936 



DR. A. HOPEWELL-SIIITH AND DR. H. W. MARETT TIMS OX 



iHrectioii of this digitiform involution is inwards and sliglitly 

 upwaxds. There is an involution on either side of the syinphysis 

 and they ai-e qnite symmetrical. The position makes the inter- 

 pretation somewhat doubtful, otherwise we should have but little 

 doubt in ranking them as tooth rudiments. Regarding the origin, 

 connection, and histological characters as of more importance 

 than mere position, we shall I'egard it as such and provisionally 

 indicate it by the letter d (text-fig. 188). 



Close to the middle line, but on the alveolar margin of the 

 mandible, is a more globular involution containing cells commenc- 

 ing to be arranged as a concentrical epithelial body such as several 

 authors now recognise as being tooth A'estiges. This will be 

 referred to as h' . This also is a bilatei'ally symmetrical structui'e 

 and extends through several sections. Immediately above this is 

 a fissure in the oral epithelium containing some deeply stained 

 librous-looking material. The appearance suggests the possibility 

 of this marking the situation where the minute calcified tooth, 

 present in the jaw in this position in the earlier stage, may have 

 been erupted. There is otherwise no trace of the calcified vestige. 



Text-fig. 189, 



Showing the relative positions of the teeth in Stage II. 

 Calcified teeth more heavily outlined. 



A broad bulbous involution of the oral epithelium is seen close 

 to the middle line (c') which soon loses its connection with the 



