. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. EiG. 220.—Diagram of a LoNGITUDI^"AI. Section theougf the Head of THE Labval (A) AND ADULT (B) Peiromyzon. Ep JnfmML Ch. It. Fig. 221.—Longitudinal Section thkough the Head of an Ammoccete. V, velum ; P, papilla of mucous membrane ; K, K, K, three anterior gills ; Th, thyroid (hjrpobranchial furrow) ; N, nasal sac; *, communication be- tween the ventricle of the olfactory lobe and that of the prosencephalon ; Ep, epiphysis; Jnf, infundibulum; HH, meteneephalon; 211, medulla oblongata; h, c, ventricles of the mid-
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. EiG. 220.—Diagram of a LoNGITUDI^"AI. Section theougf the Head of THE Labval (A) AND ADULT (B) Peiromyzon. Ep JnfmML Ch. It. Fig. 221.—Longitudinal Section thkough the Head of an Ammoccete. V, velum ; P, papilla of mucous membrane ; K, K, K, three anterior gills ; Th, thyroid (hjrpobranchial furrow) ; N, nasal sac; *, communication be- tween the ventricle of the olfactory lobe and that of the prosencephalon ; Ep, epiphysis; Jnf, infundibulum; HH, meteneephalon; 211, medulla oblongata; h, c, ventricles of the mid- and hind-brain ; o, subdural cavity; Ch, notochord ; R, spinal cord. Fishes.—From the Elasmobranchii onwards, the gills are in close relation with the visceral skeleton, and in these Fishes they consist of closely-approximated transverse laminae (Figs. 222 A, 223), which are firmly attached to both sides of the septa which separate the individual gill-sacs from one another, so that each septum bears a half-gill, or hemibranch, on both its anterior and posterior surface. A gill, or holobranch, thus consists of the branchial arch plus the posterior hemibranch of the sac in front of it and the anterior hemibranch of the following sac. The gill-sacs, of which there are commonly five,^ open separately to the exterior, and a rudimentary ^ There are six in Hexanchus and Chlamydoselaohe and seven in 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
