230 



NOTOUNGULATA 



ORDER VIII 



developed clavicle. The humerus has an entepicondylar foramen. Ulna and 

 radius are not fused and are but slightly bent. The arrangement of carpals is 

 always alternating. The centrale is fused w^ith the scaphoid. There are 

 four metacarpals, the pollux is entirely atrophied, and the fifth finger some- 

 what reduced. In the case of Typotherium, however, the second to fifth digits 

 are almost of the same length, and the first is short, but having phalanges. 

 The terminal phalanges are pointed, but expanded on the under side into a 

 triangular flat surface, or hoof-like and cleft in front. 



The femur has a fairly large projecting third trochanter. The tibia 

 and fibula are sometimes free, sometimes fused at the extremities. The 

 calcaneum (Fig. 312 a) has a long, thick tuberosity, a broad, convex facet for 

 the articulation of the fibula, and a large articular surface for the cuboid, 

 whereas the sustentaculum projects only slightly. The astragalus (Fig. 

 312 B, c) is distinguished by the narrow, not very deeply-grooved trochlea, 

 and the well-rounded, stalked head. Of the four metatarsals those laterally 

 placed are often somewhat more slender than the others. On the whole, 

 the skeleton agrees closely with the original carnivore type, exhibiting, 

 however, many peculiar rodent-like specialisations. 



3.1.4.3. 



Family 1. Notopithecidae Ameghino. 



in compact rows, hrachyodont and with roots. Incisors, canines and 



premolars gradually intergrading. I^ to P^ trenchant, the lower incisors and canines 

 chisel-shaped, P'^ to P* triangular, 3P to M^ rhombic, M^ rounded triangular with 

 ectoloph, two dissimilar transverse ridges confluent on the inner side and posteriorly 



'^. 



'^2JS?SD3?(^fi^«?»' 



Fio. 313. 



Ailpithecus secans Ameghino. Upper Eocene (Xoto- 

 stylops beds), Patagonia. A, Upper and lower series 

 of teeth, l/i- -B, Upper and lower molar, 2/j. C, Upper 

 jaw, !/„. D, Lower jaw, i/.,. 



Fig. 314. 



Frotypotherium australe Ameghino. Upper 

 Miocene (Santa Cruz beds), Patagonia. A, 

 Fore foot, 3/^. B, Hind foot, 1/2- (After 

 Sinclair.) 



with a basal cingulum, together with a small mesially placed spur. Lower molars with 

 two outer crescents and two inner cusps, of which the first is fused with the first crescent 

 and the second is free. Mandible rather weak. 



