72 ANIMAL LIFE PAST AND PRESENT. 



Another peculiar although not absolutely character- 

 istic feature of the skull of the Primeval Salamanders 

 is the net-like sculpture with which the external 

 surface of all the bones is ornamented (Fig. 21). The 

 reappearance of a similar sculpture in the skulls of 

 Crocodiles has suggested that those reptiles may trace 

 their ancestry directly back to the group under con- 

 sideration. We must not, however, omit to mention 

 the small round aperture which occurs in the bones of 

 the skull immediately over the brain-cavity in all 

 Primeval Salamanders, and is seen to the left of the 

 letter P in Fig. 21. This aperture corresponds to one 

 found in the skull of that curious New Zealand Lizard 

 known as the Tuatara, which is one of the most 

 primitive reptiles now living, having but little affinity 

 with true lizards. In that creature this aperture over- 

 lies the rudiment of an eye now totally useless and 

 lying deep down in the brain, but which was probably 

 functional in the earlier ancestors from which the 

 Tuatara sprang. The comparatively large size of this 

 aperture in the Primeval Salamanders suggests the 

 possibility that the central cyclopean eye may still 

 have been capable of receiving some impressions of 

 light, although it is probable that we should have to 

 go back to some long-lost piscine, or even invertebrate 

 ancestor, before we found it of any real use to its owner. 



The majority of the Primeval Salamanders had their 

 back-bone composed of biconcave joints much like 

 those of ordinary fishes, or Fish-Lizards. In some of 

 the earlier and more primitive forms the body of each 



