THE ACOUSTIC COMPLEX OF THE OPOSSUM 433 



SUMMARY 



1. The cochlear reception nuclei lie internal to the restiform 

 body. 



2. The corpus ponto-bulbare apparently is structurally con- 

 nected with both the tuberculum acousticum and the pons. Its 

 failure to follow the course between the seventh and eighth nerves 

 described for other brains can be explained by the low develop- 

 ment of the pons in the opossum, and the position of the cochlear 

 nuclei, as compared with other mammalian brains. 



3. No distinct striae medullares were recognized, the dorsal 

 path of impulses from the cochlear nuclei being by way of an ohvo- 

 cochlear bundle to the region of the superior olive of the same side. 

 This bundle receives fibers from both nuclei, but principally from 

 the dorsal. 



4. The ventral path is by way of the corpus trapezoideum, 

 which originates largely in the ventral cochlear nucleus. 



5. The corpus trapezoideum presents indications in these prep- 

 arations of a connection with the base of the cerebellum ante- 

 riorly. 



6. The anterior part of the ventral cochlear nucleus presents 

 evidence of a connection with the base of the cerebellum in the 

 region of the before-mentioned trapezoidal connection. 



7. The ventral cochlear nucleus apparently presents a connec- 

 tion with the region of the superior nucleus of the vestibular 

 system. 



8. The superior olive in the opossum is distinctly bilobed, and is 

 not anatomically continuous with the nucleus lemnisci lateralis. 



9. The peduncle of the superior olive and the fibers passing 

 to the median line from the superior end of the nucleus of the 

 lateral lemniscus are easily recognizable in the opossum. 



10. Of the vestibular system the superior, the lateral, and the 

 medial nuclei, and the nucleus of the descending root, together 

 with the bifurcation of the entering fibers into ascending and 

 descending paths, and the nucleo-cerebellar tract, can be identified. 



11. The comparatively undifferentiated cerebellar base makes 

 the cerebellar relations of the vestibular apparatus uncertain. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 12, NO. 4 



