1 88 Journal of Comparative Neurology. 



IX^+^ ; that is, the region between tracts a and b, separated 

 therefore from Vllb^ by tract a. Some of the fibers appear to 

 terminate immediately ; most of them, however, turn caudad 

 and may be readily followed for but a short distance, since they 

 soon lose their myelin, and become indistinguishable ; some 

 even as amyelinic fibers may be followed for a short distance 

 farther, that is to a little caudad of the exit of the eighth nerve. 



Vllb^ and Vllb- unite immediately to form Vllb which 

 soon divides into two approximately equal portions, one of 

 which joins the motor and fasciculus communis portions of the 

 seventh and the eighth nerve, while the other division goes 

 cephalad to the Gasserian ganglion. 



The close comparison in origin between IX'+- and Vllb" is 

 evident : both end in approximately the same region caudad of 

 the eighth ; the fibers of IX^+^ turning cephalad to it, those of 

 Vllb^ caudad to it. The difference in origin between VI Ib^ and 

 and VIIb\ though slight, might seem to indicate that the two 

 roots were different; that VI Ib^ passed to the Gasserian gang- 

 lion and should be considered as belonging to the fifth proper, 

 as was interpreted by Herrick ('94), and representing perhaps 

 the dorsal root of Trigeminus II of Goronowitsch in Acipcnser. 

 This does not seem to be the case however ; the fibers of both 

 roots are of the same size and appearance ; further, the divis- 

 ion between the roots is not the the division between the por- 

 tions which join the fifth and seventh, a portion of the Vllb^ 

 undoubtedly joining the seventh and eighth. In smaller forms, 

 e. g., Amblystoma and Diemyctylus, a division into two roots is 

 less marked, due partly to the weaker development of a tract 

 separating them.^ 



1 Pinkus, '95, has examined the larvte of Salamandra maculosa and atra, Des- 

 niognathus fusca and Salatnandrina, and recognized in all the lateral line root of 

 the VII (Vllb of Strong). In the adult of Salamandra atra and Geolriton Jtiscus 

 the lateral line nerves are absent, although in the first genus a delicate strand 

 pasess from the seventh nerve to the Gasserian'ganglion and at that point atro- 

 phies. I have examined in this connection the brains of adult forms of Atn- 

 blysto7na punctatu77i, Diemyctyhis viridescens, Desmognathus fusca and Plethodon 

 erythronottis. In the first three genera the lateral nerve roots of the VII were 

 present, although in Desmognathus the bundle to the Gasserian ganglion was 



