4f>2 



BIRD. 



her stoop (which, from the goodness of hr eye, am 

 the firmness of her body and wing, is not often) she 

 abandons, and takes the sky anew for fresh game 

 whereas when the falcon misses, she can continue 

 her flight and strike again. The falcon thus more 

 resembles the lightning from the cloud, which pro- 

 duces its effect by its own proper and inherent motion, 

 and the eagle more resembles the ball from a piece 

 of ordnance, which is urged onward by a force not 

 its own. 



In the sternum of the swift we have the maxi- 

 mum development of that bone as a carrying 

 basket in the air, but still accompanied with con- 

 siderable power of wing, though the swift never 

 rushes, either by its power of flight like the falcon, 

 or by a momentum of gravitation like the eagle. Its 

 sternum bears up the whole under-part of the body, 

 and thus it can remain longer on the wing without 

 fatigue than any other bird with which we are familiar. 

 The rest of the tribe are inferior in this respect to the 

 swift ; but they all have the same general character 

 of sternum and the same style of flight. 



The coracoids in these birds are short and strong ; 

 the clavicle open, but an elliptic arch more than a 

 circular one ; the scapulars are shorter than the ster- 

 num, nearly straight, rather slender, but enlarged a 

 little toward their terminations, which however are 

 pointed. 



Night-feeders, or those which feed only in the dusk 

 or twilight, and rest during the day, have their sternal 

 apparatus considerably different. They have the 

 sternum short, widened in front, concave at the sides, 

 and the general outline to the rear convex, but 

 divided into three processes by two large notches. 

 The keel well developed, concave in front, convex 

 in the lower line anteriorly, but becoming straight or 

 even concave toward the rear. The lateral processes 

 with elevated points. The coracoids round in the 

 middle of the bone, but enlarged at the heads, and 

 with a pointed process on their posterior sides, near 

 their junction with the sternum. The furcal bone 

 open, but slender, and the sides not so much arched 

 as in the swift. The following is a representation of 

 these bones in the common goat-sucker of the size of 

 nature. 



Goat-sucker. 



The cuckoo is the bird whose sternal apparatus 

 most resembles that of the goat-sucker ; and though 

 the one is a day feeder and the other a night or twi- 

 light one, there is a very considerable resemblance in 



their styles of flight. They are both tree or copse 

 birds, and they never take very long flights when 

 they are in search of their food ; and the sternum, 

 from the deep notches in its posterior edge, is not 

 nearly so well adapted for bearing up the body upon 

 long flight as that of the swifts and swallows. Here 

 we may remark, by the way, though the assumption 

 which suggests the remark is now exploded, that 

 there is nothing in the sternum of the cuckoo to pre- 

 vent that bird from setting upon and hatching eggs 

 in the same manner as other birds do. In their ordi- 

 nary habit these birds neither fly fast nor take long 

 flights ; but the ordinary habit of a bird while resident 

 in one locality is not a certain proof to the full extent 

 of what it can do. The cuckoo flies only from copse 

 to copse, or from one tree in the hedge-row to another ; 

 and when feeding its motions are even more limited. 

 But both are very light birds in proportion to their 

 size, and their plumage is soft and loose, so that they 

 float in the air with very easy though not rapid wing. 

 Thus they are able to change their habitat by migra- 

 tion, and appear with us only as summer visitants. 

 In their sterna they bear some resemblance to the 

 owls, with which they also agree in some of their 

 other characters and habits. 



Sterna of the syndactyli. These birds are also 

 chiefly dependent on the wing in the finding of their 

 food; but their flight is in general lower than that of 

 the swallows, the prey on which they feed larger, 

 and though not water-birds, or at all capable of swim- 

 ming, their habits are more aquatic. It is rather a 

 remarkable coincidence with this aquatic habit that 

 the sternum is elongated, and deeply notched in its 

 posterior edge, as in many of the swimming-birds. 

 There is, however, considerable difference between 

 the sternal apparatus of the bee-eater and that of the 

 kingfisher. 



That of the kingfisher is more indicative of a power 

 of resisting pressure on the anterior part of the body 

 than of rapidity or even duration of flight ; but still 

 it indicates a wing of considerable flying power : the 

 sternum is rather short, and much broader toward the 

 rear than in the anterior part. The keel pretty large, 

 nearly straight in its under edge, and a little concave 

 in front, with the angle advanced a considerable wav 

 brward between the coracoid bones. The lateral 

 processes are pointed and prod-*ced in front of the 

 unctions of the coracoids. The coracoids are long 

 and strong ; and their unions with the sternum are 

 rendered very firm by the projection of the central 

 jart of that bone and the lateral processes, which 

 receive and sustain each coracoid as in a fork. The 

 'urcal bone is long, open, bent downwards, and much 

 enlarged at the heads of the branches, which are 

 divided into two processes, one in contact with the 

 coracoid and the blade-bone ; and the other, which 

 s much larger, passing under and bearing up the head 

 of the coracoid. The blade-bones are also large, 

 lattened, sithe-shaped, and pointed at their ter- 

 minations. 



Thus the greatest strength of this sternum is con- 

 centrated upon the coracoids, the furcal, and the blade 

 )ones ; but when we come to examine the posterior 

 part of it we find it proportionally weaker, so that 

 he keel or origin of the muscles of flight is not so 

 well supported as the shoulder-joint ; and that there- 

 ore there is, in the sternum of this bird, an indication 

 of some other action of the fore-part of the body 

 >esides that of simple flight. 



