276 On some Variations in the Scotch Wild Cat. 
extra teeth may be interpreted as pm? of the mandible—a 
tooth which is typically missing in Felide (text-figs. A, C, 
pm). 
The Interlocking of the Carnassials. 
In the Felidee, as a rule, the upper carnassial is provided 
with an anterior cuspidate lobe projecting inwards towards 
the middle line of the palate. This lobe varies considerably 
in size even in closely related forms, and in some cases, as in 
F. manul, is reduced to a more vestigial stage even than in 
Acinonya (Cynailurus) jubatus, where it is generally described 
as absent. In neither of these species, so far as I am aware, 
does it ever carry a cusp, and in both of them the anterior 
blade of the lower carnassial slides over the position this lobe 
occupies when present in other cats. When this lobe is 
present and of large size, the blade in question of the lower 
carnassial typically passes behind it when tne mouth is 
closed. 
These facts suggest that the reduction of the inner lobe and 
of its cusp are modifications that have arisen in connection 
with a slight alteration in the relative positions of the car- 
nassials either by movement of the teeth themselves or by 
requisite changes of the upper or lower jaws, enabling the 
anterior blade of the lower carnassial to slide over practically 
the whole depth of the enlarged fore part of the upper. 
Similarly, the suppression or reduction of the talon or third 
cusp of the lower carnassial enables the whole of the large 
cutting-blade of that tooth to pass along the inner side of the 
posterior portion of the upper carnassial without obstruction 
from the upper molar. It would be incorrect, in my opinion, 
to say that the cusps in question have been actually worn off 
by the action of the appropriate opposed teeth; but that 
would be the Lamarckian inference to be drawn from the 
observed facts. At all events, the removal of these cusps 
gives the greatest possible value to the cutting action of the 
carnassials in the cats, just as the removal of the anterior 
premolars increases the depth of penetration of the canines. 
That the mutual fitting of the carnassials is not to be 
trusted absolutely as a systematic character in Felis is shown 
by its inconstancy in my series of F. sylvestris from Scotland. 
Jn one specimen (fig. B, 2) the anterior blade of the lower 
carnassial closes upon the summit of the inner lobe of the 
upper, a condition representing the theoretical stage precedent 
to the suppression of the lobe in /. manul and A. jubatus. 
