XVI INTEODUCTION. 



Mexico (/. e. Soutlicrn Vera Cruz, Oaxaca, Chiapas), British Honduras, and Guatemala. 

 In this area 41 species occur, and to the north of it the Cichlid fauna is a very poor 

 one, comprising one species from the Balsas, another from tlie lowland streams ot 

 Sinaloa and Jalisco, four from the Panuco (one of which also occurs in the Rio Soto 

 Marina and the Bio Grande), and an additional species from the tributaries of the 

 Rio Grande in Nuevo Leon. 



The great lakes of Kicarai^ua, I^akes Managua and Nicaragua, have a peculiar 

 Cichlid fauna, consisting of 18 species, all but one of which arc endemic. These 

 include some remarkable types, such as the genera Ilerotihipia and Nectroplus, and 

 specialized forms of the genus C/chlosoma, sirch as C. lahiatum and C. lohochilus, with 

 thick lips and large blunt teeth, C. manacjuense and C. dovii, with very protractile 

 month, and C. laJteafum and C. ■iiicaraguense, with the profile of the snout nearly 

 vertical. It is certainly curious that each of the sections Theraps, Archoceiitnia, 

 Astatlieros, and Parapetenia is represented in the Great Lakes of Nicaragua by its 

 most specialized types. 



Nothing is known of the Cichlid fauna of Llonduras, Salvador, and Nicaragua north 

 and Avest of the Great Lakes, but it may be inferred that it is of the same general 

 character as that of Guatemala and that many of the species will prove to be the 

 same, seeing that Cichlosoma macuUcaiida of Guatemala is also foimd in the Rio 

 Chagres. Except C. maculicauda and the two species belonging to the South-American 

 genera Acara and Geoiiliagiis, only four Cichlids have been described from Costa Rica 

 and Panama. These are: (1) Cicl/loson/a cifrineJJvm, also found in Lake Nicaragua; 

 (2) Cichlosoma altifrons, very close to C. rosfrafum of Lnke Nicaragua ; (3) Cichlosoma 

 alfari, allied to C. haJtcafvm of Lake Nicarfigna ; and (4) Farccncctroiilus siebolclii, 

 congeneric with P. Ivllcri from Southern Mexico, but also near to Xeetroplas 

 iiemaiojms of the Great Lakes of Nicaragua. 



The Peecid/E are fresh-water fishes of North America, east of the Rocky Mountains, 

 and Western Eurasia. Of nearly 100 species about SO belong to the North-American 

 genera Etheos/oriia, Percina, llolcosovia, &c., comprising the dwarf Perches known as 

 " darters." Only G species of these extend southward to the basin of the Rio Grande 

 and the rivers of C'hihuahua and Durango. Fossil Percidse are found in the middle 

 Eocene deposits of Wyoming. 



The CEKTiiAiiC'iiJDJi are fresh --water fishes of North America. Of about 30 species, 

 which may be grouped into 8 or 9 genera, all but one, the Calilbrnian AmhIo]_)Htes 

 ivtirrupdys, are found east of the Rocky Mountains. Six species extend southward to 

 the Rio Grande, and one a little iurllier, into Tamaulipas. 



