350 MR. W. P. PYCRAFT ON THE MORPHOLOGY 
This hemipterygoid varies greatly in its relative size in dif- 
ferent groups. In some it has become so greatly reduced that 
it ceases to segment off from the main body, and remains as a 
kind of peg projecting from the antero-dorsal angle of the 
pterygoid trunk. ‘This is the case in the Galli and Anseres. In 
these groups the vomer, when present, is therefore supported 
entirely by the palatines. 
In the Falconide, amongst the Accipitres, again it has entirely 
disappeared, the support of the vomer being undertaken by the 
palatines. 
As a consequence, then, of the inward movement of the 
palatines, the hemipterygoid element is slowly undergoing sup- 
pression. In some cases, as we have just remarked, only the 
merest vestige remains. In the majority of cases its connection 
with the vomer is but of the slightest. The support of this 
element has practically been transferred to the palatines. 
The nature of this support is seen with almost diagrammatic 
clearness in the Penguins. Herein the palatines, caudad, are 
plate-shaped. The mesial border of each runs at first beneath 
the hemipterygoid, then beyond this upward and forward for a 
considerable distance. The whole of this region beyond the 
hemipterygoid is applied to the dorsal border of the vomer, 
which only just reaches back to the tip of the hemipterygoid. 
Numerous stages in the decay of the disappearing hemi- 
pterygoid are to be found. The skull of an immature Tetra- 
pteryx paradisea in the British Museum collection affords an 
admirable object-lesson in this degeneracy. Here (PI. 82. fig. 4) 
the free end of the bemipterygoid failsto reach the vomer, which 
is now entirely supported by the palatine in the manner just 
described. 
The vomer, like the hemipterygoid, is also in many cases 
completely suppressed. 
Attention must now be directed to the palatal bones of certain 
Coraciomorphe (Gadow). 
Lack of suitable material (in the shape of embryos or nestlings) 
has greatly hampered me in the investigation of these groups ; 
but enough has come to light to enable me to deal therewith in 
the present contribution. It is to be hoped that help in this 
matter will come to hand shortly. We should be very grateful 
at the Natural History Museum for ripe embryos and nestlings 
