. Elements of Comparative Anatomy. 160 COMPAEATIVE ANATOMY. of the intestine is attached by laterally-directed fibrous chords to the body-wall, as a rule, along the lateral lines. The hind-gut, which arises from the mid-gut, is the shortest portion of the whole canal, and is distinguished from the part in front of it by its diminished breadth. In the Gordiacea the enteric canal is present in the entoparasitic larval stages only, and undergoes retrogressive metamorphosis when the sexual organs are developed. In Gordius even the mouth dis- appears. The organism, when it is free, uses up the mate
. Elements of Comparative Anatomy. 160 COMPAEATIVE ANATOMY. of the intestine is attached by laterally-directed fibrous chords to the body-wall, as a rule, along the lateral lines. The hind-gut, which arises from the mid-gut, is the shortest portion of the whole canal, and is distinguished from the part in front of it by its diminished breadth. In the Gordiacea the enteric canal is present in the entoparasitic larval stages only, and undergoes retrogressive metamorphosis when the sexual organs are developed. In Gordius even the mouth dis- appears. The organism, when it is free, uses up the material which it ingested by its enteron during the earlier stages, in forming genera- tive products, after it has given up its parasitic habit, and the ingestion of food. The enteric canal of the Cha3- toguathi resembles in many points that of the Nemathelminthes, but the enteron is connected to the body-wall in a different way, namely along its dorsal and ventral median lines. Setiform hooks, arranged in rows at the sides of the mouth, serve as organs of prehension. § 130. Although the digestive organs of the Bryozoa are sharply marked off into the three primitive di- visions, they are exceedingly simple in character. The mouth, which is surrounded by the tentacles, or placed in the centre of the lobate process which carries them, is in one division (Phyiactolsemata) over- living by a movable process—the epistom. Thence it passes straight back to an oesophageal portion (Fig. 71, ve), which in some is widened out or even converted into a gizzard by the development of denticular processes in one part of. Fig. 71. Organisation of Bryozoa. A Paludicella Ehrenbergii. B Plu- matella fruticosa. hr Tentacular brancliiaj. oe CEsophagus (fore-gut). V Stomach, r Hind-gut. a Anus, i Covering of the body (cell), a; Posterior; X' Anterior chord, at the insertion of which into the body the generative liroducts are developed. t Testes. 0 Ovary, on Eetractor muscles of the anterior portion of
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