154 PEOPESSOR OWEN OX THE GENUS DINOENIS. 



The fourth cervical vertebra oi Binoriiis maximus (figs. 12, 13), representing, with 

 increase of size, the proportional characteristics of the third, resembles that of the 

 Ostrich in the greater production of the pleurapophysis, pi, and in the absence of the 

 hypapophysis. 



The interzygapophysial plate, r, not extending to the postzygapophysis, z, does not 

 circumscribe the space forming the foramen, s, in figs. 8 & 11 ; and the pneumatic 

 foramen (fig. 12, pn) comes into view. The zygapophysial articulations, z, z, become 

 elongated ; the posterior outlets of the vertebvarterial canals expand. 



There is little, if any, modification of the pre- or post-axial articular surfaces {ac, pc) 

 of the centrum. The haemal depression (fig. 13, c) behind the preaxial surface {ac) is 

 deeper than in the third cendcal ; and the angle between this and the hind half of the 

 centrum, c, owing to the non-development of the hypapophysis, is more marked. The 

 spine (fig. 12, ns) repeats its small basal extent and bifid character. 



The diapophysial plate (fig. 12, d) extends its origin from the outer side of the 

 prezygapophysis, z, halfway towards that of the postzygapophysis, before it bends 

 down to coalesce with the pleurapophysis, pi ; the broad outer wall of the vertebrarterial 

 canal (fig. 13, ti) thus formed is the ' pleurapophysial band' of Mivart '. It sends 

 forward from its lower anterior angle a short obtuse parapophysis (fig. 12, p). The 

 riblet, pi, extends backward from the opposite or hinder angle. The vertical hind 

 border of (he 'band' has two semilunar insertional impressions, the angle (fig. 12, a) 

 between which is less produced than in Struthio. 



The pleurapophysial band has a relatively greater vertical extent than in Struthio ; 

 and this relates to the corresponding excess of vertical over longitudinal dimensions in 

 the entire vertebra of Dinornis as compared with Struthio. 



In the direct under \1ew (fig. 13) the pleurapophysis extends almost to the vertical 

 level of the postzygapophysis, z' (compare with fig. 24, Mivart, loc. cit.); a more 

 marked difference from Struthio is in the bifid neural spine of Dinornis. There is no 

 medial hypapophysial ridge in B. maximus. 



In 1). elephantopus the fourth cervical has the hinder half of the lower surface of the 

 centrum relatively wider than in fig. 13, c/; the prezygapophyses are less produced 

 forward than in fig. 12, z. 



Glancing along the ceiTical region, in the articulated skeleton of Binornis maximus, 

 one sees, as in that of B. elephantopus, that the two (parial) neural spines continue to 

 be developed throughout that series of vertebrae, the uniting basal band subsiding some- 

 what in the fifth cervical, and each spine being then represented by a ridge continued 

 forward from the hyperapophysis, converging toward its fellow as it rises ; but it 

 attains no great height in any vertebra. In the fourteenth cervical, where the parial 

 neural spines are most marked in this respect, the uniting base gains in vertical extent. 



' Loc. cit. p. 398. 



