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398 DENTA L ANA TOMY.
the posterior end of the series. They describe the same curves, so as to
oppose those of the upper series. The incisors of the upper jaw, as has
already been stated, are lodged in the pre- or intermaxillary bones,
which limit the anterior part of the oral cavity above. The definition,
therefore, of an incisor tooth of this series is one tchich has a pre- orinter-
maxilku'ij imphtntatlon irrespedlce of its size or form. The incisor teeth
of the lower jaw are the corresponding ones whieli are brouf/ht info opjposi-
tion with those of the upperjaw ichen the mouth is dosed. The teeth thus
defined are three-in number upon each side above and below in this animal,
and are implanted by single slightly recurved fangs in distinct sockets or
alveoli. In the upper series the median pair is the smallest, the outer
ones gradually increasing in size. The base of the crowns of the four
middle teeth is somewhat trihedral in form, with the apex flattened from
before backward and produced into three cusps, of which the central
one is the largest. The entire apex of the crown is slightly recurved.
Upon its inner aspect the crown presents a basal ledge or cingulum,
M'hich sends out a low ridge to each of the lateral cusjis. The lateral
incisors are the largest and are somewhat caniniform. Like the median
ones, their crowns have a strong basal cingulum posteriorly, but the
lateral cusps a"re absent ; the apex terminates in a strong hooked point.
The iiicisors of the lower jaw are similar to those of the upper, with
the exception of the median pair, which is much the smallest and occu-
pies a more anterior position than the others. The intf^rnal lateral cus])s
of these teeth are very faintly indicated, if indeed they can be at all
made out, while the external lateral cusp is present and situated high
up in the two median pairs. In the lateral ones it has a position nearer
the base of the crown, and is separated from the median cusp by a deep
fissure.
Between the lateral incisors and canines of the upper series there is a
space or diastema about equal to the width of the lateral incisor. This
space serves to receive the lower canine when the mouth is closed. At
the back part of it upon the outside may be seen the suture by which
Fig. 190.

Vertical Vie«" of the Lower .Taw of a Dor {C. /nmiHuris) : ic, incisors; r, canine; pm, premolars;
m, molars; .«, sectorial.
the premaxillary bone joins the maxillary in the dentigerous border
of the jaw. Just behind this suture the .superior canine is lodged.
The definition, then, of a superior canine tooth is one which is situated
in the maxillary bone immediately behind, the maxillo-prcmaxiJlarg suture,
pr^ovided it be not too far back, whatever may be its form, size, or func-