484 PROFESSOU OWEN ON THE DENTITION OF PHACOCH(ERUS, 
In none of the other members of the Hog family is the first true molar {m\) so 
much worn down at the corresponding early stage of development of the second true 
molar, and it is upon this precocious growth of the first true molar that the chief 
peculiarity of the order of shedding of the teeth of the Phacochoeri depends. 
In the Phac. JEliani, the penultimate and last milk-teeth {d 3, d 4) in the upper jaw 
are displaced and succeeded by corresponding premolars, which therefore answer to 
jo 3 and JO 4 of the typical series. The anterior small rnilk-grinder, d2, is sometimes 
succeeded by a minute premolar, but occasionally this is abortive, or absorbed before it 
cuts the gum. In the lower jaw both milk-molars {d 3 and dA) are succeeded by the 
corresponding premolars jo 3, /? 4, at least in the Phac. JEUani. 
The stage of dentition of the Phac. jplliani, given in figs. 1, 2 and 3, corresponds 
with that in the common Hog, illustrated by the teeth in the lower jaw in Plate XX. 
fig. 1 of the Philosophical Transactions for 1801. In that figure the last grinder in 
place is the first true molar, m 1 ; the penultimate is the last milk-molar, c?4; the next 
is d^, the next d2-, and a little in advance of this, between it and the rudimental 
canine, is the small anterior premolar, p 1, The germs of the other premolars, p 2, p 3 
and p 4, are shown in their formative sockets beneath the deciduous teeth they are 
destined to replace. 
If the symbols above given be marked upon the teeth in the figure cited, the homo- 
logies of those in the reduced dentition of the young Wart-Hog will be readily appre- 
ciated. The teeth developed in the lovver jaw of that species are, — c?3, dA, p3, p A 
and m 1 : in both jaws m 2 has only its crown developed, and m 3 only the commence- 
ment of its crown. The teeth which are suppressed in the Phac. JEliani are, in the 
lower jaw, d\, d2,p \ and p2. In the upper jaw d 1 and p 1 are suppressed, and 
sometimes alsoj»2. 
The next stage of dentition (Plate XXXIV. figs. 4 and 5) shows the shedding of the 
deciduous molars to be concomitant with the coming into place of the second true 
molar, m2; it is well illustrated in the cranium of a young PAac. jEliani from Senegal 
in the Museum of Comparative Anatomy in the Garden of Plants : in which each of 
the three deciduous molars of the upper jaw have been succeeded by a premolar 
(jo 2, JO 3, j9 4, fig. 4), and the same with regard to the two deciduous molars in the 
lower jaw (jo 3, jo 4, fig. 5). The anterior angle of the crown of the last huge molar 
has also begun to protrude from the formative alveolus, so that the permanent or 
second molar series now shows ^^ = 22, which is the greatest number of grinders 
presented at any given time in the genus Phacochoerus. The first true molar, m 1, is 
however worn to near the fangs, and its grinding surface, as compared with that in 
Plate XXXIII. fig. 2, begins to be simplified. The homologies of the teeth at this 
period are indicated by the symbols attached to them in the figures. 
The stage of dentition of the young Phac. Pallasii, figured by Home in tab. xix. 
of lus memoir, is a little more advanced than that of the Phac. Pallasii above de- 
