384 ^^^^ F. Holm 



posterior« another ganglion is found. It is situated in the sensory 

 region of the Medulla, just above the »Fibrae arcuatae internae« 

 (Fig. 18 Gl.spr) and I have named this ganglion the »Ganglion cen- 

 trale superior«. Another ganglion in the sensory region is situated 

 in the rostral and lateral part of the Oblongata (Fig. 20 Nc.ant. VIII). 

 This is the »Nucleus anterior« of the lateral root of the Ramus an- 

 terior acustici. Between the anterior and posterior nuclei of the 

 Ganglion centrale, a ganglion of smaller motor cells is found which 

 I call the »Ganglion rostratum trigemini«. The latero-ventral gan- 

 glia are caudally situated on the level of the central canal but sink 

 towards the base the further rostrally they are situated and the 

 most rostral, one of the Facialis ganglia, is situated near the base 

 of the brain (Fig. 19—21). 



The longitudinal tracts in the Oblongata are very similar 

 to those of the cord, only more pronounced. Below and a little 

 laterally of the central canal the Fasciculi longitudinales posteriores 

 are found (Fig. 23], more laterally and ventrally the systems which 

 connect the cord and Medulla with the Mesencephalon and are known 

 under the name of Tracti tecto-bulbares and spinales (Fig. 23 L) or 

 with one name as the Laqueus. Laterally and dorsally of the central 

 canal we find a longitudinal system of fibres which is absent in 

 the cord and is first observed in the caudal part of the Oblongata. 

 They seem to end in its rostral part and show the same arrange- 

 ment as those fibres Edingee (9) has described under the name of 

 Tractus breves in Cephaloptera and other fishes and which he states 

 exists in the same place in all vertebrates, being probably an im- 

 portant system of association-fibres. Dorsally from the central canal 

 we find the continuation of a longitudinal system already existing 

 in the spinal cord, the Funiculus dorsalis. 



Metameric Cranial Nerves. 



The Olfactorius and Opticus, not being metameric, have already 

 been described together with the respective parts of the brain to 

 which they belong and the next nerve to be described is generally 

 the S'^'i or Oculomotorius, but all authors who have investigated the 

 matter have pronounced this to be absent in Myxine. I also have 

 failed in finding any trace of the nerve itself, but in the rostral part 

 of the Ganglion interpedunculare I have found a group of triangular 

 cells which stain very black with Irou-haematoxylin and in every 



