310 THE MECHANICAL FUNCTIONS. 



tremitles of the salamander make their appearance earlier 

 than the hind legs, and the tail remains as a permanent part 

 of the structure. The rudimental ribs are exceedingly small, 

 and the sternum continues cartilaginous. The pelvis has no 

 osseous connexion with the spine, but is merely suspended 

 to it by ligaments. The land salamanders have a rounded 

 tail, but the aquatic species, or Tritons, have it compressed 

 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 length- 

 ened 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.^ In 



* Professor Mayer has, however, traced obscure rudiments of pelvic bones 

 in the Unguis fragilis, the Anguis ventralis, and the Typhlops avcotatus, 

 and is of ophiion that they exist much more generally in this order of rep- 

 tiles than lias been commonly imag-ined. Some serpents, as the Boa, Python, 

 Tortryx and Eryx, have claws, which may be considered as rudiments of feet, 

 visible externally. Ln others, as the Jnguis, Typhlops, and Amphisbocna, 



