68 ANIMAL LIFE PAST AND PRESENT. 



of the back-bone ; an arrangement and this is a very 

 significant point similar to that which obtains in 

 Mammals. In Eeptiles (and likewise in their near 

 relations, the Birds), on the other hand, there is but a 

 single knob-like occipital condyle, situated in the 

 middle line, and received into a single cup in the first 

 joint of the back-bone. 



With this preliminary explanation we may proceed 

 to the consideration of the Primeval Salamanders. In 

 this country the first evidence of the bony skeleton of 

 these creatures that was brought under notice was 

 afforded by teeth from the New Eed Sandstone (at the 

 lower part of the Secondary system of rocks) of 

 Warwickshire and Cheshire. These teeth, which are 

 of conical form, are remarkable for the circumstance 

 that when a transverse section of their base is made, 

 and examined under a lens or microscope, the whole of 

 the internal portion is seen to be made up of a most 

 complex series of foldings, forming a peculiar and 

 characteristic labyrinth-like structure (Fig. 20). From 

 this feature the veteran comparative anatomist, Sir 

 E. Owen, proposed the name of Labyrinthodonts, or 

 Labyrinth-toothed Saurians, for the owners of these re- 

 markable teeth; and although some of the smaller 

 species subsequently discovered do not exhibit the 

 same complexity of tooth-structure, this name may 

 well be adopted as the technical designation of the 

 whole group. By a masterly piece of induction the 

 great anatomist also showed that certain gigantic skulls 

 of the type of the one represented in Fig. 21, which 



