AXD ITS APPENDAGES. 653 



or furrow, as a sort of cicatrix, to mark the line of union between 

 them. 



Sometimes the superior maxillary and the intermaxillary pro- 

 cesses fail to unite with each other; and we then have the mal- 

 formation known as hare-lip. The 

 fissure of hare-lip, consequently, as a 

 general rule, is not situated exactly in 

 the median line, but a little to one side 

 of it, on the external edge of the inter- 

 maxillary process. Occasionally, the 

 same deficiency exists on both sides, 

 producing "double hare-lip ;" in whicli 

 case, if the fissures extend through 

 the bony structures, the central piece 

 of the superior maxilla, which is de- 

 tached from the remainder, contains HEAD OF HCMA* EMBRYO, about 



i r, . m ' m thp eud of the second month. From a 



the four upper incisor teeth, and cor- specimen ln the anthor , s P098e8s iou. 

 responds with the intermaxillary bone 



of the lower animals. In some rare instances the fissure of hare- 

 lip is situated in the median line, the two intermaxillary bones 

 never having united with each other. A case of this kind has 

 been observed by Prof. Jeffries Wyman. 1 



The eyes at an early period are situated upon the sides of the 

 head, so that they cannot be seen in an anterior view. (Fig. 243.) 

 As development proceeds, they come to be situated farther forward 

 (Fig. 244), their axes being divergent and directed obliquely for- 

 ward and outward. At a later period still they are placed on the 

 anterior plane of the face (Fig. 245), and have their axes nearly 

 parallel and looking directly forward. This change in the situa- 

 tion of the eyes is effected by the more rapid growth of the pos- 

 terior and lateral parts of the head, which enlarge in such a manner 

 as to alter the relative position of the parts seated in front of them. 



The palate is formed by a septum between the mouth and nares, 

 which arises on each side as a horizontal plate or offshoot from the 

 superior maxilla. These two plates afterward unite with each 

 other upon the median line, forming a complete partition between 

 the oral and nasal cavities. The right and left nasal passages are 

 also separated from each other by a vertical plate (vomer), which 

 grows from above downward and fuses with the palatal plates be- 



1 Transactions Boston Soc.ety for Medical Improvement, March 9th, 1863. 



