284 



this and the hamular 

 process cau be seen 

 the cartilage of the 

 great wing which is 

 undergoing ossification 

 CO. and below it is the 

 wedge - shaped 'mem- 

 branous' external ptery- 

 goid plate M.O. also 

 undergoing ossification, 

 but, as can be seen, this 

 ossification takes place 

 directly in membrane. 

 Figure 5 may be 

 described as a lucky 



Fig. 3. Coronal section 

 of head of an 11 weeks em- 

 bryo. E.T. mouth of Eu- 

 stachian tube. M.G. Meckel's 

 ganglion. S.M.N, sup. maxil- 

 lary nerve. O.e. ossific con tre 

 in internal pterygoid plate. 

 T.P. tensor palati. V.N. 

 Vidian nerve. 



section which cuts 

 through both pterygoid 

 plates and the hamular 

 process. The specimen 

 was a little older than 

 the previous one and 

 it was cut neither coro- 

 nally nor horizontally, 

 but somewhere between 

 the two. Here the 'mem- 

 branous' centre M.C. 

 of the internal ptery- 



Fig. 4. Coronal section 

 of head of 3 months fetus. 

 CO. ossific centre iu carti- 

 lage of great wing below 

 foramen rotundum. H.P. 

 hamular process shewing 

 cartilage bone at root and 

 unossified towards tip. M.O. 

 membrane bone in pterygoid 

 process. P. palate bone. 

 T.P. tensor palati muscle. 



