LIFE AND KINSHIP OP DINOSAURS. 



611 



What the Dinosaur needed for its mode of terrestrial locomotion the Bird has not; 

 and what the Bird possesses for its mode of terrestrial locomotion the land Reptile is 



devoid of. 



I have alluded to the modifications, extreme and beautiful they are, of the hind limb- 

 bones of the Bird for the functions concentrated therein ; the suppression, viz., of the tarsal 

 seo-ment; the simplification, unification, consolidation of the segments above and beneath 

 it; the tibia alone (woodcut. Pig. 14, t) articulating with the metatarsus, ib., mf, by a 

 finely fashioned, close-fitting, interlocking joint. 



As in all warm-blooded quadrupeds and the majority of cold-blooded ones, recent and 



Fio. IG. 





Scelidosaunis. 



^'al■i^nus. 



Yoiino; Dinoruis. Rumiiiaut. 



extinct, the articular ends of the tibia are ossified independently of the shaft, are in the 

 condition of epiphyses in the young Bird (Fig. 10, Dinortiis, p 0> f^nc^ retain longer that con- 

 dition in the Reptile (Pig. 16, Varanus, p ^ and Scelidosaurus, p t). Tlie attachment of the 

 distal epiphysis with the shaft of the tibia [t) is made firmer in the biped [Dinornis, p t) 

 than in the quadruped (Pig. 10, Ruminant, ;) t) ; and the extent of the attachment is greater, 

 is more irregular or interlocking in the warm-blooded quadruped than in the cold-blooded 

 one; it is still greater in the Bird, in which a process, longer than that in the Ruminant, 

 ascends upon the front of the diaphysis, closely fitting to a groove there, and clamping, as it 

 were, the articular epiphysis to the main shaft of the leg bone. The bigger the Bird the 

 greater the shai-e of locomotion allotted to the hind pair of limbs in standing, walking, or 

 running, the longer is the clamping process and the later is the period of the coalescence of the 

 epiphysis with the shaft. The Ostrich among existing Cursores, and the Dinornis amongst 



