. Zoology for high schools and colleges. Zoology. 606 ZOOLOGY. nine in number. The jaws are toothless, being, as in birds, encased in liorny beaks ; there are rarely fleshy lips; the tongue is spoon-shaped and immovable. The heart consists of two auiricles and a ventricle. The brain has larger cere- bral lobes than in the lizards. The eyes have a third lid, or nictitating membrane. The student can best obtain an idea of the organization of the turtles by studying the skel- eton and dissecting a turtle witli the aid of the accompany- ing description and figure of the common turtle. * The common
. Zoology for high schools and colleges. Zoology. 606 ZOOLOGY. nine in number. The jaws are toothless, being, as in birds, encased in liorny beaks ; there are rarely fleshy lips; the tongue is spoon-shaped and immovable. The heart consists of two auiricles and a ventricle. The brain has larger cere- bral lobes than in the lizards. The eyes have a third lid, or nictitating membrane. The student can best obtain an idea of the organization of the turtles by studying the skel- eton and dissecting a turtle witli the aid of the accompany- ing description and figure of the common turtle. * The common swamp-turtle (Chrysemys picta) is a good type of the Chelonia. The animal is enclosed in a hard shell made up of an arched dorsal portion, and a flat ventral por-. Flg. 445.—Veniral epijermal plates of C/iiysemyspicta.—Drawn by C. S. Minot tion, the two connected laterally, but widely separated an- teriorly to give exit to the head and fofe limbs, and pos- teriorly for the tail and hind limbs. These parts can all be withdrawn within the protecting shell, by being doubled or folded back upon themselves. The soft parts of the skin are covered wi^h scale", formed by overlapping folds. The limbs are stout; iipon the anterior feet there are five, upon the posterior four claws. On the under surface of the short tapering tail near its base is the wide opening of the cloaca. The ventral plastron consists of twelve symmetrical pieces, six on each side, Fig. 445. The first and last pair, are tri- angular, the others are four-sided ; the fourth pair is the *This description has been prepared and the illustrations drawn by Dr. C. S. 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 Packard, A. S. (Alpheus Spring), 1839-1905. New York, H. Holt and Company
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
