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large complex in the brain easily recognisable by the large 
size of the fibres, and the density with which they stain. 
There can hardly be said to be a single root to the 
acusticus, its fibres becoming associated into at least two 
rami just before or on leaving the medulla. As in 
Menidia the very minute ganglion cells are not found on 
the acusticus until it breaks up into its ramuli. In front, as 
above described, the auditory nerve leaves the medulla in 
conjunction with the motor vii., and is confused with it. 
Its division into an anterior Ramus vestibularis and a 
posterior R. cochlearis is not so obvious as in other fishes, 
on account of the manner in which it emerges from the 
medulla. Its further divisions or ramuli are therefore 
now described. 
1. R. acusticus ampullz anterioris (7. a. «.)—Most 
anterior branch, and courses forwards wedged in between 
the motor vii. and the utriculus. It then passes upwards 
and outwards to the outer wall of the ampulla, the sense 
organ of which it enters from the front. 
2. R. acusticus recessus utriculi. (7. 7. w.)—Some- 
what diagrammatic in the figure, as it really passes back- 
wards to the floor of the utriculus to reach its sense organ. 
3. R.acusticus ampulle externe (1. a. e.).—Passes 
almost straight outwards underneath the floor of the 
utriculus towards the outer wall of the external ampulla 
direct to its sense organ. 
4. R. acusticus sacculi (7. sac.)—Courses at first 
straight downwards at right-angles to the preceding 
ramulus, and then backwards and downwards internal to 
the sacculus to reach its sense organ. As it passes back- 
wards it was connected with a small nerve bundle, the 
nature of which was not determined. 
The nerve extending backwards to supply the two 
posterior sense organs of the ear is separated off from the 
