1894.] IN THE BRITISH MUSEUM. 119 



The cervical (Plate XV. figs. 2, 3, 4) is of the following dimen- 

 sions : — 



cm. 



Length of centrum - 4*1 



Width between anterior ends of pre-zygapophyses . 2*5 

 Width between outer edges of post-zygapophyses . . 2*6 



Diameter of neural canal 1*0 



Longest diameter of anterior end of vertebrarterial 

 canal 1*4 



The centrum is much compressed from side to side in its 

 middle portion, but widens out towards the ends. The articular 

 surfaces are of the characteristic avian form ; the anterior is wide 

 from side to side and narrow from above downwards, owing to 

 its upper and lower borders being deeply concave ; tbe posterior 

 is slightly wider than high and all hs borders are concave, the 

 lower deeply so. On the ventral surface of the centrum, about 

 one thud of its length from the anterior end, is a median haema- 

 pophysis, the front of which rises steeply, while its hinder border 

 passes by a more gradual slope into a median ridge which runs 

 back for about 1*5 cm. in the middle ventral line. There is no 

 pneumatic fossa in the side of the centrum. 



The lateral portions of the neural arch are remarkably thin. 

 The diapophyses and parapophyses are well developed, and, on 

 the left side, the fused cervical rib is nearly complete, only its 

 hinder portion being broken away. The vertebrarterial canal is 

 very large, much larger, indeed, than the neural, a condition not 

 occurring in the living Eatites or, to the same extent, in Dinornis. 

 The interzygapophysial bar has behind and beneath it a pneumatic 

 fossa, and above and in front of it on the dorsal surface, imme- 

 diately behind the anterior zygapophyses, there is a still larger fossa 

 into which several pneumatic foramina open. On the upper sur- 

 face of the post-zygapophysis, near its outer hinder border, is a small 

 tubercle (hyperapophysis), from which there runs forwards and 

 inwards a ridge which increases in size as it goes ; this does not 

 meet its fellow of the opposite side to form a median neural spine, 

 but is separated from it by a groove, which is shallow in front but 

 deepens suddenly behind, forming a pit for the intervertebral 

 ligament. 



The cervico-dorsal vertebra differs from the one just described 

 in possessing a broader and less compressed centrum, into the sides 

 of which open a pair of large pneumatic fossa?. The arch also is 

 more massive and the ridges running forward from the post-zyga- 

 pophyses very much higher and broader ; as in the cervical, 

 however, they do not unite to form a median neural spine. The 

 pneumatic fossae of the arch closely resemble those of the cervical 

 vertebrae. The parapophyses and diapophyses have smooth articular 

 surfaces for the free rib. 



The smaller dorsal vertebrae are very similar to the larger ones, 

 and since the latter are the more complete they will be here 

 described, though measurements of both will be given. 



