CARINAT^. 259 



members of the same order is further exemplified by the 

 occurrence of remains of birds belonging to the South 

 American genus Bhea in the Post-Tertiary cave-deposits of 

 Brazil. 



Lastly, the Post-Tertiary deposits of Australia have yielded 

 the remains of an extinct Struthious bird allied to the Emeu, 

 which has been described under the name of Dromceornis. 



Sub-class II. — Caeinat^. 



Okdek I. ISTatatoees (Pahnijjedes). — The order of the 

 JVatatores, or Swimmers, comprises a number of Birds which 

 are as much or even more at home in the water than upon 

 the land. In accordance with their aquatic habit of life, 

 the JVatatores have a hoat-shaped hody, usually toith a long 

 neck. The legs are short, and placed behind the centre of gravity 

 of the hody, this position enalling them to act admirably as 

 paddles, at the same time that it renders the gait upon dry 

 land more or less awkward and shuffling. In all cases tlie toes 

 are " webbed " or united by membrane to a greater or less extent. 

 In many instances the membrane or web is stretched com- 

 pletely from toe to toe, but in others the web is divided or 

 split up between the toes, so that the toes are fringed with 

 membranous borders, but the feet are only imperfectly 

 webbed. 



Amongst the more important families of the Natatores 

 may be enumerated the Penguins (Spheniscidce), the Auks 

 {Alcidce), the Gulls and Terns {Laridce), the Petrels (Procel- 

 laridce), the Pelicans (Pelicanus), the Cormorants (Fhalacro- 

 corax), the Gannets {Sida), the Ducks (Anatidce), the Geese 

 (A7iserinm), and the Swans (Cygnidce). 



As might have been expected, the remains of Natatorial 

 Birds are, speaking comparatively, not uncommon as fossils. 

 The earliest traces of this order in past time appear in the 

 Cretaceous series, which has yielded in Europe the Cimo- 

 lornis (supposed to be allied to the Albatross), and in North 

 America the genera Laornis and Gractdavus, the former re- 

 lated to the Swans, while the latter has affinities with the 

 living Graculus. In the Eocene Tertiary we meet with 



