SAURIAN REPTILES. 407 



mities, and also of the sternum, make their appear- 

 ance very visibly in the Ophiosaurus, and in the 

 blind worm {Anguis fragilis). The Siren lacertina 

 has two diminutive fore feet, placed close to the 

 head. The Lacerta lumhricoides of Linnaeus, or 

 the JBipes cmialiculntus of Lacepede, which is found 

 in Mexico, and of which a specimen is preserved in 

 the collection at Paris, has a pair of very short feet, 

 also placed near the head, and divided into four 

 toes, with the rudiment of a fifth. The Lacerla 

 bipes (Linn.), or Skeltopusic of Pallas, has, on the 

 other hand, a pair of hind feet only, but extremely 

 small, together with rudiments of a scapula and 

 clavicle, concealed under the skin. Next in order 

 must be placed the Clialcides, or Snake-lizard (Fig. 

 210.), and the Lacerta seps, animals frequently met 

 with in the South of France, and which have four 

 minute feet, totally inefficient for the support of the 

 body, and only remotely useful in contributing to 

 its progressive undulations. 



Ascending from these, we may form a series of 

 reptiles, in which the developement of the limbs 

 becomes more and more extended, till we arrive at 

 Crocodiles, in which they attain a considerable 

 degree of perfection. As a consequence of this 

 greater developement of the skeleton, we find the 

 trunk divisible into separate regions. We now, for 

 the first time, meet with a distinct neck, separating 

 the head from the thorax, which is itself distinguish- 

 able from the abdomen ; and a distinct sacrum is 

 interposed between the lumbar and the caudal 

 vertebrae. 



A further approach to the higher classes is ob- 

 servable in the number of cervical vertebra?, which 



