118 



of the lateral processes. The distal portions of these processes arc over- 

 lapped by corresponding caplike processes of the basisphenoid. 



The badsphenoid is distinct from the basioccipital, and undcrlaps the 

 latter almost to its middle. It is longer than broad, and sends two processes 

 latero-anteriorly to support the pterygoids. These are not so long as in most 

 lacertilians. Latero-superiorly, it presents a broad surface, on each side of 

 the brain-case, for support of the upper side-walls. Postero-cxternally, it 

 supports the prootic. It thins out anteriorly, and overlaps the alisphenoid. 

 The suture for this bone widens anteriorly; inwardly, it is elevated into a 

 low crest of the sphenoid. 



The presphenoid appears to have been distinct ; its base was small ; it 

 is readily lost, and I have not seen it. 



The floor of the cranial cavity indicates that the medulla oblongata 

 possessed the downward flexure characteristic of reptiles ; but it docs not 

 take place till the middle of the length of the basioccipital is reached. The 

 posterior margin of the sphenoid is marked by a deep pit; its median floor is 

 a transverse elevation; it then descends again, and terminates in a deep longi- 

 tudinal groove. 



The roof of the brain-case is marked on the parietal bone by two obtuse 

 divergent ridges, which leave its posterior margin and embrace the fontancllc. 

 The grooves for the olfactory pedicels are narrow and well separated, but 

 the}' unite and are entirely inclosed by inferior processes of (he frontal bone, 

 as in serpents and Varani. These ridges then separate, and leave the hulbi 

 exposed below. Behind and between the nares, the median ridge again 

 appears, separating two strong grooves. 



The vomer is divided, and is composed of two slender compressed bones 

 in contact. 



The palatine bones have a short lateral union at their anterior end with 

 the maxillaries, and possess a great extension posteriorly, being separated from 

 the quadrates by the short pterygoids only. They are free on both sides 

 behind the maxillaries, and are flattened cither transversely or vertically, or 

 both, and support a series of strong teeth, generally similar to those of the 

 jaws. Near their posterior extremity, they send outward and forward a strong 

 and generally long process, the distal connection of which is uncertain. 

 These bones are the pterygoids of Cuvier. The true pterygoids are. rather 

 short, compressed bones, which are united by suture to the holders of a con- 



