. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. GILLS 277 giU-cleft known as the spiracle (p. 75), is as a rule present more anteriorly, between the mandibular and hyoid arches. In the Holo- cephali, however, the spiracle becomes reduced, there are only three holobranchs in addition to hemibranchs on the hyoid and fourth. Fig. 222.—Dissection of the head from the ventral side of A, an Elasmobranch (Zygtena malleus), and B, a Teleost (Gailiix aeglefinus), to show the branchial apparatus. In both figures the branchial arches on the left side are shown cut through hori
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. GILLS 277 giU-cleft known as the spiracle (p. 75), is as a rule present more anteriorly, between the mandibular and hyoid arches. In the Holo- cephali, however, the spiracle becomes reduced, there are only three holobranchs in addition to hemibranchs on the hyoid and fourth. Fig. 222.—Dissection of the head from the ventral side of A, an Elasmobranch (Zygtena malleus), and B, a Teleost (Gailiix aeglefinus), to show the branchial apparatus. In both figures the branchial arches on the left side are shown cut through horizontally. (From R. Hertwig's Zoology.) Pq, palatoquadrate, and a, its connection with the cranium anteriorly; vJc, lower jaw ; »n, oral cavity ; prm, premaxilla ; ma, maxilla ; pa, palatine ; hm, hyomandibular; is, internal apertures ; as, external branchial apertures; ops, opercular aperture ; h, branchial septum; W, anterior, and hP, posterior hemibranch of a gill-pouch ; op, operculum ; s, pectoral arch; :, tongue ; phi, inferior pharyngeal bone ; o, cesophagus. branchial arch, and an opercular membrane is present, covering the external branchial apertures and opening by a slit posteriorly ; traces of a similar structure are seen in Clilamydoselache. In and Teleosts there are no longer chambered gill- sacs. The septa on which the gill-laminse are borne become greatly reduced, so that the apices of the latter extend freely out- Avards ; the whole branchial region is, moreover, covered over by the operculum and branchiostegal membrane (comp. pp. 75 and 79),. 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 Wiedersheim, Robert, 1848-1923; Parker, William Newton, 1857-1923. London, Macmillan
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
