THE AUDITORY NERVE. 127 



in other series of sections it remains an uncomfirmed ob- 

 servation, Allis ('97, p. 624) describes an anastomosis 

 between the r. ampullae posterioris of Amia and the later- 

 alis component of the IX root. As in the present case, 

 the farther course of the fibres could not be followed. 



The apparent origin of all of the acustico-lateral fibres 

 from the tuberculum acusticum is a single fibre complex, 

 the separation into the roots as we enumerate them taking 

 place just before their emergence from the oblongata. 

 The auditory rami break up to supply the papilla acustica 

 lagenae, the three cristae acustici, the macula neglecta, the 

 macula acustica sacculi, and the macula acustica recessus 

 utriculi. The glossopharyngeal nerve runs along the 

 inner face of the caudal ramus and as it emerges from the 

 cranium passes between the ramulus ampullae posterioris 

 and the ramulus lagenae just at their point of separation. 

 There is no exchange of fibres between the VIII and the 

 IX nerves. The r. lateralis vagi arises at the same trans- 

 verse level as the caudal acoustic ramus but farther dorsal. 

 It is crossed externally by the ramulus ampullae posteri- 

 oris but, though the two nei"ves are in contact for a con- 

 siderable distance, there is no anastomosis. The cephalic 

 ramus arises at the same transverse level as the VII nerve 

 and its ramuli closely follow the outer face of the V + VII 

 ganglionic complex. In this case also I think that there 

 is no interchange of fibres. 



Ganglion cells are not found in the auditory roots 

 until they begin to break up into their ramuli, beyond 

 which point they are freely scattered among the fibres 

 reaching in some cases quite to the sensory epithelium. 

 The cells are exceedingly minute, smaller than those 

 of the lateral line ganglia and scarcely larger than the 

 diameter of the medullary sheaths. The calibre of the 



