242 A VES ORDERS PTEROCLETES AND COLUMBIFORMES. 



lying spots of pale purple. The eggs are, moreover, oval in shape, but 

 equally rounded at each end. 



Although the sand-grouse are not often observed during the day-time, they 

 are to be obtained in the mornings and evenings, when they assemble at the 

 water-pools to drink. Of Pallas' sand-grouse the late General Prjevalski 

 writes : ' At the drinking-places, as well as at the feeding-places, these birds 

 never settle on the ground without first describing a circle, in order to assure 

 themselves that there is no danger. On alighting, they hastily drink and 

 rise again ; and, in cases where the flocks are large, the birds in front get up 

 before those at the back have time to alight. They know their drinking- 

 places very well, and very often go to them from distances of tens of miles, 

 especially in the mornings between nine and ten o'clock, but after twelve at 

 noon they seldom visit these spots." Sometimes the sand-grouse are driven 

 south by an unexpected fall of snow, and by clearing the snow from a patch 

 of ground, Swinhoe tells us that the natives sometimes manage to net an 

 entire flock of birds. It may be such a sudden snow-storm that forces the 

 sand-grouse of Central Asia to make the unexpected invasion into Western 

 Europe to which we have referred. 



The Pigeons are a large order of birds, and are divisible into two sub- 

 orders, viz. the Columbce or True Pigeons, and the Dodos (Didi). Pigeons 



have a swelling of the bill near the tip, similar to the bill of 



The Pigeons. the plovers, which we shall discuss presently. At the base of 



Order the bill is a soft bare skin, or cere, which is very prominent 



Columbiformes, in some of the fruit-pigeons, and is generally of a bright colour. 



The osteological and anatomical characters which separate 

 them from the Game-Birds (which some of the ground pigeons greatly 

 resemble) are numerous, the chief one, perhaps, being that the fore-part of 

 the sternum or breast-bone is never perforated to receive the feet of the 

 coracoids, as is the case in the Game-Birds. The nest which pigeons build 

 is one of the simplest structures known among birds, for it consists of a slight 

 cradle of sticks, and is generally placed in a tree. The eggs are white, and 

 two in number, though there are many species which lay but a single egg, 

 and in this order of birds we meet with the great exception to the rule in 

 the Class Aves, viz. that birds which lay white eggs usually nest in holes 

 or burrows, so that the eggs are concealed from view. Not only, however, 

 are the eggs of the pigeons white, but the frail platform on which they are 

 placed renders them easily visible from above, and often from below. The 

 young are hatched naked, but after a little while become clothed with hairy 

 down ; they remain helpless in the nest for a long time after they are 

 hatched, and are fed by the old birds. 



The True Pigeons, of which our ring-dove or wood-pigeon, and the ordinary 

 dove-cote pigeons may be taken as representatives, constitute the order 

 Columbw, and they are divided by Count Salvador!, the latest monographer of 

 the order, into five families. 



The first family of the pigeons consist of the fruit-pigeons (Trerontda) with 

 three sub-families, Treronince, or green fruit-pigeons, painted fruit-pigeons 



(PtHopodin(K\ and true fruit-pigeons (Carpopliagince). The 



The Fruit- green fruit- pigeons are found in Africa, India, and the Indo- 



Pigeons. Family Chinese sub-region, through the Malayan sub-region to the 



Treronidce. Molucca Islands. All the members of the sub- family 



Treronince have the tarsus short, exceeded in length by the 

 middle toe, and the tail feathers vary from 12 in number to 16, while the 



