82 Sclater on the Systema Avium. 



1 6. Gavi.e. 



In the ' Nomenclator ' I have made the Gaviae to include the 

 Petrels (Procellariidaa) as well as the Gulls (Laridaa). But I 

 now think it better to restrict the term Gaviae to the latter group, 

 the Longipennes of Nitzsch, which, not only as regards their 

 osteology, but also in respect of their pterylosis, come verv near 

 to the Limicolae.* 



The Gaviaj will therefore consist of the single family Laridse, 

 while the Procellariidae will constitute the order " Tubinares " 

 (Nitzsch). The propriety of this separation is confirmed by 

 what Prof. Garrod has stated (P. Z. S. 1879, p. 37) as to the 

 form of the nasal bone in these two groups. 



17. Pygopodes, and iS. Impennes. 



The Pygopodes of Illiger combine the two families Colymbidae 

 and Alcidae, which are also closely allied pterylographically. 

 They seem to form a natural transition between the Gavia? and 

 the Impennes. Nitzsch (Pterylogr. p. 151) has associated them 

 with the latter group : but the Penguins are very distinct not only 

 in their osteology, but also in their pterylosis. as admitted by 

 Nitzsch himself, and have full claims to constitute an order 

 per se. 



19. Crypturi. 



Under this term (of Illiger) I have placed in the •Nomenclator' 

 the Tinamidae, which, as Mr. Parker has shown (Trans. Zool. 

 Soc. v. p. 149)? have a completely struthious palate, and in other 

 respects come at the bottom of the series, and are nearest of all 

 Carinate birds to the Ratitas. In so doing I make, of course, no 

 claim to originality, but have simply followed Prof. Huxley, who 

 first located the Tinamous in their position under the title " Dro- 

 maeognathae."| 



20. Apteryges, and 21. Struthiones. 



In the table given in the 'Nomenclator' (p. iv) I have recog- 

 nized only two orders of Ratite birds — Apteryges and Struthiones. 

 But there is no doubt, I think, that the Casuaries have full claim 



* Cf. Nitzsch, Pterylogr. p. 141 ; and Huxley, P, Z. S. 1867, p. 458. 

 t P. Z. S. 1867, p. 125. 



