. Text-book of zoology for junior students. Zoology. 244 VERTEBRATE ANIMALS. throiighriut life, and by having an integumentary skeleton composed of ijiitioiil scales, plates, or spines (fig, 164, rf). The skull is com- posed of distinct bones, and there is always a lower jaw. There are usuidly two pairs of tins (pectoral and ventral), su]iported by many series of cartilages, and the ventral fins ai-e placed very far back. The hrst rays in the tins are usually in the form of strong spines. The caudal hn or tail is mostly heterocercal or unsynimetrical (fig. 167, B). The swim-bladder is always j
. Text-book of zoology for junior students. Zoology. 244 VERTEBRATE ANIMALS. throiighriut life, and by having an integumentary skeleton composed of ijiitioiil scales, plates, or spines (fig, 164, rf). The skull is com- posed of distinct bones, and there is always a lower jaw. There are usuidly two pairs of tins (pectoral and ventral), su]iported by many series of cartilages, and the ventral fins ai-e placed very far back. The hrst rays in the tins are usually in the form of strong spines. The caudal hn or tail is mostly heterocercal or unsynimetrical (fig. 167, B). The swim-bladder is always jiresent, is often cellular, and is provided with an air-duct. The gills and gill-covers are essen- tially the same as in the Bony fishes. The heart has one auricle and a ventiicle ; and the hnlhiis arteriosus is rhythmically contrac- tile, is furnished with a distinct coat of niuscuhu' fibres, and is provided with several transverse rows of valves. The best known of the living (4anoids are the Bony Pike or Tiar-. Fig. 17n.âA, lfi>i(h,itrus nsMHs, tlm " Gar-Pike" nf tlie American Lakes; B, AspiOo- rhiim^hti^, rcstnreil (altcT' Agassiz), a .JuraSf^ic Ganoid allied to Lepldosteus, but havini; a h. -i-rral tail. fish {), the Sturgeon {Aripeiixcr), and the I'uli/pterns. Of , the Bony Pike (fig. 17.'>, A), is fcmnd in the rivers and lakes of North America. It is a large fish, attaining a length of several feet, and it has the ImkIv eidiiely covered with an ai'iuovu- of ganoid .scales arranged in oblicpiely transverse rows. The jaws form a long narrow snout, armed with a double series of teeth, and the tail is heteioceieal. The vertebi"il (aihiiun is more perfectly ossified than in any other , the bodies of the being convex in front .â uid concave beldnd ('' iipixlliiiri^liiiix"). The Pn/i//ifrnix inhabits the rivers Nile .-ind Seneg;d, .â lud is remarhalile for the ]ieeuliar structure of the dorsal fin, \\hirli is bink
Size: 2369px × 1055px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1885
