. Chordate morphology. Morphology (Animals); Chordata. Myxinid The mouth of the hagfish (Figure 9-27) is super- ficially like that of the lamprey, but the funnel is without teeth and papillae. There are four pairs of tentacles around the funnel, and a nasohypophyseal opening lies above it. There is a rasping organ, in the floor of the mouth cavity, armed with two semicircles of teeth, the anterior set larger than the posterior. There is a single tooth in the roof of the mouth above the rasping organ. The nasohypophyseal canal opens into the mouth poste- riorly, and behind this junction there i
. Chordate morphology. Morphology (Animals); Chordata. Myxinid The mouth of the hagfish (Figure 9-27) is super- ficially like that of the lamprey, but the funnel is without teeth and papillae. There are four pairs of tentacles around the funnel, and a nasohypophyseal opening lies above it. There is a rasping organ, in the floor of the mouth cavity, armed with two semicircles of teeth, the anterior set larger than the posterior. There is a single tooth in the roof of the mouth above the rasping organ. The nasohypophyseal canal opens into the mouth poste- riorly, and behind this junction there is an enlargement of the pharynx, the velar chamber. From the roof of this chamber a velum is suspended from a midline frenulum. The lateral margins of this structure can be rolled and un- rolled to produce a pumping action driving water back through the pharynx. The branchial pouches open to either side from the pharynx which leads back to the intestine. The intestine is a straight tube of large diameter. There is no typhlosole, but the inner walls have longitudinal folds, as in the lamprey. The liver has a posterior left lobe and an anterior ventromedial lobe; the lobes are not joined (Figure follicles of ova pancreas gastrohepotic artery liver. ostium of both oviducts esophagus . opening of bile duct- spiral valve nidamental gland superior mesenteric vein superior mesenteric artery spleen inferior mesenteric artery abdominal pore opening of seminal vesicle B opening of MLillerian duct urinary pore lin urogenita I sinus Figure 9-25. Viscera of Hydrolagus. A, ventral view; B, lateral view of gut with the left wall cut away to reveal the interior. THE DIGESTIVE TRACT AND ASSOCIATED STRUCTURES • 277. 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 Jollie, Malcolm. New York, Reinhold
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