No. I.] THE CRANIAL NERVES OF AMPHIBIA. 171 



inasmuch as while the R. maxillaris receives a portion of this 

 root, yet no motor branches are mentioned in its distribution. 

 This ascending part is the sensory Trigeminus proper. 



Wright's account agrees with that of Goronowitsch in some 

 respects, but differs in others. Trigeminus II, or a root from 

 the tuberculum acusticum plus one from the lobus trigemini, 

 gives rise to the Rr. ophthalmicus superficialis, buccalis, and 

 oticus, and reenforces the VII. On the other hand, according 

 to Wright, the ophthalmicus profundus is derived from the 

 lobus trigemini ; according to Goronowitsch, from the non- 

 homologous Trigeminus I. There appears to be no R. lateralis 

 trigemini in Acipenser. Another important difference is that 

 Wright assigns two Rr. palatini to the Trigeminus, derived 

 from the lobus trigemini, while Goronowitsch denies the exist- 

 ence of any such branches from the Trigeminus, and asserts that 

 they belong exclusively to the Facialis. This latter point will 

 be discussed later. There should be three Rr. ophthalmici, 

 one the profundus and the other two Rr. ophthalmici super- 

 ficiales, of which one belongs to the Trigeminus proper 

 (== Trigeminus I), and the other is derived from the Facialis 

 (ventral root of Trigeminus II = dorsal VII plus, in some cases 

 at least, fibres from a root emerging from the lobus trigemini). 

 Both Goronowitsch and Wright appear, however, to describe 

 only two. This, together with the fact above mentioned, that 

 the ophthalmicus profundus of one does not seem to be strictly 

 homologous with that of the other, is difficult to account for. 



It is in Stannius' splendid memoir, Das peripherische 

 Nervensystem der Fische (57), that we find the most accurate 

 account, it seems to me, of the peripheral nervous system of 

 fishes. Stannius not merely dissected but also checked his 

 results by stimulating the roots, and, likewise, investigated the 

 character of the fibres composing the roots and branches. 



For the N. trigeminus cum nervo faciali in forms where the 

 roots are most separated {Pleurotiectes), Stannius describes 

 the following roots: 



I St root, stout ; mixed fibres, viz., mostly medium, with a 

 number of very large fibres and a smaller number of fine fibres. 

 Contains a motor element to the jaw muscles. 



