SEC. Ill 



EXTERIOR PARTS OF BIRDS 



179 



one. Besides including the evanescent tarsal element or elements 

 already specified, it consists of three metatarsal bones consolidated 

 in one, just as the metacarpal is tripartite. Among recent birds, 

 the three are partly distinct only in the penguins ; but in all, ex- 

 cepting ostriches, the original distinction is indicated by three 

 prongs or stumps at the lower end of the bone, forming as many 

 articular surfaces for the three anterior toes. The other toe most 

 birds possess, the hind toe, is hinged upon the metatarsus in a 

 different way, by means of a small separate metatarsal bone, quite 

 imperfect ; this is the accessory metatarsal, am. It is situated near 

 the lower end toward the inner side of the principal metatarsal 



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JfftUVh 



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[ JfoF^C 





Sjiig 





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::;~-~._» y^p^ -:=:j-j 



-10 



Fig. 34 &is. — Diagram of corresponding segments of hind limbs of man, horse, and bird. 

 The lines 1-11 are isoiowies, cutting the limbs into morphologically equal parts, or isoimres. 



bone, and is of various shapes and sizes ; it has no true jointing with 

 the latter, but is simply pressed close upon it, much as the fibula is 

 applied to the tibia, or partly soldered with it. Above, it is defect- 

 ive; below, it bears a good facet for articulation with the hind 

 toe. In spite of anatomical proprieties, the metatarsal part of a 

 bird's foot — from heel to base of toes — from C to D, is in ordinary 

 descriptive ornithology invariably called " The Tarsus " ; a wrong 

 name, but one so firmly established that it would be finical and 

 futile to attempt to substitute the correct name. In the ordinary 

 attitude of most birds, it is held more or less upright, and seems io- 

 be rather "leg" than a part of the "foot." It is vulgarly called 



