. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 440 ANATOMY OF VERTEBRATES. tion than truly salivary, as exercising any alterant influence on the nature of the food. A ' velum palati' is developed only in the Crocodilia: an epiglottis is not present in any Reptile : the basihyal valve of the Crocodiles is analogous to one, and some lizards show a rudiment of epiglottis. The sides of the pharynx are cleft by the gill-slits in the perennibranchlate Batrachia; and one slit on each side remaing open in some of the caducibranchiate species, as, e. g., in Menopoma. In the S
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 440 ANATOMY OF VERTEBRATES. tion than truly salivary, as exercising any alterant influence on the nature of the food. A ' velum palati' is developed only in the Crocodilia: an epiglottis is not present in any Reptile : the basihyal valve of the Crocodiles is analogous to one, and some lizards show a rudiment of epiglottis. The sides of the pharynx are cleft by the gill-slits in the perennibranchlate Batrachia; and one slit on each side remaing open in some of the caducibranchiate species, as, e. g., in Menopoma. In the Siren there are three clefts on each side, defended by inter- locking pointed processes, closely resembling the narrower of the five lateral branchial clefts in the Lepidosiren, fig. 316, i, 3, 4, 5. The oesophagus is short and wide in Batrachia, fig. 294, d, c, long and wide in Ophidia, fig. 300, d, e, f, of moderate length and width in Chelonia, narrower in Crocodilia, fig. 298, e, and still more so in insecti- vorous Lacertilia, fig. 303, e. It is remarkably dilatable and thin-coated in Snakes, as at fig. 300, f, in which its intrinsic propelling power is sup- plemented by the constriction of the surrounding trunk-muscles during the deglutition of bulky prey. The other chief peculiarities in the struc- ture of this part of the alimentary canal of Reptiles are, the perforation of its walls by certain elongated and enameled hypapophyses in Z>e!>orfo72,' ante, p. 393, and the produc- tion of the lining memljrane into pointed processes, directed to the stomach, and covered by thick epithelium in the Turtles ( Chelonc).'^ These aid in the deglutition of the long slippery seaweeds on which the Turtle feeds ; in carnivorous Chelonia they are not present; the lining membrane in Tesfiido indica, e. g., is thrown into longitudinal ruga3 when undistended, and presents a fine reticular and porous surface. The ciliated epithelimn is con- tinued along the gullet in Triton, fig. 294,
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