fust is (rue, and that consoqiiently the lit si sensory spiiio-ocoipilal 

 root of Myxiiie is lackiriii,' in (lie I.arnprey. 



We may remark liei-e tiial, in our opinion, Füiibktnüer is mistaken 

 when he considers the first root here mentioned as being a spino- 

 oceipital one. We are moi-e inchned to believe tiiat in Myxine tiie 

 same relation is found as in Iklellosloma, for which Miss WoirniiNcrroN 

 has pointed out that Fükbringer's first spino-occ. root is the Acusticus 

 b, i. e. a hiteralis root. ^) 



The topographical difference in the spino-occipital roots between 

 Mjxine and Petromyzon consequently is not so considerable as FQr- 

 RRiNGER thought, siuce the spino-occipital roots of Myxine do not 

 reach as far fi-ontally as the acusticus. 



Still there is a conspicuous frontal dis{)lacement of spino-occipital 

 elements in Myxine, as appears from a comparison of Fig. 2 with 

 F'ig. 1. In our opinion the transitory region between oblongata 

 and cervical cord is shift<^d in a frontal direction. 



The vago-spino-occipital region of the oblongata has approached 

 the trigemino-facial region, the otic and postotic part of the bulb 

 being reduced. This frontal shifting of the vago-spino-occipital i-egion 

 of the brain is accompanied by a frontal disphicement of the spino- 

 OQcipital nucleus and roots, but the vagusroots (see fig. 2) are not 

 so much displaced as their nucleus and remain behind, pei'haps 

 on account of their lying on the ear capsula. 



In consequence the spino-occipital and vagus roots have consider- 

 ably approached and the vagusroots appear crowded together on the 

 level of the caudal extremity of the nucleus, instead of being divided 

 fairly regularly over the level of the whole nucleus as is the case 

 in Petromyzon. 



That the whole vago-spino-occipital region of the bulb has shifted 

 frontally and not only the spino-occipital region, appears from the fact 

 that the spino-occipital column does not overlap the vagal column 

 in Myxine more than in Petromyzon. 



As ali-eady said, this process is accüm|)anied, if not partly caused, 

 by a reduction of the acoustic region of the brain. That the acoustico- 

 lalei'al system in Myxinoids is not very much developed results also 

 from the researches of Ayeh.s and Wortuington ^) (see further below). 

 We shall now proceed to the description of the nuclear topography 

 of the bulb and discuss at the same time the paper published by 



^) Compare: Quarterly Journal of Microscopical Science Vol. 49, J 906 p. 171 

 and 175. 



~) Avers ami Worth [ngton : The liner anatomy of Hie bram of lidellosloma 

 dombeyi 1. The acustico-laleral system. American Journal of Anatomy vol. Vill, l'J08. 



