. Chordate anatomy. Chordata; Anatomy, Comparative. 276 CHORDATE ANATOMY consequently the aortic arches are reduced. In fishes the persistent aortic arches are broken up into a capillary net-work in the gills. In urodeles the last four pairs of aortic arches persist, the blood from the ventral aorta largely short-circuiting the gills. In Anura gills are lost and blood passes directly through the aortic arches to the dorsal aorta. In the Anura the fifth pair of aortic arches degenerate. That portion, the ductus arteriosus,. Fig. 250.— Modifications of the aortic arches in difTerent vertebrates.
. Chordate anatomy. Chordata; Anatomy, Comparative. 276 CHORDATE ANATOMY consequently the aortic arches are reduced. In fishes the persistent aortic arches are broken up into a capillary net-work in the gills. In urodeles the last four pairs of aortic arches persist, the blood from the ventral aorta largely short-circuiting the gills. In Anura gills are lost and blood passes directly through the aortic arches to the dorsal aorta. In the Anura the fifth pair of aortic arches degenerate. That portion, the ductus arteriosus,. Fig. 250.— Modifications of the aortic arches in difTerent vertebrates. A, primi- tive scheme; B, dipnoan; C, urodele; D, frog; £, snake; F, lizard; G, bird; H, mam- mal, c, celiac artery; da, dorsal aorta; dh. ductus Botalli; ec, ic, external and internal carotids; p, pulmonary artery; s, subclavian; va, ventral aorta. Vessels carrying venous blood, black; those with mixed blood, shaded; those which disappear, dotted outlines. (From Kingsley's "Comparative Anatomy of Vertebrates," after Boas.) which connects the pulmonary branches of the sixth aortic arch with the dorsal aorta also atrophies. The third pair of arches persist as the roots of the carotid arteries. In reptiles as in Anura three pairs of aortic arches persist, the 3rd, 4th, and 6th in part as pulmonary. In reptiles the com- mon carotid arteries connect with the right and not with the left systemic or fourth aortic arch. In mammals portions of three aortic arches persist in the adult, the 3rd, 4th, and 6th as in reptiles. The systemic arch of the. 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 Neal, Herbert V. (Herbert Vincent), 1869-1940; Rand, Herbert W. (Herbert Wilbur), 1872-1960. Philadelphia : P. Blakiston's Son & Co.
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