16 



UNGTJLATA. 



dentine-islets present trefoils on one side of each tooth ; and the 

 upper molars are cingulated. The mandibular symphysis is short 

 and spout-like, and usually edentulous in the adult, although two 

 small incisors are frequently present in the young, one of which is 

 occasionally retained in (probably male) adult individuals. In one 

 variety the enamel of the cheek-teeth is rugose, while in another 

 it is smooth ; a small quantity of cement is present in the valleys 

 of the cheek-teeth ; premolars were apparently not developed. 

 Hab. North America. 



Fig. 3. 



Mastodon americanus ; from the Pleistocene of Missouri. 

 Much reduced. 



*. The skeleton of an adult (woodcut, fig. 3) made up from the bones 

 {Fig.) of several individuals, the incisors and some of the bones 

 being casts ; from the Pleistocene of Benton County, Mis- 

 souri, U.S.A. This specimen was brought to London by 

 Koch in 1 843, and is figured in pi. i. of Warren's memoir 

 on Mastodon giganteus (1852). Purchased. About 1844. 



345. The cranium, imperfect superiorly, showing m. 3 of either side, 



