OSTEOLOGY 



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separate vertebra*. 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). 1 



II 



FIG. 6'2. PELVIS OF APTERYX. FROM BENEATH. (AFTER MIVART.) 

 il, ilium ; />, pubis ; i, ischium ; lp, prepubie process. 



There is, however, a closer correspondence between 

 the tail of Arcliaopteryx and that of the carinate bird 



FIG. 63. LUMBAR AND SACRAL VERTEBRAE OF AN IMMATURE OSTRICH 



(AFTEK MIVART). 

 8, 9, in, sacral vertebras ; p, parapophyses ; rf, diapophyses. 



than might be assumed from the last-mentioned differ- 

 ences. The first four caudal vertebrae of Archceopteryx 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 



1 W. MARSHALL, ' Untersuchungen liber den Vogelschwanz,' Ned. Arch. f. 

 Zool. i. 1873, p. l'J4. 



