590 MR. M. F, WOODWARD ON [May 5, 
(6) The evidence advanced in support of the tritubercular 
theory is insufficient to prove that the upper molars 
primarily evolved on the lines of that theory. 
(7) Owing to want of material, trituberculists have been led 
to assume that the upper molars of the early Mammalia 
passed through similar stages to those which they have 
determined for the lower teeth, and consequently they 
have in most cases incorrectly identified the primary cone 
(save in Peralestes and the living Centetide and Chryso- 
chloris). 
(8) That as regards the primary cone, its ontogeny recapitu- 
lates its phylogeny. 
I do not mean to deny for one moment the occurrence of the 
tritubercular type of upper molar tooth, nor even to underrate its 
phylogenetic importance ; for no one who has studied cusp ontogeny 
can fail to notice the frequency of its appearance, and the fact that 
often (though not always) the three cones of the trigon are the 
first to appear during development. What I desire to point out 
is, that there is no evidence to show that this type of upper molar 
arose in the way suggested by trituberculists, and that they have 
in most cases overlooked the true primary cone. 
If the triconodont tooth be a stage in the evolution of the mamma- 
lian molar, then I should believe that the anterior cone disappeared, 
the main cone becoming enlarged as the paracone and the posterior 
one as the metacone. At this stage the upper teeth overhang and 
bite outside the lower molars, and the future antero-internal cone 
(protocone) was developed as an internal shelf acting as a mortar for 
the cusps of the lower teeth, and at a much later period developed 
acusp. The: hypocone arose in a similar way with the elongation 
of the teeth. 
The function and origin of the external cingulum with its 
numerous cusps (2-4) is difficult to understand, for in the living 
Mole it is quite outside and free from all contact with the lower 
molars ; possibly it is of use to insect-feeding animals, giving them 
greater hold of their slippery prey. 
In the Centetide and Peralestes, the upper molars could not have 
overhung the lower ones to the same extent, consequently no in- 
ternal lobe bearing the protocone was developed and the external 
cingulum was very largely developed. 
I have purposely left out all reference to the multituberculate 
and conecrescence theories. having restricted my researches to 
endeavouring to ascertain whether the trituberculate theory respect- 
ing the upper molars rested upon any solid basis, and whether cne 
of the molar cusps was more primitive in its mode of origin than 
the others. 
Ontogenetically, I have failed to find any support for the con- 
crescence theory, neither do I consider that any of the evidence put 
forward by Rése and Kiikenthal is at all conclusive in its favour. 
On comparing the several families which grouped together 
