CHAPTER XII 



saukia autosauri oe laceetilia-^lizaeds 



Sub-Clas.s XL—SAUBIA. 



Beptiles with movable quadrate hones, with a t^xmsverse, external, 

 cloacal opening, near the posterior lateral corners of which 

 open the eversihle, paired (right and left) copulatory organs. 



The Sauria, which comprise the Autosauei or Lacertilia in 

 the wider sense and the Ophidia or Snakes, are the most 

 recently developed groups of Eeptiles. No fossils are known 

 from strata earlier than those of the Cretaceous epoch. Their 

 origin has probably to be looked for among the Prosauria, of 

 which Sphenodon, cf. p. 294, is the only surviving member. The 

 Sauria have attained their great development within the Tertiary 

 period. They, both Autosauri and Ophidia, are now the two 

 dominant Eeptilian groups, and they have, so to speak, a future 

 before them, being apparently still on the increase in numbers 

 and species, but certainly not in size. 



Order I. AUTOSAURI or LACERTILIA— Z/^^i^i^.S'. 



Saurians which have the right and left halves of the mancliiles 

 connected hy a sutural symphysis. 



The overwhelming majority possess well -developed limbs, 

 movable eyelids and cutaneous scales, covered by the mostly thin 

 and horny epidermis. But there are many kinds of Autosauri, 

 especially those belonging to the degraded, burrowing families, 

 which have lost not only one or both pairs of limbs, but even 

 the limb-girdles, while the eyes have become concealed beneath 

 the skin, and in some cases the scales have been lost, or reduced 



