84 'Journal of Comparative Neurology and Psychology. 



united by considerable commissures, coin, acustica anterior and 

 posterior. 



Among the other secondary connections ot the octavus region 

 I must mention first the fasciculus lateralis longitudinalis which, 

 together with the decussated octavo-motor connection, also already 

 described, forms the frhrcc arcuata; dorsales of this region. The 

 remaining fibrcp arciiatce internee and externce are doubtless 

 partly formed by secondary connections with the ventral gray 

 substance described above in which the tecto-bulbaris fibers 

 end, while finally some very distinct little bundles are decussat- 

 ing ventral cerebello-spinal fibers probably not belonging to the 

 acusticum. 



The nervi glossopharyngeus and vagus, of which the former 

 enters the brain with the radix lateralis posterior, consist of two 

 kinds of fibers, motor and sensory. The sensory fibers of the 

 ninth end in the same region as the pars intermedia facialis and, 

 farther back, the sensory vagus. This whole sensory region is 

 situated medially to the caudal continuation of the static area and 

 has been distinguished by Haller from the latter (his "ausseres 

 sensorisches Gebiet") as "inneres sensorisches Gebiet." 



The American school calls it "fasciculus communis system," 

 following OsBORN and Strong who studied its structure and also 

 clearly distinguished it from the "acusticum" situated more dorso- 

 laterally. Now, this "communis region" may be very greatly 

 enlarged in some teleosts, as never occurs in the selachians, and 

 when treating of the nervi laterales I already mentioned that this 

 was the cause of Mayser's mistake in considering the most 

 anterior part of the lobi vagales of the cyprinoids as the homologue 

 of the swelling so strongly developed in the selachians in which the 

 nervus lateralis anterior ends. The size of the communis region 

 in bony fishes is really so considerable that generally the two 

 regions unite and in some bony fishes the formation of the so- 

 called tuberculum impar, mentioned by the earlier investigators 

 takes place. 



That the posterior part of these regions is always connected by a 

 commissure has already been described by A. von Haller, his 

 commissura infima cerebri, or com. infima Halleri. Behind it 

 decreases in circumference. In Lophius it is vaulted over by the 

 sensory enlargement in which the nucleus Rolandi lies and it 

 gradually passes into that region of the medulla spinalis of which 



