Landacre, Taste Buds of Ameiuriis. 



21 



surface. It is not possible to distinguish between the buds on the 

 lip, on the breathing valve and on the region of the premaxillary 

 teeth. Teeth are not present at this stage and the premaxillary 

 bone, being a membrane bone, is not present and the breathing 

 valve is not yet differentiated from the lip. The breathing valve 

 can, however, be distinguished easily from the roof of the mouth 

 at this stage. The epithelium of the lip and breathing valve is 

 thick, while that of the roof of the mouth is thin. This enables 

 one to separate these two structures from the roof of the mouth, 

 which receives buds much later. All these areas receive buds 

 simultaneously and all are innervated by communis fibers running 

 out through the ramus maxillaris (excepting one twig from ramus 

 mand. V to the barblet),the buds of the maxillary barblet and the 

 skin of the upper lip just in front of the maxillary barblet and con- 

 tinuous with it being supplied with the lateral branch of that 

 nerve and those of the lateral parts of the upper lip and the region 

 of the premaxillary teeth by the mesial stem of the same nerve. 

 The budsof the maxillary barblet are supplied by three twigs from 

 the same nerve. Herrick ('oi), in his description of the distribu- 

 tion of the ramus maxillaris, does not mention the upper breathing 

 valve and I infer that it is included in the description of the inner- 

 vation of the lateral lip region and the premaxillary region. 



Table V shows the number of buds and the number of sections 

 occupied in this group for series K' to P. 



TABLE V. 



Table showing time of appearance, rate of increase and length of area measured in sections occupied 

 by the dorsal lip and maxillary barblet groups. Under each age the first column gives the number of 

 buds present, the second column the extent indicated by the section numbers between which they are 

 found. 



This area, although innervated by several nerves, would un- 

 doubtedly function as a unit. The only exception to this state- 

 ment that might be taken is in regard to the maxillary barblet, 

 but as stated above its first buds appear at the base of the anterior 



