OF GALLINACEOUS BIRDS AND TINAMOUS. 219 
“Corvine” Piping Crow, Gymnorhina tibicen. 
Canary-bird, Fringilla canaria. 
Crimson Finch, Estrelda phaéton. 
Brown Linnet, Linaria cannabina. 
( Bullfinch, Pyrrhula vulgaris. 
« Sylviinze ”” Pied Wagtail, Motacilla Yarrellii. 
‘* Passerinse ” 
In these birds, however, a pair of additional bones have also been melted into the 
common mass, viz. the ‘‘ mesopterygoids,” the homologues of Professor Owen’s ‘‘ ento- 
pterygoids ” in the fish, bones which are additional to the homologues of the internal 
pterygoid plate of the human skull, and therefore not conveniently receiving a name 
which would confound them with those plates. I have not at present discovered these 
parts in the Struthionide ; but they are present in most other birds at an early period. 
The extreme state of prognathism in the bird causes the palatines to be drawn out ante- 
riorly into a very long splint of bone (Pl. XXXVII. fig. 1, pa.), the periosteal growths 
proceeding far beyond the original cartilaginous rod in which the palatine ossification 
first commenced’. In the generalized face of the Ostrich this is not so much needed, 
and consequently their palatines are but little prolonged anteriorly (PI. XLII. fig. 1, pa.). 
Nothing can be simpler than the skeleton formed in the maxillary rudiment of the 
embryo Ostrich ; this part (the anterior crus of the palato-quadrate arch) is shaped 
like a piece of knee-timber ; its thick hinder end is applied to the os quadratum ; its 
narrow front end reaches the inner edge of the prevomerine splint, and the middle 
broad part turns inwards and upwards to apply itself to the skull-beam some distance 
in front of the pituitary space. The hinder part is ossified, and is the pterygoid ; the 
front piece becomes bony, and is the palatine: they largely overlap each other, the 
palatine applying its pedate base to the outer edge of the pterygoid, whilst that bone 
runs forwards as a splintery pointed piece, and lies on the corresponding posterior 
fork of the vomer (Pl. XLII. fig. 1, pg.v.). The palatines are broadest in the Rhea, 
narrowest in the Tinamou (PI. XL. fig. 1), where there is a considerable extension for- 
wards of the bone: in all cases the outer edge of the palatine is thick, the inner thin ; 
the upper surface convex, and the lower concave. In the Rhea the bone is but little 
perforated, but in the Emu all its centre becomes mere membrane; in the Tinamou 
each bone has two or three fenestra—a state of things by no means uncommon in the 
Grallatorial tribes. The palatines of the Fowl-tribe (Pl. XXXVI. fig. 6) are but little 
in advance of those of the Ostriches; yet in them the long premaxillary process of the 
bone is certainly an ornithic advance, and at times there is a faint rudiment of that 
mesopalatine keel which gives such finish and beauty to this bone in the Plover 
(Pl. XX XVII. fig. 1, pa.), Heron, Rail, &e. In the Tinamou, as in the Ostriches, the 
‘ The palatines and pterygoids have commenced to ossify in the embryo bird whilst the tissues of the skull 
are in a very nascent condition, before the cells of the hyaline cartilage have become cemented together by 
intercellular substance. 
