The finer Anatomy of the Nervous System of Myxine glutinosa. 387 



decussated fibres and fibres from a trausversally situated group of 

 large Ganglion cells. This nucleus Mayser (26) finds doubled in the 

 Oyprinoides, the nuclei being situated one behind the other, the 

 posterior more ventral than the anterior. The latest and most complete 

 account of the central distribution of the Trigeminus in fishes is 

 given by B. Haller (17), who has investigated this matter specially 

 in Scyllium and Salmo. He finds that the sensory nucleus of the 

 Trigeminus and Acusticus commences in the posterior acustic region 

 and ends in the region of the first Trigeminus. This nucleus is 

 called by Haller the »large-celled acustico-trigemino nucleus«. The 

 motor Trigeminus root springs from the Funiculi posteriores and 

 contains both decussated and non-decussated elements, from the large 

 cells of the Cornua anterior and from the single cells situated laterally 

 and above the Funiculus medianus. The upper root of the second 

 Trigeminus originates iu the Lobi nervorum trigeminorum and the 

 inferior root arises partly in the lower half ot the exterior sensory 

 Oblongata region, partly from the large-celled Acustico-trigemino 

 ganglion and partly from a longitudinal fascicle in the exterior sen- 

 sory region. The dorsolateral longitudinal fascicle turns laterally and 

 nearly the whole of it enters the first Trigeminus. This is the only 

 sensory contribution that the F' receives. The motor fibres spring 

 from the upper anterior nucleus, which is a continuation of the motor 

 nucleus. Some motor fasciculi originate in the Cornua ventrales and 

 the Funiculi posteriores and these motor fasciculi, together with some 

 of those from the upper anterior nucleus, form the »Ramus ophthal- 

 micus profundus« which is entirely a motor nerve. Besides the ascend- 

 ing sensory tract the first Trigeminus receives some motor fibres from 

 the lower motor region, partly from ganglion cells, partly from the 

 Fibrae arcuatae. I will now give an account of the origin of the 

 Trigeminal nerve as I have found it in Myxine. The three branches 

 of the fifth nerve all leave the brain together from the most rostral 

 and lateral point of the Medulla oblongata, which is of a sharp, 

 conical shape; consequently the fibres from the difi'erent branches 

 become immediately intermixed and it is very difficult to say anything 

 definite about their separate origin, but for the entire Trigeminus it 

 is easy to find two sensory roots and two motor roots, besides decus- 

 sating elements. The sensory fibres of the Trigeminus run straight 

 down the Oblongata until the acustic region is reached; arriving in 

 this, the fibres begin to turn in right angle to the sides and end 

 amongst the gray matter. This end nucleus (Fig. 19 ?ieu.V^) is very 



