Elements of Comparative Anatomy (1878) Elements of Comparative Anatomy elementsofcompar78gege Year: 1878 Fig. '74. Enteric canal of Aphrodite, o An- terior jDortion. h Middle (muscular) portion of the fore-gut. c Branched csecal appendages of the mid-gut. a Anus. trance is armed with chitinous ridges, which are the first signs of jaws. But in most the mid-gut is beset by pouch-like diverticula (Fig. 73), which are branched in Clepsine; the last two of these diverticula sometimes form longer csecal tubes (c) on the narrow hind-gut, which extends to the end of the body (Clepsine, Haemopis). The
Elements of Comparative Anatomy (1878) Elements of Comparative Anatomy elementsofcompar78gege Year: 1878 Fig. '74. Enteric canal of Aphrodite, o An- terior jDortion. h Middle (muscular) portion of the fore-gut. c Branched csecal appendages of the mid-gut. a Anus. trance is armed with chitinous ridges, which are the first signs of jaws. But in most the mid-gut is beset by pouch-like diverticula (Fig. 73), which are branched in Clepsine; the last two of these diverticula sometimes form longer csecal tubes (c) on the narrow hind-gut, which extends to the end of the body (Clepsine, Haemopis). These are the only cseca of the gut of Aulacostomum. In others the cseca are merely indicated by constric- tions. In all cases these arrangements correspond to the metamerism expressed also in the nerve- chord. In nearly all Annelids the fore-gut is separated into several, often very different, portions. A median portion is distinguishable by its more powerful muscular investment, and is separated from the mid-gut by a tract of varying length. Among the Scoleina, this portion, which is knoWn as the ' muscular stomach,' is very greatly de- veloped (Lumbricus). It forms the end of the fore-gut. It is placed more towards the middle of the latter in most Chastopoda, and is frequently provided with denticles, which work on one another like Fig. 75.' Maxillary apparatus of a Euni- cea (Lysidice). a^e Pairs of jaws (after Milne-Edwards).
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