Miscellan eous. 
391 
nized a perfectly similar canal, terminated by a pavilion and placed 
in the same situation. As in Pedicellina, it appears very early in 
the bud. 
In the group Endoprocta, including the highest forms of the 
Bryozoa, we may therefore regard as constant the presence of a 
segmental organ — that is to say, an organ which is very generally 
diffused among the Yermes. 
Considering the endeavoirrs that have been made of late years to 
approximate the Bryozoa to the Annulata, I have thought it an 
advantage to bring this new argument iuto the debate, as it seems 
to me to possess a real value . — Comptes liendus, February 24, 1879, 
p. 392. 
The Origin of the specialized Teeth of the Carnivora. 
By E. D. Cope. 
The specially developed teeth of the Carnivora are the canines 
and sectorials. The former are largo in many orders of Mammalia ; 
and their origin is probably to be sought among the Theromorphous 
Reptilia*, such as Clepsydrops and Deuterosaurus, if not in still lower 
types. The successive modifications of form which have resulted 
in the existing specialized single sectorial tooth of the Eelidae have 
been already pointed outf. They were shown to consist in the 
gradual obliteration of the internal and posterior tubercles and the 
enlargement of the external anterior tubercle in connexion with an 
additional anterior tubercle. The modification in the character of 
the dentition, taken as a whole, was shown to consist in the reduction 
in the number of teeth, including the sectorials, until in' Felis &c. 
we have almost the entire function of the molar series confined to a 
single large sectorial in each jaw. 
Observation on the movements of the jaws of Carnivora shows 
that they produce a shearing motion of the inferior on the superior 
teeth. This is quite distinct from the subhorizontal movement of 
Ruminants, or the vertical motion of hogs and monkeys. Exami¬ 
nation of the crowns of the sectorials shows that the inner side of 
the superior and the external side of the inferior are worn in the 
process of mastication. The attempt to cut the tough and stringy 
substances found in animal bodies is best accomplished by the 
shearing of the outer edge of the lower molar on the inner edge of 
the external tubercles of the superior molar in an animal with 
simple tubercular teeth. The width of the mandible is too great 
to allow the inferior teeth to shear on the inner edge of the inner 
tubercles of the superior series. The cusps of both superior and 
inferior teeth engaged in this process have developed in elevation 
at the expense of those not engaged in it, viz. the internal cusps of 
the same teeth. The atrophy of the latter cannot have been due to 
friction, since the internal cusps of the inferior series, which have 
* ‘ American Naturalist,’ 1878, p. 829. 
f Cope, ‘ Proceedings Academy Philad.’ 1865, p. 22. 
