ABNORMAL INCISORS. 
123 
which is fortunate enough to possess as enthusiastic and capable 
naturalists^ as evidently live in Manchester. 
Yours very truly, 
Belmont, Mass., Dec. 9, 1900. Ralph Hoffman. 
Abnormal Incisors. 
BY WILLIAM H. HUSE. 
There is no limit to the growth of the incisors of rodents. 
They are kept from becoming too long by the constant wearing 
away of the ends in the process of gnawing. By a curious ar¬ 
rangement of the enamel which is much thicker in front than on 
the backside the back wears away the faster and leaves the ends 
chisel-shaped. Sometimes an accident to one tooth or eating 
soft food for a while causes one or more of the teeth to attain an 
abnormal length that will in time prevent the animal from eating 
and cause his death. 
An example of such a growth of the teeth was recently exhib- 
ted in the Institute rooms in the shape of a mounted woodchuck 
head from the zoological collec¬ 
tion of Mr, S. F. Heath of thii 
city. The woodchuck was found 
several years ago in a sewer and 
shot. He had entered the pipe 
in some way and found himself 
a prisoner with no food except 
the soft, water soaked, edible 
matter that floated down to the 
river. As a result the lower in¬ 
cisors grew to a length of two inches, projecting beyond the nose; 
while the left upper tooth passed outside the mouth and formed 
a hook beside the cheek. The other upper incisor curved in 
and upward till it entered the roof of the mouth. During his 
latter days it must have been impossible for the woodchuck co 
close his jaws and he must of necessity have subsisted upon 
what he could drink from the sewage. 
