TOXODONTIA. 605 



trochanter ; scapular and neural spines as in the next, carpus with centrale, 

 humerus with entepicondylar foramen. Coryphodon Ow., dentition com- 

 plete, canines large, grinders ridged, neural spines weak, skull smooth, 

 without horns ; scapula characteristic, narrow above, shaped like a leaf ; 

 tibia articulates with the calcaneum and astragalus ; femur with third 

 trochanter ; about the size of a tapir, probably omnivorous ; this genus 

 was first made known by a fragment of a jaw dredged in the sea off the 

 coast of Essex. Lower Eocene of Europe and America. Dinoceras Marsh 

 ( Uintatherium Leidy), approaching the elephants in size, with three pairs 

 of bony horn-like prominences on the skull, formed by prolongations of 

 the parietals, maxillaries, and nasals. Dentition i c \ p 3 -^ m f , 

 canines as large tusks ; neural spines short ; scapula broad above ; limbs 

 elephantine, carpus without centrale (Fig. 319, B) and femur without 

 third trochanter, fibula articulating with the astragalus only ; M. and U. 

 Eocene, X. Amer. Tinoceras Marsh (Loxolophodon), contains the largest 

 forms (Fig. 318). The genus Arsinoitherium, Beadnell * from the Upper 

 Eocene of the Fayum of Egypt may be placed provisionally in this order. 

 It was a large animal with a massive skull bearing two pairs of horns, 

 the larger of which were furnished by the great nasal bone, and the smaller 

 by the frontals. The squamosal is large and there are large post-tympanic 

 and postglenoid processes, which approach one another below the auditory 

 meatus. The dentition is^fcyp^mf, the tooth series is closed, and 

 there is no clear distinction between the incisors, canines, and premolars. 

 The premolars and molars are hypsodont and lophodont and easily dis- 

 tinguishable. The scapula resembles that of Dinoceras. as do the tibia and 

 tarsus. The femur is without a distinct third trochanter. 



Order 10. TOXODONTIA. + 



Extinct semi plantigrade or plantigrade animals with tridactyle 

 limbs, hypsodont, rodent-like grinders, without clavicles and 

 entepicondylar foramen in the humerus. There is a centrale in 

 the carpus. The carpal bones interlock but the tarsals are 

 serial. 



They are all extinct, South American forms and were herbiv- 

 orous and plantigrade. The dentition is usually complete, but 

 the canines tend to be weak or aborted. The grinders are 

 prismatic and somewhat rodent-like, resembling those of the 

 Typotheria. The fibula articulates with the calcaneum. 



* Beadnell, A preliminary note on Arsinoitherium zitteli, Beadn., from 

 the Upper Eocene strata of Egypt, Survey Department Public Works 

 Ministry, Cairo, 1902. Andrews, Geological Mag., n. s., 5,' 1, p. 109 and 

 157. 



f Burmcister, Ann. Mus. Buenos Ayres, 1, 1867, and 3, 1869. Cope, 

 On Toxodon, Proc. Amer. Phil. Soc., 1881, Owen. Toxodon in the Zoology 

 of the Voyage of the Beagle, 1840, and Nesodon, Phil. Trans., 1853. 

 Lydekker, op. cit., under Typotheria. Roth, Revista Mus. La Plata* 6, 

 1895, p. 333. 



