EVIDENCE FROM PALAEONTOLOGY 89 



are remnants of a more ancient vegetation. Among 

 animals, the most conspicuous groups are the mam- 

 mals, or warm-blooded quadrupeds, and the birds; 

 the reptiles occupy a very subordinate position and 

 only five orders of them are found, lizards and 

 snakes, turtles and crocodiles, including a single 

 lizard-like creature which is confined to New Zealand. 

 The overwhelming majority of Cenozoic fishes be- 

 long to the sub-class of the bony fishes or teleosts, 

 and of the remainder almost all are sharks. But 

 there are, almost exclusively in fresh waters and 

 consisting of very few forms, two groups of very 

 ancient date, the ganoids, and the lung-fishes of the 

 southern hemisphere. Of the vast host of Cenozoic 

 invertebrates it is impossible to make the most hasty 

 survey and nothing more can be attempted than to 

 mention a few of the most conspicuous kinds. There 

 are countless insects, especially of the higher orders, 

 beetles (Coleoptera), moths and butterflies (Lepi- 

 doptera), ants, bees, wasps (Hymenoptera) and flies 

 (Diptera). There is a great profusion of marine 

 life, crustaceans, molluscs, star-fishes, sea-urchins, 

 and others innumerable; survivals of formerly abun- 

 dant groups are the lamp-shells, or brachiopods, and 

 the sea-lilies or crinoids. 



While this general statement will serve to give 

 some conception of Cenozoic life as a whole, the 

 periods and epochs of that era are each char- 

 acterized by stages of constant progress, which 

 may sometimes, when conditions are favourable, 



