XXXIIl] THE MID-BRAIN AND INTER-BRAIN 267 



The nucleus of the 3rd nerve is nearer the middle line than in 

 man. 



The br. of p. c. q. is on the surface about midway between the 

 pes and the a. c. q. 



Note : 



The large cells in part of the crossed sup. cer. 

 ped. the beginning of the red nucleus', fibres of the 

 3rd nerve are seen running through its medial por- 

 tion. The dorsal tegmental decussation (Meynert's) 

 just ventral to the p. 1. b. ; and the ventral tegmental 

 decussation (Forel's) in the ventral part of the raphe. 

 All of these are more marked a little farther up. 



In the a. c. q. the blood vessels take a direction in 

 general at right angles to the surface ; some rather 

 large pyramidal cells will probably be seen in the deep 

 grey substance of the a. c. q. 



11. Section through the a. c. q. and internal corpus 

 geniculatum (dog). The pes is farther from the middle 

 line. Note : 



The internal corpus geniculatum, a round mass of 

 grey substance on the lateral surface; on its medial 

 or medial and ventral border are bundles of nerve 

 fibres (brachia of i. c'" g. and of p. c. q.). 



A small bundle of fibres near the ventral surface and the raphe, 

 Meynert's bundle. 



12. Section through a. c. q., the external corpus 

 geniculatum and the corpora mammillaria (dog). The 

 3rd nucleus (chief nucleus), 3rd n. fibres, and red 

 nucleus are not present, bundles of fibres (passing to 

 the optic thalamus) are seen in the place of the red 

 nucleus. 



