. A manual of zoology. 136 MANUAL OF ZOOLOGY tegument. The leaf-like form exemplified in the liver-fluke prevails in most (Fig. 71), but a more elongated form some- times occurs. The anterior end is distinguished from the posterior by its shape, by the arrangement of the suckers, and, in many of those Trematodes that are external para- sites, by the presence of eyes. Suckers are universal in their occurrence. They are always ventrally placed, their chief function being to fix the parasite to the surface of its. Fig. 71.— Trematodes. A, Amphistontztm; B, HomaUgaster. rp, genital aperture; ;//,
. A manual of zoology. 136 MANUAL OF ZOOLOGY tegument. The leaf-like form exemplified in the liver-fluke prevails in most (Fig. 71), but a more elongated form some- times occurs. The anterior end is distinguished from the posterior by its shape, by the arrangement of the suckers, and, in many of those Trematodes that are external para- sites, by the presence of eyes. Suckers are universal in their occurrence. They are always ventrally placed, their chief function being to fix the parasite to the surface of its. Fig. 71.— Trematodes. A, Amphistontztm; B, HomaUgaster. rp, genital aperture; ;//, mouth; s, posterior sucker; te, testes; vit. vitelline glands (After M. Braun.) host in such a way as to facilitate the taking in by the mouth of animal juices and epithelial debris. Their number and arrangement vary considerably. There are nearly always present an anterior set (or, as in the liver-fluke, a single anterior sucker surrounding the mouth), and a posterior set or a single large posterior sucker. There. 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 Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Ltd.
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