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Transactions of the 
After another week or two the pointed fore-end of the pterygoid 
becomes detached as a distinct “ meso-pterygoid,” which after a few 
weeks coalesces with the palatine. The “ trans-palatine ” cartilage 
gets endostosis, completely ossifies, and then ankyloses with the 
palatine, so also do the vomerine forks ; and at their fore-end, on 
each side, a new hone appears — the “ septo-maxillary.” 
The septum-nasi ossifies in some degree, hut most of the nasal 
labyrinth is permanently cartilaginous, yet the ecto- and meso- 
ethmoidal elements are well ossified and quite ankylosed. Almost 
every part of the skull and face undergoes this intensive and exten- 
sive ossification, hut the quadrate bones and pterygoids keep distinct 
from their surroundings, and the palatines from each other behind. 
In their “ etlimo-palatine ” regions they are tied together by the 
vomer which coalesces by its forks ; in front the palatines are fused 
with the rest of the face. The twisted, fusiform lachrymals are 
permanently distinct, and a trace or two of sutures can he seen 
over the “ cranio-facial hinge.” All the twelve pieces of the lower 
jaw become one V-shaped hone. 
In the second post-oral the medio-stapedial is ossified, and all 
but the tips of the distal cerato-hyals ; the upper ends of the third 
arch, and the greater part of the “ uro-hyal ” remain soft. 
In conclusion, if anyone shall ask me why this multitude of 
bones should so soon melt into so few? I have only one answer, 
namely, that the reason lies, I suppose, first, in their genetic history 
in the “ auld lang syne,” and tlien in slow adaptive modifications 
during epoch after epoch. 
DESCRIPTION OF PLATES. 
Plate XXXIY. — Development of skull in Hooded Crow ( Corvus cornix ), 
fifth or sixtli day of incubation. 
Plate XXX Y. — Figs. 1-6. Skull of Rook ( Corvus frugilegus), eighth or 
ninth day of incubation. Fig. 7. Skull of Carrion Crow ( Corvus corone), end of 
incubation. 
Plate XXXVI. — Skull of Corvus corone, end of incubation — continued. 
[It is necessary to state that only three of Mr. Parker’s Plates — Plates 
XXXIV., XXXV., and XXXVI. — appear in this number of the Journal. The 
remainder will be given in the succeeding number. — Ed. ‘ M. M. J.’] 
