48 'Journal of Cotnparative ISl e urology and Psychology. 



is conceivable that the specialized portions of the communis sys- 

 tem may be derived from that portion of the geniculate ganglion 

 which came from the epibranchial placode. In that case its 

 specialized character could be traced to the fact that it w^as 

 derived from a specialized sensory area before it became buried 

 and a part of the ganglion. The question of where buds 

 appeared first phylogenetically becomes then of secondary 

 importance, since they might appear at any place where these 

 specialized communis fibers reached the surface. 



12. THE GROSS DISTRIBUTION OF THE PHARYNGEAL GROUP. 



The pharyngeal group of buds, like the oral, appears on K' 

 (113 hours), where buds appear on the first, second and third 

 gill arches simultaneously. The smaller number, two, on the 

 third arch indicates, however, that if series had been taken at 

 small intervals preceding K', they would have been found on 

 the first gill arch first, then on the second, and then on the third. 

 This probability is strengthened by the fact that buds on the 

 fourth gill arch do not appear until in O and on the fifth or 

 posterior demi-branch until in R. 



TABLE XV. 



Table showing the gross distribution of the taste buds on the distal portion of the hyoid arch, the gill 

 arches, the roof and floor of the pharynx and in the oesophagus. 



In the earlier series the first buds to appear lie on the free 

 portions of the gill arch, that is, not on the point of attachment, 

 although they are quite near the median ventral line, and do not 

 reach to the dorsal portion of the gill, but appear here later, so 



