1 6 Journal of Comparative Neurology. 



especially of the acusticums, the form might be easily reduced 

 to that of the following order. 



Haplomi, In Esox and Fimduhts, the two representatives 

 of this order examined, the conditions are even somewhat more 

 satisfactory than in Amiurus, since the communis system is 

 much more weakly and evenly developed. The exact caudal 

 limit of this system is in Esox somewhat difficult to determine 

 exactly from the material at hand. A common mesal area rep- 

 resentating the cojnm. infiuia Halleri appears between the dor- 

 sal cornua and is soon divided into the paired tracts at the 

 caudal end of the metatela. The Xth arises by 4 or 5 closely 

 associated roots which contain both sensory fibers from the fas- 

 ciculus communis and motor from the vagal nidus («z)- These 

 all pass ventrad of the spinal Vth. Cephalad of these the 

 acusticum appears in transection dorsad of the spinal Vth, and 

 is soon capped by the cerebellar crest. An isolated root 

 (IX ?) composed of commuhis and motor components enters, 

 penetrating the acusticum, cephalad of which and near the en- 

 trance of the lateral line root another small root from the com- 

 munis system and motor nidus enters. The lateral line nerve 

 enters the acusticum immediately beneath the molecular layer. 

 The VIII nerve springs from the acusticum by 2 (or 3 ) roots, 

 dorsad and cephalad of which arises Vllb, followed by Vllaa 

 and Vllab, the former at about the same level, the latter 

 farther ventrad. The spinal Vth leaves the brain a short dis- 

 tance cephalad accompanied by motor strands (2 or 3) from the 

 trigeminal motor nidi. 



Fundtdus, in the structure of its oblongata closely agrees 

 with Esox ; the caudal limit of the fasciculus communis systems 

 was clearly defined and easily distinguished from the dorsal cor- 

 nua. The Xth arises in 3 divisions, the sensory fibers ( from 

 the communis system ) dorsad and the motor ventrad of the 

 spinal Vth. Isolated sensory and motor roots (IX?) enter far- 

 ther cephalad, the former from the fasciculus communis, the 

 latter from a motor nidus. The lateral line nerve is small ; its 

 relations are as already described. VIII, Vllb and Vllaa 

 leave the brain very near each other and the Vth follows closely. 



