394 



ANATOMY OF VERTEBRATES. 



of larger ones, which gradually decrease in size as they are placed 

 further back. There are teeth of similar size and proportions in 

 each premandibular bone. These teeth are separated by intervals, 



266 



267 



Dentition, upper jaw, Python. CCL. 



from which other teeth, similar to those in place, have been 

 detached. The base of each is anchylosed to a shallow alveolus, 

 extending obliquely across the alveolar groove, of which the outer 



is higher than the inner wall. 



~ 



The palatine teeth, ib. 20, are as large as the maxillary, and 



are similarly attached. The 

 pterygoid teeth, ib. 24, 

 which complete the inter- 

 nal dental series on the 

 roof of the mouth, are of 

 smaller size, and gradually 

 diminish as they recede 

 backward. In the inter- 

 spaces of the fixed teeth 

 in both of these bones, the 

 places of attachment of the 

 shed teeth are always visi- 

 ble ; so that the dental for- 

 mula, if it included the 

 vacated with the occupied 

 sockets, would express a 

 greater number of teeth 

 than are ever in place and 

 use at the same time. 



The smaller non-veno- 

 mous serpents, Colubridce, 

 e. g. have two rows of teeth 



Roof of the mouth of the Rattlesnake, showing the poison- . -i c \ j_ i 



fangs, 10, 11, and pterygoid teeth, 9. CCL. OU the TOOI OI tllC HlOUtll, 



