Vol. 4] Sinclair. — John Day Rodents and Ungulates. 



129 



coehoerus beds on Rudio Creek, Grant Co., Oregon. Three small 

 incisors and an incisiform canine are represented by roots. The 

 crowns and a portion of the adjacent alveolar border have not 

 been preserved. P, was functional as a canine. Its crown is unfor- 

 tunately missing. P 2 is also broken off', but the roots remain and 

 are separated by long diastemata from P x and P 3 . Small ledge- 

 like cuspules are present on the sides of the outer molar cresents 

 and in the intervening valleys, except in M 3 where they are 

 developed only on the antero-external crescent and in the valley 

 behind it. There is but one mental foramen, situated anterior 

 to P 2 . In the specimen figured by Scott*, there is an additional 

 mental foramen below P :! , and the mandible is somewhat deeper 

 than in No. 1343. The posterior portion of the ramus is not 

 preserved and has been restored in outline, together with the 

 crown of the canine, to correspond with Scott's figure. 



Type. — Cranium, No. 104, Univ. of Cal. Palaeont. Coll. The cranium 

 lacks the portion anterior to P 2 and is without mandible. 



Locality. — Diceratherium beds, Middle John Day. Turtle Cove on the 

 South Fork of the John Day, Grant Co., Oregon. 



Distinctive Characters. — Dentition ? ; ?,-,-. P 3 three rooted. 

 P 4 with inner and outer crescents. Molars without mesostyle, ex- 

 ternal ribs prominent and about equally developed. Metastyle 

 on M 3 much produced. Forehead flat. Sagittal crest low and 

 not elevated above interorbital plane, terminating posteriorly in 

 a prominent triangular knob. Brain case well rounded at sides, 

 somewhat flattened above. Orbits prominent and completely 

 inclosed with strongly developed frontal and jugal processes. A 

 prelachrymal vacuity present. Bullae small, with outgrowth of 

 petrosal between bulla and basioecipital. 



* W. B. Scott. Trans. Wagner Free Inst, Sci., Vol. VI, PI. 1, Fig. 3. 



Measurements. 



Length Lj-Ma inclusive 



Length P 3 -M 3 inclusive 



Length of diastema behind P 2 . 

 Depth of ramus at middle of P, 



<il mm 



35 

 3.5 

 9 



ALLOMEEYX planiceps, n. gen. and sp. 

 PL 14, Figs. 1 and 2. 



