File:Image from page 232 of "On the anatomy of vertebrates (electronic resource)" (1866) (14755202552).jpg

Identifier: b20416039_001 Title: On the anatomy of vertebrates [electronic resource] Year: 1866 (1860s) Authors: Owen, Richard, 1804-1892 Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds Publisher: London : Longmans, Green Contributing Library: Wellcome Library Digitizing Sponsor: Wellcome Library

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Text Appearing Before Image: second row of tarsalsanswer to the os cuboides of higher ani-mals ; the other three bones to the threeossa cuneiformia. The astragalar part ofthe single proximal bone includes also the naviculare. In the Trionyx, fig. 117, the proximal row consists of a singlebone, a, answering to the astragalus and naviculare : the distalrow consists of five bones, of which the three cuneiformia are verysmall: the two divisions of the cuboides, b, c, are very large ;the first may include the articular part of the calcaneum; theoutermost is dilated and angular. In Chelone and Chelys thecalcaneum is distinct from both the cuboid and the astragalo-navi-cular bones. The digits are moderately long, rather flattened anddivaricated, supporting the hind webbed foot; the metatarsal sup-ports two phalanges in the first toe; in the other toes it supportsthree, the last having a claw. In Trionyx the fifth digit, fig. 117, v, has two small phalangesand no claw. In Emys and Cistudo the digits decrease in strength

Text Appearing After Image: Bones of leg and foot,Trionyx. cli. 188 ANATOMY OF VERTEBRATES. from the first to the fifth, and in length from the second to thefifth. In the Land tortoises, the fifth toe is reduced to a metatarsal rudiment: the others are short and thick, fig.118 . 118, each with two phalanges, the second sup-porting a claw, and adapted, like those of the forefoot, for burrowing. The two extremes of modi-fication of the hind foot in the chelonian seriesare presented by the Turtle and Tortoise: thegreat comparative weight and bulk of the bodyto be supported on dry land involve a form oflimb and foot resembling that in the Elephant;whence the largest kind of Land-tortoise has beentermed Testudo elephantopus. The general homology of the pelvic bones ofthe Crocodile has been previously discussed,pp. 67-69, and illustrated, figs. 55, 56, 57. Theserial homology of the two hsemapophysial elements derives satis-factory elucidation from their crocodilian condition. Of those of thescapular arch, called clavi

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