PHYLOGENETIC 59 



tion of new nesting habits, and so on. But of all this we have 

 little or no evidence, except that, in all probability, the Ostrich 

 tribe of to-day are the most primitive survivors thereof. So 

 far as the evidence of fossil forms goes, however, it would seem 

 that some of these terrestrial types must have found very early 

 that the neighbourhood of water furnished the most suitable 

 conditions of life, since, after Archreopteryx, the earliest known 

 fossils are of aquatic birds, and this too of a remarkably 

 specialised, intensified type. And it is significant that aquatic 

 and semi-aquatic types dominate to-day, for, except the Gallin- 

 aceous and Raptorial types and the forms presently to be con- 

 sidered, all the rest of modern birds are either waders or 

 swimmers, in greater or less degree, though here and there are 

 isolated exceptions — such as the Bustards among the Crane 

 tribe on the one hand, or the curious Dippers among the Passer- 

 ine birds on the other. The principal types of these waders 

 and swimmers we have already cursorily outlined, and they will 

 be dealt with later in greater detail as occasion demands. As 

 to the Gallinaceous birds, they are still essentially forest birds, or 

 birds which frequent thick undergrowth ; while the birds of prey 

 have adopted a roving life, they are essentially birds of the air. 

 The Coraciomorpha;, to which reference has been made, 

 make up a very heterogeneous collection, which may be divided 

 into Passerine and non-Passerine, derived, there seems good 

 reason to believe, from a stock nearly akin to the Gallinaceous 

 birds, and this stock apparently split up at a very early date, in- 

 asmuch as their present-day descendants are for the most part 

 separable into a number of sharply defined groups affording 

 no very decided connecting links. Probably the oldest are the 

 Ctia^li — Cuckoos, and Plantain-eaters {ATusop/iagi) — and the 

 Parrots {Psittaci). They may be safely regarded as divergent 

 branches of a common stem, which may be assumed to have 

 its roots in that which gave rise to the Gallinaceous birds. In 

 common with these two branches — the Cuculine and Psittacine, 

 there came off a third, which, splitting up, gave rise to the 

 Upupidae (Hoopoes and Hornbills), the Pici (Woodpeckers), 

 Capitoniidae (Barbets) and the Coraciiformes, this last branching 

 into the Coraciidae and Bucconidae (Rollers, Puff-birds), the 

 Meropidae (Bee-eaters), Momotidae (Motmots) and Halcyones 

 (Kingfishers). 



