File:Image from page 603 of "On the anatomy of vertebrates (electronic resource)" (1866) (14753273864).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: whichstart from the sternal or abdominal ribs, or coalesced groups ofribs, figs. 372, 373, called hyosternal, hs, hyposternal, ps, andxiphisternal, xs. Occasionally, ossification extends into the skinfrom the entosternal, s {Emyda ceylonensis), and from the epi-sternals, es (Cryptopus Peter sir). The dermal bones are leastdeveloped in the Trionycidm, and are not covered by horny epi-derm. c Neural and 4 costal plates are present in all. Onepair of dermal bones is developed from the hyosternals in Trionyxsubplanus; in Trionyx niloticus and some other species dermalbones are developed from the hyo-, hypo- and xiphi-sternals, the 1 clxii. p. 165. 558 ANATOMY OF VERTEBRATES. hyo- and hypo-sternal plates on each side being naturally unitedtogether; in Emyda ceylonensis dermal bones are developed fromthe epi-, hypo- and xiphi-sternals, and from the entosternal orsternum proper, forming seven pieces : the skin of the hindermargin of the broad depressed trunk is strengthened in Emyda 369 370

Text Appearing After Image: Inner surface, Carapace, young Tortoise. Outer surface, Carapace, young Tortoise. by a few dermal ossicles; much of the skin of the trunk, wherenot ossified, in Triojiycidce, has the dermal tissue of cartilaginoushardness. In the Turtles, or marine Chelonia, besides the eight connateneural plates, fig. 52, 51-58 (p. 61), dermal bones are developedin advance of and behind them, and are commonly unattachedto the subjacent vertebrae. The anterior one, ib. ch, is the( nuchal plate: the posterior one, ib. py, is the pygal plate ;the costal plates, ph-ph, articulate suturally with the neuralplates, but do not extend to the end of the ribs; the marginalplates, mi-mvi, are articulated with each other and with thenuchal and pygal plates suturally, and eight on each side receivethe ends of the eight ribs supporting the costal plates. Two TEGUMENTS OF REPTILES. 559 pairs of dermal bones are developed from the hyo- and hypo-sternals, fig. 53, lis and ps: but these do not articulate with themargin

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