OSTEOLOGY OF BIRDS 



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At the distal extremity we find that the entire end is considerably 

 bent toward the inner side, a character it presents in many other 

 Anatidae. The intercondylar notch is for the most part very wide 

 and shallow, being deepest anteriorly. Above it, in front, the di- 

 rection of the deeply excavated groove for the extensor tendons 

 is influenced by the obliquity of the bone spoken of above. The 

 bony bridge that spans it is thrown directly across. 



Nothing of particular interest characterizes the fibula, it having 

 the form we usually find among birds. In the Spoonbill its feeble 

 lower end anchyloses with the tibiotarsal shaft at about half way 

 down its length. 



Equaling about half the length of the leg bone it articulates 

 with, the tarsometatarsus also proves to be a strong, stout segment 

 in the limb of Spatula. Its hypotarsus is flat and inconspicuous, 

 being marked by three vertical grooves for tendons. The four 

 ridges thus formed graduate in size, the innermost one being the 

 longest and most prominent. The sides of the shaft of this bone 

 are, for the major part, flat, a slight excavation being seen at the 

 upper end of the anterior one. 



The trochleae at the distal extremity are very prominent and 

 well individualized by the deep clefts that severally divide them. 

 They all have median grooves passing around them from before 

 backward. The mid trochlea is much the lowest of the three, as 

 well as the largest, while the inner one is placed the highest on the 

 shaft, being at the same time turned slightly to the rear. The 

 usual arterial foramen occupies its site, as in other birds. 



Agreeing with the group generally, Spatula possesses but a 

 feebly developed accessory metatarsal, with a correspondingly weak 

 hallux composed of a basal phalanx and claw, the whole being sus- 

 pended rather high on the tarsometatarsal shaft by ligament. This 

 discrepancy in size of the hind toe is likewise seen in the swans, 

 where it is even still more evident. Second, third, and fourth digits, 

 however, having three, four, and five joints, respectively, are quite 

 the reverse of this, being Composed of bones fully in keeping, 

 so far as their size and strength go, with the substantial segments 

 of the limb to which they belong. 



Of these joints the basal ones take the lead in point of length, 

 and it is only in the outer podal digit of the duck that we find 

 its penultimate phalanx exceeds the joint that precedes it in 

 this particular. Apart from the differences in lengths, calibers and 

 other matters of proportional sizes, the various bones of the pectoral 



