93 
suggests that the primitive mammalian teeth really are formed by 
concrescence. The three cusps of Triconodon being equal does not 
prove that each of them represents a single tooth, nor do the two 
roots and the undivided basal cingulum point in that direction. 
Kiikenthafs referring to the multituberculate teeth as a funda¬ 
mental type is equally unfortunate. The Multituberculata are such an 
aberrant order — with rodent-like incisors (or rather like 
tweezers), with no canines and with never more than six cheek-teéth 
— that they can by no means be u in the direct ancestral line” of 
the several far more generalized recent mammalian orders. It 
would also be preposterous to suppose that the Mesozoic ancestors 
of the mammals should have started with very complicated teeth 
which afterwards were simplified to the condition of the Eocene 
forms, whose direct descendants have again acquired more and more 
complicated teeth upto the present time. To suppose the highly 
complicated form to be the most primitive, the simpler form to be 
the derivative condition goes against all experience. — The same 
objections can be made to Forsyth Majors “Polybuny-Theory”; 
he has made the same mistake in choosing his starting-point in the 
Rodentia, an order at least as specialised as the Multituberculata 
and developed partly in analogy with them (a real generic affinity 
is out of the question). One finds not only among the Sciuridæ, 
but also among many of the other primitive rodents, teeth which 
without the least difficulty can be brought into accord with one of 
the Differentiation Theories; and the aberrant forms of the others 
due to excessive gnawing activity, can easily be traced back to the 
typical pattern through intermediate forms. (Vide e. g. Winge: 
“Jordfundne og nulevende Gnavere”; E Museo Lundii I 1888). 
The palæontology having failed we must search for evidence 
of the Concrescence Theory in the ontogeny. Kliken t, hal has dis¬ 
covered that in the embryos of Mystacoceti some of the teeth 
(though not all and not always the same) are separated into two 
or three papillæ and hence he concludes that the mammalian teeth 
have originated through a fusion of several separate germs. It 
