~ 
334 Mr. O. Thomas on new 
situations in Central Asia, F. pajeros in the pampas of 
S. America, /. caracal and Acinonyx jubatus in the sandy or 
grassy plains of Africa and tropical Asia. All of these 
species have a comparatively high partition and large outer 
chamber. On the other hand, Panthera pardus and onca, 
Felis pardalis, nebulosa, marmorata, aurata, and others 
with a very low partition and small outer chamber are 
essentially dwellers in thick forest. /. concolor, however, 
is apparently exceptional. In the skulls examined the 
partition is as low and the outer chamber practically as 
small as in the typical forest and jungle species. Neverthe- 
less, this cat, as is well known, lives both in swampy jungles 
and in high rocky hills. I have not seen sufficient numbers 
of skulls to know whether or not there is any variation in 
the bulla according to the habitat ; but in view of the above- 
mentioned facts, I should infer that the puma has com- 
paratively recently adapted itself to open-country conditions. 
This brief enumeration of the main facts is sufficient to 
establish some interesting conclusions. First, that within 
the limits of the species, or genera, of Felide intergradation 
exists in the size and position of the partition and the relative 
capacity of the two chambers of the bulla. Second, that the. 
structure of this part of the skull cannot by itself be regarded 
as evidence of affinity between species, as is shown by the simi- 
larity between such evidently unrelated forms as Felis manul 
and F. pajeros and Uncia uncia. ‘Third, that species which 
for other reasons must be regarded as allies—namely, those 
belonging to Felis, in a restricted sense of the word (such as 
sylvestris, ocreata, chaus), and the lynxes (L. lynx, canadensis, 
and caracal)—have bull of a similar type, varying a little 
according to the species. 
XXXIX.—Two new Species of Akodon trom Argentina. 
By OLDFIELD THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
Akodon dolores, sp. n. 
A rather large coarsely lined brown species. 
Size about as in A. obscurus. General colour a uniform 
pale olive-brown (darker than “drab” of Ridgway, paler 
than ‘ olive-brown”’), not nearly so olivaceous as in arenicola 
