ILLUSTRATIONS 



Figure 761. World chart of 1900 explaining Osborn's theory of the central Asiatic origin of orders of holarctic mammals-- 900 



762. Chief centers of known zoogeograpliic distribution of titanotheres 901 



763. Map of eastern and central Asia, showing area of central Mongolia explored by American Museum Asiatic 



expedition of 1922 and 1923 902 



764. Route map of American Museum expedition of 1922 and 1923 in southeastern and central Mongolia, showing 



the three localities where titanotheres were discovered 902 



765. Map of central Mongolia (Gobi Desert region) traversed by third Asiatic expedition 903 



766. Map and section of eastern Altai region, showing location of Tertiary formations 904 



767. Map and section of east-central Gobi Desert, showing location of chief Cretaceous and Tertiary formations 



discovered in this region 906 



768. Ardyn Obo formation (lower Oligocene) 908 



769. Ardyn Obo formation and American Museum camp of 1923 909 



770. Field sketch of chief fossihf erous beds of the Shara Murun formation. 910 



771. Field sketch map of exposures of Irdin Manha formation 911 



772. Irdin Manha formation, Irdin Manha bluff, looking northward across the Kalgan-Urga trail 912 



773. Type lower jaw of Protitanotherium grangeri from the Irdin Manha formation 914 



774. Comparative views of jaws of upper Eocene titanotheres from the Irdin Manha and Shara Murun formations. 917 



775. Comparative occipital views of chief titanotheres of Mongolia in descending geologic order 917 



776. Crania and jaws of the type and parat^'pe of Dolichorhinus haiseni 920 



777. Comparative views of superior and inferior grinding teeth of Dolichorhinus kaiseni and of the lower jaws of D. 



kaiseni and Protitanotherium grangeri 921 



778. Internal aspect of inferior grinding teeth of five species of titanotheres from Mongolia, Burma, and Utah 922 



779. Comparison of superior grinding teeth of Protitanotherium andrewsi and P. mongoliense 923 



780. Jaws oi Protitanotherium gra7igeri in plsLce, Irdin Manha formation 924 



781. Female skuU and jaws of Protitanotherium grangeri (type), altered by vertical crushing of symphyseal region 



of jaw 925 



782. Type female cranium and jaws of Protitanotherium grangeri 926 



783. Type right ramus, fragment, vnth six grinding teeth, of Protitanotherium mongoliense 927 



784. Palate and superior dentition of Protitanotherium mongoliense (neotype) 928 



785. Complete female skull of Protitanotherium mongoliense (referred) 929 



786. Lower jaw of Protitanotherium andrewsi, a finely preserved specimen, for comparison with the imperfect lower 



jaw of the type of Protitanotherium mongoliense 930 



787. Type cranium of Protitanotherium andrewsi 931 



788. Referred cranium and jaw of Protitanotherium andrewsi 933 



789. Types of Telmatherium and of Dolichorhinus from the Irdin Manha and Shara Murun formations 934 



790. Jaws and maxillae of type and paratype of Telmatherium berkeyi 935 



791. Cranium and superior dentition of type of Brontops gobiensis 937 



792. Referred jaw of Brontops gobiensis and lower grinding tooth of Menodus mongoliensis (type) 938 



793. Type jaw of Manteoceras? irdinensis, Irdin Manha formation 939 



794. Type jaw (fragment) ot Metarhinus? mongoliensis compaved with Protitanotherium grangeri 940 



795. Titanotheres of Rumelia, in the Balkan Peninsula; of Transylvania, in southeastern Hungary; and of Bohemia- 942 



796. Restoration of Embolotherium andrewsi 943 



797. Crania of three species of Embolotherium 944 



