. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 183 imitation of a natatory to a saltatory type of hlnd-limlj, irre- spective of efforts and exercises throuo-h successive o-cnerations producing and accumulating small changes, and independently of any selection liy nature of such generations as were enal)led, through the accidental A'ariety of a slightly lengthened hind-limb, to conquer in the battle of life, and to transmit the tendency towards such dispro]iortion to their posterity. It the law l)y which so much of the change of structure adapt
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 183 imitation of a natatory to a saltatory type of hlnd-limlj, irre- spective of efforts and exercises throuo-h successive o-cnerations producing and accumulating small changes, and independently of any selection liy nature of such generations as were enal)led, through the accidental A'ariety of a slightly lengthened hind-limb, to conquer in the battle of life, and to transmit the tendency towards such dispro]iortion to their posterity. It the law l)y which so much of the change of structure adapted to terrestrial life takes place in the active independent aquatic animal be a mystery, and seeming exception, it does not the less impress the lielicver in the derivative origin of species with the idea of unseen and undiscovered powers, that may operate in produc- ing such residt, ' according to a natural Law or Secondary Cause.'' The hind-limb of the Frog (Rana) closely accords at first with that of the Menopome; a rib-like continuation, fig. 42, 62, of the pleurapophysis, ^/, of the last abdominal vertebra, gives attachment to a short femur, 65; ossification of the shorter tibia, 56, and fibula, 57, S]icodily unites them proximally; five subeqnal digits bud out of the primitive fin-like i)rojection from the integument; and a simple cartllaginouR tarsus, 08, at first intervenes between the toes and the leg. The due length and power of the hind-limlj is produced by elongation of all its elements, including tlie iliac parts of the sustaining arch. In the Toad (Bufo) the sacral process, or anchy- loscd riblets, transmitting thereby the weight of the trunk upon the legs, are depressed and expanded at their extremities ; in Pipo, fig. 44, B, s, remarkably so, and resting upon the anterior halves of the ilia. In the Toad the femur is shorter than the ilium, and the tiliia is shorter than the femur. In tlie Frog, fig. 44, contrary proportions prevail. The im- pulse of the hind-li
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
