568 REPTILES. 



Class Rhynchocephalia. 



The only living representative of this class is the New 

 Zealand " Lizard " — Hatteria or Sphenodon punctatiis, the 

 Tuatara of the Maoris. Lizard-like in appearance, it mea- 

 sures from one to two feet in length, has a compressed 

 crested tail, is dull olive-green spotted with yellow above 

 and whitish below. It is now rare, but is being preserved 

 in some small islands off the New Zealand coast. It lives 

 in holes among the rocks or in small burrows, feeds on 

 small animals, and is nocturnal in habit. 



The skull, unlike that of any lizard, has an ossified 

 quadrato-jugal, and therefore a complete infra-temporal 

 arcade ; the quadrate is firmly united to pterygoid, squa- 

 mosal, and quadrato-jugal ; the pterygoids meet the vomer 

 and separate the palatines ; there are teeth on the palatine 



Fig. 195. — Hatteria or Sphenodon. (After H.WEK.) 



in a single longitudinal row, parallel with those on maxilla 

 and mandible, and the three sets seem to wear one another 

 away ; there is also a single tooth on each side of a 

 kind of beak formed by the premaxilla; ; the nares are 

 divided. 



The vertebra; are biconcave, as in geckos among lizards 

 and in many extinct Reptiles. Some of the ribs bear 

 uncinate processes, as in Birds ; as in crocodiles, there are 

 numerous "abdominal ribs," ossifications in the sub-cutane- 

 ous fibrous tissue of the abdomen. The anterior end of the 

 " plastron " thus formed overlaps the posterior end of the 

 sternum. Clavicles and interclavicle present. 



The pineal or parietal eye, which reaches the skin on the 

 top of the head, is less degenerate than in other animals, 

 retaining, for instance, distinct traces of a complex retina. 



