Text-fig. ]. 



In this and the ensuing figures the following general statement 

 holds good of all, and need not be repeated. The figures are of 

 sections cut deliberately thick, the diameter being 25 n (i. e. 

 4\j mm. ). The direction of all the sections is transverse to the long 

 axis of the head. Where necessary for explanation, the sign * is 

 on the lingual side. The following lettering is employed : 



. a, rudiment of milk tooth, b, rudiment of permanent tooth, 

 c, residual lamina. d.p., rudiment of dentine papilla. E., 

 Epithelium of mouth cavity which gives origin to dental lamina. 

 S, side of head. U.J., upper jaw. L.J., lower jaw. 



Fig. 1 represents a portion of the upper and lower jaw to show 

 the i^osition of the tooth germs of these two jaws in relation 

 to each other. The tooth of the lower jaw is seen to lie outside of 

 that of the upper jaw. 



B 2 



