1 8 ^^ournal of Comparative Neurology and Psychology. 



uity as they spread backward and all are innervated by the seventh 

 nerve in common with buds in the anterior oral regions. 



The pharyngeal group includes, in the region of the overlap, 

 buds on the floor of the pharynx, on the distal portion of the hyoid 

 and on the gills. These are all innervated by fibers from the ninth 

 and tenth nerves, and, with the exception of the distal portion of 

 the hyoid, appear in segmental order from the first gill back- 

 ward. 



The oral group begins at the extreme anterior end of the mouth 

 and in series U extends back to section 174, the most posterior 

 buds of the oral group at this time being situated on the proxi- 

 mal portion of the hyoid. 



The pharyngeal group begins at section 68 in K' and appears 

 in 116 in L and its anterior buds then remain constantly near the 

 89th section in the remaining series. The most striking excep- 

 tion is in O', in which the group extends forward to section 67. 



The most anterior buds of the pharyngeal group as catalogued 

 here always lie in the median ventral line in front of the union 

 of the hyoid with the copula and the overlapping described above 

 is due to the growth of the oral group backward over the pharyn- 

 geal and not to the growth forward of the pharyngeal, since the 

 anterior pharyngeal buds lie grouped about the 8gth section and 

 the oral move back from the 15th to the 174th section. 



In series S, T and U the oesophageal buds are included with 

 the pharyngeal. If we subtract 3 sections from S, ten from T 

 and 26 from U, it will give the exact limit of the pharyngeal group. 

 This makes the total in the three groups, respectively, 131, 142 

 and 182 sections. 



The preponderance of taste buds in the pharynx where there 

 are 477 in U as compared with 188 in the oral group is not accom- 

 panied with a corresponding elongation of the pharyngeal areas 

 as compared with the oral areas in the early stages of Ameiurus. 

 Even in U, where the areas occupied by oral and pharyngeal buds 

 are nearly equal, being 172 and 182, respectively, the number of 

 buds in the pharynx is more than two and a half times as great 

 as that in the oral group. 



A comparison of the posterior limit of the oral and cutaneous 

 groups shows a much slower rate of progression in the cutaneous 

 group. In series N, for instance, where the cutaneous buds first 

 appear, the posterior limit of the oral group is section 65, while 



