98 
The so-called protocone of the horse-molar is really but a cingulum- 
cusp which is about to arise in Anchitherium, is high but still 
isolated in Hipparion and united by a narrow bridge with the true 
protocone (falsely called protoconulus) in Equus. — Scott’s modifi- 
cation for the case of the premolars is no improvement; he considers 
every premolar with few cusps as primitive and in searching for 
premolars with successively increasing number of cusps he thinks he 
finds the succession of the premolar cusps. But at all events pf 
and pi are molariform in primitive forms of Didelphyidæ and In- 
sectivora (the circumstances of pi and pf are more doubtful). A 
hind premolar with few cuspsi s in reduction, and Scott’s progressive 
series shows rather the succession in which the cusps disappear. — 
Similar objections may be made against the premolar analogy theories. 
Baume’s theory can be treated in a few words, Rost’s 
thorough criticisms already having been mentioned, I need only 
refer the reader to the consequences in systematic relation drawn 
by Baume himself. Vestigia terrent. 
Thus we have only left Winge’s differentiation theory from 
1882. „welche“ — using Leche’s words (1. c. pag. 5o9) 
„unbedingt einen der gediegnesten neueren Beitråge zur Morphologie 
des Gebisses hildet.“ To my mind it has all the advantages of 
Osborn’s theory — being plain, logical, practicable, in accordance 
with the mechanical-biological principles and with the palæontological 
evidence — without having its defects: It presupposes no doubtful 
rotation of any cusp, it allows an easy and precise homologising of 
the main cusps of any tooth and thus gives important information 
about the history of the various mammalian orders (vide Winge: 
E Museo Lundii I-III, 1888—1906); it deserved therefore a far 
greater appreciation than it has received. — The objection has 
been made against it, that it presupposes the reptilian cone to be 
one of the earliest disappearing cusps of the upper molars; but 
however early the origin of a cusp may be, from the time that 
its position causes a loss of function it must atrophy and finally 
disappear. And the more the grinding surface of the teeth is 
