There is still, however, a slight resemblance in the formation of the body, the skeleton and the nervous system are still there. These features first disappear when we turn from this main division, which embraces all the vertebrates, and go to the molluscs (soft bodied animals) or to the polyps.
The entire animal world may thus be arranged into divisions and subdivisions. Had every different kind of animal been created entirely independent of all the others, there would be no reason why such orders should exist. There would be no reason why there should not be mammals having six paws. We would have to assume, then, that at the time of creation, God had taken Linnaeus' system as a plan and created everything according to this plan. Happily we have another way of accounting for it. The likeness in the construction of the body may be due to a real family relationship. According to this conception, the conformity of peculiarities show how near or remote the relationship is; just as the resemblance of brothers and sisters is greater than between remote relatives. The animal classes were, therefore, not created individually, but descended one from another. They form one trunk that started with simple foundations and which has continually developed; the last and thin twigs are our present existing kinds. All species of cats descend from a primitive cat, which together with the primitive dog and the primitive bear, is the descendant of some primitive type of rapacious animal. The primitive rapacious animal, the primitive hoofed animal and the primitive monkey have descended from some primitive mammal, etc.
This theory of descent was advocated by Lamarck and by Geoffrey St. Hilaire. It did not, however, meet
