402 



STERNA OF THE GRALLIDjK. 



Though the birds which form this order, even 

 when restricted by leaving out those groups which 

 have been already mentioned in the course of 

 these observations, differ very .much in the struc- 

 ture of their bills, yet there is far less diversity 

 in their sternal apparatus than the consideration 

 of the bills, as their chief character, would lead us to 

 suppose. But, when we consider that none of them 

 are habitual fliers, that they fly only for chaimv of 

 place, and that their flight is generally taken by rather 

 short and swiftly-moving wings, we might be prepared 

 to find that agreement which there is in the sternal 

 apparatus. 



It suits the walking and the wading habits of those 

 birds, and also the tangled herbage through which 

 many of them have to make their way, to have the 

 body narrow in proportion to its depth. The sternum 

 is in consequence long, and rather narrow, a little 

 enlarged towards the posterior portion, and divided 

 there by four notches of considerable depth, the 

 lateral ones generally the deepest ; the processes 

 between the notches feeble, but generally enlarged at 

 their extremities, so as to form the posterior outline 

 of the sternum into a convex curve. The crest is 

 generally large, convex below, concave in front, with 

 the angle terminating in a process ; lateral processes 

 not nearly so much developed as in the petrel family ; 

 the basis of the coracoids not nearly so large, and 

 their attachment to the sternum not so firm ; the 

 coracoids are, however, short, stout, and considerably 

 enlarged at the heads, but their position is too parallel 

 to each other, and too much in the general line of the 

 sternum, for giving that stability to the shoulder-joint 

 which is essential to long-continued and rapid flight. 



