AESINOITHEEIUM. 27 



ventral border produced downwards into a pair of blunt hypapophysial prominences. 

 The transverse process (t.j).) is perforated by a vertebrarterial canal (v.c.) ; the 

 dorsal bar is slender and is continuous above with the outer edge of the neural 

 arch ; the ventral bar is much larger, and its base is elongated so that it arises 

 from almost the whole length of the side of the centrum. 



From the large series of vertebrse preserved in the Museum at Cairo it has 

 been possible to make up a set of cervicals with some degree of certainty ; at 

 the same time, owing to the great variability in size of the animals from which 

 they were derived and the circumstance that so far no associated specimens have 

 been found, the following account of the successive vertebrse must be taken as 

 provisional, and subject to revision if at any time an associated series should become 

 available for description. 



The most notable characteristic of the cervicals as a whole is the shortness of 

 their centrum compared to its great width and height. The neck must have 

 been as short and massive as in the Elephants, and the movements of the head 

 much restricted. 



In the third cervical (text-fig. 10, A) the centrum is roughly quadrate in outline 

 with broadly rounded angles. Its neural border is nearly straight, and the ventral 

 surface bears a pair of blunt hypapophysial ridges. Both the anterior and posterior 

 faces are slightly concave, and the body is very short in proportion to its width and 

 height, the length (thickness) of the middle of the centrum being only 3-3 cm., while 

 its width is 13'6 cm. and its height 11 cm. The pedicles of the neural arch are 

 stout, but its upper portion is thin, except towards the summit, where a W-shaped 

 thickening represents the neural spine {n.sp.). The zygapophyses are large and 

 their articular faces nearly flat. The anterior zygapophyses {a.z.) bear on their 

 outer side blunt metapophyses. The vertebrarterial canal {v.c.) is enclosed by a 

 comparatively thin diapophysis {dp.) above and a much stouter parapophysis {pp.) 

 below. This latter arises from the lower part of the side of the centrum. After 

 enclosing the canal these processes again diverge into a small upwardly projecting 

 process and a much larger one which is directed downwards and backwards. 



The fourth cervical (text-fig. 10, C, D) is much like the last, except that (1) the 

 arch slopes a little forwards, (2) the spine is higher, (3) the diapophysial bar of 

 the vertebrarterial canal is wider and straighter. 



The fifth cervical (text-fig. 10, B) is generally similar to the fourth, but diff'ers 

 in the following respects : — (1) the upper part of the arch is more slender and 

 slopes more forwards, (2) the diapophysis is still larger and ends in a large tuberosity, 

 (3) the vertebrarterial canal is smaller and rounder, (4) the ventral process of 

 the transverse process {t.p.) is much elongated and projects considerably below 

 and behind the centrum. 



The sixth differs from the last in having shorter parapophysial processes. A 



152 



