72 TEETIAET VEETEBEATA OF THE FATtTM. 



has been selected from the collection at Cairo as forming an approximately complete vertebral 

 column. Owing, however, to the great variation in size in individuals of the present species it v\as 

 impossible to make a very satisfactory set, and it is not even certain that some of the smaller 

 vertebrae may not belong to Palceomastodon. Only the discovery of an associated series can make 

 it possible to settle definitely the structure of the vertebral column and the number of vertebrae 

 composing its different regions. The description given above (pp. 27-32) is founded on this series, 

 and the figures also are, for the most part^ taken from vertebrae composing it. The numbers of 

 the vertebrae behind the cervical region are only approximate. 



C. 8303. Third cervical vertebra (text-fig. 10, A). 



C. 9097. Fourth cervical vertebra. 



C. 8294. Fifth cervical vertebra (text-fig. 10, B). 



C. 9083. Sixth cervical vertebra. 



C. 9083. Seventh cervical vertebra (text-fig. 10, E). No vertebrarterial canal. Rib-facets on 

 hinder face at ventral outer angle of centrum. 



Tl 



The dimensions (in centimetres) of these cervicals are given in the following table : — 



C.8303. C.9097. C. 8294. C. 9083. C. 9082. 



Greatest width of centrum 13-6 14-5 13 13 13 5 



height „ 11 11 11-3 11 11 



Length of centrum (in middle) 3'3 4'7 4-7 6 5 



Height to top of arch 18 IT'l 17-5 . . 18-7 



"Width at transverse processes 29 . . 21-5 . . 23'5 



Height of neural canal 4 4 4-3 . . 5 



C. 9089. Anterior thoracic vertebra. Spine higher than in last cervical. 



C. 8270. Anterior thoracic vertebra. At this point there is probablj' a gap in the series. 



C. 7806. Thoracic vertebra (text-fig. 11). Spine very high, broad. 



C. 8316. ^Thoracic vertebra belonging to a smaller individual than the la.-^t. 



C. 9215. Thoracic vertebra of a small individual. Neural spine shorter than in last. 



C. 9091. Thoracic vertebra (text-fig. 12). Centrum is somewhat narrowed ventrally. Broad, 



flattened, transverse processes, with oval flat rib-facets (t.f.) towards the front of their 

 outer ends. Neural spine (n.sp.) strongly inclined backwards, upper end slightly bifid. 



The dimensions (in centimetres) of the last six vertebrae are given in the following table : — 



C.9089. C. 8270. C. 7806. C.8316. C.9215. C. 9091. 



Height of centrum 10 10-2 10-5 8-2 8-2 7-7 



Width „ 13-7 13-5 12-5 11 10 10-3 



Length (on ventral side) 6-5 7'4 G-8 . . 6 6-5 



Height to top of neural spine . . . 22-|- . 27 24 26-2 19-7 



Width at transverse processes ... 24 . . 26-7 . . 26 25-6 



Behind C. 9091 there seems to be a gap in the series, in which the neural spines shortened, the 



capitular rib-facets moved higher up, and the zygapophyses became cylindroid. This type of 

 vertebra is shown in text-fig. 13. 



