. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. SKlTLL 105 especially in the parts surrounding the gapu, an essentially different and much more complicated development, and cannot in any way be directly derived from that of tailed Amphibians, so that the common ancestral form must be sought ^n very^early geological periods. The chondrocranium (Figs. 77 and 78) is much more extensive than in Urodeles, and is largely retained in the adult, the bones not gaining the upper hand to such an extent. The larva, or tadpole, in adaptation to the nature of its food and mode of fe
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. SKlTLL 105 especially in the parts surrounding the gapu, an essentially different and much more complicated development, and cannot in any way be directly derived from that of tailed Amphibians, so that the common ancestral form must be sought ^n very^early geological periods. The chondrocranium (Figs. 77 and 78) is much more extensive than in Urodeles, and is largely retained in the adult, the bones not gaining the upper hand to such an extent. The larva, or tadpole, in adaptation to the nature of its food and mode of feeding, possesses a suctorial mouth, provided with 't. i<o*1nt \ \ Parietal fontanellt A far cart. \Sup. prt- nasal cart, Inf. pre- nasal cart. <-</rt. Frontal ontanett. , Tect. --,. Fenestra nvoUis s tympanicus Artie, proces^'of quadrate, FIG. 77, C. LATERAL VIE\V OF A WAX MODEL, RECONSTRUCTED FROM SECTIONS, OF TIIK CHONDROCRANIUM OF A YOUNG liana ttmporan'a, ABOUT -2 CM. LONG. The Stapedial Plate and Columella are removed, and the Ossifications are not indicated. (After (-Jaupp.) labial cartilages and horny jaws and denticles. The articulation of the lower jaw with the palatoquadrate is situated very; far forwards, and at metamorphosis becomes shifted backwards, thus causing a considerable widening of the gape of the mouth. An important advance on other Amphibia is seen amongst Anura ( Ranidoe) in connection with the auditory organ. The first visceral (hyomandibular or spiracular) cleft disappears entirely during development in the Urodela and Gymnophiona, but becomes modified in many Anura to form a EustacMan t-ulc, opening into the pharynx and leading into a tympanic cavity. The latter is closed externally by a tympanic membrane supported by a cartilaginous ring (annulus tympcmicus^ Figs. 77, C, and 78), and to it the distal end of the columella (p. 98) is attached. 1 Cf. under Auditory Organ. The tympanic ring is a derivative of the Please n
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