994 The American Naturalist. [December, 
archetype. This has been opposed in one form or other by 
nearly all English morphologists, namely: Lankester, Forsyth- 
Major, Newton Parker, M. A. Woodward, E. S. Goodrich, 
Marion Tims. It has been accepted only by Flower and 
Lydekker. In Germany it has been accepted by v. Zittel, 
Schlosser and Riitimeyer; Schlosser, especially, has made 
important contributions to the evidence. The theory is ac- 
cepted somewhat reservedly by the embryologists Röse, Leche, 
Taeker and others, who have attacked rather the homologies 
of the upper and lower cusps than the theory itself. In 
France it appears to have made little headway. In America, 
Scott, Allen, Wortman, Earle and many others are working 
upon the tritubercular theory and have made important addi- 
tions to it. It is difficult for the writer to take the “ primitive 
polybuny ” hypothesis seriously, although it is advocated more 
ma ps or less positively by 
such able morpholo- 
gists as Forsyth-Major, 
Lankester, Goodrich 
and Parker. The fact 
that the Multitubercu- 
oralno. A otistik lates and Monotremes 
Fig. 1.—Horse Morar, Merychippus, Show- and certain Rodents 
ing secondary folds. exhibiting this type 
are primitive is no evidence that the polybunic type itself is 
primitive. We know nothing of the history of the degenerate 
Monotreme teeth, but we know that the further we go bac 
among the ancestors of the Multituberculates and Rodents 
the less “ polybunic” and more tritubercular they appear. 
This demonstration once made, as a matter of convenience 
in thought and description, we must revise the old systems of 
nomenclature which were based upon secondary forms rather 
than upon primary homologies, and which, as a rule, differ 1n 
every type of mammals and among odontologists of every land 
and establish a new odontography or descriptive method. 
Finally, we must trace out all the lines of divergence in both 
forms and determine the principles which guide them. The 
importance of a uniform nomenclature is seen at once in the 
postfossette= c+ 
