Chromides and Pharyngognathi 381 



analogy to the black bass of farther north. A vast number 

 of species belonging to Heros, Acara, Cichlasoma, Geophagus, 

 Ch&tobranchus, and related genera swarm in the Amazon region. 

 Each of the large rivers of Mexico has one or more species ; one 

 of these, Heros cyanoguttatus, occurs in the Rio Grande and the 

 rivers of southern Texas, its range corresponding with that of 

 Tetragonopterus argentatus, just as the range of the whole family 

 of Cichlida corresponds with that of the Characinida. No other 

 species of either family enters the United States. A similar 

 species, Heros tetracanthus, abounds in the rivers of Cuba, and 

 another, Heros beani, called the mojarra verde, in the streams 

 of Sinaloa. In the lakes and swamps of Central America Cich- 

 lid(z and Characinidoz are very abundant. One fossil genus is 

 known, called Priscacara by Cope. Priscacara clivosa and 

 other species occur in the Eocene of Green River and the Great 

 Basin of Utah. In this genus vomerine teeth are said to be 

 present, and there are three anal spines. None of the living 

 Cichlidcs have vomerine teeth. 



The Damsel-fishes: Pomacentridae. The Pomacentrida, called 

 rock-pilots or damsel-fishes, are exclusively marine and have in 

 all cases but two anal spines. The species are often very bril- 

 liantly colored, lustrous metallic blue and orange or scarlet 

 being the prevailing shades among the bright-colored species. 

 Their habits in the reef pools correspond very closely with those 

 of the Ch&todontida. With the rock-pilots, as with the butterfly- 

 fishes, the exceeding alertness and quickness of movement make 

 up for lack of protective colors. With both groups the choice 

 of rocky basins, crevices in the coral, and holes in coral reefs 

 preserves them from attacks of enemies large enough to destroy 

 them. In Samoa the interstices in masses of living coral are 

 often filled with these gorgeous little fishes. The Pomacentridce 

 are chiefly confined to the coral reefs, few ranging to the north- 

 ward of the Tropic of Cancer. Sometimes the young are colored 

 differently from the adult, having sky-blue spots and often 

 ocelli on the fins, which disappear with age. But one species 

 Ckromis chromis, is found in the Mediterranean. Chromis 

 punctipinnis , the blacksmith, is found in southern California, 

 and Chromis notatus is the common dogoro of Japan. One of 

 the largest species, reaching the length of a foot, is the Gari- 



