OSTEOLOGY 



113 



separate vertebrae. In all other birds the tail is short and does 

 not extend far beyond the sacrum. In the majority of carinate 

 birds the terminal vertebrae are fused together into the highly 

 characteristic ploughshare bone (urostyle or pygostyle).' 



Fig. 62 Pelvis of Aptebyx. From Beneath. (After Mivart.) 



?7, ilium ;,iJ, pubis ; z, iscliium ; Zp, prepubio process. 



There is, however, a closer correspondence between 

 the tail of Archceopteryx and that of the carinate bird 



I 



Fio. 63.— Lumbar and Sacral Vertebra of an Immature Ostrich 

 (after Mivart). 

 8, 9, 10, sacral vertebrae ; p, parapophyses ; d, diapophyses. 



than might be assumed from the last-mentioned differ- 

 ences. The first four caudal vertebrae of Archesopteryx have 

 strong transverse processes, which are weaker, but present, 

 on the fifth, which thus affords a transition to the remaining 

 sixteen, upon which there are no such processes. In the 



' W. Marshall, ' Untersuchungen iiber den Vogelschwanz,' Ned. Arch./. 

 Zool. i. 1873, p. i94. 



