306 MR. W. P. PYCRAFT ON THE MORPHOLOGY 
pterygo-vomerine articulation. Distally, the palatines are seen to 
have come into relation with the maxillo-palatine processes, inasmuch 
as they just touch their hindmost extremity. The quadrato-jugal 
(inferior temporal) fossa has greatly increased in length. 
Fig. 4. The palate of Rissa tridactyla showing the typical Neognathine palate. 
The inward movement of the palatines has reached its maxi- 
mum, meeting one another in the middle line, beneath the pterygoid 
and vomer. Following upon this, the distal end of the pterygoid has 
become divorced from the main body, to form the hemipterygoid 
(fig. 1, Pl. 32). Later, the latter fuses with the palatine; and at the 
point of fracture, immediately caudad of the palatine, a joint is formed. 
Thus, in the adult Neognathx by the disappearance of the hemi- 
pterygoid element the pterygoid appears to bea free bone, articu- 
lating with the palatine, instead of being connected therewith by 
squamous suture. The vomer in the adult skulls of this type appears 
now to be completely divorced from all association with the 
pterygoid. 
Fig. 5. The palate of the Common Fowl (Gallus bankiva var. domestica). 
The bones in this palate have undergone still further specialization | 
The hemipterygoid appears to be totally suppressed, so that the vomer 
is actually supported only by the palatine (see also Zetrapterye, 
fig. 4 a, P1.32). The slight groove indicated in the figure immediately 
caudad of the vomer was, in the freshly prepared skull, filled by two 
threads of cartilage running backwards from the vomer, and indi- 
cating its sometime further backward extension, wedged in between 
the palatines and articulating with the now suppressed hemi- 
pterygoid. 
Puate 32. 
Fi 
ee) 
.1. The pterygoid of a nestling Podiceps cristatus, lateral view ; showing 
the still distinct hemipterygoid element which extends forwards to 
the vomer. Later the hemipterygoid, losing itself by fusion with the 
palatine, gives the appearance, in the adult, of a true palato-pterygoid 
articulation, thereby making it appear that the vomer in the Neo- 
enathe is unconnected with the pterygoid, and thus, on this account, 
sharply distinguishing the Neo- from the Palzognathex. 
g. 2. The pterygoid of a nestling Oceanodroma leucorrhoa, lateral view. 
The palatine has extended backwards beneath the hemipterygoid to 
share in the articulation with the main shaft of the pterygoid. 
g. 3. The pterygoid of a nestling Pygoscelis teniata, lateral view. At this 
stage the hemipterygoid appears as if wedged into the distal end of 
the main shaft, as by fracture; later a perfect glenoid cavity is deve- 
loped between the distal end of main shaft and the hemipterygoid 
element. 
Fig. 3a. The dorsal aspect of fig. 3, showing an early stage in the decline 
of the hemipterygoid, which just fails to reach the vomer. 
BR 
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