-Skull and Dentition of Aard-Wolf (_Proteles
cristatus_.)]

The three well-characterized species of _Hyaena_ are divisible into
two sections, to which some zoologists assign generic rank. In the
typical species the upper molar is moderately developed and
three-rooted; and an inner tubercle and heel more or less developed on
the lower molar. Ears large and pointed. Hair long, forming a mane on
the back and shoulders. Represented firstly by _H. striata_, the
striped hyena of northern and eastern Africa and southern Asia; and
_H. brunnea_ of South Africa, in some respects intermediate between
this and the next section. In the second section, forming the subgenus
_Crocuta_, the upper molar is extremely small, two- or one-rooted,
often deciduous; the lower molar without trace of inner tubercle, and
with an extremely small heel. Ears moderate, rounded. Hair not
elongated to form a mane. The spotted hyena, _Hyaena (Crocuta)
crocuta_, of which, like the striped species, there are several local
races, represents this group, and ranges all over Africa south of the
Sahara. In dental characters the first section inclines more to the
_Viverridae_, the second to the _Felidae_; or the second may be
considered as the more specialized form, as it certainly is in its
visceral anatomy, especially in that of the reproductive organs of the
female. (See HYENA.)

(B) _Arctoidea_.--So far as the auditory region of the skull is
concerned, the existing representatives of the dog tribe or _Canidae_
are to a great extent intermediate between the cat and civet group
(_Aeluroidea_) on the one hand, and the typical representatives of the
bear and weasel group on the other. They were consequently at one time
classed in an intermediate group--the Cynoidea; but fossil forms show
such a complete transition from dogs to bears as to demonstrate the
artificial character of such a division. Consequently, the dogs are
included in the bear-group. In this wider sense the Arctoidea will be
characterized by the tympanic bone being disk-shaped and forming the
whole of the outer wall of the tympanic cavity; the large size of the
external auditory meatus or tube; and the large and branching
maxillo-turbinal bone, which cuts off the naso-turbinal and two adjacent
bones from the anterior nasal chamber. The tympanic bulla has no
internal partition. There is a large carotid canal. Cowper's glands are
lacking; and there is a la