Anatomy &c. of the Colies. 245 
concealed from the outside ; and so also is the Jasisphenoid, 
which is underfloored by the basitemporal plate. 
The alisphenoid is at present unossified, and forms a large 
cartilaginous plate extending outwardly to join the squamosal, 
terminating immediately above and in front of the free end 
of this element to form the postorbital process, which appears 
to be represented by the alisphenoid alone. 
The orbito-sphenoid aud mesethmoid are still cartilaginous, 
while the quadrate differs in no way from that of the adult. 
The Membrane-bones. 
The parietal is roughly quadrangular in form, but has 
the inferior border slightly hollowed to receive the supra- 
occipital. 
The frontal has a straight posterior border, and imme- 
diately in front of the squamosal sends down a narrow 
tongue to the orbito-sphenoid. In the supraorbital region 
it is reduced to a very narrow band, and finally terminates 
as usual under the nasals. 
The sguamosal takes the form of a cone, having its apex 
slightly bent forwards; the inner half of its base rests upon 
the tympanic ring of the lateral occipital, while its outer 
half forms the margin of the tympanic cavity. Superiorly 
it extends far beyond the parietal, forming the outer 
boundary of the frontal and terminating at the base of the 
postorbital process. 
The lachrymal is represented here by aslender rod of bone 
running parallel to the descending process of the nasal, 
and sending backwards a long delicate supraorbital rod of 
cartilage along the frontal. In later Jife the lachrymal fuses 
completely with the antorbital plate and frontal. 
The premawilla has moderately long palatine processes. 
The mazilla is small, while its palatine processes are 
greatly reduced, forming an “oat”-shaped plate of bone 
concealed from below by the palatine rod. These processes 
are, however, relatively larger and more distinct than in the 
adult. 
The palatine differs from that of the adult in that its mesial 
