_Germs or Embryos of four different Vertebrate Animals_, namely, Tortoise (_A_ and _E_), Hen (_B_ and _F_), Dog (_C_ and _G_), and Man (_D_ and _H_). Figs. _A_, _D_, an early stage of development; Figs. _E_, _H_, a later stage. All the eight embryos are represented as seen from the right side, the curved back turned to the left. Figs. _A_ and _B_ are seven times enlarged, Figs. _C_ and _D_ five times, Figs. _E_ and _H_ four times. Plate II. exhibits the very close blood relationship between birds and reptiles; Plate III. that between man and the other mammals. PLATE IV. (_Between pages 34 and 35, Vol. II._) _The Hand, or Fore Foot, of nine different Mammals._ This plate is intended to show the importance of Comparative Anatomy to Phylogeny, in as much as it proves how the internal skeleton of the limbs is continually preserved by _inheritance_, although the external form is extremely changed by _adaptation_. The bones of the skeleton of the hand are drawn in white lines on the brown flesh and skin which surrounds them. All the nine hands are represented in the same position, namely the wrist (where the arm would be joined to it) is placed above, whilst the ends of the fingers or toes are turned downwards. The thumb, or the first (large) fore-toe is on the left in every figure; the little finger, or fifth toe is to the right at the edge of the hand. Each hand consists of three parts, namely (i.) the _wrist_ (carpus), composed of two cross rows of short bones (at the upper side of the hand); (ii.) the _mid-hand_ (metacarpus), composed of five long and strong bones (marked in the centre of the hand by the numbers 1-5); and (iii.) the five _fingers_, or _fore toes_ (digiti), every one of which again consists of several (mostly from two to three), _toe-pieces_, or _phalanges_. The hand of _man_ (Fig. 1), in regard to its entire formation, stands midway between that of the two large human apes, namely, that of the _gorilla_ (Fig. 2), and that of the _orang_ (Fig. 3). The fore paw of the _dog_ (Fig. 4), is more different, and the hand or breast fin of the _seal_ (Fig. 5) still more so. The adaptation of the hand to the movement of swimming, and its transformation into a fin for steering, is still more complete in the _dolphin_ (Ziphius, Fig. 6). The extended fingers and bones of the central hand here have remained short and strong in the swimming membrane, but they have become extremely long and thin in the _bat_ (Fig. 7), where the hand has developed into a wing. The extreme opposite of the latter formation is the hand of the _mole_ (Fig. 8), which has acquired a powerful spade-like form for digging, with fingers which have become extremely short and thick. What is far more like the human hand than these latter forms, is the fore paw of the lowest and most imperfect of all mammals, the Australian _beaked animal_ (Ornithorhynchus, Fig. 9), which in its whole structure stands nearer to