CYPRINODONTS, a family of fishes, soft-rayed and with abdominal pelvic fins, but without a duct to the air-bladder. The head is flat-topped, the mouth generally small and protractile, with bands of small teeth in the jaws, the scales usually large. About 40o species are known, none of which exceeds a foot in length ; they are found in all warm countries, but are especially abundant in America ; many species are marine, but these espe cially frequent lagoons and estuaries ; others are confined to fresh water. The Cyprinodonts are much appreciated as aquarium fishes, on account of their small size, pretty colours, and lively habits. Courtship and pairing are general throughout the group, and in many species the sexes are very dissimilar, the males being brilliantly coloured and having large and beautifully orna mented fins. Cynolebias of South America is unique among fishes, the dorsal fin of the male being not only much larger than that of the female, but having many more rays. There are seven sub families, of which the Fundulinae and Cyprinodontinae are oviparous and occur in Africa, southern Europe, and Asia, as well as in America. In the extraordinary Phallostethinae, from Johore and the Philippines, pelvic fins are absent and the male has a large muscular appendage under the head. The other viviparous groups, four in number, are American, and in them the anal fin of the male is modified into an intromittent organ. Lebistes retic ulates, the "Millions" fish of the Nest Indies, devours mosquito larvae and so helps to prevent malaria. Xiphop/iorus helleri of Mexico, named "sword-tail" because the lower half of the caudal fin of the male is produced into a long pointed process, is remark able for "sex inversion," about half the females becoming con verted into males before they reach an inch in length. One of the most curious types is the "four-eyed fish" (Anableps) of Central and South America, in which the eyes project above the top of the head, and are divided by a black horizontal band into an upper part for vision in the air and a lower for vision in the water. Spermatophores have been described in the Phallostethinae and Poeciliinae, and may be characteristic of the group. The Ambly opsidae, which include the blind cave fishes of North America, are a related family. (C. T. R.)