372 H. W. NORRIS AND SALLY P. HUGHES 



ertzoff gives no figures or exact descriptions of these nerves in 

 Acanthias, and his citation of Bender ('06) as an authority for 

 their occurrence in the latter form is of little weight, since Bender 

 gives neither figures nor description of them in Acanthias. After 

 an examination of the figures of Sewertzoff and Bender there can 

 be little doubt of the presence of these so-called rami pretre- 

 matici interni in Heptanchus, Scyllium, Raja, and Centrophorus, 

 but in Squalus acanthias the ramus pharyngeus of the branchial 

 nerves does not divide into a dorsal pharyngeus and a latero- 

 ventral ramus pretrematicus internus. The entire ramus phar- 

 yngeus is distributed dorsally. The pharyngeal rami of the third 

 and fourth branchial nerves of the vagus do divide immediately 

 on emerging from the main nerve, but into anterior and posterior 

 divisions, both distributed dorsally and not laterally. Pharyn- 

 geal, pretrematic and posttrematic rami occur in all the branchial 

 nerves including the facialis proper. Bender regards the ramus 

 palatinus of selachians as a combination of a ramus pharyngeus 

 with a ramus pretrematicus. In quite similar fashion the ramus 

 pharyngeus of the glossopharyngeal nerve unites for some dis- 

 tance with the ramus pretrematicus. In both the facialis and 

 the glossopharyngeus of Squalus the ramus pretrematicus near 

 its dorsal end gives off small twigs, in one case to the pseudo- 

 branch, in the other to the wall of the first gill cleft. In the vagal 

 branchial nerves the pharyngeal and pretrematic rami arise from 

 the main nerve sharply distinct from each other. The accessory 

 posttrematic rami occur in a double condition in the glossophar- 

 yngeus and fourth vagal branchial (fig. 48). 



8. The ramus intestino-accessorius X 



As this nerve trunk leaves the ganglion posteriorly, its coarse 

 motor constituents form a narrow band along its dorsal border. 

 These soon separate as a distinct nerve that passes posteriorly 

 along the dorsal border of the visceral sensory elements of the 

 nerve trunk, finally rising in a few divisions into the trapezius 

 muscle which it innervates (figs. 48 and 51, trap.). The fine 

 motor and I he sensory elements of the ramus continue straight 



