942 On Lemurine Reversion in Human Dentition, (November, 
This is owing to two facts, viz., the fifth tubercle is not the an- 
terior inner which completes the anterior triangle of the primitive 
inferior molar, but is a median posterior, such as is not uncom- 
mon in Mammalia of Puerco and Eocene age; and second, be- 
cause this tubercle is of quite small size and is, therefore, more 
liable to variation from insignificant causes. 
In the nearest allies of man, the anthropoid apes, the superior 
true molars are quadritubercular, the posterior internal tubercle 
of the last or third molar being usually smaller than in the other 
molars in the chimpanzee. The inferior molars are quinquetu- 
bercular in the human sense, the gorilla not infrequently adding 
a sixth lobe on the external posterior margin of the crown. The 
molars of both series are quadritubercular, with an occasional 
posterior fifth in the inferior molars, in the Semnopithecide and 
Cebide, excepting the genus Pithecia of the latter, where the su- 
perior molars are tritubercular. The superior molars of the Ha- 
palidz are tritubercular. In the Lemuridz the second and third, 
and frequently the first superior true molars, are tritubercular. In 
the Tarsiida the superior true molars are tritubercular through- 
` out. The superior molars of the extinct lemuroids differ like 
those of the recent forms. Thus in Adapis and its allies they 
are quadritubercular, but in Necrolemur they are tritubercular. 
In Chriacus (whose reference to the Lemuroidea is uncertain 
they are tritubercular, as is the case also with Indrodon. In 
Anaptomorphus they are of the true tritubercular type. This 8 
the genus of Lemuroidea, which in its dental character most 
nearly approaches the anthropoid apes and man, as I have ae 
where! pointed out. The formula is I. $; C.1; Pm. $; M. 3: 
The canines are small and there is no diastema in either jaw. 
It may be readily seen in consideration of these facts that the 
appearance of tritubercular superior molars in the genus Homo 
constitutes a reversion to the lemurs, and not to the anthropoid 
= apes or to the monkeys proper. And among lemurs the reve" 
sion is most probably to that type which presents the closest f° 
semblance to Homo in other parts of the dentition. The goe 
_ which answers most nearly to this requirement among those # 
~ present known is Anaptomorphus. 
= Imwstudying the dentition of man, I have examine 
_ AReport U. S. Geol. Survey Terrs. F- V. Hayden. Vol. 111, 1885, p- 245+ Pl 
and Pl. xxv, fig. 10; and AMERICAN NATURALIST, 1885, P- 466, fig. 12- 
d the crania 
xxives 
