For convenience of study they are here grouped under the 

 following heads : — 



Smooth, Glossy, Porcellanous, Greasy, Chalky-Film, Dull, 

 and Granulated. 



The eggs of the Ostrich (Struthio camelus) of South Africa are 

 rough and pitted, whilst those of the North African Ostrich are 

 quite smooth and free from any pit marks. The birds themselves 

 present no differences and are regarded as one species. 



Specific Differences.— The eggs of the Mute swan {Cygnus 

 olor) have very little gloss and are rough, but those of the Hooper 

 or Whooper swan {Cygnus musicus) although about equal in 

 glossiness are more coarse in texture. The eggs of the Grey la» 

 goose {Anser cinereus) are smooth and dull, but those of the Bean 

 goose {Anser segetum), are rough with just a little gloss. The 

 Hooded crow {Gorvus comix) and the Black crow {Corvus corone) are 

 by many ornithologists regarded as but different forms of the same 

 species, yet the grain of their respective egg-shells differs very 

 considerably from each other. It is even possible to distinguish by 

 its grain the egg of a hybrid between these two crows. 



Smooth.— The majority of birds lay eggs with a smooth surface, 

 including nearly all the Game birds {Gallifor'mes),'PloYeTa {Gharadrii- 

 formes), and Perching birds {Fasseriformes). 



Glossy. — The grain of the egg-shells of a large number of the 

 Picarian birds (Kingfishers, Rollers, Hoopoes, &c.), and Wood- 

 peckers {Piciformes) is so fine as to cause the surface to be glossy. 

 The shell is also colourless and semi-transparent, so that the 

 contents may be seen through the thin shell. 



Porcellanous. — The Tinamous (Tinamiformes) are an order 

 of Central and South American birds, which in general form and 

 habits resemble Game birds. The thick shells of their eggs are 

 quite opaque, deeply coloured, and so highly glazed as to have a 

 burnished appearance. Their eggs are quite unlike those of any 

 other birds. 



Greasy. — The eggs of all the Ducks {Anseres) have a greasy or 

 oily surface ; this may be useful as a protection against damp, as 

 the parent birds are continually in and out of the water. 



Chalky-Film. — The eggs of the Grebes {Podicipedidiformes) and 

 of all the Cormorants, Gannets, and Pelicans {Pelecaniformes), with 

 the exception of the Tropic birds {Phcethontes)^ are covered with a 



