author's abstract of this paper issued by 



THE bibliographic SERVICE, SEPTEMBER 13 



THE BRANCHES OF THE BRANCHIAL NERVES OF 

 FISHES, WITH SPECIAL REFERENCE TO 

 POLYODON SPATHULA 



EDWARD PHELPS ALLIS, JR. 



Palais de Carnoles, Menton, France 



A branchial nerve was long considered to have but three 

 typical branches, a ramus posttrematicus, a ramus pretrematicus, 

 and a ramus pharyngeus. The rami posttrematicus and pre- 

 trematicus were said to both lie along the convex, and hence 

 external surface of the branchial bar of the arch to which they 

 are distributed, the ramus pretrematicus lying in the arch next 

 anterior to the ramus posttrematicus, and posterior and parallel 

 to the ramus posttrematicus of that arch. Stannius ('49) 

 found, in nearly all of the many fishes examined by him, the 

 basal portions of the rami pretrematicus and pharyngeus of the 

 nervus glossopharyngeus fused with each other for a certain 

 distance, thus fonxdng a so-called ramus anterior s. hyoideus, 

 but he makes no mention of similar fusion in any of the other 

 nerves. The ramus posttrematicus of each branchial arch is 

 said by him to send an important branch or branches to the 

 dermal tissues that cover the anterior surface of the branchial 

 bar of the arch, but neither this branch nor the rami dorsales 

 of the nervi glossopharyngeus and vagus are spoken of as typ- 

 ical branches of a branchial nerve. 



In 1911 Sewertzoff recognized and described what he con- 

 sidered to be a fourth typical branch of a branchial nerve, and 

 as it is pretrematic in position and Hes along the concave, and 

 hence internal, surface of the arch to which it is distributed, he 

 called it the ramus pretrematicus internus, the ramus pretre- 

 maticus of earher descriptions then becoming the ramus pre- 

 trematicus externus; Sewertzoff gives me credit for having 

 shown, in one of my drawings of Amia (Allis, '97, fig. 59, pi. 35), 



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