Landacre, Taste Buds of Ameiurus. 53 



continuous series of buds running from section 132, where they 

 first appear, back to the oesophagus, but in the two preceding 

 series this is not the case. 



In the region of the dorsal pharyngeal teeth it is not possible 

 to separate buds lying on the fourth and fifth pharyngobranchials 

 (or rather epibranchials, since there is only one cartilage present 

 for both these arches), and the mucous membrane is disarranged 

 by the presence of numerous teeth. 



From the table it will be seen, however, that the buds appear 

 on the pharyngobranchials in the same order as on the gills; that 

 is, on the first, then on the second, then in P on the third, and in 

 Q on the fourth. 



No buds are found on the outer sides of the gill arches on the 

 areas occupied by the gill filaments and no buds spread from 

 the dorsal end of the ceratobranchials or the roof of the mouth 

 in the region of the pharyngobranchials out to the inner surface 

 of the operculum up to a period at least as late as the 20J mm. 

 embryo. In this embryo there are buds on the inner surface 

 of the anterior portion of the operculum which belong with the 

 mandible, and buds also extend back on the inner side of the 

 hyoid belonging to the proximal hyoid group, but there is a wide 

 area from this point back to the posterior free border of the 

 operculum totally devoid of buds, so that unless they appear 

 later than any of my series there is no evidence that buds reach 

 the outer body surface from the gill region. 



If they should prove to be found in older embryos to spread 

 back from the mandibular and proximal hyoid groups to the 

 inner side of the operculum beyond the point I have indicated, 

 it would furnish no evidence that buds move from endodermic 

 to ectodermic territory, since these areas are continuations of 

 ectodermic groups and have their innervation from the seventh 

 nerve and not from the ninth and tenth. It should be noted 

 that the spreading here is from anterior to posterior, so that it 

 would be much more likely that buds spread from ectodermic 

 to endodermic territory, provided the anterior limit of the 

 pharynx is cephalad of the area occupied by the proximal hyoid 

 and suspensorium. 



Buds lying on the floor of the pharynx on either side of the 

 median line are innervated by the dorsal branches of the post- 

 trematic branchiomeric nerves in serial order. These nerves 



