306 



A MANUAL OF DENTAL ANATOMY. 



worn they are bilobed, as may be seen in sections of the tooth 

 germs. 



In the accompanying figure the milk teeth are represented, 

 and beneath them their permanent successors : the divari- 

 cated bases of the milk teeth are due to the absorption set 

 up by the approach of their successors, and not to the 



FIG. 130 0). 



X2 N.S. 



formation of any definite roots. Successional teeth have 

 been detected in this armadillo only (except also in T. 

 kappleri, which is perhaps a mere variety) ; but material 

 does not exist in our museums which would enable us to 

 positively deny their occurrence in other forms. 



Professor Flower has failed to discover any succession of 

 teeth in the sloths, and I have myself, through the kindness of 

 the late Professor Garrod, examined microscopically the jaws 

 of a foetal Choloepus, in which the teeth were but little 

 calcified, and failed to detect any indication of a second set 

 of tooth germs. The probability is, therefore, that they are 

 truly Monophyodont. 



In the armadillos the teeth are always of simple form and 

 about thirty- two in number, except in Priodon, which has as 

 many as a hundred teeth, a number altogether exceptional 

 among mammals. 



Sloths have fewer teeth than armadillos, and these softer 

 in character, the axis of vaso-dentine entering more largely 



( : ) Lower jaw of a young Armadillo (Tatusia peba), showing the milk- 

 teeth (a) in place, and their successors (6) beneath them. From a specimen 

 in the Museum of the Royal College of Surgeons. 



