200 ELEMENTARY ANATOMY. [LESS. 



Instead of being free as in man, the tibia may anchylose at 

 each end with the corresponding extremities of the fibula, 

 as is the case in the Armadillos and often in the Seals. 



Very often it anchyloses with the fibula below only, as in 

 the Rabbit and in some Birds, e.g. Adjutant and Ostrich (and 

 as in one member of man's own order, Tarsius) ; or above 

 only, as, at least sometimes, in the Cape Ant-eater. 



There may be an apparently single representative of the 

 two bones of the leg which are completely fused together, ar; 

 in the Frog. 



FIG. 171. RIGHT PELVIC LIMB OF GIRAFFE. 



n, astragalus ; c, calcaneum ; at, cuboides ; d^>, proximal phalanx of third digit ; 

 </ 4 , proximal phalanx of fourth digit ;/", femur ;_/', rudiments of fibula (the 

 line is not continued far enough the rudimentary fibula is a small ossicle 

 reposing on the upper surface of the calcaneum, as shown in the figure ; : 

 7// 3 +4, metatarsals of digits 3 and 4 united into one "cannon-bone"; 

 J>a, patella ; t, tibia. 



The tibia may be the only long bone of the leg, through 

 the small development of the fibula, as is the case in Rumi- 

 nants and in the Horse tribe. 



The space which exists in man between the tibia and the 

 fibula may be exceedingly reduced, as is the case, e.g., in Birds" 



