40 



ON THE STRUCTURE OF THE TEETH IN THE « EDENTATA," 

 FOSSIL AND RECENT. By Richard Harlan, M. D. 



Read April 28th, 1834. 



Profiting by recent opportunities that have offered 

 themselves, for the examination of the intimate nature 

 of the structure of the teeth in several genera of the or- 

 der Edentata, both fossil and recent, I have observed 

 some peculiarities not hitherto noticed, and have been 

 enabled to correct a few previous errors existing in re- 

 lation to this subject. 



The close relation of the results of these inquiries to 

 comparative anatomy and fossil geology, may, in the 

 opinion of this society, render them worthy of publica- 

 tion. 



To the " Ossemens Fossiles" of Baron Cuvier, and 

 the "Dents des Mammiferes" of M. Fred. Cuvier, 

 we must refer for the most recent information on the sub- 

 ject in question. 



The following is a translated extract from the work 

 of the former. Vol. v. part i. p. 84. 



" In both species of sloth, there are four molar teeth 

 above and three below on each side ; all are conical 

 during youth, but become cylindrical when the summit 

 is worn off by detrition. The truncature of the sum- 

 mit produces a hollow in the osseous substance ; the 

 borders, which are of enamel, remain projecting, but 

 unequally, sometimes more on one side, sometimes on 



