No. 1.] TRITUBERCULAR MOLAR. 21 
cause which produced this modification of the Esquimaux den- 
tition is still active, and its recent appearance in the most civil- 
ized races must be due to this unknown cause. The progressive 
character of the French dentition in this respect is in broad 
contrast with the primitive character of that of Italians and 
Greeks. The characters seen in the latter go far towards sus- 
taining Professor Huxley’s hypothesis, that the dark Mediterra- 
nean sub-races consist of a mixture of Egyptian with the Indo- 
European stock. 
In conclusion it may be stated, that the tritubercular superior 
molars of man constitute a reversion to the dentition of the 
Lemuridz of the Eocene period of the family of Anaptomorphi- 
dz. And second, that this reversion is principally seen among 
the Esquimaux and the Slavic, French, and American branches 
of the European race. Observations on some of the races of 
the Indo-Europeans are yet so imperfect that some additions to 
the above list yet remain to be made, as for instance, probably, 
the English sub-race. The neolithic dentitions examined are 
intermediate between the two extremes, thus showing an ad- 
vance over the lowest existing races. 
The Origin of the Quadritubercular Molar. 
This question has an interest beyond the history of human 
dentition. I will now inquire whether any mechanical cause 
can be assigned for the retention of the quadritubercular 
structure. 
It may be recalled ‘that I have shown that the development 
of a fourth tubercle on the posterior side of the internal tubercle 
of the tritubercular superior molar has been the origin of the 
dentition of the non-carnivorous types, which are principally 
Ungulata. The mechanical action of the inferior against the 
superior molars cannot have been very different in the early 
Ungulates from what it was in the early flesh-eaters, since the 
canine teeth, which partly direct this motion,! are equally de- 
veloped in both. But the history of the canines in the develop- 
ment of the Ungulates is exactly the reverse of what it has been 
in the flesh-eaters. In the former the canine has grown suc- 
cessively smaller, and has been in most of the lines completely 
1 See mechanical origin of the dentition of the carnivora, Proceedings American 
Association Advanced Science, 1887. 
