X CONTENTS 



Figure Page 



6S3. Limb structure of perissodaotyls: Fore limbs of Equidae 753 



684. Limb structure of perissodactyls : Hind limbs of Equidae 754 



685. Limb structure of perissodactyls: Fore limbs of titanotheres 765 



686. Limb structure of perissodactyls : Hind limbs of titanotheres 756 



687. Carpus of Creodonta, Amblypoda, and Condylarthra, showing "alternating" and "serial" types 758 



688. Evolution of the upper molar pattern in condylarths and titanotheres 759 



689. Generalized carpus of insectivore-creodont type 760 



690. Progressive stages of structural evolution in the skull and molar teeth of titanotheres 761 



691. Astragali of Phenacodus and Heptodon 762 



692. Manus of Heptodon, Lambdotherium, and Eotitanops 762 



693. Fore and hind feet in perissodactyls 763 



694. Skulls of Eocene titanotheres, other perissodactyls, and one condylarth 765 



695. Skulls of Eocene condylarth and perissodactyls 766 



696. Skulls of Lophiodon leptorhynchus 768 



697. Family tree of the titanotheres 769 



69S. Family tree of the Perissodactyla 770 



699. Fore and hind feet of paraxonic and mesaxonic ungulates 771 



700. Carpus of Eocene perissodactyls 772 



701. Evolution of the astragalus in the titanotheres 773 



702. Back view of the carpus of a middle Eocene titanothere 775 



703. Left magna of an Eocene titanothere and two chalicotheres 775 



704. Left magna of Heptodon and Eotitanops . 776 



705. Phylogenetic tree of the Perissodactyla 777 



706. Family tree of the Perissodactyla , 777 



707. Outlines of body form of perissodactyls 781 



708. Disharmonic evolution shown in characters of Brontops, Menodus, and Brontotherium 783 



709. Evolution of the skull in the titanotheres 784 



710. Relative proportions of the skulls of Manteoceras and Brontotherium 785 



711. Proportions of skulls of Palaeosyops, Dolichorhinus , and Eotitanops 786 



712. Evolution of the frontonasal horn swelling in Manteoceratinae and Brontopinae 791 



713. "Brain casts" of titanotheres compared with the brain of a recent rhinoceros 792 



714. Relative size of brain and skuU in titanotheres and other Eocene perissodactyls, an artiodactyl, and an amblypod 793 



715. Brain of Menodus, Rhinoceros, and other quadrupeds 795 



716. " Brain casts " of titanotheres 796 



717. Evolution of the upper molar tooth in titanotheres 796 



718. Pattern of an upper molar of five perissodactyls 797 



719. Evolution of proportions in grinding teeth of Oligocene titanotheres 797 



720. Atlas and axis of titanotheres and other perissodactyls, showing probable course of arteries 798 



721. Evolution of the pelvis in titanotheres 799 



722. Three stages in the evolution of the manus in titanotheres 801 



723. Six stages in the evolution of the manus in titanotheres. ^ 801 



724. Evolution of the magnum in titanotheres 801 



725. Restorations of Eotitanops borealis and Brontotherium platyceras 805 



726. Relations of heredity germs of Eotitanops and Brontotherium 806 



727. Continuity of heredity germ from Eotitanops to Brontops 808 



728. Germinal origin and disappearance of characters 810 



729. Contrast between the ontogenetic and phjdogenetic velocity of a biocharacter 810 



730. Limbs of four embryos, showing ontogenetic velocity of limb bones in horses 811 



731. Relative velocities of a series of biocharacters 811 



732. Rectigradations in the teeth of Eocene ungulates 814 



733. Rectigradations and allometrons in skuUs, teeth, and feet of titanotheres 815 



734. Independent appearance of horn rudiments in different phyla of titanotheres 816 



735. Cusp rectigradations in Telmatherium 817 



736. Separability of rectigradation biocharacters in hybrid offspring of ass and horse 820 



737. Harmonic and disharmonic brachycephaly and dolichocephaly 821 



738. Disharmonic and distinctive increment in biocharacters of Palaeosyops and Dolichorhinus 822 



739. Continuous origin of allometron biocharacters in man and titanotheres 822 



740. Proportions and flexure of skull in horses and titanotheres 823 



741. Skulls of three species (probably successive) of Palaeosyops 824 



742. Outlines of skulls of Palaeosyops, Dolichorhinus, and Eotitanops 825 



743. Skull of Dolichorhinus hyognathus, type of " Telmatotherium cornutum" 829 



744. Differences in proportions of premolars and molars corresponding to differences in proportion of the skull 830 



745. Skulls of Eocene titanotheres, showing changes in proportion and in development of horns 831 



746. Models of heads of Oligocene titanotheres 832 



747. Separability and imperfect blending of allometric biocharacters in the facial bones of the horse, ass, and mule 832 



748. Contrasts between hypotheses of Lamarck, Weismann, and Osborn regarding the causes of evolution 834 



749. Cumulative or favorable influence of heredity, ontogeny, and environment 837 



750. Diagram illustrating the tetraplastic theory -- 837 



