370 NOTICES OF THE MEETINGS [Feb. 10, 
zygoma, but by developmental characters exclusively. The first 
set are the ‘‘ deciduous molars ;” the teeth which displace and 
succeed them vertically are the “ premolars ;"’ the more posterior 
teeth, which are not displaced by vertical successors, but succeed 
each other horizontally, are the “ molars ” properly so called. 
The phenomena of the development and succession of the 
teeth were then explained and illustrated in examples of Carnivo- 
rous, Herbivorous, and mixed-feeding ‘species of Diphyodont 
Mammalia. 
Genus Felis.—In the Cat, the deciduous incisors begin to appear 
between two and three weeks old ; the canines next, and then the 
molars follow, the whole being in place before the sixth week. 
After the seventh month they begin to fall in the same order; but 
the lower sectorial molar and the tubercular tooth above, appear 
before the deciduous molars are shed ; they do not push out any 
predecessors, and have no successors ; they are, therefore, true 
molars. The first deciduous molar in the upper jaw is a very 
small and simple one-fanged tooth ; it is succeeded by the corre- 
sponding tooth of the permanent series, which answers to the 
second premolar of the hyena and dog. The second deciduous 
molar is the sectorial tooth; its blade is trilobate, but both the 
anterior and posterior smaller lobes are notched, and the internal 
tubercle, which is relatively larger than in the permanent sectorial, 
is continued from the base of the middle lobe, as in the deciduous 
sectorial of the dog and hyena; it thus typifies the form of the 
upper sectorial, which is retained in the permanent dentition of 
several Viverrine and Musteline species. The third or internal 
fang of the deciduous sectorial is continued from the inner 
tubercle, and is opposite the interspace of the two outer fangs. 
The Musteline type is further adhered to by the young Feline in 
the large proportional size of its deciduous tubercular tooth. In 
the lower jaw, the first milk-molar is succeeded by a tooth which 
answers to the third lower premolar in the dog and civet. The 
deciduous sectorial, which is succeeded by the premolar, an- 
swering to the fourth in the dog, has a smaller proportional 
anterior lobe, and a larger posterior talon, which is usually 
notched ; thereby approaching the form of the permanent lower 
sectorial tooth in the Mustelide. The last tooth which is func- 
tionally analogous to the carnassial above, is the first of the true 
molar series, and is the homotype of the little tubercular tooth 
above. 
The true nature of the dentition of the Lion and other Felines, 
as determined by the above phenomena of development is :— 
3—3 1—1 3—3 a TR ae ere 
—, ¢ Toop PP oaaast m. aa signifying that there are 
3 incisors, 1 canine, 3 premolars and 1 molar, on each side of the 
upper jaw, and the same, with the exception of a small premolar, 
on each side of the lower jaw. The teeth, which are the seat of 
