Turner, Morfliology of the Avian Brain. 377 



(Plate XVIII, Fig. 8). — This is a small tract which passes 

 from the lateral sensory nidulus of the trigeminal nerve 

 laterad into the root of that nerve. 



Deep Motor I-^'asciculus of the Trigeminal Nerve (Plate 

 XVIII, Figs. 8, 15). — This is a broad bundle of fibres v^^hich 

 passes from the root of the trigeminal nerve directly mesad 

 to the raphe. It intersects the raphe immediately dorsad of 

 the deep motor nidulus of the fifth nerve. This faciculus is 

 composed of several narrow, isolated bundles. 



In addition to the these tracts, there is a tract which de- 

 scends from the epencephalon and enters one of the roots of 

 the fifth nerve. There appears to be no trace of what Pro- 

 fessor Osborn has called the direct encephalic tract, but there 

 appears to be a tract passing into the mesencephalon. Prob- 

 ably that tract communicates with the mesencephalic nidulus 

 of the fifth. 



Tract of the Abducens Nerve (Plate XV, Fig. 12; Plate 

 XVIII, Figs. 10, 13). — As in the amphibian(') and in the 

 reptilian(-) and in the mammalian( ') brain, so here, the 

 internal course of the abducens nerve consists of a single 

 narrow fasciculus. This bundle passes from the nidulus of 

 the abducens nerve ventro-laterad to the external root of that 

 nerve. Although small, this tract is relatively larger than 

 the corresponding tract of the mammalian brain. 



Fasciculi of the Facial and Auditory Nerves (Plate XVIII, 

 Fig. 18). — In birds the root-fibres of the facial and auditory 

 nerves are so intimately associated that it is not now possible 

 to say which fibres belong to the eighth and which to the 

 seventh nerve. In this connection we find four fasciculi, (^) 

 one of which passes to the epencephalon. For convenience, 



1 H. F. Osborn, "Amphibian Brain Studies," p. 70. 



2 C. L. Herrick, " Notes on the Alligator Brain," p. 153. 



3 Ambrose L Rankev, op. cit., p. 339. 



4 Among my notes I have one, dated several months ago, in which is described for 

 the avian brain a tract resembling the genu of the seventh nerve as it appears in the 

 mammalian brain. Since that time the series that furnished the note has faded so much 

 that verification has been impossible. Other series have been carefully studied, but no 

 such tract has been since encountered. — C. H. T. 



