in eaisting Species of Felide. 329 
bulla and the anterior extremity of the inner chamber is 
less narrowly compressed. 
A species which agrees very nearly with /. manul in the 
structure of the bulla is /. pajeros, allowance being made 
for the greater expansion of the inner chamber posteriorly— 
a feature observable, by the way, in many of the smaller 
and medium-sized American Felide as compared with 
tropical African and Asiatic species. F. manul and 
F’, pajeros, indeed, differ from all the other species of Fels 
Fig. 3. 
Felis canadensis. (No precise locality.) 
A. Right bulla, from below, with inner chamber laid open. 
B. The same, from the inner side. 
C. The same, from the outer side. 
p-, partition; x., periotic ; p.’, line of origin of partition. 
whose bullz I have examined in the extension of the outer 
auditory chamber well in advance of the inner chamber. 
Between the extremes presented by the bulle of /. manul 
and F. pardalis, for example, there is almost every gradation 
in the size of the partition and of the relative dimensions of 
the two chambers. 
In the skulls that I have examined, two that come nearest 
to #. manul and F. pajeros are those of Felis lynx (or Lynx 
lynx) isabellina. But in these, the partition, though large, 
does not reach the summit of the bulla and terminates in front 
