ON THE ORIGIN AND DEVELOPMENT OF THE 



(n), under which the needle was easily inserted for a short 

 distance. In the middle, this lip (m) was thin, elevated, and 

 curved over the groove (h). Anteriorly it became broader, 

 and curved still more over the groove, and was divided into 

 two median larger lobules (d) y and two lateral smaller (e). 

 Between the two median (d) there was a notch at the attach- 

 ment of the lingual frenum. The outer lip (/) was defi- 

 cient anteriorly, so that the groove was bounded in that 

 situation by the under lip (a), which was loose, free, and 

 turned outwards. Posteriorly the outer lip (/) was well de- 

 veloped, and came out from under the posterior lobe (n) of the 

 inner lip, so as to render the grove (h) pointed, and curved 

 backwards and inwards. This lip (/) extended only about 

 half-way towards the median line, and appeared flat, or in the 

 same continuous plane with the floor of the groove. It was 

 also curved outwards, so as to overhang the labial mucous 

 membrane. 



The groove presented an elevation (o) of its floor near its 

 posterior extremity. There was a labial frenum. The mucous 

 membrane possessed the same physical properties as at the 

 sixth week. The lobes were not so granular, but tougher and 

 more consistent. Breadth of superior arch 1 J line, length 1. 



3. The jaws of an embryo at the second month, having 

 /% been prepared in the usual man- 

 ner, presented the following ap- 

 pearances : 



Upper Jaw. The lip (a, Fig. 

 6) was more movable, and its free 

 edge less extended. The cleft in 

 the palate had diminished, exist- 

 ing only as a small angular defi- 

 ciency (x) in the pendulous por- 

 tion. The horse-shoe lobe was still perceptible under the 



