Fishes . thin;yvddos, jaw) are characterized by the absence of teeth in thejaws and by the high degree of specialization of the lower phar- 382 Series Ostariophysi yngeals, which are scythe-shaped and in typical forms are armedwith a relatively small number of highly specialized teeth ofpeculiar shape and arranged in one, two, or three rows. Inall the species the gill-openings are restricted to the sides; there isno adipose fin, and the broad, flat branchiostegals are but threein number. In all the species the scales, if present, are cycloid,and the ventral fins, of course, abdominal. The modi
Fishes . thin;yvddos, jaw) are characterized by the absence of teeth in thejaws and by the high degree of specialization of the lower phar- 382 Series Ostariophysi yngeals, which are scythe-shaped and in typical forms are armedwith a relatively small number of highly specialized teeth ofpeculiar shape and arranged in one, two, or three rows. Inall the species the gill-openings are restricted to the sides; there isno adipose fin, and the broad, flat branchiostegals are but threein number. In all the species the scales, if present, are cycloid,and the ventral fins, of course, abdominal. The modificationof the four anterior vertebrae and their connection with theair bladder are essentially as seen in the catfishes. The name PlectospondyU is often used for this group {nXeKTo?,interwoven; anovSvXos, vertebra), but that term originally in-cluded the Characins as well. The Cyprinidae.—The chief family of the Evcntognathi and thelargest of all ihe families of fishes is that of Cyprinidcc, comprising. Fig. 291.—Pharyngeal bones and teeth of European Chub, Leuciscus cephalus(Linnaius). (After Seelye.) 200 genera and over 2000 species, found throughout the north tem-perate zone but not extending to the Arctic Circle on the north,nor much beyond the Tropic of Cancer on the south. In thisfamily belong all the fishes known as carp, dace, chub, roach,bleak, minnow, bream, and shiner. The essential character of thefamily lies in the presence of one, two, or three rows of highlyspecialized teeth on the lower pharyngeals, the main row con-taining 4, 5, 6, or 7 teeth, the others i to 3. The teeth of themain row differ in form according to the food of the fish. Theymay be coarse and blunt, molar-like in those which feed on shells; Series Ostariophysi 383 they may be hooked at tip in those which eat smaller fishes;they may be serrated or not; they may have an excavatedgrinding surface, v/hich is most developed in the species whichfeed on mud and have long intestines. In the Cyprinid
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