XI. Serrasalmonina.—Dorsal fin rather elongate; an adipose fin. Gill-membranes free from the isthmus; belly serrated. Tropical America.
Although the fishes of this family do not attain any considerable size, the largest scarcely exceeding two feet in length, their voracity, fearlessness, and number renders them a perfect pest in many rivers of tropical America. In all, the teeth are strong, short, sharp, sometimes lobed incisors, arranged in one or more series; by means of them they cut off a mouthful of flesh as with a pair of scissors; and any animal falling into the water where these fishes abound is immediately attacked and cut in pieces in an incredibly short time. They assail persons entering the water, inflicting dangerous wounds before the victims are able to make their escape. In some localities it is scarcely possible to catch fishes with the hook and line, as the fish hooked is immediately attacked by the “Caribe” (as these fishes are called), and torn to pieces before it can be withdrawn from the water. The Caribes themselves are rarely hooked, as they snap the hook or cut the line. The smell of blood is said to attract at once thousands of these fishes to a spot. They are most abundant in the Brazils and Guyanas; some forty species are known, and referred to the genera Mylesinus, Serrasalmo, Myletes, and Catoprion.
Fig. 279.—Serrasalmo scapularis, from the Essequibo.
Sixth Family—Cyprinodontidæ.
Head and body covered with scales; barbels none. Margin of the upper jaw formed by the intermaxillaries only. Teeth in both jaws; upper and lower pharyngeals with cardiform teeth. Adipose fin none; dorsal fin situated on the hinder half of the body. Stomach without blind sac; pyloric appendages none. Pseudobranchiæ none; air-bladder simple, without ossicula auditus.
Small fishes, inhabiting fresh, brackish, and salt water of Southern Europe, Africa, Asia, and America. The majority are viviparous; and to facilitate copulation the anal fin of the adult male of many species is modified into a copulatory organ, which is probably (partially at least) introduced into the vulva of the female; but it is uncertain whether it serves to conduct the semen, or merely to give the male a firmer hold of the female during the act. Also secondary sexual differences are developed in the Cyprinodonts; the males are always the smaller, sometimes several times smaller than the females, quite diminutive; and they are perhaps the smallest fishes in existence. The fins generally are more developed in the males, and the coloration is frequently different also. Some species are carnivorous; others live on the organic substances mixed with mud. Fossil remains have been found in tertiary strata, all apparently referable to the existing genus Cyprinodon; they occur near Aix in Provence, in the marl of Gesso, St. Angelo, in the Brown coal near Bonn, near Frankfort, and in the freshwater-chalk of Oeningen. In the latter locality a Poecilia occurs likewise.
The genera can be divided into two groups:
I. Cyprinodontidæ Carnivoræ.—The bones of each ramus of the mandible are firmly united; intestinal tract short, or but little convoluted. Carnivorous or insectivorous.
Cyprinodon.—Cleft of the mouth small, developed laterally and horizontally. Snout short. Teeth of moderate size, incisor-like, notched, in a single series. Scales rather large. Origin of the anal fin behind that of the dorsal in both sexes, both fins being larger in the male than in the female. Anal not modified into a sexual organ.