3 o 4 BIRDS. 



7. Steganopodes — Pelicans, Cormorants, and Gannets. 



8. Herodiones — Herons and Storks. 



9. Odontoglossi — Flamingos. 



10. Anseres — Ducks, Geese, and Swans. 



1 1 . Pal amede^e — Screamers. 



12. Columb^e — Pigeons, Dodo, and Sand-Grouse. 



13. Galling — Fowls and Game-Birds. 



14. Fulicarle — Rails and Coots. 



15. Alectorides — Cranes and Bustards. 



16. LimicoLuE — Plovers, Curlews, Snipe, etc. 



17. Gavi,e — Gulls and Terns. 



18. Tubinares — Petrels and Albatrosses. 



19. Pygopodes — Divers, Auks, and Grebes. 



20. Impennes — Penguins. 



21. Odontorxithes — Toothed Birds (extinct). 



22. Crypturi — Tinamus. 



23. Stereornithes — Patagonian Flightless Birds (extinct). 



24. RATIT.E — Ostriches, Emus, Cassowaris, etc. 



25. Saurur^e — Long-Tailed Birds (extinct). 



Of these groups the first twenty-two, which are reckoned as orders, are 

 brigaded together to form the subclass of Carinate Birds (Carinatae), the great 

 majority of which possess the power of flight, and have a strong keel (carina) to 

 the breast-bone. The twenty-fourth group, or Ratitae, constitutes, on the other 

 hand, a second subclass, characterised by the absence of a keel to the breast-bone, 

 and the loss of the power of flight ; while the extinct long-tailed birds (group 

 25) form a third main division differing from all the others by the retention 

 of the long reptilian tail. 



The number of existing species of birds being in all probability considerably 

 over ten thousand, it will be obvious that in the space at our command the various 

 groups must be treated much more briefly than were the Mammals ; and in many 

 instances we shall be able to allude only to the families, without referring to the 

 genera, and in some cases not even the whole of the former are mentioned. 



It will be noticed that in the course of this Introduction practically nothing 

 has been said as to the anatomy of the soft parts of birds ; for this we must refer 

 the reader to other works. 



