ventralia", the latter of which extending (varying in size) from the 

 entrance of the V to the X. 



In Gegenbauk's Festschrift Fürbringer '; describes the spinal, occi- 

 pito-spinal and vagal roots (p. 616 et seq.) and gives a drawing of the 

 roots of the American Myxinoid : Bdellostoma (Text figure 1). Accord- 

 ing to him the vagus leaves the brain with 1 — 4 rootlets (he 

 draws 2) and j)0ssesses a prevailing motor character (p. 619). 



FiiKBRiNGKR statcs that this also holds good for Mjxine. He con- 

 siders the glossopharyngeus — not mentioned by preceding authors — 

 as represented by elements of the nervus pharyngeus X, although 

 he states that a branchial sack innervated by the IX is failing in 

 Myxinoids. In other words he grants the absence of an indepetident 

 IX, but supposes that elements of it are included in the pharyngeus 

 branch of the X. *) 



FüRBRiNGKR cmphasizcs that the spino-occipital roots are shifted in 

 a frontal direction in Myxine. This holds good as well for his 

 first sensory spino-occi|)ital I'oot as for his second S|)ino-occipital 

 root. The first in his opinion enters the brain on the level of 

 the ramus aciisticus posterior, the second near the level of the vagus 

 roots. FüRBRiNGKR poiuts out that, in conti-ast to Myxine, in Petromyzon 

 the spino-occipital roots are located on a fairly large distance behind 

 the vagus roots. 



This difference between Myxine and Petromyzon, according to 

 him, can be explained in two ways, either the first spino-occipital 

 root of Myxine is lackijig in Petromyzon, or the spino-occipital 

 roots are shifted forward in Myxine. Fürbringkr believes that the 



1) Fürbringer, Uebei- die spinooccipilalen Nerven der Selachier iind Holoce- 

 plialen und ihro verglcicliende Morpliologie. Festsclirift fur Gegenbaur Teil ill 1897 

 p. ct4y-7GG. 



We do not deal here with llie papoi' of Ransom and d'Arcy Thompson (quoted 

 by Fühbringer) because it contains very little on our subject. Compare : On the 

 spinal and visceral nerves of Gyclostoinata. Zoologischer Anzeiger No. IX, 1886 

 p. 421. 



~) We may add here that Miss Worthington, to whom we owe such an excellent 

 series of papers on the American Myxinoid Bdellostoma, considers this branch as 

 a real IX (1. c. p. 172), "lying so close to the X that it is difficult to distinguish 

 one from the other". She also mentions that they have a common foramen and 

 that (p. 173) "the glossopharyngeus runs in the same sheath with die vagus as 

 far as the second branchial arch"'. Consequently — as far as these points are 

 concerning — • the presence of a real glossopharyngeus is nol very conspicuous either 

 in Bdellostoma nor in Myxine — Since its periferal territory also is fairly well 

 atrophied — - (see the following pages; these arguments for the |)resence of a IX 

 seem to be open to criticism, though in a very rudimentary way it may be 

 present. 



