BY R. BROOM. 



203 



KSection B (fig. 14) is through near the middle of the external 

 nares. The nasal capsules are seen joined in the middle line. 

 A portion of the premaxilla is seen below the base of the cartilage. 

 The flap of cartilage, which passes forwards and forms a floor to 

 the nostril, is cut across. In the lower jaw (not figured) the 

 symphysis of Meckel's cartilages is seen, and a portion of the 

 dentary. 



Section C(fig.l5) is through the posterior border of the nostril. 

 The nasal septum now shows no sign of having a double origin. 

 Inferiorly it passes far down towards the papilla palatina, and is 

 wedged between the premaxillary bones. The cartilage of the 

 nasal floor extends inwards to the base of the septum, against 

 which it abuts. Above its outer end is a small triangular piece 

 of cartilage which stretches across from the alinasal at the back 

 of the nasal opening, to the nasal floor-cartilage. Tiie front of 

 the maxilla is cut across. 



Section D(fig.l6) is through the posterior part of the nasal 

 capsule. The alinasal cartilage is open above; and, attached to 

 its upper part, is the large orbitos})henoid cartilage. The lower 

 part is short and thick. The paraseptal is seen joining on to the 

 middle region of the alinasal. The median or septal cartilage is 

 short and broad. The maxilla appears to be much thickened, 

 but this is due to the secondary palate being cut obliquely. The 

 lachrymal can be detected, but it is not yet ossified. 



Section E (Pl.xiv., fig.17) shows the relations of parts at the 

 anterior end of the alisphenoid. The basal cartilage is partly 

 divided by the almost obliterated pituitary canal. External to it 

 lies the rounded alisphenoid. Above the alisphenoid is seen the 

 second branch of nerve v., and further up the well developed 

 orbito-sphenoid cartilage. 



Section F(fig.l8) is through the middle of the alisphenoid 

 cartilage. At this stage the cartilage difl'ers from that of the 

 earlier in having an upward growth towards the orbitosphenoid 

 on the outside of the Gasserian ganglion. Though the alisphenoid 

 is partly fused with the basal cartilage, the division is still well 



