154 ANATOMY OF VERTEBRATES. 



34. Skull of Lacertilia.- -Lizards, like Serpents, have the cra- 

 nial bones, especially those of the haemal arches and appendages, 

 more elongated, slender, and liberated than in Crocodiles and Che- 

 lonians; the temporal vacuities and orbits are large, and the external 

 nostrils are apart. Lizards retain the malo-squamosal bar connect- 

 ing the maxillary with the tympanic ; and some of them develope, 

 as in the Crocodile, the upper zygomatic arch formed by the post- 

 frontal and mastoid. The neurapophysial walls of the parietal and 

 frontal segments retain much of their fibro-cartilairinous tissue ; and 



O O 



the cranial roof is there sustained by a bony pillar on each side 

 ( f columella ' of Cuvier), which has its base implanted in a fossa 

 of the pterygoid, and underprops the parietal near its outer border. 

 The homologies of the cranial bones of the Python, figs. 96 and 

 97, with those of the Crocodile, figs. 93, 94, and 95, being recog- 

 nised, those of any Lizard will be readily understood. 



In a New Zealand Gecko (liliynclioceplialus ! ) the occipital con- 

 dyle is unusually elongated transversely, and presents the form of 

 a crescentic, convex bar, bent upward. The basisphenoid sends 

 down two short processes to abut against the pterygoids. The 

 parietal bone is perforated by a small median fontanelle close to 

 the sagittal suture : its upper surface presents two strong curved 

 and approximated temporal crests, divided by a median, angular, 

 longitudinal furrow : the crests are continued outward upon the 

 posterior bifurcated part of the parietal to be continuous with that 

 forming the upper border of the mastoid : the frontal is divided 

 by a median suture, as is the parietal in the common Gecko. 

 The posterior frontal supports a strong, obtuse ridge forming the 

 back part of the frame of the orbit, and unites below \vith the 

 malar and behind with the mastoid. The premaxillary bones are 

 divided by a median suture, and their dentigerous border projects 

 below the level of that of the maxillary bones. The vomer is 

 likewise divided by a median suture. The palatal apertures of 

 the nostrils are bounded behind by the vomer and palatal plate of 

 the maxillary : this plate is of unusual breadth, as compared with 

 the Lizards generally, and presents the unusual peculiarity of a 

 dentigerous ridge parallel with the posterior half of the alveolar 

 border. It is situated close to the inner side of this border, leav- 

 ing only space sufficient for the reception of the teeth of the 

 under jaw. The teeth are confluent with the summits of the 

 proper and accessory alveolar ridges. The palatine bones are 

 united together along the anterior halves. The rami of the lower 

 jaw are not anchylosed at the symphysis. The alveolar border is 



1 CLVIII. 



