The Skeleton 65 



they all have sockets. The premaxillary and more 

 anterior of the maxillary teeth are slightly recurved 

 and are sharper than the posterior maxillaries which 

 besides being blunt have a constriction above the 

 surface of the socket. 



The crocodilian tooth consists of three layers 

 (Fig. 20 A). 



The enamel (e) forms a fairly thick layer over the 

 crown of the tooth ; it exhibits a very clear striated 

 structure, the striations being apparently due to 

 stratification. 



Some of the tubules of the dentine (d) continue 

 into the enamel, where they may be distinguished 

 by their remarkable fineness and their straight 

 course. 



The cement (c) covers the root of the tooth that 

 projects into the alveolus of the jawbone; it is 

 much more strongly developed than in the lizards 

 and contains a very large number of bone corpuscles 

 which are distinguished from the bone corpuscles 

 proper by their greater circumference. 



The fairly large pulp cavity (p) has, like the 

 tooth itself, a conical form. 



Parallel to the teeth is a row of small foramina, 

 a continuation of those noted in the premaxilla; 

 some or all of these foramina open into a longitud- 

 inal sinus along the alveolar border of the maxilla ; 

 this sinus opens posteriorly by one or more large 

 apertures into the posterior palatine vacuity. 



The palatines (9) form a broad bar of bone from 



