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Abnormal Incisor Growth of Rodents. C. E. Newlin, Indianapolis. 



The omnipotent and omniscient hand of Mother Nature in providing for the 

 varied wants and conditions of her children is nowhere better shown than in the 

 constant and rapid growth of the incisor teeth of that order of little animals 

 known as Rodents. Securing their food as they do by gnawing the hard bark, 

 roots and nuts, their incisor teeth would soon be worn off to the very gums if it 

 were not for the constant and rapid growth of these teeth. To show the rapidity 

 of this growth is the object of this short paper. 



It is no unusual thing to kill a squirrel or rat that by some accident has lost 

 one of its incisor teeth. The opposing tooth, having no direct opponent to hold 

 the food against it, often becomes abnormally long, often becoming very incon- 

 venient to the owner in procuring its food. But usually the remaining tooth is 

 brought into more or less use in procuring food, and is thus kept ground oflP to 

 some extent, though I have sometimes found them quite long. 



I have in my possession the skull of a Ground Hog, Actomys Monax, which 

 shows such abnormal growth of all the incisors that I thought it might be of in- 

 terest to the members of the Academy to call their attention to it. 



The specimen that was the unhappy possessor of this skull in life was killed 

 in a meadow on a farm near Shannondale, Ind., by Wm. T. Beck, now of Craw- 

 fordsville. He noticed his dog attacking some animal and going to its assistance 

 found a Ground Hog offering poor resistance, and killed it by crushing the back 

 of its head with his fork handle. Picking it up he noticed the two white tusk- 

 like teeth projecting up over its nose. He cut its head of!" and took it to his 

 woodshed and laid it upon a cross-beam over the door, and there the insects did 

 what they could to preserve it by denuding it of its tlesh. The teeth became 

 loose, and in handling it the longest lower incisor dropped out and was broken. 

 But I had a dentist carefully reproduce the part broken off with paste dentine, 

 and wired the skull together. Otherwise it is just as it was when it thwarted his 

 wood-chuckship in his struggle for existence. The right lower incisor is 3 j inches 

 long and correspondingly a})normally large in circumference. The lower incisor 

 on the left side seems to have come in contact with the left upper incisor to some 

 extent and did not grow so long. Both lower incisors extend up over the nose 

 and securely locked his mouth, so that securing food was almost impossible. 

 This was possible at all only on the left side and then only by separating his lips 

 and biting off clover leaves, etc., with his back molar teeth. He had done this so 

 long that the lips on that side remained wide apart, exposing all the back teeth, 

 while the lips on the opposite side grew fast together and fast to the gums. 



