Kingsbury, Brain of Nechims. 193 



the immediate neighborhood of the large cells in this region, — 

 the second oculomotor nidus of Osborn, — is suggestive. 



Cerebellum. — The structure of this may be reviewed here. 

 It is very rudimentary indeed in Necturits, consisting simply of 

 fibers in two groups, as described by 'Osborn for Crjptobranchus; 

 coarse fibers which pass up from the oblongata and turn into the 

 mesencephal on each side of the meson ; fine fibers, some of 

 which turn caudad into the metencephal, and some cephalad 

 into the mesencephal, — thought by Osborn to be decussating 

 tracts from the auditory nerve. The rudimentary condition of 

 the cerebellum did not permit me to recognize the prepedun- 

 cles ' (Bindearme), which are present in other Amphibia, and 

 decussate cephalad of the mesencephalic pit (Burckhardt, '91). 



Postcontuiissiire. — This is well developed. Its fibers are 

 readily followed toward the base of the brain, but soon become 

 dispersed, some of them appearing to assume a caudal direc- 

 tion. Koppen ('88) states that in the frog they end in the cin- 

 erea dorsad of the pars pediincidaris. 



Meyncrfs bundle is a close though small tract in NecUmis. 

 It arises in the region of the habenas and passes caudo-ventrad 

 to the ectal surface of the base of the brain, where it becomes 

 diffuse, but may be traced caudad to the mesencephalic pit. 

 Considerable obscurity has existed concerning the relations of 

 this tract in lower forms. It is generally described as terminating 

 in the interpeduncular ganglion ; Ahlborn however, stated that 

 in Petroniyzon it might be traced into the oblongata ; Osborn 

 ('88) traced it slightly caudad of the interpeduncular nidus in 

 CryptobrancJms, while Burckhardt ('91) has apparently recog- 

 nized two tracts in Protopterns, a fasciculus retroflexus terminat- 

 ing at the ganglion interpedunculare, and a Meynert's bundle 

 entering the oblongata. The recent application of the Golgi 

 method by Gehuchten ('94) to this problem (in the trout) has 

 shown that the fibers of Meynert's bundle spring from cells 

 in the habenas and terminate in end-brushes in intimate relation 

 to the cells of the interpeduncular nidus. 



' Herrick has called these in the frog medipeduncles. In the absence of 

 a pons this interpretation seems to me erroneous. 



