DISCOVERY OF THE TITANOTHEEES AND ORIGINAL DESCRIPTIONS 



191 



Metarhinus riparius Riggs, 1912 



Cf. Metarhinus riparius, this monograph, page 429 



Original reference. — -Field Miis. Nat. Hist. Pub. 159, 

 Geol. ser., vol. 4, No. 2, p. 28, pi. 7, fig. 1, June, 1912 

 (Eiggs, 1912.1). 



Type locality and geologic horizon. — White River 

 canyon and divide, northeastern Utah; "entire upper 

 Metarhinus beds," base of Metarhinus zone (Uinta B 1). 



Figure 138. — Type (holotype) skull of Metarhinus riparius 

 Field Mus. 12186. After Eiggs, 1912. About one-fourth natural size. 



Holotype.— Skull (Field Mus. 12186). (See fig. 138.) 

 Paratype {"cotype"). — "Lower jaws" (Riggs, pi. 7, 

 figs. 2, 3). 

 Specific characters. — Riggs writes: 



Skull long and narrow (405 by 210 mm.). 

 Anterior cranial region expanded, sagittal crest 

 short. Interorbital region relatively narrow and 

 rounded, rudimentary horn cores above orbits, 

 canines large, molar series short (88-93 mm.), 

 hypocone usually present on m', mandible 

 straight in the ramus, lower canine long and 

 recurved. 



Etymology. — cristatus, crested; in allusion to the 

 high sagittal crest. 



Present determination. — A valid stage in the Meta- 

 rhinus fluviatilis phylum. 



Dolichorhinus fluminalis Riggs, 1912 



Cf. Dolichorhinus fluminalis, this monograph, page 417 



Original reference. — Field Mus. Nat. Hist. Pub. 159, 

 Geol. ser., vol. 4, No. 2, p. 33, pi. 10, 

 figs. 1-3, June, 1912 (Riggs, 1912.1). 



Type locality and geologic horizon. — 

 Uinta Basin, northeastern Utah; "Amy- 

 nodon sandstone," summit of Eohasileus- 

 Dolichorhinus zone (Uinta B 2). 



Holotype. — A fine skull. Field Mus. 

 12205; collector M. G. Mehl. (See fig. 

 140.) 



Specific characters. — Riggs writes: 



Skull small and narrow (520 by 230 mm.), 

 facial region much shorter than cranial, nasals 

 narrow and slightly tapering, posterior nares 

 opening between hamular processes, postorbital 

 process of jugal back of the last molar, molar- 

 premolar series 171 millimeters; canines short and recurved, in- 

 cipient horn cores in the form of high, narrow ridges. * * * 

 The skull is slender, light and complex in structure as com- 

 pared with the massive and rounded D. cornutus. The molar 

 teeth are no longer in the crown than those of Metarhinus 



Etymology. — riparius, riparian, in allu- 

 sion to the nature of the habitat. 



Present determination. — A valid species 

 in the Metarhinus phylum. 



Metarhinus cristatus Riggs, 1912 



Cf . Metarhinus cristatus, this monograph, page 429 



Original reference. — Field Mus. Nat. 

 Hist. Pub. 159, Geol. ser., vol. 4, No. 2, 

 p. 28, pi. 9, fig. 3, June, 1912 (Riggs, 

 1912.1). 



Type locality and geologic horizon. — 

 White River canyon, northeastern Utah; 

 "upper Metarhinus beds," lower section 

 of Metarhinus zone (Uinta B 1). 



Holotype. — A skull, lacking the muzzle (Field Mus. 

 12194). (See fig. 139.) 



Specific characters. — Riggs writes: 



Skull length approximately 380 millimeters, molar series 94 

 millimeters. Frontal region broad, sagittal crest long and 

 high, molars short-crowned, no hypocone on m', arches rela- 

 tively heavy. Represented by a single skull lacking the 

 nasals and the premaxillaries. 



Figure 139. — -Type (holotype) skull of Metarhinus cristatus 

 Field Mus. 12194. After Eiggs, 1912. One-third natural size. 



earlei. The jugal process of the maxillaries arises at a point 

 back of the last molar rather than beside it as in Z). longiceps. 

 There is no offset in the palate between the last molars, though 

 the primary position of the posterior narial opening is marked 

 by a slight rugosity. 



D. fluminalis is most nearly related to D. intermedins. The 

 skull exceeds in length the type of that species in the ratio of 

 520:465 millimeters. The molar teeth are proportionately 

 much smaller; the series measures relatively 99:109 millimeters. 



