1 1 34 CLASS REPTILIA. 



larger dimensions. The Simaedosauria may perhaps be regarded as 

 an offshoot from a stock related to Hyperodapedon. 



Suborder 2. Sphenodontina. — This group is characterised by 

 the short and more or less triangular skull, in which the premaxillae 

 are produced into a distinct beak ; by the longitudinal series of 

 palatine teeth, separated by a groove (into which the hinder mandi- 

 bular teeth are received) from those of the maxilla (fig. 1037) ; and 

 by the presence of uncinate processes to the ribs. 



Family Rhynchosaurid^e. — This is the most specialised family, 

 and as being most nearly related to Champsosaurus, may be noticed 

 first. The nares are single ; there are no teeth either in the beak 

 or in the opposing part of the mandible, which were probably cased 

 in horn ; there may be more than a single row of palatine teeth ; 

 and the presacral vertebras may be more or less opisthoccelous. 



Fig. 1036. — Left lateral view of the skull of Hyperodapedon Gordoni, as restored by Professor 

 Huxley; from the Trias of Elgin. Reduced. Or, Orbit ; t, Infratemporal fossa. 



The most specialised genus Hyperodapedon was originally made 

 known to us by some very imperfect specimens from the Keuper 

 or Upper Trias of Elgin and Warwickshire ; but the subsequent 

 discovery of a nearly entire skeleton in the former locality has 

 enabled Professor Huxley to illustrate its full affinities. Remains 

 referred to the same genus also occur in the Maleri stage of the 

 Gondwana system of Central India. The European species attained 

 a length of from six to seven feet, but the Indian form must have 

 been nearly or quite double these dimensions. The skull (fig. 1036) 

 is remarkable for its depressed and triangular form, in which it re- 

 sembles that of the Chelonian family Chelydridcz ; and also for the 

 upward direction of the small orbits ; the reduced size of the infra- 

 temporal fossae ; the strongly-curved and thick premaxillary beak ; 

 the diverging clawlike processes of the mandibular symphysis ; and 

 the absence of a parietal foramen. Professor Huxley considered that 

 the forked extremities of the mandibular symphysis embraced the 

 premaxillary beak, as is shown in the figure ; but later observations 

 indicate that they were received in a pit beneath the beak, which Pro- 

 fessor Huxley regarded as containing the apertures of the posterior 



