MAMMALIA. 581 
habits and the structural modifications involved. The sub- 
order Sissipedia are terrestrial and the /innifedia are 
aquatic. 
SUB-ORDER 1.—-FISSIPEDIA. 
The Fissipedia (or Carnivora Vera) have always the full 
complement of incisors (3), and one of the cheek-teeth in 
each jaw is formed by the carnassial tooth (see page 525). 
The limbs are formed for terrestrial locomotion and, as in 
the typical pentadactyle limb, have the third digit as long as, 
or longer than, the rest. 
The present day /issifedia can be divided into the 
A luroidea, Cynoidea and Arctoidea, having affinities with 
the cats, dogs and bears respectively. 
The -£luroidea are the most specialised. Their teeth 
are reduced in number and the skull is shortened. They 
are nearly all digitigrade. The characters of the auditory 
region are found to form a useful distinction between these 
and the other two divisions. Thus in the 4/urordea the 
auditory bulla is large, divided into two by an internal bony 
septum and partially covered externally by the paroccipital 
process of the exoccipital bone. 
Family 1.—Felidae.—The Fede comprise the true cats, with re- 
tractile claws. Amongst them are the lion and leopard of the Ethiopian 
and Oriental regions, the jaguar of Neogcea, the tiger of Asia, the puma 
of America and the wild-cats and lynxes of Europe. 
Family 2.—Viverridae.—The Viverride comprise the civets and 
mongooses, found only in Arctogoea. They have more teeth than the 
Fehide and non-retractile claws. 
Family 3.—Protelidae.—The Protelide consist of a single genus 
(Proteles), the aard-wolf of South Africa, a nocturnal burrowing animal 
of degenerate necrophagous habits. 
Family 4.—Hyenidae.—Lastly, the Hyenide comprise the hyzenas 
of Arctogcea, with more teeth than the Fedde, but with no septum to 
the auditory bulla. 
The Cynoidea have a larger number of teeth (3443) and 
longer jaws than the -@/wroidea, in correlation with which 
they are less strictly carnivorous. ‘There is only a trace of 
an auditory septum and the paroccipital process does not 
overlap the bulla. They are mostly digitigrade but never 
