262 PROFESSOR OWEN ON CNEMIORNIS. 
which is not definable by reason of fracture. The breadth of the anterior articular 
surface of the centrum is 1 inch 7 lines; its height at the middle is but 5 lines; this 
bilobed character is more strongly shown in the next. 
The second dorsal presents a structure which seems not to have hitherto been noted 
in birds. Besides the median process (hypapophysis) (Pl. XXXVI. fig. 11, hy) from 
the fore part of the under surface of the centrum, there is a pair of processes (ib. 
ib. Al, hl) from the sides of that part of the centrum, which part extends vertically 
below the anterior articular surface (ib. fig. 11, c, c) for an extent of from 2 to 5 lines, 
and is festooned below by the emarginations between the origins of the median (hy) 
and lateral (AJ) inferior processes. This character is rudimentally indicated in the 
first dorsal vertebra of Cereopsis (ib. fig. 13, hy, hl); the processes (h/) are broader and 
more transversely extended in Tachyeres (ib. fig. 14). The articular surface for the 
tubercle of the rib is supported in Cnemiornis by a distinct process (ib. figs. 11 & 12, dt) 
from the under part of the base of the diapophysis (d). ‘The process is feebly indi- 
cated in Cereopsis and Tachyeres (ib. fig. 14, dt). The length of the second dorsal 
vertebra in Cnemiornis from the postzygapophysis (z') to the broken end of the mid 
hypapophysis (/y) is 2 inches 4 lines. The length between the same points of the 
corresponding vertebra in Cereopsis is 1 inch. The rib has a short, straight sternal 
portion tied by ligament to the anterior small tubercle of the costal border of the 
sternum. 
In the third dorsal (Pl. XXXVI. figs. 15, 16) the hypapophysis (hy) extends its 
base the whole length of the centrum, and curves forward as it narrows to a trituber- 
culate end, the mid tubercle projecting beyond the lateral pair (ib. fig. 16, h/, hi), and 
also beyond the vertical parallel of the joint between’ the third and second dorsal 
centrums. The upper spine (ib. fig. 15, ms) also curves forward, its anterior apex 
reaching the same vertical parallel as that below (hy). One or two longitudinal ridges 
strengthen the neural spine near its summit. The hypapophysis of the fourth dorsal 
(ib. fig. 17, hy) has a less extensive base, but equal length; it is also curved forward, as 
is the neural spine; but this is longer, and gains more antero-posterior breadth toward 
its truncate summit. 
The fifth and sixth free dorsals cease to develop hypapophyses; their neural spines 
continue to gain in antero-posterior breadth. The principal pneumatic aperture in the 
dorsal vertebree of Cnemiornis is at the base of the diapophysis (ib. figs. 15, 17, d), 
between the articular surfaces (ib. p/ and dt) for the bifurcate head of the rib; in the 
cervical vertebree it is at the base of the neural arch. 
The ribs, both vertebral and sternal, increase in length; and epipleural appendages 
are attached to the former from the second to the seventh pair. 
The chief things notable in the dorsal vertebree of Cnemiornis, as compared with 
Cereopsis and existing Anserines, are the great breadth of the centrum in proportion 
to the length, the minor fore-and-aft extent of the neural spines in proportion to their 
a 
