File:Image from page 227 of "On the anatomy of vertebrates (electronic resource)" (1866) (14755510325).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: tously attached the short andsimple femur. To this succeeds a shorter tibia and fibula — thelatter reminding us of the plesiosaurian fibula, by its outwardcurve. The tarsus is cartilaginous in Menopoma; the metatarsalssupport 1, 2, 3, 3, 2 phalanges, respectively, from the innermost, I,to the fifth, v. The toes are webbed to near the last joint. Everyjoint in the limb is syndesmotic, and the ossification of the bones islimited to an outer crust, covering persistent solid cartilage. Inthe decomposing body this dissolves away; and if the ossifiedparts become petrified, the fossil bone appears to have had a largemedullary cavity. In the Land-salamander the broad ischio-pubic plate, fig. 113,j becomes ossified at b, but remains cartila- ginous at the angles c, and the symphysis;whence it extends forward, and bifurcates,as at d, representing the last pair of abdo-minal ribs in higher reptiles. There is avascular perforation in each pubic part ofthe plate. The ilium, a, retains its simple

Text Appearing After Image: Pelvis, S The Tadpole, fig. 42, affords a significant example of the trans- Pelvis, Salamander. *i ti i rib-like character. ANATOMY OF VERTEBRATES. 183 mutation of a natatory to a saltatory type of hind-limb, irre-spective of efforts and exercises through successive generationsproducing and accumulating small changes, and independently ofany selection by nature of such generations as were enabled,through the accidental variety of a slightly lengthened hind-limb,to conquer in the battle of life, and to transmit the tendencytowards such disproportion to their posterity. If the law by which so much of the change of structure adaptedto terrestrial life takes place in the active independent aquaticanimal be a mystery, and seeming exception, it does not the lessimpress the believer in the derivative origin of species with the ideaof unseen and undiscovered powers, that may operate in produc-ing such result,c according to a natural Law or Secondary Cause.1 The hind-limb of the Frog (Rana) cl

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