]68 MR. W. K. PARKER ON THE OSTEOLOGY 



in the Guans {Penelope), as they do in some of the Pigeons ; and beautiful crests, 

 often crisped and curled in the most exquisite manner, are the rule in this group. The 

 hones sometimes take more or less part in the ornamentation of the head ; the face is 

 enormously expanded into a bony tumulus in Ourax pauxi ; the " cere " is more or less 

 strengthened by an elevation of the subjacent bone in Crax ; and the anterior frontal 

 region is elevated to a great height, to form the " horn" of Oreophasis. The skull in 

 these birds, as in many others, is the great problem to the morphologist ; and on it we 

 must be willing to bestow the most care and labour. 



On the whole, the degree of divergence from the Gallinaceous type in the structure 

 of the Curassow's skull is somewhat greater than what is seen in the Talegalla. The 

 skull of Crax globicera reminds one more strongly of that of Tetrao urogallus than that 

 of the Turkey ; it is also manifestly columbine in many respects, but it does not strike 

 me as being at all more related to the skull of a medium-sized Pigeon (e. g. Columba 

 palumbus) than to that of one of the " Musophagidae " or Plantain-eaters, e.g. the 

 Touraco {Corythaix huffoni). There is but little difference as to thickness in the 

 skulls of the Turkey, Cock-of-tlie- Woods, and Curassow ; but that of the first is 

 dense and hard, like a Mammalian skull ; that of the second is very coarsely spongy ; 

 whilst the Curassow's skull, although thick and heavy, is more ivory-like, and alto- 

 gether comes nearer to the skull of a typical bird. The occipital plane forms a more 

 obtuse angle with the basicranial axis than in the Fowl, whilst in the Turkey it forms 

 a right angle, and in Tetrao urogallus an acute. The occipital plane is more rounded 

 and smooth than in the Fowl, whilst in the Fowl it is much more so than in the gigantic 

 Turkey. The condyle is perfectly typical. 



There is a falling-off in the breadth of the basitemporal region ; but the ear-drum is 

 as hollow as in the Fowl. The great "incus" has got a second head, not, however, 

 very separate from the first. The temporal fossa is bridged over as in the Fowl tribe 

 generally, but the orbit is better formed ; it is evenly round for about three-fifths of a 

 circle, and the massive frontals grow outwards into the supraorbital region, as in the 

 larger Pigeons, so as to be flush at the edge with the lachrymal. There is a shallow 

 fossa between each convex frontal. The lachrymal, which is a flat, fatty bone in the 

 Fowl, the Turkey, and the Grouse, is in the Curassow spongy and pneumatic ; and the 

 descending process is also thick and expanded, coming close to the condition of the 

 bone in the Screamers, Pigeons, and Plantain-eaters. The interorbital septum is perfect, 

 but rather thin : in this it differs from Columba and Corythaix, and agrees with the large 

 GaUincB proper ; that partly depends, however, upon the large size of the bird. The 

 antorbital and the ali-ethmoidal laminae are ossified at their roots ; but the alse of the 

 septal and ali-nasal regions are, with all the upper part of the " septum nasi," wholly 

 cartilaginous. The lower, outspread portion of the septum — that part which in all air- 

 breathing Vertebrata tends in the embryo to enclose the air-tubes, and to make them 

 into complete cartilaginous pipes — this broad base of the etlmio-vomerine cartilage is 



