92 ON THE MORPHOLOGICAL CONSTITUTION OF 



Now, in regard to the so-called " superior maxillary lobes," 

 it is clearly established that the palate and pterygoid bones 

 are formed in them, but there is no sufficient evidence that 

 they contain the germs of the superior maxillary bones. No 

 traces of the superior maxillary bones appear until these so- 

 called "superior maxillary lobes" have extended forwards, and 

 united with the "lateral frontal processes" and the "nasal 

 process," and until the maxillary margin has become con- 

 siderably extended. I am, therefore, of opinion that the 

 "lateral frontal processes" of Eeichert are, in fact, the real 

 maxillary lobes, and contain not only the germs of the 

 lachrymal, but those also of the maxillary and malar bones. 

 This view of the place of origin of the superior maxillary, is 

 in accordance with the adult relations of these bones. The 

 position of the superior maxillary is in front of the eye ; the 

 orbit being, in fact, an expanded cleft between it and the 

 palate bone. 



Again, the nasal bones of the mammal are formed in the 

 upper part, and the intermaxillary bones in the lateral angles 

 and palatal lobes of the " anterior frontal process." The notch 

 or cleft on each side of this process cannot therefore become 

 the external nostrils, for these are not situated in the mammal 

 behind the intermaxillary bones, but in front of them. From 

 these circumstances, I am inclined to consider the external 

 nostrils of the mammal to be formed by the transverse union of 

 the palatal lobes of the " anterior frontal process," and by the 

 formation of the cartilasres of the external nose in the mesial 



O 



portion of the free margin of that process. 



Embryologists generally consider the so-called superior 

 maxillary lobes to be the upper portions of the " first visceral 

 laminse" bent forward, and the "lateral" and "anterior 

 frontal processes" to be superadded structures in no way 

 related to the " visceral" or " branchial laminse." It appears 

 to me, however, that the general aspect, the relations, and the 



