FAMILY V. CYPRINID/E. 37 



slender and have a larger eye than the adults. Often the young have 

 a lateral band and a dark caudal spot which the adults do not possess. 

 In the following descriptions the rudimentary rays of the dorsal and 

 anal fins are not counted. Besides the native species here mentioned, 

 two other species* from Europe and Asia have been introduced into 

 some of the streams and lakes of Mexico, where they have become quite 

 abundant, especially so in the Rio Lerma and the lakes in the Valley 

 of Mexico. Both of these species are offered for sale in the markets 

 in the City of Mexico. They are easily distinguished from the native 

 fresh-water fishes by the long dorsal fin which is preceded by a serrated 

 spine. 



KEY TO THE GENERA OF CYPRINID^E. 



a. Dorsal fin short, without developed spine. PAGE 



b. Air bladder surrounded by many convolutions 

 of the long alimentary canal; pharyngeal 

 teeth 4-4, or i, 4-4, o, with oblique grinding 

 surface, the tips slightly hooked; peritoneum 

 black Campostoma 40 



*Dorsal fin elongate, its rays 18 or more; dorsal and anal fins each preceded 

 by a serrated spine; teeth molar. PAGE 



a. Barbels 4 ; teeth i , .1 , 33 , i , i Cyprinus 3 7 



aa. Barbels none ; teeth 4-4 Carassius 3 7 



Genus Cyprinus (Artedi) L. 



Body deep, robust; mouth moderate, terminal, with 4 long barbels; snout 

 blunt, rounded; pharyngeal teeth i, i, 3-3, i, i, molar-like; dorsal fin very 

 long, with a stout spine, serrate beMnd; lateral line complete; scales large. 

 Large fishes of the fresh waters of Asia. 



Cyprinus carpio Linnaeus'. CARP; CARPA. 



Dorsal in, 20; A. in, 5; scales 5-38-5. Body stout, more or less com- 

 pressed, heavy anteriorly; color silvery. Length 3 feet. 



This species was introduced into Europe and America from Asia. The carp 

 is normally covered with large scales; in domestication several varieties have 

 arisen, the prominent ones being the " Leather Carp," having no scales, and the 

 "Mirror Carp," with a few series of very large scales. 



Genus Carassius Nilsson. 



Body oblong, compressed and elevated; mouth terminal, without barbels; 

 teeth 4-4, molar- like, but compressed; dorsal fin very long, with a stout spine 

 which is serrate behind; anal short with a similar spine; ventrals well forward. 

 Large fishes of the fresh waters of Asia. 



Carassius auratus (Linnaeus). GOLD-FISH. 



Dorsal n, 18; A. n, 7; scales 26; teeth 4-4. Body rather robust, much 

 compressed; lateral line complete. 



Color olivaceous, orange, or variegated in domestication. Length about 

 1 8 inches. 



The streams of China and Japan are the native homes of this species. Owing 

 to its bright coloration it has been introduced everywhere as an aquarium fish, 

 where it has taken on numerous and strange variations. In the lakes in the 

 Valley of Mexico it has become quite an important food fish. 



