FROM THE CAPE OF GOOD HOPE. 195 
fossil; and the cavity was further exposed to its termination, which 
became closed at a distance of half an inch from the obtuse and 
consolidated end of the root. No trace of a reserve alveolus or 
rudiment of a successional canine could be discerned. 
To test this character in the opposing inferior canine, a more de- 
cisive step was taken. 
A vertical section was made across the canine transversely to the 
axis of the jaw, and an extent of the root of that tooth of 2 inches 
9 lines (68 millims.) was exposed, as in fig. 8, Pl. XI. From a 
breadth of 35 millims. the root gradually contracted to one of 10 
millims. and terminated obtusely atv; the pulp-cavity , 18 millims. 
across at the upper part of the section, contracted to a breadth of 
5 millims., and closed obtusely 8 millims. from the end of the root, 
which presented a solid imperforate body of dentine. The thickness 
of the dentinal wall, s, of the pulp-cav a0 at the lower third part of 
the root is 5 millims. ; ; it increases to 9 millims. at the upper part. 
Thus the remains of the pulp occupy a closed cavity, save, probably, 
to some minute channels for the passage of blood-vessels, whieh 
however, were not demonstrated in this section. 
The part of the root toward the inner side of the dentary bone de- 
scribes a sigmoid curve in the section, being convex at the upper 
half and concave at the lower half, the fang slightly bulging toward 
that side ; the opposite side descends at almost a straight line to the 
obtuse end. 
The socket, which is indicated by the black matrix, shows a simi- 
lar form in the section, and also the extent which was occupied by 
vascular membrane or other substance between the tooth and jaw- 
bone. On the inner side of the section the interspace increases 
from a breadth of 2 millims. at the upper part to one of 5 millims. 
along about two thirds of the descending root; it then diminishes to 
less than 1 millim. round the obtuse end of the root. On the outer 
side of the root the pulp-cavity also gains width as the root descends, 
but in a less degree than on the opposite side; its greatest breadth, 
at one inch distance from the obtuse end, is 4 millims., and it gra- 
dually narrows towards both ends of tho exposed root, but most so 
at the closed end. 
Here, therefore, was demonstrated what was very plainly indicated 
in the more curved fang of the upper canine, that the pulp-cavity 
contracted and became closed before attaining the end of the im- 
planted root, and that in both cases the root terminated solidly and 
obtusely. That no trace existed of any provision for a successor was 
more plainly demonstrated in the section which is the subject of 
fie. 8. If no other evidence than a canine tooth of Titanosuchus 
had come under observation, it might weli have been inferred to be 
the second or permanent one of a huge carnivorous mammal. 
Comparing the subject of fig. 6, at the commencement of this quest, 
and when the uncut symphysial part of the lower jaw of Zitano- 
suchus suggested Crocodilian affinity, I found no other example of 
recent or extinct Crocodile comparable in bulk to the South-African 
fossil in hand, saye that huge Miocene Gayial from the Siwalik 
