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Fig. 28 Cranium of albino rat, showing the overgrown upper incisors recurv- 
ing to the left side. The left incisor passes to the outer side of the skull, while 
the apex of the right incisor has penetrated the bone of the maxilla in the region 
of the basal end of the left incisor.  X 1. 
Fig. 29 Cranium of the same albino rat shown in the preceding figure, viewed 
from the right side. It shows the overgrown lower incisors recurving to the 
right side, and the cavity which the right incisor has worn in the palate bone. 
Figures 28 and 29 show a skull obtained some years ago from 
the rat colony of The Wistar Institute by Dr. Stotsenburg, 
and prepared in the Histological Laboratory by Miss E. F. 
Brooks. ‘The upper teeth curved to the left side of the head 
and the lower to the right side. As seen in figure 29, the right 
lower has penetrated through the bone of the palate into the 
