346 



TITAJSrOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



portion of the masseter, and the posterior end of 

 the malar has a deep vertical flange. In dentition, 

 as enumerated above, T. ultimum is directly progressive 

 from T. validum. 



Figure 294. — Type skull and lower jaw of Telmatherium ultimum 

 One-fifth natural size. Am. Mus. 2060, from Uinta C (true Uinta); White River, Uinta Basin, Utah 



Measurements of Telmatherium ultimum, in millimeters 



SkuU, basal length 



Skull, breadth across zygomata. 



Face, length 



Cranium proper, length 



Free nasals 



Dental series, total length i'-m^. 



Pi-m3 



Pi-p^ 



Mi-m3 



P, ap. by tr 



P, ap. by tr 



P, ap. by tr 



C, ap. by tr 



C, vertical 



P', ap. by tr 



P^, ap. by tr 



P^, ap. by tr 



PS ap. by tr 



Ml, ap. by tr 



M\ ap. by tr 



MS ap. by tr 



Am. Mus. 



2060 



(type); 



Uinta C 



510 



"300 



270 



"250 



85 



303 



218 



90 



129 



14X14 



15X15 



19X18 



19X12 

 20X19 

 21X28 

 26X35 

 38X40 

 46X49 

 46X51 



Am. Mus 



2004 



(paratype); 



Uinta C 



320 



229 



95 



137 



15X14 



15X17 



22X20 



25X22 



44 



19X12 



20X22 



23X28 



27X35 



40X37 



49X44 



50X48 



568 



In general comparison with Manteoceras the skull 

 of this species of Telmatherium presents very pro- 

 nounced differences: (1) the occiput differs widely in 

 its height and rounded summit and in the presence 

 of two large facets above the foramen magnum; 

 (2) in front of this, on the vertex of the skull, is a 

 relatively long, delicate sagittal crest without the 

 characteristic pit of Manteoceras and lacking the over- 



hanging supratemporal ridges; (3) the nasals are 

 laterally recurved and distally truncate, as in Manteo- 

 ceras, but the free portion is relatively shorter; (4) 

 the zygoma resembles that of the Palaeosyops or 

 LimnoJiyops type — that is, it is without 

 the infraorbital shelf — and especially 

 parallels that of Palaeosyops in the de- 

 velopment of a deep flange on the lower 

 surface of the malars, which is an ad- 

 vance on the M. manteoceras condition. 

 The above table shows rather marked 

 differences in proportions of the teeth 

 between the type and paratype; the 

 cheek teeth in the paratype are all 

 relatively longer and narrower. 



As a whole the skull is mesaticephalic. 

 Comparison of the outline dorsal and 

 palatal views of Telmatherium ultimum 

 and Manteoceras (figs. 296, 303) brings 

 out a large number of very distinctive 

 characters. 



The horn rudiments are so inconspicu- 

 ous in both the male and female skulls 

 that they were not observed by the 

 author for a long time. In the female 

 they may be said hardly to exist, and in the male (PI. 

 XVI) they can be seen only by very close scrutiny. 

 As above noted, it is difficult to say whether they 

 are in a retrogressive or stationary condition. They 

 are certainly far less progressive than in Manteoceras. 

 Slcull of T. ultimum. — The cranium of this species is 

 represented by the type, a superbly preserved female 

 skull (Am. Mus. 2060), and by the anterior portion of 

 the paratype, a male skull (Am. Mus. 2004), in which 

 the youthful age is such that many of the sutures can 

 be made out. The skuU of the type is laterally crushed 

 in the anterior half, but the width across the zygomata 

 has probably not been greatly lessened. The general 

 proportions are mesaticephalic, the cranium being very 

 much longer than that of P. leidyi but much less 

 elongate and deeper vertically than that of D. hyogna- 

 thus. The measurements are, length 510 millimeters, 

 breadth 300 (estimated). It is readUy distinguished 

 from all other crania by the combination of the follow- 

 ing principal characters: (1) Nasals relatively short 

 (free length 78 mm.), the lateral downward extensions 

 being wholly covered by the maxUlaries; (2) prominent 

 narrow sagittal crest; (3) greatly elevated occiput; 

 (4) deeply extended malar and squamosal flanges of 

 the zygomatic arch; (5) premaxillary symphysis ver- 

 tically extended; (6) frontals with horn swellings rudi- 

 mentary — that is, consisting of convexities so slight 

 (paratype) that they are with difficulty observable. 



In palatal aspect the brachycranial proportions 

 decidedly predominate over the dolichocranial in the 

 basicranial region of the skull as shown in the following 

 characters: (1) The shortness of the anteroposterior 

 measurements (as from glenoid facet to mastoid proc- 



