74 The Bird 
The remaining vertebre, those of the upper and lower 
back, are very different from those of the neck. The 
flexible neck enables the bird to reach all parts of its 
plumage with its beak, and to pick up food from the 
ground or from twigs overhead, but the all-important 
function of flight must be provided for by means of a 
Fic. 51.—White-throated Sparrow, three inches tall, with fourteen neck vertebra. 
(Compare with Fig. 52.) 
rigid body-frame. In reptiles and in the embryos of 
birds only two pelvic vertebrae are fused together, but 
in adult birds many dorsal and caudal vertebre (as many 
as 23 in some cases) are fused into a single bone. Thus 
the rib-bearing upper back vertebre are partially fused 
together, and below them those of the lower back have 
merged until it is difficult to realize that this portion of 
