with Descriptions of New Genera and Species. 109 

 Measurements of Holotype. 



mm. 



Total length of skull 160* 



Superior molar series, length 31_7 



Superior premolar series, length 30 



Cranium, max. width 52.5 



Diameter, postorbital constriction 42 



* Approximate. 



Paroreodon marshi, gen. et sp. nov. 



(Figs. 14-16.) 



Holotype, Gat. No. 12415, Y. P. M. Upper Oligocene (middle John Day), 

 Haystack Valley-Turtle Cove area, John Day Eiver, Oregon. Collected bv 

 L. S. Davis in 1875. ^ 



Distinctive characters. — Size small; brachycephalic ; 

 facial vacuities in advance of orbits, bounded by lacrymal, 

 frontal, and maxillary bones ; enormous brain chamber ; 



/24/^, TYPE 

 v. P. M. 



Fig. 14. — 'Paroreodon marsM, gen. et sp. nov. Holotype. Eight lateral 

 view. X 2/3. 



extremely short sagittal crest; face short and muzzle 

 narrow; steep basicranial axis; bulla very large and 

 robust, ending inferiorly in a sharp ridge; paroccipital 

 process triangular, with greatest diameter transverse, 

 abutting against bulla for two-thirds its length, and 

 descending outward, forward, and downward ; very small 

 diastema between C and P^ ; palate produced posterior to 

 M^ ; palatal vault uparched ; three very small incisors 

 crowded against each other and the canine; lacrymal 

 fossa shallow and open, maximum diameter vertical; 



Am. Jour. Sci. — Fifth Series, Vol. II, No. 8, — August, 1921. 



