ADAPTATIONS OF THE SKELETON 6i 



a grip of the ground or of the perch, and also abetting the 

 leap into the air. But special adaptations are numerous. 

 The toes of the Jacana are greatly elongated, well suited for 

 walking on leaves in the water, and something of this is 

 seen in the Water-hen. Two of the toes of the cuckoo are 



T5 'riTV 



Fig. 12. — Comparison of bird's leg and ape's leg. f., femur; Fi., 

 fibula, a mere splint in the bird, complete in the ape ; t.t., tibio-tarsus 

 in bird, i.e., tibia plus the distal tarsals ; T., tibia of ape ; P.t., proximal 

 tarsals of bird, fused on to the base of the tibia ; A. and c, astragalus and 

 calcaneum in ape, the proximal tarsal ; d.t., the distal tarsals of the bird, 

 fused on to the top of the three fused metatarsals, making the tarso- 

 metatarsus, peculiar to birds ; T., in bird, the tarsal region, the meta- 

 tarsal portion is represented solid black ; mt.i., in the bird, the first 

 metatarsal, free by itself ; l.-iv., the bird's toes; d.t., in rhe ape, the distal 

 tarsals ; mt.i., in the ape, the metatarsal of the big toe ; MT.V., the meta- 

 tarsal of the little toe (5) ; p.^., patella or knee pan. 



turned forward and two backward, the better for gripping 

 the perch. In the swift they are all turned forwards, which 

 is well suited for clinging to the nest. 



In some old-fashioned birds, such as divers, there is a 

 strong upward prominence, often about an inch long, rising 

 above the upper end of the tibia at the knee-joint. It 

 serves for the insertion of muscles and helps in the strong 



