GEOLOGICAL SURVEY OF THE TERRITORIES. 563 



caused by tlie fact that the Ryracoidea present the ratlins of tlie Frohos- 

 cidia witii the hind foot of the Ferissodaciiila. These animals are, how- 

 ever, well regarded as a distinct order. Whether all the animals to be 

 included in the Proboscidia possessed a proboscis or not, is of secondary 

 importance. It is nevertheless highly i>robable that LoxoJophodon and 

 Eohasileus possessed one, and not nnUkely that snch forms that ap- 

 proach still nearer the tapirs were not withont an organ such as they 

 possess, and which Cuvier ascribed to the Palccother la and other allies. 



PEOBOSCIDIA. 



One incisor or canine on each side ; molars compound, with postero- 

 auterior replacement; nasal bones abbreviated; astragalus articulating 

 with navicular only; no third trochanter Elephant'uUv. 



Neither incisors nor canines ; molars simple, with vertical replacement; 

 nasal bones shortened; (f) foot; no third trochanter I>inoiherud<e. 



No incisors; nasal bones elongate; astragalus articulating with both 

 navicular and cuboid; no third trochanter EohaslUidie. 



Dentition complete, /. e., incisors present; '? nasal bones. Astragalus 

 articulating with both navicular and cuboid; a rudimental third tro- 

 chanter Bathmodontidce. 



These suborders ]iresent a series of approaches to the Perissodacfyla. 

 Thus the Eobasiliidw agree with the typical Proboscidia in addition to 

 the above points, in the jiosterior expansion of the scapula, and its 

 apical acumination ; in the very short cervical vertebrte ; in the flat 

 carpal bones; in the absence of pit for round ligament of the femur; in 

 the flattened great trochanter, contracted condyles, and flssure-like in- 

 tercondylar fossa of the same bone. In the longitudinal crest of the 

 tibia separating glenoid articular faces which are on a transverse line. 

 In the short calcaueum, which is wider than long, and tubercular on 

 the inferior face. In the Ave digits; the acetabulum not separated by a 

 peduncle from the iliac plates, and the lacli of angular production of 

 the latter beyond the sacrum. Also in the three distinguished sacral 

 vertebra, as contrasted with the .five closely co-ossified ones of tlie 

 Bhinocerotidcc. These characters are, some of them, of subordinate 

 value only. 



The chief differences are seen in the cranium, though here also there 

 are imi:>ortant resemblances. Thus, the palate is not excavated be- 

 the molars posteriorly, as is Perismdactyla, nor are the palatine bones 

 produced posteriorly and separated from the maxillaries, as in Artio- 

 dactyla generally. They have a shallow excavation and accompany tlie 

 maxillaries posteriorly without interruption, as in Eleplias. In Loxolopho- 

 don the malar bone forms the middle element of the zygomatic arch, send- 

 ing a narrow strip only forward to the neighborhood of the lachrymal. 

 In Uintailierium, according to Marsh, its extentiou toward the side of the 

 face is rather greater, much as in some Perissodactyla. The dentition is 

 not far removed from that of Dinoiherinin, and the mode of succession of 

 the teeth was in all probability similar. The premaxillariesand nasals are 

 excavated and exostosed for the attachment of a trunk in LoxoJophodon. 

 The lateral and occipital crests of the cranium, though ditterent from 

 the enlarged sinuses of the diploe of Ele[)hants, represent the external 

 walls of this structure, and furnish a hint as to its mode of origin, and 

 serve to ease the transition to Perissodactyles. 



The differences in the cranium are consequent upon its anterior elonga- 

 tion, the nasal bopes and premaxillaries becoming thus much extended. 

 The lachrvmal is perforated by a small lachrymal canal in Uintalherium, 



