[166] See W.K. Parker, "On the Structure and Development of the Skull in the Pig." _Phil. Trans._ pp. 289-336, 1874. [167] See W.H. Flower, "On the value of the characters of the base of the cranium in the classification of the order Carnivora." _P.Z.S._ 1869, p. 5. [168] See W.K. Parker, _Monograph of the shoulder-girdle and sternum of the Vertebrata_, _Ray Soc._ 1868. [169] See p. 405. [170] See E. Lydekker, _P.Z.S._ 1895, p. 172. [171] See H. Wincza, _Morph. Jahr._ XVI. p. 647, 1890. [172] See K. Bardeleben, _P.Z.S._, 1889, p. 259. [173] See E. Cope, "The origin of the foot structures of Ungulata," _Journ. of Philad. Acad._ 1874. H.F. Osborn, "The evolution of the Ungulate foot," _T. Amer. Phil. Soc._ 1889. [174] See O.C. Marsh, various papers including "Fossil horses in America," _Amer. Natural._ 1874; "Polydactyl horses," _Amer. J. Sci._ 1879 and 1892. M. Pavlow, "Le développement des Equidés," _Bul. Soc. Moscou_, 1887, and subsequent papers in the same. Osborn and Wortman, "On the Perissodactyls of the White River beds," _Bull. Amer. Mus._ Dec. 23rd, 1895. [175] See H.F. Osborn, _Chalicotherium and Macrotherium, Amer. Natural._ 1889--91--92. [176] See p. 409. [177] See p. 412. LIST OF AUTHORS REFERRED TO. Abbott, E.C., 112 Ameghino, F., 351, 424 Andrews, C.W., 299 Balfour, F.M., 16 Ballowitz, E., 424 Bardeleben, K., 504 Bateson, W., 50, 344 Baum, H., 374 Baur, G., 27, 189, 190, 344, 346 Beneden, P.J. van, 353 Benham, W.B., 51 Bettany, G.T., 16, 87, 154 Boulenger, G.A., 169 Brandt, J.F., 352 Bridge, T.W., 123 Brühl, C.B., 210 Burmeister, H., 351, 424 Cope, E.D., 135, 199, 204, 351, 359, 361, 363, 368 Credner, H., 135 Dean, B., 63, 104 Dobson, G.E., 369, 370 Earle, C., 432 Ecker, A., 151 Ellenberger, W., 374 Flower, W.H., 28, 42, 351, 420, 422, 434 Fritsch, A., 135 Fürbringer, M., 295 Gadow, H., 40, 112, 190, 295, 343, 350 Gegenbaur, C., 127 Gervais, P., 353 Günther, A.C.L.G., 70, 104 Haslam, G., 151 Hasse, C., 112, 113 Haswell, W.A., 127 Hertwig, O., 169 Hoffmann, C.K., 190, 202, 210 Howes, G.B., 164, 451 Hubrecht, A.A.W., 104 Hulke, J.W., 192, 204 Hurst, C.H., 71, 297 Hutton, F.W., 299 Huxley, T.H., 11, 13, 133, 135, 191, 210, 295, 297, 334, 343, 351, 374, 437 Kirkaldy, J.W., 51 Klein, E., 11 Kölliker, A., 9 Kükenthal, W., 349, 422 Lankester, E. Ray, 51 Leche, W., 344, 423 Lindsay, B., 336 Lydekker, R., 36, 42, 190, 195, 495 Macbride, E.W., 50 Marsh, O.C., 204, 209, 299, 348, 361, 364, 365, 508 Marshall, A.M., 71, 151 Masterman, A.T., 51 Meyer, H. v., 135 Miall, L.C., 135, 243 Mivart, St G., 369 Morgan, C. Lloyd, 11 Newton, E.T., 283 Osborn, H.F., 348, 420, 429, 508