.'398 



THE MECHANICAL FUNCTIONS. 



meiits. The land salamanders have a ronnded tail, 

 but the aquatic species, or Tritons, have it com- 

 pressed vertically ; thus retaining the fish-like form 

 of the tadpole, and the same radiated disposition of 

 the muscles. 



§ 3. Ophidia. 



In the class of serpents we see exemplified the 

 greatest possible state of simplicity to which a 

 vertebrated skeleton can be reduced ; for, as may 

 be seen in Fig. 201, which shows the skeleton of a 



Viper, it consists merely of a lengthened spinal 

 column, with a head but little developed, and a 

 series of ribs ; but apparently destitute of limbs, 

 and of the bones which usually connect those limbs 

 with the trunk ; there being neither sternum, nor 

 scapula, nor pelvis. Professor Mayer has, how- 

 ever, traced obscure rudiments of pelvic bones in 

 the Anguis fragilis, the Anguis ventralis, and the 

 Typhlops crocotaUis, and is of opinion that they 

 exist much more generally in this order of reptiles, 



