File:Image from page 258 of "Introduction to zoology; a guide to the study of animals, for the use of secondary schools;" (1900) (14785056945).jpg

Identifier: introductiontozo00dave Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company London, Macmillian and co., ltd. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: FIG. 220. — Gasterostea.s bispinvaux, the two-spined stickleback. Above, nestwith eggs, and male entering. Below, male depositing its mil on the eggs. Figs. 219 and 220 are reproductions of water-color paintings in the Museumof Comparative Zoology at Harvard College. the species the male builds an elaborate nest from bits ofaquatic plants, firmly united by a special mucilaginoussecretion. The nest, which is built among the plants ofthe stream, consists of a short cylinder, through the hori- THE SMELT AND ITS ALLIES 239 zontal cavity of which the fish can lie while it deposits itseggs. The male is polygamous, and guards the singlenest, which receives the eggs from various females (Figs.219, 220). The codfishes, among the most important of food fishes,are characterized by having ventral fins without spines,and articulated fin-rays, well-developed caudal fin, isocercaltail, and barbel on chin. Our common codfish (Fig. 221)

Text Appearing After Image: . 221. — Gad its morrhua, the codfish. About one-seventh nat. size. After Storer. occurs over the whole of the North Atlantic ; but themost important fishing localities are the banks near New-foundland, especially Grand Bank. The flatfishes are peculiar among fishes in that theyhave the habit in the adult stage of lying on one side. Inconsequence the under eye migrates to the upper side, sothat both eyes come to lie on the same side of the body.The mouth also tends to become unsymmetrical. Theflatfish, consequently, illustrates well the principles of self-adaptation to a peculiar environment. The catfishes are distinguished by the possession offour to eight long barbels around the mouth, and by the 240 ZOOLOGY absence of scales on the body. They are characteristic ofSouth America, but there are a large number of species inthe United States, mostly found in the Mississippi valley

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