March, 1914. List of Fishes of Costa Rica — Meek. 105 



Family Cyprinidae. 



Carassius auratus (Linnaeus). 



Introduced species, which has escaped from aquaria. 



Pacific side (i), 124 mm.; San Jose (in captivity) (i), 112 mm. 



Family CharacidsB. 



Astyanax aeneus costaricensis var. nov. 



Astyanax cerstedii Meek, Pub. Field Mus., Zool. Ser., vii, 1907, 145 

 (Turrialba) . 



Tetragonopterus cBneus Regan, Ann. & Mag. Nat. Hist., 1908, 455, 

 part (Rio Iroquois, Costa Rica). 



Astyanax ceneus (Gunther) is very variable and when studied in 

 more detail will, no doubt, be found to comprise a number of fairly well 

 marked varieties. Specimens examined by me from both sides of 

 Guatemala appear to be the same, Astyanax a. micropthalmus (Gunther). 

 In these the inner premaxillary teeth are 5-5, though occasionally 

 these are 4-5. The maxillary teeth are 2-2, but these are sometimes 

 1-2 or 2-3. The anal rays range from 26 to 30. In form those from 

 any one locality vary greatly, some being slender, others comparatively 

 deep. Specimens from Lake Managua, Nicaragua, resemble those 

 from Guatemala, except that the snout averages a little shorter and 

 slightly blunter, the inner row of premaxillary teeth is 5-5, except 

 occasionally 4-5. There are also a few more teeth on the maxillary; 

 these are usually 2-3, but are occasionally 3-3 or 3-4. The anal rays 

 average a little less, ranging from 25 to 29. This form is the Astyanax 

 a;rstedii (Kroyer) and the Astyanax nicaraguensis Eigenmann and 

 Ogle. 



In Costa Rica there are two well-marked varieties or species. Those 

 from the Atlantic slope resemble the preceding forms, in that the inner 

 premaxillary teeth are 5-5 (occasionally 4-4 or 4-5). The maxillary 

 teeth are 2-2 ; these occasionally vary from o to 3 ; the anal rays vary 

 from 28 to 31 {Astyanax a. costaricensis Meek). 



Specimens from the west side of Costa Rica have the inner maxillary 

 teeth 4-4, occasionally 4-5; the anal rays vary from 26 to 31. The 

 form from the west side of Costa Rica differs rather more from the 

 other forms than they do from each other {Astyanax albeolus Eigen- 

 mann) . 



