342 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



internal alveolar border 38 millimeters, length from 

 anterior border to the anterior edge of the canine 45, 

 extreme length 96. Behind the canine convexity 

 the sides of the maxillaries are somewhat flat. The 

 infraorbital foramen is well exposed on the side of the 

 face, the distance from the antorbital border of the 

 malar being 36 millimeters. Only the anterior portion 

 of the malar is preserved, but the relations of the malar 

 and maxillary are shown by close examination and 

 comparison to have been about as they were in 

 Manteoceras and Limnohyops — that is, the maxillary 

 contributed an antorbital process and a long internal 

 inferior sliver; there is no infraorbital shelf; imme- 

 diately below the orbits the malars are gently convex 

 on the outer surface and broadly flattened on the 

 inferior surface, the vertical extent of the outer face 



pas. pci- nts. 

 FiGUEB 290. — Upper jaw of Telmatherium cultridens 

 One-half natural size. Princeton Mus. 10027 (type), reversed, showing the region of the horn swelling (A) and the overlap 

 of the maxilla on the nasal. The fragment of the nasofrontal region here figured is said to be associated with this type- 

 Upper part of Bridger formation, Bridger Basin, Wyo. 



being 27 millimeters, and the transverse extent of 

 the slightly concave inferior face opposite m^ 23. 



The teeth in general are distinguished by the 

 sharply defined, finely sculptured character of all their 

 elements. 



Incisors. — In the type (Princeton Mus. 10027) the 

 superior incisors have the typical generic character 

 of the opposite sets, forming acutely convergent or 

 V-shaped rather than gently convergent series; the 

 incisors increase rapidly in size from i' to i^, the fangs 

 measuring S, 10, and 14 millimeters, respectively. The 

 antero-external faces of the crowns are readily distin- 

 guished from those of Mesatirhinus megarlnnus by a 

 sharp anterior ridge, wliich divides the crown into a 

 flattened external portion, feebly convex and cingulate, 

 and a narrow anterior portion, feebly concave. Simi- 

 larly the postero-internal face is flattened, with a median 

 basal ridge and a very prominent postero-internal 

 cingulum, especially upon i^ 1^, which is less per- 

 fectly preserved, is a large subcaniniform tooth, with 



a sloping and less prominent internal cingulum. The 

 single infei'ior incisor preserved (is. Am. Mus. 1560) is, 

 in contrast to its mate above, typically incisiform, 

 with a more uniformly convex antero-external face, 

 feebly cingulate, and a nearly plane postero-internal 

 face, ^vith a median ridge and sessile postero-internal 

 cingulum; the long axis of this tooth is oblique, the 

 diameters being 14 by 11 millimeters. 



Canines. — In the type the superior canines have not 

 fully emerged, the crown measuring 49 millimeters verti- 

 cal, 24 anteroposterior, 22 transverse (estimated); the 

 tusk has the true generic lanceolate or lateraUy com- 

 pressed character, the anterior and posterior ridges being 

 sharply defined and terminating in the piercing apex; 

 the outer face is broadly convex; the inner is more 

 nearly plane, with a convex median swelling. The 

 inferior canines belonging 

 to an animal of the same 

 size (fig. 293; Am. Mus. 

 1560) are somewhat smaller 

 (vertical 30 millimeters, 

 anteroposterior 17, trans- 

 verse 15), distinctly lanceo- 

 late, with a sharply defined 

 anterior ridge, which be- 

 comes especially prominent 

 and inflected near the base 

 of the crown; the posterior 

 ridge is much less sharply 

 defined. 



Premolars. — The superior 

 molar-premolar teeth in 

 the type specimen (see PI. 

 LXIII, fig. 291) have the 

 laterally compressed, sharp- 

 cusped, secant, and pierc- 

 ing form so characteristic 

 of T. validuin, the type of 

 this genus; they are distinctly smaller — ISO milli- 

 meters, as against 195 millimeters in T. validuin. 



The superior premolars (81 mm.) exhibit nearly 

 complete internal cingula, excepting p^ also an exter- 

 nal cingula except directly opposite the protocone 

 sweUing. P' is a narrow tooth (ap. 15 mm., tr. 9), 

 with sharply compressed ridges extending forward and 

 backward from the protocone, a rudimentarj^ trito- 

 cone, and well-defined but low anterior style. P^ is a 

 subtriangular tooth; the deuterocone in this tooth is 

 double, extending backward to the postero-internal 

 portion of the crown. As seen externally (fig. 292) 

 the protocones and tritocones of p^~* are of equal 

 height, but the convexity of the protocone broadens 

 characteristically at the base into an anterior and 

 posterior cingulum; the tritocones present narrow 

 vertical external ridges, which enable us to distinguish 

 these teeth from the typically more flattened tritocones 

 of Mesatirhinus mega.rhinus and Manteoceras manteo- 

 ceras. In p' the ectoloph exhibits the same characters 



