xxviii INTRODUCTION. 



eaters cause more trouble, and the small kinds, at all 

 events, cannot be kept long without a good supply of 

 insects either fresh or dried. Meal-worms and such 

 dried insects as " dried flies " and " dried ants' eggs" 

 (really the cocoons) are readily obtainable in Europe, 

 and should be taken abroad by anyone intending to 

 try to bring home insectivorous birds. Bread and milk, 

 however, and raw meat or hard-boiled egg minced fine 

 and mixed with stale bread-crumbs, will keep them 

 for some time, and the more omnivorous kinds will live 

 on this indefinitely. Honey-eating birds will live on 

 condensed milk suitably diluted. As will be seen, there 

 are very few families of which some species or other 

 has not been kept in captivity, and the number of those 

 which have been bred in that state is constantly in- 

 creasing, to the great advancement of ornithological 

 knowledge and of biology generally. 



The classification of birds has long been regarded as 

 a subject of great difficulty, owing to the close inter- 

 relationship of so many of the numerous families, and 

 hence the various standard works on birds present 

 the greatest divergence as to the numbers of " orders " 

 under which these families are grouped, and in some 

 one case writer will put a family under a different order 

 from that in which it is placed by another. Thus 

 much confusion arises ; but the families themselves are 

 at any rate natural assemblages, and easily recog- 

 nisable by external as well as internal characters. 

 The number of them in this book may, no doubt, 

 be reduced by future writers, as in some cases what 

 are here ranked, according to custom, as separate 

 families, would be better united. Thus, the Pelicans, 

 Gannets and Cormorants might well go all in one 

 family, along with the Frigate and Tropic- birds, while 

 the Toucans and Barbets might also be classed together, 

 and so forth, no doubt, in some other cases. 



