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 
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