Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget .. . in the flesh, and quitedetached from the spine, two small bones, appa-rently corresponding to pelvic bones, for thepresence of which no more probable reason canbe assigned than the tendency to preserve ananalogy with the more developed structures ofthe same type. A similar adherence to the law of uniformityin the plan of construction of all the animals be-longing to the same class, is strikingly shown inthe conformation of the bonesof the anterior extremities ofthe cetacea; for although the
Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget .. . in the flesh, and quitedetached from the spine, two small bones, appa-rently corresponding to pelvic bones, for thepresence of which no more probable reason canbe assigned than the tendency to preserve ananalogy with the more developed structures ofthe same type. A similar adherence to the law of uniformityin the plan of construction of all the animals be-longing to the same class, is strikingly shown inthe conformation of the bonesof the anterior extremities ofthe cetacea; for although theypresent, externally, no resem-blance to the leg and foot ofa quadruped, being fashionedinto fin-like members, with aflat oval surface for strikingthe water, yet when the bonesare stripped of the thick in-tegument which covers themand conceals their real form,we fijad them (as may beseen in Fig. 216) exhibitingthe same divisions into carpaland metacarpal bones, andIDhalanges of fingers, as existin the most highly developed organization, notmerely of a quadruped, but also of a monkey,and even of AMPHIBIA. 487 § 3. Amphibia. In the small tribe denominated by CuvierAmphibia, and consisting of the Phoca, or Seal,and the Trichecus, or Walrus, we perceive thatan advance is made towards a fuller develope-ment of the limbs: these animals having adistinct neck and pelvis, and both hind andfore extremities. In the seal the hind legs aredrawn out posteriorly to a considerable length,and placed parallel to each other: w^hen unitedand alternately raised and depressed, they per-form the same office as the tail of the cetacea,and propel the animal forwards: but when em-ployed separately, they are more qualified to actas oars. The walrus has feet still more deve-loped, and distinctly divided into toes, which aredisposed so as to strike backwards against thewater. § 4. Mammi/erous Quadrupeds in general. From the imperfectly developed aquatic andamphibious tribes we gradually ascend to t
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