OF GALLINACEOUS BIRDS AND TINAMOUS. 207 
which the sheathing of the upper jaw is very perfect; they thus retain a struthious 
character, but have it in an exaggerated condition. There is a somewhat faint 
condition of this in the Albatroses (Diomedea exulans and others), but it is more 
perfectly developed in the Petrels (e. g. Procellaria glacialis). In the Petrels the 
strong and highly arcuate ‘‘neb” is marked off from the sides by a deep groove, as 
in the ‘‘Struthionide.’” The breaking-out again, as it were, of these characters 
in the pluvialine and larine oceanic birds does not at all affect their value as indi- 
cating the affinities of the Tinamou; for many very high and noble birds amongst 
the typical groups betray, by their dress, gait, speech, and behaviour, a certain kinship 
to the low, soil-stained Ostriches—just as a Horse, with much good blood in him, may 
unfortunately possess the back-stripe which brands him as germane to the Ass. The 
plumage of the Tinamou comes very near to that of the subtypical ‘‘ Gallinz ;” but in 
wisdom the bird is very far inferior to the Grouse and Partridge ; and the easy manner 
in which it is caught with the ‘‘lasso”’ shows that it has no right to sit in the same 
zoological seat as the running ‘‘ Gallinacee.’’ As far as posture is concerned, they 
often assume that peculiar mode of sitting upright which the Ostriches so frequently 
adopt, and which is imitated also by some of the great clownish ‘‘ Grallz” of higher 
types. I suppose that the Carrion-Crow (Corvus corone) is about the same weight as 
Tinamus robustus ; its cranium, however, is twice the breadth, and will hold 110 grains 
of powdered nitre; whereas that of the Tinamou will only hold 35 grains—less than 
one-third. Here we see that in these two birds, of almost equal bulk, the typically 
ornithic bird has more than thrice as much brain as the low aberrant kind. Any one 
who has watched the Tinamou must have noticed its peculiar, forlorn, wandering 
manner—like a half-witted person whose mind is not easily made up, and whose 
actions are feeble and indefinite. 
The occipital plane of the Tinamou (Pl. XXXIV. fig. 8, & Pl. XL. figs. 1 & 3) is not; 
on the whole, less vertical than in the Common Fowl, and this latter bird agrees very 
much with the genera Rhea and Dromeus in this respect; but in the Tinamou the 
“foramen magnum” Jooks more downwards, and is really more basal than in the larger 
forms; it thus approaches in some degree to that of the Syrrhaptes and the Peewit 
(Vanellus). The whole plane is evidently an ossification of a thick mass of preexisting 
cartilage, as in the Fowls and typical Ostriches,—there being not the least trace of the 
middle fontanelle, nor more than a large, vertical, descending channel (Pl. XXXIV. 
fig. 8, and Pl. XL. fig.1) on each side for the veins that carry the blood from the sinuses. 
These veins glide through the primary chink between the periotic capsule and the super- 
occipital cartilage; the canal for them is relatively very large, and becomes a mere 
rough-edged channel for the lower half of its course. Between these channels the 
superoccipital is gently convex; but the upper half is produced into a thick, low keel 
(Pl. XXXIV. fig. 8, so.). On the outer side of each channel is the periotic eminence, 
bulbous and cellular, and holding within itself, posteriorly, the crossing of the horizontal 
VOL. V.—PART III. 25 
