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Fig. la. 



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Showing the reduction in the frontal part of the vagal column. 



since the overlapping of the caudal part of the vagal cohnnn and 

 spino-occipital column, as well as the topography of the posterior 

 extremity of the ■ vagal column to the spino-occipital roots, are the 

 same in both Petromyzon and Myxine. 



The reduction of the roots and of the frontal part of the vagal 

 colunm in Myxine is also in harmony with Stockard's observation 

 that in Myxinoids, at least in its American foi-ni Bdellostoma, the 

 branchial sacks behind the hyomandibular arch are atrophied. ^) 



The vagal column begins fairly near the posterior extremity of 

 the mixed V — VII nucleus, lying in a somewhat more dorsal position 

 (Comp. Fig. 3, 7 and 8). A few scattered cells lie between them, thus 

 constituting a sort of broken link. 



The size of the vagust-ell-^ is considerably smaller than that of 

 the frontal V nucleus, more like the cells of the mixed V — VII 

 nucleus, specially the smaller caudal cells of the latter. 



In its frontal part the vagus nucleus is rather small and the cells 

 do not attain their largest size here. The nucleus as well as the 

 cells attain their maxinnun development in the middle part. We 

 have not been able however, to state a dixision of the nucleus in 

 three parts as Holm did. 



1) Stockard : The development of the Mouth and Gills in Bdellostoma Stouti. 

 American Journal of Anatomy Vol. V 19ÜÖ, specially p. 511 and fig. 33 — 3(5. 

 Compare also for further knowledge of these animals : 



Ayers. Bdellostoma dombeyi. Woodsholc lectures for 181>3. 



VVoRTHiNGTON. Contribution to our knowledge of the Myxinoids. American 

 Naturalist Vol. 3'J, 19Uü. 



