. Principles of economic zoo?logy. Zoology, Economic. 250 BRANCH C'HfJRDATA dermal boiiew, all fused into one bony carapace which is covered by epidermal plates. The plastron consists of epidermal plates underlaid with bony shields. The head, limbs, and tail may be more or less withdrawn under the carapace for protection; in some forms so completely that there is no part of the turtle visible outside of the shell. They have four short, strong, clawed, pentadactyle limbs, or, in the case of some marine forms, flippers. The marine paddle- limbed forms are usually designated as turtles, and those
. Principles of economic zoo?logy. Zoology, Economic. 250 BRANCH C'HfJRDATA dermal boiiew, all fused into one bony carapace which is covered by epidermal plates. The plastron consists of epidermal plates underlaid with bony shields. The head, limbs, and tail may be more or less withdrawn under the carapace for protection; in some forms so completely that there is no part of the turtle visible outside of the shell. They have four short, strong, clawed, pentadactyle limbs, or, in the case of some marine forms, flippers. The marine paddle- limbed forms are usually designated as turtles, and those with walking limbs as tortoises. The bones of the head arc firmly united. The jaws are toothless, but are inclosed in sharp horny beaks, with which they seize and crush their prey and then swallow it whole. The pectoral arch is a "triradiate structure, of which the. Fig. 206.—Skeleton of snapping-turtic with portion of carapace sawed off to show interior. Cleaned and mounted by students; (much reduced.) most ventral and posterior ray ending in a free extremity is the coracoid, while the other two are the procoracoid and the scapula with the suprascapula, which are fused at their glenoid ;' The pelvis is strong, consisting on each side of the pubis, the ischium, and the ilium. These meet at the articular surface of the hind limb. The vertebra are few as compared witli those of the snake. Those of the neck fit into one another with ball-and-socket-joint. There is no trace of a sternum or of sternal ribs. Digestive System.—The tongue is usually soft and wide and not extensible. The esoi^hagus is co^'ere^l with " conical pro- jections pointing toward the ; There is no cecum. Food.—Sonu- species are carnivorous, some are herbivorous, ' Parker and Haswell, vol. ii, p. 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
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherphila, bookyear1915
