172 THE MAMMALIA OF THE DEEP RIVER BEDS. 



the hyoid apparatus, a feature which is cervine rather than antelopine ; the auditory 

 meatus is a long tube which is directed more posteriorly than in Antihcapra. 



The frontal zone extends considerably in front of the orbits, though but little 

 behind them, and hence takes but a small part in roofing the brain-chamber; these 

 bones lie in nearly the same plane throughout their length, and the descent at the 

 forehead is slight, very much less than in the prong-buck and apparently less than 

 in Dicroceros. Apart from the horns, the upper contour of the skull is thus almost 

 a straight line. The horns are very peculiar and quite unlike those of any other 

 known genus, fossil or recent. At the base the section forms a spherical triangle, 

 the three sides of which present forward, backward and inward; the anterior face is 

 concave, a feature which is much more marked in this species than in B. borealis ; the 

 other faces are convex. In the specimen before us the horns are broken away about 

 three inches above the base, but Prof. Cope's numerous skulls of the larger species 

 show that in that form, at least, the horns were remarkably long, perfectly simple and 

 non-deciduous, none of them exhibiting any burr or any tendency to branch. The 

 young stages of Dicroceros have a very similar unbranched horn, but the many 

 known skulls of Blastomeryx show that this simplicity is not a transitory character 

 in this genus (see Filhol, No. 13, PI. XXXIV, Fig. 3). Faintly marked grooves 

 and ridges may be seen on the surface of the horns, but their smoothness indicates, 

 with great probability, that they were permanently covered with skin. The external 

 angle of the base of the horn is in B. borealis continued into a wing-like process 

 which extends outward behind the orbit. In the type of B. antilopinus this process 

 is broken away, but it can hardly have been so prominent as in the larger species. 

 As in Dicroceros and AnlilocajJra, the horns rise directly above the orbits, but are 

 more erect than in the former genus ; the postorbital process is given off from the 

 base of the horn. A large foramen, the supraorbital, pierces the base of the horn 

 and two smaller ones perforate the frontal in advance of the latter; these foramina 

 have a more anterior position than in the prong-buck. 



Between the frontal and the lachrymal there is a narrow, slit-like fontanelle, the 

 incipient stage of the much larger vacuity which occurs in the deer and many ante- 

 lopes. Cope's figure of B. borealis (No. 7, Fig. 16) does not show this vacuity; if 

 it be really absent in that species it will form an important specific distinction. The 

 nasals, premaxillaries, and most of the maxillaries are destro} x ed, but enough of the 

 latter remains to show that the alveolar portion is very low in correspondence with 

 the extremely brachyodont character of the dentition and that the facial portion is 

 high. In consequence of this, the face is deep vertically, quite as much so as the 

 cranium, and the line from the molars to the occipital condyle is straight and nearly 



