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The tract may be described best by beginniDg at a point behind 

 the cerebellum, corresponding to Edinger's Fig. 12, where it is a 

 distinct bundle. The bundle runs forward and upward immediately 

 lateral to the dorso-lateral angle of the ventricle and at the same time 

 the acusticum bends up and gradually merges with the cerebellum, 

 thus disappearing from the sections. The course of the bundle from 

 this point forward until it enters the tectum is shown in Figs. 1—4. 

 As the tract reaches the point at which the fourth ventricle extends 

 into the cerebellum, it divides into three bundles (Fig, 2). The mesial 

 and most ventral one bends at nearly a right angle around the angle 

 of the ventricle and enters the velum, running close beneath the troch- 

 learis as it approaches its point of bending down around the same 

 angle of the ventricle. The course of the fibers (Vr. m.) as they pass 



Fig. 1. 



Fig. 2. 



under the trochlearis is such that they cannot be confused with the 

 latter (Fig. 3). The second bundle runs. upward on the lateral sur- 

 face of the portion of the ventricle which leads into the cerebellum, 

 curves around the cephalic surface of this, turns sharply ventro- 

 mesially on the caudal surface of the decussatio veli, bending around 

 a blood vessel (Figs. 1, 2), and enters the tectum beneath the troch- 

 learis and the decussatio veh, and mesial to the first bundle. In this 

 course the bundle has really run through a small fold of the cere- 

 bellum. The third bundle is most lateral and appears to enter the 

 cerebellum. What it really does is to make a longer loop similar to 

 that made by the second bundle. It runs considerably farther up into 

 the fold of the cerebellum, bends around the ventricle (Figs. 3, 4) and 



