394 BRITISH BIRDS. 



Family COLUMBID.E, OR PIGEONS. 



The Pigeons are a large and well-defined group of birds which are some- 

 what isolated. Sclater and Gadow regard them as allied to the Gallina- 

 ceous birds through the Sand-Grouse ; but Forbes traced their relationship 

 through the Sand-Grouse and Pratincoles to the Plovers. The sternum of 

 the Pigeons resembles in many respects that of the Game Birds. There 

 are two notches on each side of the posterior margin of the sternum ; but 

 the internal pair are small and generally closed at the entrance (the gulf 

 thus becoming a lake), and the external pair are very deep and wide. The 

 cranial bones of the Pigeons present a modification different from that to 

 be found in any family of which we have hitherto treated. The Pigeons 

 are said by Huxley to be schizognathous, like the Game Birds, Sandpipers, 

 Gulls, Auks, &c. (Gadow, however, assures me that many species of Birds 

 of Prey and Owls are also schizognathous). In their pterylosis the 

 Pigeons partake of the characters of both the Sandpipers and some of the 

 Game Birds, which latter family they also somewhat resemble in their 

 digestive organs, and still more closely in their myology. 



In spite of what has been written by Naumann, Meves, and others on 

 this subject, there can be no doubt that, in a wild state, Pigeons moult 

 twice in the year, in spring and autumn, as carefully dated specimens 

 in my own collection abundantly prove. Young Pigeons are covered 

 with yellow down when they are first hatched, but are born blind. 



The most striking external character of the Pigeons is the bill, which 

 is thinnest in the middle, expanding towards the point, as in the 

 Plovers ; the basal portion is covered by a soft skin, in which the nostrils 

 are situated. The hind toe and claw are small, as in Picarian birds. 

 The Pigeons are divided into several subfamilies, which show considerable 

 modification both of the wings and tail. The number of primaries in the 

 former is ten, but the feathers in the latter vary considerably in this 

 respect. 



The number of species of Pigeons probably exceeds 350, which are dis- 

 tributed all over the world, except in the Arctic regions. They are rarest 

 in the Palsearctic and Nearctic Regions, and most abundant in Australia. 



