DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



195 



Type. — Am. Mus. 14917. Right ramus and sym- 

 physis of jaw containing ps-mz of right side, also left 

 canine. (See fig. 147.) 



Specific characters. — Osborn writes: 



P2-P4 16.5 millimeters. Second, third, and fourth lower 

 premolars progressive. Rudiment of metaconid on p2. Pswith 



Figure 144. — Type (holotype) of Eotitanops 

 Left lower grinding teetii. Am. Mus. 296. After Osborn, 1913. 



elevated metaconid subequal with protoconid, broad talonid 

 with rudimentary entoconid. P4 with bifid metaconid and 

 distinct entoconid. 



This species is readily distinguished from both 

 L. priscum and L. popoagicum by the advanced con- 

 dition of p3, which may be described as submolariform. 



pnnceps 

 Natural size. 



AM 14894^ 



Figure 145. — Type (holotype) of Eotitanops 

 major 

 Metatarsal (A) and fragment of tibia (B). Am. Mus. 14894. After Osborn, 1913. 

 A, Median metatarsal: A', posterior view; A', anterior; A', distal; A*, projdmal. 

 B', Distal end of left tibia, anterior view; B^ the same, distal view. All one- 

 half natural size. 



Measurements of type 



Millimeters 



Second to fourth lower premolar, inclusive 26 



Second premolar, anteroposterior 8 



Second premolar, transverse (trigonid) 4. 8 



Third premolar, anteroposterior 9 



Third premolar, transverse 6 



Fourth premolar, anteroposterior 9. 3 



Fourth premolar, transverse 7. 3 



First molar, anteroposterior 11.5 



First molar, transverse 8. 5 



Second molar, anteroposterior 12. 5 



Second molar, transverse 9. 5 



Etymology . — progressum , progressive . 

 Present determination. — A valid specific stage. 



Diploceras Peterson, 1914 



Cf. Eolitanolherium, this monograph, page 435 



Original reference. — Carnegie Mus. Annals, vol. 9, 

 Nos. 1-2, pp. 29-52, text figs. 1-15, pis. 6-10, 1914; 

 "issued August 17, 1914" (Peterson, 1914.1). 



Type species. — Diploceras oshorni. 



Generic characters. — Peterson writes: 

 Dentition: I|, C^, P-J, M|; premolar series proportionally 

 long; p5 with two distinct internal tubercles; horn cores well 

 developed; limbs relatively long and slender; tibial trochlea not 

 extended back on the calcaneum. 

 Astragalus high, with long neck, cal- 

 caneal and cuboidal facets laterally 

 located. 



Etymology. — SittAoj, double ; 

 Kepai, horn. 



Present determination. — The 

 name Diploceras being preoccu- 

 pied, Eotitanotherium was later 

 substituted. (See below.) The 

 genus itself is probably related 

 to the typical Diplacodon Marsh. 



Diploceras osborn! Peterson, 1914 



Cf. Eotitanotherium oshorni, this monograph, page 435 



Original reference. — Carnegie Mus. Annals, vol. 9, 

 Nos. 1-2, pp. 29-52, text figs. 1-15, pis. 6, 7, 1914; 

 "issued August 17, 1914" (Peterson, 1914.1). 



Type locality and geologic horizon. — On Duchesne 

 River near Myton, Uinta County, Utah; Eohasileus- 

 Dolichorhinus zone (upper levels of Uinta B 2). 



Type. — Front of skull, lower jaws, portion of pelvis, 

 atlas, portion of axis, fragments of scapula and foot 

 bones, No. 2859 (Peterson, figs. 2, 3, 4, 7, 12; pis. 6, 

 7, 10). (See figs. 148, 149.) 



Paratypes. — Front of skull, No. 2858; vertebral 

 column, fragments of ribs, bones of limb and foot, No. 

 2860; crowns of two upper molars, No. 2860a; hu- 

 merus, No. 2861; tibiae. No. 2862 (Peterson, figs. 1, 5, 

 6, 8, 9, 10, 11, 13, 14, 15; pi. 8). 



Figure 146.- 



-Type (holotype) of Lamhdotherium 

 priscum 



Am. Mus. 12822. Ai, Anterior part of lower jaw; As, inner view 

 of right pj-p (reversed). After Osborn, 1913. Natural size. 



Specific characters. — Peterson writes: 



Alveolar borders of the premaxillaries extending well in front 

 of the canines; nasals long and relatively thin, their anterior 

 portion abruptly turned downward and convex on the anterior 

 border; incisors well in front of the canines and relatively sub- 

 equal in size; canines proportionally small. 



