236 GAME-BIRDS OF INDIA 



The keel of the sternum is vwy high, and there are usually two 

 notches on each side of the posterior margin, but the inner is some- 

 times reduced to a foramen. 



The gall-bladder is present, and the Sand-Grouse possess a nude 

 oil-gland and their contour-feathers have after- shafts. 



Palate schizogaathous ; nasals generally schizorhinal, but very 

 variable ; basipterygoid processes present ; cervical vertebrae fifteen or 

 sixteen. 



The dorsal feather-tract has an interscapulary fork, and the lateral 

 bare tracts extend on the shoulders as far as the base of the neck. 



Pigeons, of course, have their young hatched naked and singu- 

 larly helpless, but the young of the Sand-Grouse are covered with 

 richly-coloured down and are able to run, and, to some extent, feed 

 themselves directly they leave the egg. 



The tarsus is well-feathered in all the genera of this family, in 

 one genus the feathering extending also to the toes. They are birds 

 of swift powerful flight, with comparatively long wings. 



The order contains but three genera, Pterocles and Pterodnrus, 

 which are very closely allied, and Si/rrJiaptcs, which is fairly distinct. 

 All three genera have representatives in India, and some species are 

 to be found in Africa, South and Central Europe, and Asia. 



Most Sand-Grouse are migratory, and in all species the two sexes 

 differ in plumage, the male bird being much the more brilliantly 

 coloured . 



