Fig. 312.—Viviparous Perch (male), Hysterocarpus traski Gibbons. Battle Creek, Sacramento River. (Photograph by Cloudsley Rutter.)
CHAPTER XXII
CHROMIDES AND PHARYNGOGNATHI
Suborder Chromides.—The suborder Chromides contains spiny-rayed fishes similar to the perch-like forms in most regards, but strikingly distinguished by the complete union of the lower pharyngeal bones, as in the Holconoti and Pharyngognathi, and still more remarkably by the presence of but one nasal opening on each side. In all the perch-like fishes and in nearly all others there are two nasal openings or nostrils on each side, these two entering into the same nasal sac. In all the Chromides the lateral line is incomplete or interrupted, and the scales are usually large and ctenoid.
The Cichlidæ.—The suborder Chromides includes two families, Cichlidæ, and Pomacentridæ. The Cichlidæ are fresh-water fishes of the tropics, characterized by the presence of three to ten spines in the anal fin. In size, color, appearance, habits, and food value they bear a striking resemblance to the fresh-water sunfishes, or Centrarchidæ, of the eastern United States. This resemblance is one of analogy only, for in structure the Cichlidæ have no more in common with the Centrarchidæ than with other families of perch or bass. The numerous species of Cichlidæ are confined to tropical America and to corresponding districts in Africa and western Asia. Tilapia nilotica abounds in the Nile. Tilapia galilæa is found in the river Jordan and the Lake of Galilee. This species is supposed to form part of the great draught of fishes recorded in the Gospels, and a black spot on the side is held to commemorate the touch of Simon Peter. Numerous other species of Cichlidæ, large and small, abound in central Africa, even in the salt ditches of the Sahara.
The species of Cichla, especially Cichla ocellaris, of the rivers of South America, elongate and large-mouthed, bear a strong analogy to the black bass of farther north. A vast number of species belonging to Heros, Acara, Cichlasoma, Geophagus, Chætobranchus, 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 Cichlidæ corresponds with that of the Characinidæ. 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 Cichlidæ and Characinidæ 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 Cichlidæ have vomerine teeth.
Fig. 313.—Garibaldi (scarlet in color), Hypsypops rubicunda (Girard). La Jolla, San Diego, Cal.
Fig. 314.—Pomacentrus leucostictus (Müller & Troschel), Damsel-fish. Family Pomacentridæ.