252 SUBUNGULATA order ix 



Suborder C. PROBOSCIDEA.i 



Large fim-ioecl, usually tall-limbed, semidigitigrade herbivores with proboscis. 

 Skull large, usually with large air-cells. At first there is a pair of enlarged upper 

 and lower incisors; finally only one pair above. Canines present only in primitive 

 genera. Cheek teeth at first bunolophodont, then lophodont, and in the final 

 stage consisting of narrow, transverse lamellae. Femur almost cdways without third 

 trochanter. Carpals serially arranged. Astragcdus broad with slightly convex 

 trochlea. Calcaneum articulating with fibula. 



The origin of the Proboscidea has remained obscure until recently, although 

 Blainville suspected that they were related to the Sirenia. This conjecture 

 has been confirmed by recent discoveries in the Oligocene of Egypt, which 

 show that the earliest forms have among other characteristics a large number 

 of teeth, the cheek teeth and also the cranial structure being similar to those 

 of the Sirenia. 



The dentition of the Proboscidea consists only of incisors and cheek teeth, 

 except in the case of the Moeritherium, but even in this form a pair of incisors 

 has become enlarged. Soon the remaining incisors disappear entirely and 

 the single enlarged pair develops into enormous tusks. In the later species of 

 Mastodon even this last remaining jDair is lost in the lower jaw. The tusks are 

 composed of dense elastic ivory, which is seen in cross-section to be traversed 

 by fine lines extending from the centre of the tusk to its periphery in two 

 sets crossing each other like the enchased ornament of a watch-case. The 

 proximal portion, in particular, of the tusks is frequently covered with a thin 

 layer of enamel. The teeth are seated in deep alveoli in the premaxillary, 

 and have large, open pulp cavities. 



The cheek teeth of recent elephants are distinguished from those of all 

 other ungulates by their large size and numerous compressed transverse ridges, 

 as well as by the thick coating of cement in the valleys between the ridges. 

 These teeth, however, display features in common with the bunolophodont 

 teeth of Moeritherium, which are made up of two pairs of cusps joined by a 

 slight ridge and a small talon. In Palaeomastodon the number of ridges is 

 increased, but in the lower jaw the number of cheek teeth is reduced by 

 one. In -Mastodon the reduction of the simultaneously functional teeth is 

 extensive, and there is an increased number of ridges. The number of 

 transverse ridges is even greater in Stegodon, which has from 6 to 12, and 



1 Adams, A. Leith., British Fossil Elephants. Palaeont. Soc, 1877. — Andrews, C. W., 

 Catalogue, 1906, auJ Evolution of the Pi-oboscidea. Philos. Trans., ser. B, 1903. — Bach, F., 

 Mastodon aus Steiermark. Beitr. z. Palaont. Ost.-Uiigarns, vol. xxiii., 1910. — Cope, E. D., 

 The Proboscidea. Amer. Naturalist, 1889. — Deptret, Ch., Archives du Musee de Lyon, 1887, 

 vol. iv. — Falconer and Cautley, Fauna antiqua sivalensis, 1846, and Palaeont. Mem. ed. 

 by Murchison, 1863, vol. i. — Kaup, J. J., Ossements fossiles de mammiferes, 1832-35, Cah. 

 I. and IV.. and Akteu der Urwelt, 1841, Heft IV. — Beitrage zur Kenntnis urweltlicher Saugetiere, 

 1857, Heft \\\.—Larlet, Ed., Bull. Soc. Gcol. de France, 1^5^.— Lartet and Chantre, Arch. 

 Mus. de Lyon, vol. i., 1872 ; vol. ii., 1879. ^Lydekker, R., Catal. British Mus., vol. v., 1886. — 

 Meyer, H. von, Mastodon. Palaeontogr., 1867, vol. xvii. — Pohlig, H., Nova Acta Acad. Carol. 

 Leopold., 1888-91. — Schlesinger, G., Mastodonten. Denkschr. natur. Hofmuseums, Wien, 1917. r- 

 Stratigr. Bedeutung europ. Mastodonten. Mitth. geol. Ges. Wien, 1918. — Mastodonten. 

 Geologia hungarica, ii. fasc. 1, 1922.— Sis-monda, E., Osteographia di Mastodonte. Mem. Accad. 

 Torino, vol. xii., 1851. — Vacek, M., Osterr. Mastodonten. Abh. K. K. Geol. Reichsanst., 1877, 

 vol. vii. — Weithofer. K. A. Proboscidier des Arnotales. Beitr. Palaont. Osterr. -Ungarns, vol. 

 viii., 1890. 



