32 THE CLASSIFICATION OF BIRDS 



In both these suborders the oil-gland is nude, and the down in 

 adult birds is restricted to the feather-tracts, and in neither of 

 them is the ambiens mu&cle present. None of these characters 

 can be regarded as of much taxonomic value; in many other 

 groups instances are to be found of the independent acquire- 

 ment or loss of all of them. The similarity of the syrinx in the 

 Striges and the Caprimulgi is more important, but appears to me 

 to be far outweighed by the presence of the cere in the Psittaci, 

 Striges, and Accipitres, and the abnormal plantar tendons of the 

 Caprimulgi. 



The Striges may be regarded as cosmopolitan. 



EALLIFORMES. 



The Ralliformes may be briefly diagnosed as aquincubital 

 birds with normal plantars, holorhinal nasals, and schizognathous 

 palatines ; the bill is not furnished with a cere ; and the hallux 

 is small, elevated above the plane of the other digits, sometimes 

 quite rudimentary, and occasionally absent altogether. The 

 nostrils are said to be always pervious, though in some genera 

 (Corethrura, Thyorhina) they are furnished with an operculum. 



The Ralliformes consist of three sharply denned Suborders, 

 respecting whose relationship to each other some difference of 

 opinion exists : 



Tubinares. External nostrils produced into tubes. 



Pygopodes. Cnemial process of tibia produced forwards to a 

 remarkable degree. Posterior processes of the ilium approximated 

 to such an extent that the sacrum is almost entirely concealed. 



Fulicarice. Ralliformes possessing none of the above-menr 

 tioned characters. 



8. TUBINARES. 



The association of the Petrels with the Divers and the Rails 

 may at first sight appear somewhat startling. The old school of 

 ornithologists placed the Petrels near the Gulls, but more recently 

 they have been associated with the Pelicans and the Penguins. 



The Tubinares frequent the seas of the whole world, and the 

 special modification of their nostrils, a character in which they 

 differ from all other birds, is specially adapted to their aquatic 



