Kingsbury, Oblongata in Fishes, 17 



In these two fish the fasciculus communis system is evenly 

 developed. At the exit of the Xth it is dorsal but it is soon 

 displaced by the acusticum. There is no " lobus trigemini "; 

 Vllaa develops as the fasciculus communis diminishes and has 

 a short cephalic course before leaving the brain. In Fundulus 

 this root and also the entire communis system is somewhat 

 better developed than in Esox. In Esox there is a division in- 

 to two quite well defined regions. No vagal fibers were seen 

 to spring from the spinal Vth. No Weigert preparations were 

 made and on further study no doubt such a component will be 

 found to exist. Important it is in view of the conditions in the 

 forms to be mentioned, that in these, as in Amiurus, there are 

 no secondary fusions of endymal surface in the oblongata 

 (Fig. 20). 



Acanthopteri. Four spiny-rayed teleosts were studied, rep- 

 resentatives of as many families, — Roccus, Perca, Cottus, Lepo- 

 mis. In these one important general difference from the forms 

 hitherto mentioned occurs in the dorsal fusion of the acusticums 

 across the meson (Fig. 19). It extends from about the region 

 of entrance of the lateral line nerve cephalad nearly to the exit 

 of the Vllth. It is substantial, involving the molecular layer 

 and the portion beneath it, obliterating the endyma and giving 

 passage to fibers from side to side. Aside from this the relative 

 development of the regions of the oblongata is much as in the 

 Haplomi. The communis system is but slightly developed and 

 there is no differentiation of pre- and postauditory portions, A 

 few words may be said in description of each separately. 



In Roccus, (Fig. 23) the fasciculus communis system ap- 

 pears some distance caudad as a mesal area between the dorsal 

 cornua. The development of the spinal Vth tract upon the 

 dorsal and lateral sides of these and its direct continuity with 

 the dorsal fibers of the myel are very clearly shown. 



The Xth arises by 7-8 poorly defined roots which pass ven- 

 trad of the spinal Vth. It derives a distinct component of fi- 

 bers from this tract. The lateral line nerve enters in the char- 

 acteristic place just beneath the cerebellar crest, and at the 

 same level a fine fibered root from the Xth which passes cephal- 



