46 ON THE ORIGIN AND DEVELOPMENT OF THE 



nearly in their original condition. Although the latter recover 

 in some degree their lost ground, yet, as every one knows, the 

 inferior central incisive almost always cuts the gum before the 

 superior, and the lateral sometimes does so also. In order to 

 explain this apparent exception to the law above mentioned, 

 it will be necessary to go a little into the history of the inter- 

 maxillary bones, in doing which reference must necessarily be 

 made to some of the other bones of the face and head. 



When the superior portion of the large common nasal 

 buccal and pharyngeal cavity is exposed in an embryo of the 

 sixth or seventh week, by removing the lower jaw, we observe 

 the boundary of the future palate to be defined by what has 

 been denominated in a former section the horse-shoe lobe (c, 

 Fig. 2). Attached to the posterior inner edges of this lobe 

 two other lobes are seen. These grow from behind forwards, 

 and from without inwards, and complete the palate by joining 

 in the median line, being assisted in doing so posteriorly by 

 two other smaller lobes behind the posterior extremities of 

 the horse-shoe lobe. In the two first lobes become developed 

 the palatine plates of the superior maxillary bones, and in the 

 two smaller posterior the palatine plates of the palate bones. 



The bar (h, Tigs. 2 and 4), which ultimately coalesces 

 below with the median line of suture of the four last men- 

 tioned lobes, is proved by development to contain the nucleus 

 of the vomer. 



The median lobule (m) and its' two lateral and anterior 

 appendages (n ri) form the anterior division of the embryonal 

 palate. Of these three, the two lateral are observed in the 

 course of development to contain the nuclei of what are 

 usually denominated the intermaxillary bones. With regard 

 to the median it may be stated that, as all the other lobules 

 which appear in the soft pulpy texture of the foetal palate 

 are proved by development to contain the nuclei of all the 

 well-known bones of this region, I am inclined to consider it 



