22 'Journal of Comparative Neurology and Psychology. 



surface where they are continuous with the inner and lateral por- 

 tion of the lip. And when buds appear later distally on the bar- 

 blet, they are accompanied by other buds farther back on the body 

 which would increase the area innervated from the lip region, 

 that is, the long maxillary barblet bearing buds on its distal por- 

 tion is equivalent to enlarging the cutaneous group by spreading 

 over the head and body. 



This group is isolated in position from buds on the top of the 

 head by an area devoid of buds between it and the nasal group 

 which appears later and from the anterior palatine group by the 

 later appearance of that group as well as by the diffjerent histo- 

 logical character of the epithelium on which they are situated. 

 The buds on the maxillary barblet supplied b}^ the ramus mand. 

 V cannot be separated from those supplied by the ramus maxil- 

 laris. There is no reason, however, for supposing thrt they do 

 not appear along with the other maxillary buds in point of time 

 rather than with buds appearing later in other areas which are 

 innervated by the ramus mand. V. The almost invariable rule 

 is for buds to appear with their functional group regardless of the 

 various nerves supplying them. 



5. THE VENTRAL LIP AND BARELET GROUP. 



This group includes buds Iving inside the mouth on the lower 

 lip and mucosa covering the mandible and on the outside cover- 

 ing the outer anterior surface of the mandible and on the mental 

 and post-mental barblets. All these buds are placed under one 

 head because those lying on the anterior portions of the lips are 

 continuous both with those inside the mouth and with those under 

 the lips on the outside of the body. They probably comprise 

 two groups, however, at least functionally. Those lying inside 

 the mouth w^ould function with those buds occupying a similar 

 position on the upper lip and breathing valve and the region of 

 the premaxillary teeth, while those lying under the lower jaw and 

 on the mental and post-mental barblets would function with the 

 buds situated on the maxillary barblet and those of the nasal group. 



Structurally this group is isolated, both those lying inside the 

 mouth and those outside, from groups lying farther back by well 

 defined areas devoid of buds at the time the posterior groups 

 appear and by the later appearance of those groups. 



