. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. s^ ANATOMY OF AMPHIOXUS. region of the twenty-seventh myotome, where the pharynx ends and the intestine begins. They were discovered in 1875 by Lankester, who called them the atrio-ccelomic or broivn funnels, on account of the rich accumulation of brown pigment in their walls. We have already referred to this brown pigment as occurring very generally in the atrial epithelium. The brown funnels have the shape of an. Fig. 28. — Plastic diagram illustrating the positions and relations of the atrio- ccelomic fun

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. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. s^ ANATOMY OF AMPHIOXUS. region of the twenty-seventh myotome, where the pharynx ends and the intestine begins. They were discovered in 1875 by Lankester, who called them the atrio-ccelomic or broivn funnels, on account of the rich accumulation of brown pigment in their walls. We have already referred to this brown pigment as occurring very generally in the atrial epithelium. The brown funnels have the shape of an. Fig. 28. — Plastic diagram illustrating the positions and relations of the atrio- ccelomic funnels. A rod is passed through the peri-enteric ccelom into the sub- chordal (suprapharyngeLil) c(£lom. (After Lankester.) ao. Dorsal aortce. at. Atrial cavity, b.f. Atrio-ca?lomic funnels, go. Gonads. l.d. Ligamentum denticulatum (pharvngo-pleural folds, Lankester). I.m. and r.vi. Left and right metapleural folds, my. Muscles. pk. Roof of pharynx, w. Point of union of the right and left aorta? into the median aorta. elongated cone, the apex of which is directed forwards. At the wide end each funnel opens into the atrial cavity, while at the narrow end it is possible, but not certain, that an opening exists into the dorsal ccelom (Fig. 28). The funnels are adherent throughout their entire length to the roof of the dorsal ccelom.'*. 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 work.. Willey, Arthur, 1867-. New York, London, Macmillan

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