MAMMALIA. 



71 



during the Eocene period, Zcnglodoii (yoke-tooth), thus Gallery of 

 named by Owen in allusion to the shape of its hinder teeth rp^\^^^\ 

 (hig. b/B), has jaws so peculiar that they were originally 

 supposed to belong to a reptile, which was termed Basilo- 

 saurus. The skull (Fig. 67a) is not completely that of a 

 whale, though it is elongated and depressed, with the nostril 

 on the middle of the upper surface. Each side of either jaw 

 is provided with four simple teeth in front and five double- 

 rooted teeth behind. The neck must have been unusually 

 long for a whale and not rigid. Plaster casts of the skull 

 and teeth, l:)esides actual teeth of the typical Zciuflodon 

 ectoidcs, from the Eocene of Alabama, U.S.A., are exhibited, 

 proving the animal to have been of rather large size. Pro- 

 zcufflodon, represented by a plaster cast of a skull from the 

 ^liddle Eocene of the Fayum, Egypt, lias some three-rooted 

 teeth, and seems to connect toothed whales with Creodonta 

 (see p. 16). 



OjiDER IX.— EDENTATA. 



The sloths, anteaters, and armadillos have been character- 

 istic of the South American region since early Tertiary 

 limes, and they do not appear to have wandered farther than 

 the southern part of Xorth America at any period. They are 

 ([uite a degenerate and insignificant race at the present day, 

 compared with their former representatives. 



The modern sloths and anteaters are almost unkno\vii Wall-ease 

 among fossils, Init the peculiarities of both these families arc 26. 

 combhied in the skeleton of the extinct ground-sloths. '^i4b^"ifa^^ 

 These animals, in fact, exhibit tlie head and teeth of a slotli 

 associated with the back-bone, limbs, and tail of an anteater. 

 They lived in great num])ers in South America during the 

 latter part of the Tertiary period, ranging even so far north 

 as Kentucky in the Pleistocene ; and some of them survived 

 lo 1)1' contempornries of man at a very recent Prehistoric 

 date. The ^Miocene or perhaps earlier forms are small, ])ut 

 they l)ecome larger as they are traced upwards in the 

 geological sequence, and many of the Pleistocene and Pre- 

 liistoric species rival elephants and rhinoceroses in bulk. 



The best known ground-sloths are Mefjanicrmm, Scelido- 

 llicrium, and Mijlodon, all well represented in the collection. 

 Tliey obviously could not live in trees like the little sloths 

 which exist at present in the South American forests ; but 

 tbeir liind quarters are very massive and their stout tail 

 would serve with their hind legs to form a rigid tripod orx 



Case Y. 



