No.l.\ NIMRAVIDvE AND CANIDJi: OF THE MIOCENE PERIOD. 177 

 SCIURUS BALLOVIANUS Sp. DOV. 



This squirrel is the second species of its genus supposed to occur in 

 tlie Truckee beds of Oregon, and the third Sciurus obtained thus far from 

 the Lower Miocene or Oligocene of the West. The tyi)ical specimen for- 

 tunately includes the cranium, with both rami of the mandible, so that 

 its reference to the genus Sciurus rather than to Gi/mnojptychus is assured. 

 Like the latter genus, the infraorbital foramen is reduced to a slit, but, 

 unlike it, there is but one internal tubercle of the crowns of the superior 

 molars instead of two. 



The skull is flat above, and the interorbital space is also flat, and is 

 remarkably wide. Temiioral ridges none. Muzzle short and narrow. 

 Palate wide, its i)osterior notch extending as far forwards as the last 

 superior molar. The ascending ramus of the mandible originates oppo- 

 site the anterior x)art of the last inferior molar. The massateric fossa 

 extends to opposite the anterior border of the second inferior molar. The 

 mental foramen is near the superior border of the posterior part of the 

 diastema. The second and third superior molars, the only ones pre- 

 served, have two cross-crests and a strong anterior cing-ulum. The 

 external extremities of the cross-crests are little elevated, and there are 

 no other cingula. The inferior molars have basin- shaped grinding faces, 

 with a lobe at each angle. There is a small tubercle between the lobes 

 of the inner and outer x)airs. The incisors of both jaws are much com- 

 pressed, strongly convex in front, and, in the lower jaw at least, without 

 sculpture. 



Measurements. 



M.. 



Lengtli of skull to orbit 0090 



Width between orbits 0090 



Wicltb of muzzle 0047 



Width between last molars 0040 



Lengtli of superior dental series 0054 



Diameters of second molar i^^^^^^-l^"^*'^^^^^ ^^^^ 



( transverse 0016 



Width of superior incisor 0013 



Length of mandibular ramus 0150 



Elevation of ramus at coronoid 0080 



Length of diastema 0030 



Length of inferior dental series 0070 



Depth of ramus at second molar 0045 



This species is much smaller than the Sciurus vortmani, from the same 

 horizon of Oregon. The type specimen was discovered by 3Ir. L. S» 

 Davis, of ]Mr. Wortman's party. The name is given in honor of Mr. 

 M. H. Ballon, of Chicago, a naturalist and journalist. 



CANIDJE. 



Species of this family were very abundant during the Miocene period 



in North America as in Europe. Those of the Lower and ^Middle 



Miocene epochs belong to genera allied to, but distinct from, Canis; 



while those of the Upper Miocene (Loup Fork) and later horizons, per- 



12 as 



