OSSEOUS SYSTEM OE AVES. 81 



flattened.' In the Birds of Prey the metatarsal is most modified 

 by the muscles and tendons operating upon the raptorial toes. 

 There are three calcaneal processes, the innermost large, the 

 two outer ones small and approximate. The fore part shows 

 a tuberosity for the insertion of the strong ' tibialis anticus ' 

 (fig. 35, 48) : below this is the process on the inner margin 

 extending the surface of attachment for the metatarsal of the 

 back toe (z). The trochlear ends of the three confluent meta- 

 tarsals are nearly on the same level, the inner one is the 

 broadest, the outer one the narrowest : each is produced, at an 

 opposite angle, so as to bound the wide concavity behind this 

 end of the metatarsal. In the King- Vulture {Sarcoramphus), 

 the mid-trochlea is broadest and most produced: in the Snake- 

 Vulture ( Gypogeranus) with a metatarsal of stilt-like length, the 

 inner trochlea is shorter than the others and further apart. In 

 most Owls the metatarsal is shorter in proportion to its breadth 

 than in diurnal Raptores ; a bony bridge overspans the beginning 

 of the tendinal canal on the fore part : the outer trochlea is the 

 shortest and is bent backward and inward. In most Cantores 

 and Volitores the distal end of the metatarsal is little expanded, 

 and the three trochlea? are of nearly equal length : in Podargus 

 and Dacelo the outer trochlea is the shortest. In Cypselus the 

 trochlea terminate on the same transverse line : in Trochilus the 

 middle one is a little more prominent. In the short and strong 

 metatarsal of the Parrot-tribe, the middle trochlea extends wholly 

 below the others, which are oblique and twisted, especially the 

 outer one, backward and inward : a like twist is noticeable in 

 most Scansores, especially the Woodpeckers and Cuckoos. In 

 the spurred Gallince the weapon is supported on a conical process 

 from the back part of the metatarsal ; sometimes there are two, 

 as in Pavo bicalcaratus. In all Rasores the mid-trochlea is 

 longest; in Pigeons and Curassows the outer (iv) is shorter or 

 higher than the inner {ii) trochlea : in the Tinamou and Syrrhaptes 

 it is longer. In the Apteryx and tridactyle Cur sores the mid- 

 trochlea is largest, and extends by almost its whole length beyond 

 the other two which are nearly on a level. In Struthio the inner 

 metatarsal (ii) terminates in a point near the base of the great 

 trochlea (m): the outer trochlea (/v) is comparatively small and 

 short. In Grallatores the mid-trochlea is lono^est, the other two 

 of equal or nearly equal length in most : the inner (ii) trochlea is 

 the shorter in the Demoiselle Crane ( Scops Virgo) ; the outer one 



VOL. II, 



XVI-. vol. iii. part iv. (184G), pp. 321, 322; xliv. p. 274, &c. 



