The class Aves

The class Aves. - Though this class contains a great number of specific forms, the structural modifications which they present are of comparatively little importance; any two birds which can be selected differing from one another far less than the extreme types of the Lacertilia, and hardly more than the extreme forms of the Chelonia, do. Hence the characters by which the following groups are separated appear almost insignificant when compared with those by which the divisions of the Reptilia are indicated.

1. The metacarpals not anchylosed together. The tail longer than the body.
I. - SAURURAE
1. Archaeopterygidae.
2. The metacarpals anchylosed together. The tail considerably shortei than the body.
1. The sternum devoid of a keel.
II. - RATITAE
1. The wing with a rudimentary, or very short, humerus and with not more than one ungual phalanx.
1. hallux.
2. Apterygidae (The Kiws).
2. No hallux.
3. Dinornithidae (The Moas).
4. Casuaridae (The Cassowaries).
2. The wing with a long humerus and with two ungual phalanges.
1. The ischia uniting immediately beneath the sacrum, and the pubes free.
5. Rheidae (The American Ostriches).
2. The ischia free and the pubes uniting in a ventral symphysis.
6. Struthionidae (The Ostriches).
2. The sternum provided with a keel. (The keel is rudimentary in the singular Parrot Strigopa)
III. - CARINATE.
1. The vomer broad behind, and interposing between the pterygoids, the palatines, and the basispheuoidal rostrum
(Dromaeognathae.)
7. Tinamomorphae (The Tinamous).
2. The vomer narrow behind; the pterygoids and palatines articulating largely with the basisphenoidal rostrum.
1. The maxillo-palatines free. (With the exception of Dicholophus and some species of Crax.)
1. The vomer pointed in front.
(Schizognathae.)
8. Charadriomorphae (The Plovers).
9. Cecomorphae (The Gulls).
10. Spheniscomorphae (The Penguins).
11. Geranomorphae (The Cranes).
12. Turnicimarphae (The Hemipods).
13. Alectoromorphae (The Fowls).
14. Pteroclomorphae (The Sand-grouse).
15. Peristeromorphae (The Pigeons).
16. Heteromorphae (The Hoazin).

2. The vomer truncated in front.
(Aegithognathae.)
17. Coracomorphae (The Passerines).
18. Cypselomorphae (The Swifts).
19. Celeomorphae (The Woodpeckers).

2. The Maxillo-palatines united.
(Desmognathae.)
20. Aetomorphae (The Birds of Prey).
21. Psittacomorphce (The Parrots).
22. Coccygomorphae (The Cuckoos, Kingfishers, Trogons).
23. Chenomorphae (The Anserine Birds).
24. Amphimorphae (The Flamingoes).
25. Pelargomorphae (The Storks).
26. Dysporomorphae (The Cormorants). (The subjoined Table, which shows with which of the above groups the old orders of Birds correspond, may be useful to the student):

I. - ACCIPITRES or RAPTORES	...............	=Aetomorphae.
II. - SOANSORES	...............	=Psittacomorphae, Coccygomorphae (in part)
III. - PASSERES or INSESS0RES	...............	=Coracomorphae, Cypselomorphae, Celeomorphae, Coccygomorphae (in part).
IV. - GALLINAE (with COLUMBAE)	...............	=Alectoromorphae, Peristeromorphae, Pteroclomorphae, Turnicimorphae,
V. - CURSORES	...............	=Ratitae,
VI. - GRALLAE	...............	=Charadrimorphae, Geranomorphae, Amphimorphae, Pelargomorphae.
VII. - PALMIPENES	...............	=Cecomorphae, Spheniscomorphae, Chenomorphae, Dysporomorphae.