PHYLOGENY OF THE PAL^EOGNATILE AND NEOGNATH.E. 



273 



lumbar neural spines but little axially extended, but considerably 

 extended dorso-ventrally and not subequal in height ; synsacrum with 

 post-sacrals not at all raised dorsad of acetabula, but rather depressed 

 ventrad ; post-sacrals perfectly ossified ; sacral plainly distinct from 

 post-sacral vertebrae ; no lumbo-sacral vertebrae ; pre-caudal vertebrae 



ten; pygostyle a laterally compressed plate . Struthio. 



f. Total number of vertebrae forty-nine; cervical vertebrae fourteen; pre- 

 axial articular dorsal surface of atlas with only a minute dorsal notch ; 

 no hyperapophysis to atlas ; hypapophysis of axis not very large ; 

 neural spine of axis not very high ; hyperapophyses of axis well deve- 

 loped; neural spines of cervical vertebrae almost obsolete, those of 

 fourth to seventh vertebrae abort; neural spines of thirteenth to 

 sixteenth vertebrae bifurcate laterally; hypapophyses developed from 

 last cervical to second dorsal vertebra; hypapophyses narrow and 

 pre-axially produced ; a conspicuous fossa on each side of pre-axial part 

 of neural spines from twelfth to the fifteenth inclusive ; cervical ribs 

 short and not styliform ; free cervical ribs nine ; synsacrum with post- 

 sacral vertebrae raised quite dorsad of acetabula, also very imperfectly 

 ossified and much reduced ; sacral plainly distinct from post-sacral 

 vertebrae ; post-sacrals nine ; free caudal vertebrae five ; pygostyle small 

 and cylindrical Rhea. 



The vertebral formula is : — 



Synsac. 



t " — "\ 



Dromceus Cv. 18 : Cv. Th. 3 : Th. 3 + 1 + 2: Lb. 6 : Lb.sc.2: Sc.2: Cd. 9+9 = 55. 



_ 6~ 18 



Synsac. 



f ~ > 



Casuarius Cv. 15 : Cv. Th. 4: Th. 5 + 1 + 3: Lb. 5: Lb.sc.2: Sc.2: Cd. 9 + 9=55. 



~~ 9~~ 18 



Synsac. 

 / " \ 



Struthio Cv. 17: Cv. Th. 3: Th. 5+2: Lb. 8 : Sc.2: Cd. 8 + 10 =55. 



~W 18 



Synsac. 



Bhea Cv. 14: Cv.Th.3: Th. 3 + 2+1: Lb. 3 : Lb. sc. 4 : Sc.2: Cd. 9 + 8 = 49. 



~~6~ 17 



Synsac. 



< " > 



ApUryx Cv.15: Cv. Th. 1 : Th. 4 + 3 + 1: Lb.4: Lb. bc. 4 : Sc.2: Cd. 3 + 8 = 45. 



(A. a. mantelli.) ' » ' ' " ' 



V 8 11 



