Evolution of Mammalian Molars. 
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€ proto- and metaconules in the Artiodacty 
1077 
Adapis and Anapto- 
morphus are examples 
of Sub-types a, c, asso- 
ciated ; for it frequently 
happens that the para- 
conid atrophies without 
a complete enlargement 
of the hypocone. A 
study of tthe diagram 
demonstrates, however, 
that the association of 
Sub-types b and c is im- 
possible. The recent 
monkeys Tarsius and 
Loris afford a good il- 
lustration of the asso- 
tritubercular 
ciation of 
quinguetubercular 
sextubercular 
quadritubercular 
molars. 
The subsequent evo- 
was 
the loss of the primary 
cusps, e.g., the metaco- 
nid in the Carnivora,' 
the paraconid in the 
Ungulata. Second, by 
the loss of some of the 
secondary cusps, eg., 
la.! Third, by the met- 
- amorphosis in the form of the cusps. This subject has been fully 
* Schlosser: “ Beitrage zur Kenntniss der Stammgeschichte der Huf- 
thiere,” Morph. Jahrb., 1886, p. 123, has especially drawn attention to 
the probability that the Artiodactyla were derived from sexitubercular 
