Kingsbury, Oblongata in Fislies. 7 



fibers identical in appearance with those of the lateral line nerve 

 and entering the acusticum, and the latter from the fasciculus 

 communis system which disappears with the exit of this root. 

 (Fig. 18). Cephalad of the Vlllth is the motor Vllth (Vllab) 

 which has the typical mode of ental origin so constant in verte- 

 brates and so well described in Acipenscr by Goronowitsch. In 

 addition to these there arises, sometimes ventro-cephalad of the 

 Vlllth, sometimes dorsad, — there being a variation in this re- 

 spect apparently, — a root composed of fibers from the spinal 

 Vth. When it arises ventrally the fibers are drawn directly 

 from the spinal Vth tract ; when farther dorsad the fibers which 

 form it have a course upon the ectal surface of the acusticum, 

 from which the bundle may be easily distingushed, and may be 

 traced caudad as a distinct strand as far as the cephalic root- 

 lets of the Xth where it joins the spinal Vth proper. To which 

 nerves (rami) these fibers eventually go has not been deter- 

 mined. 



Some distance cephalad the remainder of the spinal Vth 

 leaves the brain in connection with two rootlets from the tri- 

 geminal motor nidus to constitute the Vth nerve proper. A 

 mesencephalic component was not recognized although the 

 characteristic cells of the roof were found, and doubtless a 

 root exists although I have not been able to determine its pres- 

 ence. So much as has been said of the cranial nerves in Ainia, 

 while not sufficient for a consideration of the nerves themselves 

 will permit the recognition of the components recognized by 

 Strong, and may serve to introduce a discussion of the corres- 

 ponding regions of the oblongata, namely, as before mentioned, 

 the spinal Vth tract, the fasciculus communis system, and the 

 acustic system, the acusticum, A more minute discussion of 

 the origin of the nerves and the structure of the oblongata is 

 reserved. 



Spinal Vth tract. The existence of the spinal (ascending) 

 root for the trigeminal nerve has been quite generally recog- 

 nized throughout the vertebrate branch and needs no comment 

 here. Among Ganoids in Acipenser only had the presence of 

 "ascending" trigeminal fibers been recognized, by Gorono- 



