PROPESSOE OWEN ON MACROPUS. 427 



The transverse processes of the other five cervical vertebrae are perforated. The 

 spine of the third is compressed, laminate, truncate, coextensive with the neural arch ; 

 iu the fourth (ib. fig. 7, lis) it contracts antero-posteriorly, loses height, but gains in 

 breadth at its summit ; this character of the spine increases in the fifth ; the spine 

 lengthens and becomes obtusely pointed in the sixth, is still longer and more merits 

 the name of spine in the seventh cervical (ib. fig. 9, c, ns). 



The parapophysis projects as an angular plate in the fourth (ib. fig. 7, jj) and fifth, 

 and more so with increased thickening in the sixth (ib. fig. 8, p) ; it is reduced to a 

 mere tubercle in the seventh cervical, in which the pleurapophysis is longest and 

 strongest. 



The neural arch is perforated vertically on one or both sides by epineural canals 

 (fig. 7, en, en) between the fore (z) and the hind {z') zygapophyses in the third to the 

 seventh vertebrae ; each nem-apophysis is also perforated lengthwise near the inner 

 surface by " entoneural canals " (fig. 8, in), the orifices being within the neural arch ; 

 they are largest in the sixth and seventh cervicals, but coexist here with the vertebro- 

 arterial canals (ib. figs. 8 & 9 c, «) in their usual position external to the arch. The 

 anterior surface of the centrum is transversely concave (figs. 7, 8, c), the posterior one 

 convex in all the cervicals following the axis. 



The entoneural canals are repeated in the first dorsal, which shows a sudden increase 

 in the length of the neural spine (PI. LXXV. fig. 9, d i, ns). The transverse concavity 

 of the fore part of the centrum, as in the cervicals, is retained in the first dorsal ver- 

 tebra. There is one large cup for the head of the first thoracic rib on each side of the 

 anterior half of the centrum and contiguous part of the neurapophysis. This element 

 (ib. n) articulates and has coalesced with the corresponding part of the centrum, leaving 

 the hinder half free. The half-cup for the second rib impresses the angle between the 

 hinder concave articular surface and the free lateral surface of the centrum. 



The strong diapophysis is impressed below its outer end by the large and deep cup 

 (ib. fZ) for the tubercle of the first rib. The right side of the neural arch has an epineural 

 canal. 



The second dorsal (ib. fig. 9, D 2) has a longer and more slender spine {ns). The 

 neural arch shows the vertical perforation on the left side. The intraneural canals are 

 reduced to two minute posterior perforations. The anterior articular surface of the 

 centrum is convex. In the third dorsal (ib. fig. 9, D 3) the centrum lengthens and the 

 sides are defined by an angle from the under surface. There are neither eato- nor epi- 

 neural foramina. 



The anterior costal pit in this and succeedmg dorsals seems to be a mere folding-back 

 of the outer ends (fig. 9, d 3) of the anterior convex articular surface of the centrum. 

 In like manner the half-surface for the head of the next rib seems to form the outer end 

 of the posterior transverse surface of the centrum. 



The diapophyses (ib. d) increase in antero-posterior extent and become more de- 



3m 2 



