2l4 EDWARD PHELPS ALLIS, JUN. 



root of Trigeminus II could not be a motor one, but, after 

 renewed investigation, he reaffirms liis belief that it is such. 

 Johnston (39) follows Strong and Kingsbury in assigning 

 this ventral root to the lateral sensory system, the dorsal root 

 of Trigeminus II being said by him to also belong to the same 

 system, he thus here agreeing with Kingsbury as against 

 Strong. Herrick (32), still later, also asserts that the ventral 

 root is sensory, and not motor, and such is unquestionably 

 the case. 



Groronowitsch does not give, in Acipenser, the separate 

 peripheral distribution of the fibres arising by each of the two 

 roots of Trigeminus II, but Strong assumes that the fibres of 

 the two roots are completely mingled, and that they must 

 accordingly be found in all the so-called lateral sensory 

 branches that have their origin from this root (60, p. 179). 

 This would seem to be practically established by what I find 

 in Mustelus. Strong says that the branches said by Gorono- 

 witsch to be derived from the nerve Trigeminus II, his 

 (Strong's) facialis, have, in Acipenser, the same course and 

 position as the lateral sensory branches of the facialis in the 

 tadpole. They also have the same course and position as the 

 lateral sensory facialis branches in xlmia and Scomber (3 and 

 7), excepting only the branch said by Groronowitsch to join 

 and accompany the ramus hyoideus facialis. This lateral 

 branch of Acipenser seems to be represented in Amia by 

 that part only of the mandibularis externus facialis that goes 

 to the preopercular lateral canal, or perhaps even to the dorsal 

 part alone of that canal. These latter fibres of the mandi- 

 bularis externus of Amia arise directly from the truncus 

 hyoideo-mandibularis, as apparent branches of that nerve, 

 while the remaining, more distal, branches all arise from the 

 ramus mandibularis externus after it separates from the ramus 

 hyoideus, to which nerve the mandibularis externus has, in its 

 further course, no relations whatever. The absence, in Aci- 

 penser, of this distal and independent part of the mandi- 

 bularis externus nerve of other fishes was noticed by van 

 Wijhe, who says (65, p. 237) that his failure to find it was 



