56 'Journal of Comparative Neurology and Psychology 



accompanied by the much smaller pre-trematic branch of the vagus for the first gill. The vagal branch 

 follows the ventro-mesial border of the ceratobranchial bone, the glosso-pharyngeal the ventro-lateral. 

 Large taste buds are found along the whole length of the ceratobranchial bone on its mesial and dorsal 

 surfaces and on the gill rakers which spring from it. All of these buds seem to be innervated from the 

 dorsal IX branch. The fibers for the buds on the gill rakers are very delicate and feebly medullated 

 and I was not able to observe their origin with certainty. 



Before the distal (ventral) end of the ceratobranchial is reached the vagal nerve has disappeared, 

 probably distributed to the gill filaments, the ventral IX branch meanwhile moving mesially to lie in the 

 center of the gill arch. It sends twigs into the gill filaments and their muscles, but is not greatly 

 reduced in size. The dorsal branch of the IX disappears before the first gill joins the copula. The ven- 

 tral branch of the IX is the true lingual nerve. At the union of the first gill with the copula this nerve 

 curves up to lie immediately under the mucosa just behind the union of the hyoid with the copula and 

 then breaks up into smaller branches. One considerable branch turns backward along the dorsal sur- 

 face of the hyoid (see theAmeiurus paper, Herrick, '01, p. 193). The others distribute to the mucosa 

 over the hyoid at its juncture with the copula, extending from the median line far laterally and cephalad 

 as far as the basihyal bone extends. The hyoid arch is very large at its union with the copula in the 

 adult of these fishes and this whole area is covered with large taste buds which I think are all supplied 

 by this nerve. 



As stated, the first pre-trematic branch of the vagus does not reach the copula at all, and I do not find 

 any evidence in the adultinnervation of any such segmentation of the floor of the pharynx in the glosso- 

 pharyngeus region as you describe in the embryo. 



In the other gills the relations are, mutatis mutandis, the same as in the first gill. On the dorsal side 

 of each gill arch is one branch of the post-trematic division of the vagus. Below the arch is another and 

 the pre-trematic nerve. The latter ends before the arch joins the copula. The upper, or dorsal, post- 

 trematic nerve ends also before the copula is reached, while the ventral post-trematic nerve extends out 

 upon the copula, where it passes upward to reach the mucosa and divides to supply buds over the basi- 

 branchial and hypo-branchial, branches turning laterally to spread over the whole dorsal surfaces of 

 the latter. 



Third Truncus Branchialis Vagi of Menidia. 



The copula in Menidia, unlike that of Ameiurus, is very slender — elongated, but narrow. The slen- 

 der branchial arch follows closely parallel to the basibranchial for a considerable distance before fusing 

 with it. The basibranchial is very slender and there is a row of very large taste buds directly over it in 

 the median line and some similiar buds are found more laterally scattered over the hypobranchial, which 

 for its entire length runs parallel with the basibranchial and enveloped by the fleshy copula. The pre- 

 trematic branch of the fourth truncus branchialis vagi disappears before the third gill reaches the copula. 

 The dorsal branch of the third r. branchialis vagiterm inates among big taste buds on the dorso-lateral 

 aspect of the copula over its union with the branchial arch. It does not extend far forward on the 

 copula. The sensory fibers of the ventral branch, however, terminate in part more medially than the 

 last over both the basibranchial and the hypobranchial and in part as far cephalad as the hypobran- 

 chial extends over both it and the siender basibranchial. 



The relations here are substantially as I described them in the IX nerve of Ameiurus, save for the 

 changes produced by the elongation of the pharynx in Menidia and its widening in Ameiurus. In 

 neither case is there any possibility of the pre-trematic nerve playing any part in the innervation of taste 

 buds in the copula or very near it. The buds over the basihyal and basibranchial bones are innervated 

 by the ventral branch of the post-trematic nerve; those over the hypobranchials and hypohyal have in 

 general the same innervation, though the dorsal branch may share in their innervation laterally. 



