180 MR. H. G. SEELEl ON OSSEOUS RESEMBLANCES 



Struthious birds is an ossified prolongation of the scapula along 

 the side of the coracoid. In old age this element in the bird unites 

 again with the distal end of the coracoid so as to enclose a 

 foramen. 



The sternum and clavicle of ordinary birds are not to be com- 

 pared with those of the Chelonia. 



The testudine humerus is massive and stout, as in Parrots, from 

 which that of Testudo differs chiefly in being more curved, in 

 having the head hemispherical, and in having the ulnar process 

 prolonged beyond the articulation instead of being reflected over 

 on the posterior side of the bone as in Lizards. In the Ostrich 

 the radial crest of the humerus is suppressed. At the distal 

 end of the bone birds have the condyles much more developed 

 than Chelonians, and in this respect are more Lizard-like ; so 

 that distally the resemblance is better in the Ostrich than in 

 other birds. 



The proportions of the ulna and radius of Chelonians are 

 perhaps best matched in the Penguins, in which, however, the 

 bones are even more compressed. As in birds, the ulna is the 

 larger bone ; but the majority of birds differ in having it cylin- 

 drical and long. Both bones are best paralleled in the Ostrich ; 

 and the comparison is better made with a middle-aged Testudo 

 than with an old animal. 



The carpus, metacarpus, and phalanges are incomparable. 



The dorsal ribs are comparable in that the epipleuron in such 

 birds as the Parrot grows so as to cover the interspace between 

 the ribs, and so shows a faint approximation to the condition 

 of the same element in the young Chelonian, though in the bird 

 the epipleural parts overlap instead of abutting one against the 

 other. 



The pelvis has no common character in birds and Chelonians, 



The femur is similar to that of a bird, but differs chiefly in the 

 proximal end being twisted at right angles with the distal end, 

 the twist being more perfect than in many mammals, while the 

 proximal articulation is smaller in birds, and a sharp ridge runs 

 from the great trochanter some distance down the front of the 

 bone. The distal end in birds is thicker from front to back, and 

 has the condyles much better defined. In its proportions the 

 femur might be compared to that of the Ostrich and many cari- 

 uate birds. 



Birds often have a patella, which Chelonians have not. 



