46 A POST-PLIOCENE ARTIODACTYLE ; 
divided into an outer and inner lobe. The lateral tubercle 
is continued upwards as a ridge, slightly folding over back- 
wards. At its base it shows traces of lobular subdivision, 
and anteriorly it passes into the convexity of the crown 
without any line of separation. The inner superior tubercle 
is continuous with the inner subdivision of the anterior sur- 
face, and the groove external to it is thus interrupted on 
the summit of the tooth. Between the apical part of the 
groove and the top of the outer lateral ridge the apex is 
ground down to a subtriangular patch of dentine. A third 
specimen, with its coronal character immature, is also pro- 
bably from a young male. in all these the pulp cavity is 
wide and deep. With advancing age, as indicated by wear, 
it diminishes, though not regularly : the fang concomitantly 
lengthening below the enamel line and rapidly contracting. 
In an example, whose crown is eroded to its full breadth, 
a relatively small conical cavity is left in the much con- 
tracted end of the fang. A fifth example shows a larger 
and deeper cavity, with thinner walls, though more than 
half the height of the crown is removed by wear; and ina 
sixth, broken across the implanted end, the cavity was 
about the same as in the fourth specimen, though the crown 
is less reduced by wear. It would seem, then, that these 
teeth maintain a waning activity of growth throughout life, 
or at least during their functional period; the gradual 
eruption so effected compensating, perhaps, for terminal 
loss by wear as in the canines. 
A portion of the crown of a compressedly triangular 
tusk, longitudinally striated and transversely marked with 
downward curving lines of growth, represents, apparently, 
the left lower canine. Its hinder face, worn smooth by 
friction with the fore edge of the upper tusk, curves a little 
outwards and gradually widens as the curve of its inner 
border diminishes in its ascent. Its summit is obliquely 
truncated inwards, downwards, and backwards. There is 
no enamel on this face of the tusk, even below the worn 
surface, where in the Peccary it turns backwards from the 
outer and inner faces to cover the base posteriorly. The 
hinder side of the lower end of the outer face is impressed 
with a broad groove, as in Dicotyles; in the latter, the 
groove is bounded anteriorly by a strong enamel ridge 
