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THE I^'CISOBS. 25
The root is cone-shaped and tapering (Fig. 11, b). The ronnded
pear-shaped section continnes ahnost to the end.
Fig. 11.
The pidj) chamber is spacions and open, and of
the general form of the tooth (a and c). The radi-
cal portion of the canal gives free access, but the
flattened coronal portion is difficult to cleanse. In
young teeth the cornua or horns of the pulp may
project far toward tlie angles (c).
8. The Lateral Incisor.—This tooth approxi-
mates the central incisor on its distal side, and is The root of the upper cen-
tral incisor.
also implanted in the intermaxillary bone. It is
of similar si)ade-like form and of the same architectural design as the
central, modified by the distal half being more rounded in every direc-
tion. As the crown is narrower than the central, the destruction of the
marginal ridges on the lingual face weakens the edge still more, so
that it breaks off more easily. The crown is narrower in the mesio-
distal diameter than the central, but, still almost as wide labio-lingually,
the relative difference of thickness in the two directions is more ap-
parent. The tooth has the appearance of being compressed mesio-
distallv. The thickness increases ra})idly from the edge to the neck
(Fig. 12, B).
Fig. 12.

^ ^ B C D
The upper lateral incisor.
The labial face (Fig. 12, C) is more rounded than that of the cen-
tral. It is half incisor and half canine («), the mesial half toward the
central incisor resembling that tooth (6), and tlie distal half toward
the canine resembling it (c). The mesial angle of the edge is quite
acute, while the distal angle is rounded and obtuse. The three lobes
may be well developed, similar to those on the central incisor, but
are usually indistinct, although the central ridge is prominent.
The Ungual f than that of the central incisor. The marginal (cZ) and basal ridges (e)
are quite j^rominent. The basal ridge is often raised into a prominent
cingule or talon, an exaggerated example of which is shown in Fig.
13, which is a revival of the basal talon found in the apes,—and
the insectivora. This cingule occurs more frequently on the lateral