83 
is likewise emphasised in Winge’s paper - also by the com- 
plicated grinding movements and the specialised mandibular arti- 
culation of the mammals. These facts must have characterised 
even the most primitive true mammals, and hånd in hånd with 
their development went the first differentiations of the dental system; 
thereforo the acquiring of grinding teeth —i. e. a heterodont den- 
tition - must have been one of the characters to constitute 
the mammals. In accordance with that we find no totally homo- 
dont form among the mesozoic mammals, and all the recent 
homodont dentitions are due to reduction. Usually the homodonty 
is looked upon as constituting one of the attributes of the most 
primitive mammals; but these hypothetical “ancestral forms” are 
purely symbolical, being composed of primitive mammalian charac- 
teristics only; animals like these have really never existed. „Ge- 
schSpfe mit ausschliesslich undifferenzierten Organen werden’ nur 
am Schreibtische empfangen und geboren, weshalb sie sich auch 
noch stets als vøllig lebensunfåhig erwiesen haben“ (pag. 539). 
Forsyth Major (“Miocene squirrels”, chapter V, 1893) 
stiongly oppeses the Cope-Osborn theory or “dogma”, as he 
calls lt. It is evident that Fleischmann’s “reversed homologies” of 
the upper and lower cusps are correct; if the cusp called pro- 
tocone really is homologous with the reptilian tooth, the protoconid 
accordingly is to be looked for at the posterior border of the lower 
tooth, i. e. in the part latest in appearence of this tooth and 
tliat gives the death-blow to the whole theory. — The rodents 
have been as yet little examined as to the tooth-forms; both Scott 
and Schlosser however, who have examined extinct rodents, endeavour 
to derive their teeth from the tritubercular form. But in Sciuro- 
morpha which have preserved the most elementary tooth-forms in 
this primitive order, evidences are found of another origin, since 
their molars can be traced back, to a polybunous form. „Brachy- 
odonty is the more primitive, the more generalized condition of 
molar and so is bunodonty .. .; the more brachyodont a molar is, 
the more multitubereular it is, or, let us say, polybunous. The 
6 * 
