Vol. 6] Merriam: Virgin Valley and Thousand Creek. 



285 



Canon shows little of the form of the mandible, excepting its 

 height below the premolars. The molar teeth are the only ones 

 present, but a liberal estimate of the length of the cheek-tooth 

 series from P 2 to M 3 indicates that this form was considerably 

 smaller than M. furcatus, M. necatus, and M. osborni. The 

 molars are distinctly hypsodont, without styles between the outer 

 pillars, and are rather sharply compressed. On M 3 the heel is a 

 little smaller than the middle segment of the tooth. 



Measurements, No. 12608 



Approximate height of mandible below P 2 „ 11.2 mm. 



Length, M 1 to M 3 inclusive 25.3 



M„ anteroposterior diameter 6.8 



Mi, transverse diameter of posterior segment 3.8 



M 2 , anteroposterior diameter 7.6 



M 3 , anteroposterior diameter 11.5 



M„ transverse diameter of middle segment 3.7 



An antler obtained at High Rock Canon (fig. 6-i) is slender, 

 slightly swollen a short distance above the base, and without 

 traces of a burr. Like the lower jaw fragment, the antler is 

 smaller than in M. furcatus. but may represent a young animal. 

 It is considerably compressed in a plane inclined about 45° 

 away from the anteroposterior plane of symmetry of the skull, 

 and shows a distinctly marked concavity at the base of the horn 

 immediately behind the orbit. So far as can be determined there 

 , seems reason for suspecting that the antler of the form repre- 

 sented by this specimen was not at any stage entirely similar to 

 those of the previously described forms. 



This form seems to differ so far from the known species as 

 to make a specific correlation with any of them inadvisable, and 

 the name Merycodus nevadensis is tentatively applied to it. 



SPHENOPHALUS NEVADANUS Merriam 



S. nevadanus Merriam, Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, 

 p. 325, 1909. 



This species was based on a number of specimens represent- 

 ing portions of the skull with horn-cones. In the original descrip- 

 tion it was characterized as follows : 



' ' Prontals not cavernous at the base of the horns. Horns situated on 

 the upper posterior region of the orbits, sloping backward, slightly out 



