6o The Alli<jator and Its Allies 



& 



tion, a thick process that unites with a similar 

 process from the jugal to form the postorbital bar 

 (pb) which lies between the orbit (o) and the tem- 

 poral fossa (tf ) . The postf rontal forms the antero- 

 lateral boundary of the supratemporal fossa. 



Articulating posteriorly and laterally with the 

 parietal and the postfrontals, and forming the 

 highest point of the skull, is the single frontal bone 

 (24), which, like the parietal, is paired in the em- 

 bryo. It is a heavy bone whose dorsal surface is 

 flattened posteriorly, deeply concave in the middle 

 region, and drawn out into a long projection anteri- 

 orly. It forms part of the roof of the cranial 

 cavity and articulates ventro-laterally w^th the 

 alisphenoid and anteriorly with the prefrontals and 

 nasals. It forms a part of the median boundary of 

 the orbit. 



The prefrontal (4) is an elongated bone in the 

 latero-median border of the orbit. Medially and 

 anteriorly it articulates with the frontal and nasal, 

 laterally with the maxillary and lachrymal, and 

 ventrally, by a heavy process, with the pterygoid. 



The nasal (25) is a long narrow bone forming the 

 greater part of the roof of the nasal passage. 

 Along the median line of the skull it articulates 

 with its fellow; posteriorly with the frontal; 

 laterally with the prefrontal and maxillary; and 

 anteriorly with the premaxilla. In the crocodile, 

 caiman, and gavial it also articulates with the 

 lachrymal. In the alligator the anterior ends of the 



