. Outlines of zoology. Zoology. 500 PISCES—FISHES. Second type of Fishes. The Haddock {Gadus aglefinus) —A type of Teleosteans with closed swim-bladder (Physoclysti). Form and external features.—The elongated wedge-like form is well adapted for rapid swimming. The terminal mouth bears a short barbule; this is long in the cod (G. morrhud), and absent in the whiting (G. merlangus). The nostrils, situated near the end of the snout, have double apertures. The eyes are lidless, but covered with transparent skin. Over the gill-chamber and the four gills lies the. Fig. 214.—External characters of a T
. Outlines of zoology. Zoology. 500 PISCES—FISHES. Second type of Fishes. The Haddock {Gadus aglefinus) —A type of Teleosteans with closed swim-bladder (Physoclysti). Form and external features.—The elongated wedge-like form is well adapted for rapid swimming. The terminal mouth bears a short barbule; this is long in the cod (G. morrhud), and absent in the whiting (G. merlangus). The nostrils, situated near the end of the snout, have double apertures. The eyes are lidless, but covered with transparent skin. Over the gill-chamber and the four gills lies the. Fig. 214.—External characters of a Teleostean— a carp.—After Leurtis. R., Dorsal unpaired fin ; S., homocercal caudal fin ; A., anal fin ; £., B., pectoral and pelvic paired fins. Note also the lateral line and barbule. operculum, supported by several bones. Distinct from one another, but closely adjacent, are the anal, genital, and urinary apertures,—named in order from before backwards. Along the sides of the body runs the dark lateral line con- taining sensory cells. There are three dorsal and two anal fins, and an apparently symmetrical tail fin. Skin. — The small scales which cover the body are developed in the dermis, and are without any bone cells. Their free margin is even, a characteristic to which the term cycloid is applied, in contrast to ctenoid, which describes those scales which have a notched or comb-like free margin. Over the scales extends a delicate partially-pigmented Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Thomson, J. Arthur (John Arthur), 1861-1933. Edinburgh, Glasgow and London, H. Frowde and Hodder & Stoughton
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
