THE PRINCIPAL BIRD GROUPS 77 



all, but resembles the Gallinaceous type more 

 closely than any other. Various anatomical 

 modifications render this species unique among 

 birds, the most remarkable of which is that the 

 sternum is furnished with a keel only on the 

 posterior part, the anterior part being aborted ; 

 the double crop is also unusually capacious, and 

 rests upon the furcula or wish-bone and the fore 

 part of the sternum. Another most interesting 

 peculiarity is that the young birds (which are 

 able to run as soon as they are hatched) possess 

 two claws on the wings (on the index and pollex) 

 which they use to climb about the branches 

 with, hooking them over the twigs, and progres- 

 sing with the additional aid of bill and feet. The 

 most typical families contained in the order 

 Galliformes consist of the Pheasants, Partridges, 

 Quails and allied birds (Phasianidae) ; the Hemi- 

 podes (Turnicidae), raised to the dignity of a 

 sub-order by some ornithologists ; the Grouse 

 (Tetraonidae) ; the Guinea Fowls (Numididae) ; 

 and lastly, the Turkeys (Meleagridae). With the 

 limited space at our disposal it is impossible to 

 describe even the chief peculiarities of these 

 several families, but the following characteristics 

 are practically common to the entire order. The 

 sternum contains two very deep notches on the 



