Strigid^e.] OSTEOLOGIA AVIUM. [Bubonin^e. 



Order they are always transversely flattened. The proportional length of the humerus 

 to the ulna is, with very slight variation, as 13| to 15^ among the Falcons, and as 10 

 to 13^ among the Owls and Vultures. The femur is of moderate length ; it varies con- 

 siderably in its proportion to the tibia in different families of Eaptorial Birds, among 

 the Falcons being about 12| to 15, among the Owls and most of the Vultures as 15^ 

 to 23, and in Serpentarius as 10 to 25 ; the fibula is in no instance that I am aware of 

 united to the tibia for its whole length, but generally at its distal extremity, and at 

 about one-third of its length. 



The metatarsus is always more or less excavated in front, and among some of the Owls 

 has a bony band near the upper extremity of the cavity, for the purpose of confining the 

 exterior longus communis digitorum muscle, a little below which is a small tubercle to 

 which the tibialis anticus is attached. 



The hallux, or hind toe, has always an intervening split between it and the metatarsus. 

 The calcaneal process is well developed among the Falconidse and Vulturidse, and 

 among some of the Strigidse ; while in others it is rudimentary. 



The vertebral column is strong throughout the Order, but most so among the Vultures, 

 many of which family, as Sarcoramphus, have the vertebrae nearly as broad as long ; the 

 three or four upper cervical vertebrae have the posterior processes more highly deve- 

 loped than is the case with the remainder of them. The terminal caudal one is much 

 flattened laterally, and somewhat triangular. 



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