of the wild Boar, and Animal incognilum. 323 
similar to it in the bear ; and, in the lion and tyger, the posterior 
grinder has a small tooth placed close to it, which is a different 
mode of increasing the grinding surface. 
The rhinoceros and hippopotamus have no increase of the 
surface of the posterior grinders, beyond what is usually met 
with. 
The tapir I have not had an opportunity of examining 
in its full grown state; so that I am unable to say what ex- 
tent the masticating surfaces of the posterior grinders may 
acquire. 
In the human species, the mode of dentition is upon the same 
principle as in the wild boar ; only the last-formed grinding 
teeth in each jaw, called dentes sapientiae, from the late period 
of life at which they cut the gum, do not in size exceed the 
others, but are rather smaller, and very often have not sufficient 
room in the jaw to come into their regular place, although they 
do not make their appearance till between twenty and thirty 
years of age. 
In the negro, the dentes sapientiae have sufficient room to 
come into their place, and are in general full as large as the 
other grinders ; the growth of the posterior part of the jaw 
being evidently greater than in the European. 
When the age of man was much greater than at present, it is 
natural to suppose the growth of the posterior part of the jaw 
was continued for a longer time, and the space for the dentes 
sapientias was more extensive. Under such circumstances, these 
teeth would probably be large, in proportion to the space which 
was to receive them ; and when, instead of threescore and ten, 
a thousand years was the period of a man's life, we should be 
Tt a 
