DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



193 



typical and relatively progressive E. horealis. Its 

 primitive condition is shown in the comparison of the 

 premolars with the same teeth in E. horealis (Cope) 

 and E. princeps Osborn. 



The third inferior premolar is seen to be much less 

 progressive than in E. princeps or even in Lamhdo- 



FiGURE 141. — Type (holotype) skull of Rhadinorhinus abboiti 

 Field Mus. 12179. After Riggs, 1912. About one-fourth natural size. 



tJierium; the other premolars are also very primitive. 

 P2 short, compressed, with a very rudimentary hypo- 

 conid; ps laterally compressed, hypoconid distinct, 

 paraconid, metaconid, and entoconid extremely rudi- 

 mentary rectigradations. In the molar teeth, mi_3, 

 the metastylid and entostylid are also in an extremely 

 rudimentary or rectigradational stage. In ms the 

 hypoconulid is small, subconic, external in position. 



Etymology. — Named in honor of Dr. W. K. Gregory, 

 of the American Museum of Natural History, the 

 colleague of the author in the preparation of this 

 monograph. 



Present determination. — A valid specific stage. 



Eotitanops princeps Osborn, 1913 



('f. Eotitanops princeps, this monograph, page 295 



Original reference. — Am. Mus. Nat. Hist. Bull., vol. 

 32, pp. 410-411, fig. 4E, September 2, 1913 (Osborn, 

 1913.400). 



Type locality and geologic horizon. — Wind River 

 Basin, Wyo.; Lamidotherium-Eotitanops-CorpJiyodon 

 zone (Wind River B, "Lost Cabin," exact level not 

 recorded). J. L. Wortman, collector. 



Type. — Am. Mus. 296, including lower jaw, femur, 

 humerus, right manus, one cervical, three dorsal, and 

 one caudal vertebrae. (See figs. 143, 

 144.) 



Specific cJiaracters. — Osborn writes: 



Of still larger size, pa-ms 105 millimeters 

 (estimated). Inferior premolar teeth some- 

 what more complicated, as shown in the type 

 specimen. P2 with elevated, distinct, but very 

 rudimentary paraconid and metaconid; ento- 

 conid very rudimentary; talonid narrow. P3, 

 paraconid quite distinct, elevated; metaconid 

 small, distinct; entoconid rudimentary ; talonid 

 broad. P4, talonid broad; entoconid distinct. 

 Hypoconulid of ma rounded, more robust. 

 Ramus, larger and more robust. 



The more advanced development of the 

 premolar rectigradations, the increased size of 

 the teeth and of the jaw, the larger size of the 

 hind feet in the referred specimen (Am. Mus. 

 4902) combine to distinguish this specimen as 

 a mutation or subspecific stage between E. 

 horealis and E. maJQr. 



Etymology. — princeps, chief; in allu- 

 sion to its comparatively large size. 



Present determination. — A valid spe- 

 cific stage. 



Eotitanops major Osborn, 1913 

 Cf . Eotitanops major, this monograph, page 296 



Original reference. — Am. Mus. Nat. 

 Hist. Bull., vol. 32, pp. 412-413, figs. 

 5D, 6, September 2, 1913 (Osborn, 

 1913.400). 



Type locality and geologic horizon. — • 



From Alkali Creek, Wind River Basin, 



Lambdoiherium-Eotitanops-CorypTiodon zone 



Wyo.; 



Figure 142. — Type (holotype) teeth of Eotitanops gregoryi 



Am. Mus. 14889. After Osborn, 1913. A, Left m'-m'; B, right lower premolar 

 series (P2-ms). Natural size. 



(Wind River B, "Lost Cabin"; exact level unre- 

 corded). 



Type. — Am. Mus. 14894, a left median metatarsal; 

 also the distal end of the tibia. (See fig. 145.) 



