156 THE STORY OF ANIMAL LIFE 



found in New Zealand ;' the Lacertilia or Lizards; 

 the Ophidia, or Snakes and Serpents; and the 

 Crocodilia. 



Perhaps the most interesting point regarding 

 the reptiles that can be mentioned in brief 

 space, is the fact that they present traces of a 

 median third eye, which have been described by 

 Baldwin Spencer, in the New Zealand Hatteria, 

 and in other reptiles. It is situated on the roof 

 of the brain. While the structure in Hatteria 

 shows it to be an eye, its position corresponds 

 with that of the pineal gland of vertebrates gen- 

 erally ; so that we find, in fact, the trace of a 

 third eye in all vertebrates, including ourselves. 

 It is, however, a trace only. In the Lamprey 

 fishes as well as in Hatteria, it reaches a further 

 degree of development. This pineal eye has 

 been compared in structure to the eye of As- 

 cidians. 



The Birds, excluding the extinct form with 

 teeth and a jointed tail, to which the group 

 name of Archseornithes is given, fall into two 

 groups. These are the Ratitae, or Birds with 

 Raft-like, i.e. flat, breast-bones, and the Carinatae, 

 or Birds with keeled breast-bones. The former 

 include the African Ostrich (Struthio), the Ameri- 

 can Ostrich (Rhea), the Australian Emu, the 

 Cassowary of New Guinea, and the Kiwi, or 

 Apteryx of New Zealand ; all of them birds that 

 cannot fly. The vast majority of birds belong to 

 the Carinatae, characterised by the projecting 

 keel (Carina) in the middle of the breast-bone. 

 The presence of this, which affords a safe at- 

 tachment for strong muscles, is associated with 

 the power of flight. It is impossible to treat the 

 birds more fully in the space allotted to this little 



