the common, extinct, primary form of mammalia, than any known species. Hence man differs less in the formation of the hand from this common primary form than from the bat, mole, dolphin, seal, and many other mammals. PLATE V. (_Between pages 84 and 85, Vol. II._) _Monophyletic, or One-rooted Pedigree of the Vegetable Kingdom_, representing the hypothesis of the common derivation of all plants, and the historical development of the different groups of plants during the palæontological periods of the earth’s history. The horizontal lines denote the different smaller and larger periods of the organic history of the earth (which are spoken of in vol. ii. p. 14), and during which the strata containing fossils were deposited. The vertical lines separate the different main-classes and classes of the vegetable kingdom from one another. The arboriform and branching lines indicate, in an approximate manner, by their greater or less number and thickness, the greater or less degree of development, differentiation, and perfecting which each class probably attained in each geological period. (Compare vol. ii. pp. 82, 83.) PLATE VI. (_Between pages 130 and 131, Vol. II._) _Monophyletic, or One-rooted Pedigree of the Animal Kingdom_, representing the _historical growth of the six animal tribes_ during the palæontological periods of the organic history of the earth. The horizontal lines _g h_, _i k_, _l m_, and _n o_ divide the five large periods of the organic history of the earth one from another. The field _g a b h_ comprises the archilithic, the field _i g h k_, the palæolithic, the field _l i k m_ the mesolithic, and the field _n l o m_ the cenolithic period. The short, anthropolithic period is indicated by the line _n o_. (Compare vol. ii. p. 14.) The height of the separate fields corresponds with the relative length of the periods indicated by them, as they may approximately be estimated from the relative thickness of the neptunic strata deposited between them. (Compare vol. ii. p. 22.) The archilithic and primordial period alone, during which the Laurentian, Cambrian, and Silurian strata were deposited, was probably considerably longer than the four subsequent periods taken together. (Compare vol. ii. pp. 10, 20.) In all probability the two tribes of worms and Zoophytes attained their full development during the mid-primordial period (in the Cambrian system); the star-fishes and molluscs probably somewhat later (in the Silurian system); whereas the articulata and vertebrata are still increasing in variety and perfection. PLATE VII. (_Between pages 146 and 147, Vol. II._)