550 UNGULATES. 



are four-sided, with rounded angles, gradually diminishing to a 

 point, and showing the action of the lower tusk upon the fore 

 part of their basal half: both upper and under surfaces are 

 traversed longitudinally by a broad and shallow groove ; and the 

 tip of the first formed end of the tusk is similarly impressed 

 on its fore-part, but this is subsequently worn away; the enamel, 

 also, with which the end of the tusk is at first covered, is soon 

 rubbed ofi". The number of molar teeth present at one time on 

 either side of the upper jaw appears not to exceed five, and is 

 soon reduced to four, and finally to two or one.(l) 



I have not been able to obtain evidence of more than two 

 premolars in the upper jaw, which correspond with the third and 

 fourth in the common Hog. The anterior premolar (PL 141, 

 fig. 2, p 3) is implanted by one anterior and two posterior short and 

 thick fangs, and has an oval crown, four lines by three lines across, 

 and presenting, in a much worn specimen, a notch or enamel-fold 

 on the inner side : the last premolar, (ib. and PI. 140, fig. 4, p 4) 

 with a grinding surface nearly circular, and five lines in diameter, 

 presents four peripheral enamelled lobes or islands, surrounding a 

 central lobe : when much worn these are reduced to an external 

 and an internal lobe, with a central enamel fold or island. The 

 first true molar, which cuts the gum and is in use long before 

 the preceding teeth are developed, or their deciduous predecessors 

 are shed, presents itself, in the mature Nubian Phacohere (PI. 141, 

 fig. 2, m 1), as a smooth almost worn-out stump; squeezed, as it 

 were, between the last premolar and the second true molar : more 

 commonly its place only is indicated by a short diastema separating 

 these teeth, and showing a remnant of the socket of the displaced 

 tooth ; and this vestige soon disappears, the second true molar 

 being pushed forward in contact with the last premolar, as shown 



(1) This is the state of dentition in the old Phacochcerus Mliani, figured in Home's 

 •Lectures on Comparative Anatomy, Vol. ii, pi. 38, which M. F. Cuvier cites, in the Me- 

 moires du Museum, t. viii, p. 453, as "une jeune tete de phacochajrus tout-a-fait depourvue 

 d'incisives." The single incisor of the upper jaw and the sockets of two incisors in the lower 

 jaw are, however, plainly shown in the engraving : the original specimen demonstrates six 

 incisive sockets beloAV, and the incisor in each intermaxillary above, with other characters 

 of the Nubian species of Wart Hog, as the cartilaginous ' septum narium.' 



