492 GEOLOGICAL SURVEY OF THE TERRITOEIES. 



upper surface, as in the horn of the giraffe. It is broken off at the an- 

 tero-exterual sutural line of the bone, so that it probably extended over 

 the adjacent margin of the maxillary. It resembles in form the short- 

 horn cores of Symborodon heloceras, but is not as in that species an au- 

 togenous part of the bone, and its base is therefore not excavated by 

 the anterior part of the frontal sinuses. Thus it is probable that this 

 species possessed two pairs of osseous processes or cores on each side, 

 the one on the nasal, the other on the frontal bone. The absence of in- 

 terior sinus shows that the latter is not homologous with the horn-core 

 of the typical species of Symborodon, while the structure of the post- 

 narial walls (composed of both nasal and maxillary) is clear as to the 

 presence of those sinuses. The horu-core first described is probably 

 from the left side as indicated by its shape. Their existence is also to 

 be inferred from a fragment which resembles the base of the usual 

 horn-core of the other species, especially S. trigonoceras. From the pre- 

 ceding it may be derived that this species possesses either two pairs of 

 horn-cores, of which the posterior are on the frontal bone, or that it 

 possesses a single pair on the frontal bone only. As the former is much 

 the most probable supposition, I hesitate to separate this specie^ as a 

 genus distinct from the Miobasileus ophryas, which it resembles in many 

 respects. 



A j)ortion of the margin of the frontal bone supports an angular pro- 

 jection, doubtless postorbital. The malar bone has an extensive surface 

 of attachment with the maxillary. Its anterior portion bounding the 

 orbit below is a narrow prominent rib, as in S. trigonoceras, and difierent 

 from that of S. opJiryas. The zygomata are strong, but not expanded ; 

 they resemble those of .S. trigonoceras; but, while shorter than in a 

 specimen of the latter, the squaiuosal process is deeper. A portion of 

 the nasal bone shows that they were short and light. 



There are teeth or alveoli representing four premolars and three true 

 molars as well as a canine. In a right premolar, No. 2, there is a strong 

 basal cingulum, from which coarse plicae extend inward. The inner 

 cones are confluent into a curved ridge, which is connected by a lower 

 ridge with the outer crescents. The latter are entirely confluent. The 

 canine has a short recurved, obtusely conic crown, with a strong cingu- 

 lum round its posterior base, as in other species of the genus. 



Measurements. 



M. 



Length from front of orbit to glenoid fossa, (axial) 0.365 



Depth of malar below orbit 020 



Depth of squamosal process 082 



Length of molars and last three premolars 293 



Length of last three premolars 110 



Length from nasal meatus to orbit 103 



Length of crown of second premolar >. 029 



Width of crown of second premolar 038 



Height of crown of canine 



Diameter of crown at base 



Depth of frontal tuberosity 038 



Diameter of frontal tuberosity 075 



Diameter of horn-core, transverse 038 



Diameter of horn-core, longitudinal 049 



Although the specimen from which this species is described is as large 

 as the smaller of the 8. trigonoceras, it does not belong to an old animal, 

 as the cranial sutures are distinct. It makes one more addition to our 

 knowledge of these curious forms, whose abundance during the Miocene 



