n-ith tlie two eyes on one side; fins without spines . 1. Pleuronectid^e. 



ir. Head symmetrical. 



A. Gill-openings restricted, the gill-membranes attached to the isthmus. 



Ventral fins widely separated, jugular; dorsal and anal fins short, 



without spinous rays 2. GoBiESociDiE. 



Ventral fins not M-idely separated, thoracic; two dorsals or the dorsal 



fin long 3. Gobiid^t;. 



B. Gill-membranes free from the isthmus. 



1. Anal fin with .3 spines, 2 of which are detached from the rest of the 



fin 4. Carangid^e. 



2. Anal fin not preceded by free spines. 



a. A single nostril on each side. Dorsal with XIV-XIX 7-15* rays. 



Anal with III-XII G-12 rays 5. Cichlid^e. 



* The lloman numerals indicate the number of sijines, the Arabic figures the number of articulated rays. 



BIOL. CENTE.-AMEE., Pisces, Odoher 1906. B 



