Kingsbury, Oblongata in Fishes. 15 



examined, although it may possibly be found in older specimens. 



Of the cranial nerve roots little need be added to Wright's 

 account. The sensory portion of the Xth springs from the 

 lobus vagi in a single large root, passing dorsad of the spinal 

 Vth. A smill contingent of fibers from this tract was easily 

 demonstrable. The motor portion of the vagus springs from 

 its nidus just ventrad of the fasciculus communis in 8- 10 small 

 roots which pass on the ventral side of the spinal Vth. A root 

 bundle of the Xth. composed of coarse fibers of characteristic 

 appearance, undoubtedly the lateral line nerve, passes cephalad 

 from the Xth accompanied by a fine fibered bundle (IX) which 

 enters the brain first, penetrating the acusticum to reach the 

 fasciculus communis (Fig. 24), while the coarse fibered root en- 

 ters the acusticum just ventrad of the cerebellar crest and may 

 be traced cephalad some distance. From the lobus trigemini 

 arises an enormous root, Vllaa, the "dorsal geniculate root of the 

 Vth ;" and close to it there arise, (i) from the acusticum dorsad 

 of it a root which as Wright determined innervates the neuro- 

 masts (Vllb), (2) caudad and ventrad, the VIII, and (3) the 

 facial proper arising in its usual manner and leaving the brain 

 ventrad at about the level of Vllaa. A slight distance cephal- 

 ad there arises the Vth proper, composed of the spinal Vth 

 and two bundles from the trigeminal motor nidus. No mesen- 

 cephalic origin for any of the fibers has as yet been recognized 

 in Aniiiinis. 



It is not at all difficult to recognize here the same compon- 

 ents present in Amia ; most notable is the enormous develop- 

 ment of Vllaa. It is to be noted also that in Aininnis there 

 occur no fusions across the meson, such as are found in other 

 teleosts, neither of the lobi trigemini nor the acusticums; what 

 Wright described as a fusion of the latter is the decussation of 

 the fibers of the cerebellar crest in the cerebellum. The mass- 

 ing of the fasciculus communis system and especially the devel- 

 opment of the preauditory part as the lobus trigemini has dis- 

 placed the acusticum from its typically dorsal position and 

 crowded it to the side. By a reduction of the fasciculus com- 

 munis element and a cephalo-caudal stretching of the oblongata, 



