Landacre, Taste Buds of Ameiiirus. 31 



the post-orbital group in point of time. Even in the 11 mm. 

 embryo there is an area of 30 sections between them quite free 

 from buds. 



The posterior mandibular group buds are distributed as fol- 

 lows with reference to the mandibular lateral line organs. In 

 the II mm. embryo, four lie between the third and fourth organ, 

 and four between the fourth and fifth, while in the 14! mm. em- 

 bryo, where there are 1 1 buds, six lie between the third and 

 fourth organ, and five between the fourth and fifth. In the ijh 

 mm. embryo, not shown in the table, there are 13 buds, six 

 lying between the third and fourth organs, five lying between the 

 fourth and fifth organs, and two between the fifth and sixth 

 organs; compared with the lateral line organs, we have an evident 

 spreading from anterior to posterior. 



It is difficult, in later stages, to separate the posterior mandi- 

 bular buds from the opercular groups, but since the mandible 

 does not extend farther back than section 131 in the 9.4 mm. 

 embryo and the first buds in the opercular group appear in section 

 166, which is between the seventh and eighth mandibular lateral 

 line organs, it is altogether probable that the separation of these 

 two groups is represented by this difi^erence. In the 1 1 mm. 

 embryo the mandible does not extend beyond section 184, and 

 the last bud on the mandible lies in section 129 and the first of 

 the opercular group in 160. 



Herrick ('01) describes the recurrent twig of the mandib. 

 ex. V as supplying the skin over the dentary, articular and 

 quadrate bones. It is possible that the first two buds of the 

 opercular group, which lie in sections 160 and 163 behind the end 

 of the mandible, and 30 sections in front of the remainder of the 

 opercular group, may belong to the quadrate group, although 

 he does not say specifically that the recurrent nerve supplies 

 taste buds. 



The posterior mandibular division at the time of its appear- 

 ance is quite distinct from the anterior mandibular division 

 anteriorly and from the posterior opercular division posteriorly.' 

 Its innervation is undoubtedly at this time solely from the ramus 

 mand. ex. VII. It also shows, as mentioned above, a well de- 

 fined progression from anterior to posterior, spreading from the 

 second and third mandibular lateral line organs to the region 

 between the third and fourth and later to that between the 



