OF GALLINACEOUS BIRDS AND TINAMOUS. 211 
upper surface of the presphenoid, which is in this case, as in most birds, quite vertical. 
Half of the cranial surface of the presphenoid is between the frontal plates, and half 
between the inner edges of the alisphenoids. This bone is here about a line thick; 
but it becomes thin as it grows forwards to join the upper process of the ethmoid 
(that part of the ethmoid which in Man sends back the “‘ crista galli”’), and thinner 
still where it descends as a narrow plate to articulate, and then coalesce, with the thick 
presellar part of the basisphenoid. At its middle this plate is only half a line broad ; 
and it has in front of it a membranous space, 3 lines across and nearly 4 lines high. 
The descending part of the presphenoid is evidently formed from a separate centre, 
distinct from the upper part; it does not meet the basisphenoid until old age in 
Vanellus and Columba, and is represented by a very minute point in most Rails, e. g. 
the Weka-Rail (Ocydromus australis). It is, however, with this latter bird and its allies 
that the presphenoid of the Tinamou is to be compared, as also the membranous space— 
although the Rail exceeds somewhat in this, the middle ethmoidal plate ending in the 
Rail more abruptly. In Pigeons and Plovers the orbital plate of the frontal is deficient, 
as is also to some degree the alisphenoid at its inner edge, so that in them these bones 
combine to send inwards to the presphenoid a mere belt of bone ; the presphenoid also 
in them projects out into the interorbital space. In the Tinamou and in the Ocydromus 
the upper or posterior edge of the presphenoid is buried in the well-developed plates 
of the frontal and alisphenoid—these plates being more lateral, as in Mammals, and 
not so ¢ransverse as in most birds. ‘The postfrontal is 3 lines from the rudimentary 
zygomatic process of the squamosal (fig. 3); and, as in Ostriches generally, in Rails, 
Plovers, and in Pigeons these processes are wide apart, and leave the temporal fossa 
unbridged; so that here there is no approach to the Fowl. The fossa is an almost 
semicylindrical groove, and ascends relatively no higher than in the Ostriches, and the 
process of the squamosal which bounds it behind, and which overlaps the os qua- 
dratum, is thick, cellular, and so perfectly struthious that it cannot be mistaken for 
that of any other type of bird. 'The moderately convex fronto-parietal surface (Pl. XL. 
fig.2) is composed of very thick and spongy bone, and the parietal is but slightly 
scooped below for the temporal muscle. The upper face of the parietals, and so much 
of the frontals as goes to roof-in the brain, form together a pretty regular pentagon. 
The edges of the frontals round the orbits (fig. 3) are tolerably well developed—much 
as in the Ostriches, and more than in the Rails; for in the latter birds the margins 
are bevelled away. In the Tinamou the narrow anterior portion of the frontals (fig. 2) 
equals that of the Rails and Ostriches in relative width; but its edge is not simply 
sharp as in the Emu, nor bevelled off as in Ocydromus, but is scooped above to 
receive the inner edge of each nasal gland. These supraorbital or nasal glands in the 
typical Ostriches have crept almost wholly into the front of the orbit; but in the 
Tinamou (fig. 2) each gland lies above the forehead, and is 7 lines long, and more than 
a line broad—a little larger than in the Lapwing (Vanellus) (Pl. XXXVIL. fig. 3, f.g.d.). 
