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OF THE INC1SORES. G3
where the surfaces are continued to the narrowest side, or edge
of the fang. The body of an Incisor, in a side-view, grows
gradually thicker, or broader, from the edge or end of the

A transition between the dentition of the Kangaroos and the Wombat
is presented by a gigantic extinct Australian herbivorous Marsupial, the
Diprotodon. In this species the general dentition approached that ot
the Kangaroo ; but the median upper incisors were large curved scalpri-
forni tusks which worked against a pair of procumbent tusks below.
In the different species of the order Insectivora, the incisors differ in
number and size : in some species the anterior ones approximate more or
less to the scalpriform teeth of the Rodents. In the Cape Mole (Chryso-
chloris Capensis), the Shrew Moles of America (Scalops), in the Solenodon
paradoxus of Hayti, there are three incisors in each premaxillary, and
the median one is of large size. In Scalops this tooth is scalpriform,
in Chrysocldoris and Solenodon laniariform. In the lower jaw the
anterior incisor in these genera is of small size and procumbent, whilst
the second incisor is large and laniariform: a third lower incisor of small
size is present in Chrysocldoris and Solenodon, but is absent in Scalops
The incisor teeth in the European Mole {Talpa) are six in number in
each jaw, small, and simple in conformation ; the fourth tooth
on each side below, although resembling the incisors in shape, is
to be considered a canine—its crown passing in front of the upper
canine when the mouth is shut. The typical Shrews (Soricidce)
manifest their analogy to the Rodents by the great preponderance in
size of the first two incisors in both jaws, and the sub-genera of Shrews
are partly founded on variations in the shape of these teeth. In the
European Hedgehog (Erinaceus Europmus) these teeth are six in each
jaw, the anterior pair both above and below being larger and longer
than the rest and very deeply implanted. The number is reduced to;
four in each mandible in the tropical Hedgehogs Echinops and Ericulus;
in the Tenrecs or Tailless Hedgehogs of Madagascar (Centetes) there are
four small incisors above, whilst the typical number six is retained
below.
The incisors in Cheiroptera may be entirely wanting or present in
the numbers 1. 1. to 2. 2. in the upper jaw, and 1. 1. to 3. 3. in the lower ;
they are always very small, and in the upper jaw unequal and separated
by a median interval. In the Suctorial or Vampire Bats (Desmodus)
the anterior teeth are modified in accordance with their habits. The
upper incisors are two in number, one in each premaxillary bone,
closely approximated, with a very large compressed curved and sharp-
pointed crown, implanted by a strong fang which extends beyond the pre-
maxillary into the maxillary bone. They are succeeded by similarly-
formed canines. In the lower jaw, the incisors, two in number on each
side, are much smaller than in the upper, and have bilobed crowns. In
I 2