The origin of the Corpus Callosum, a contrib. upon the Cerebral Coram, etc. 251 



plan are given the levels of figs. 17 and IS. Laterally is seen a faint 

 division of the anterior commissure into two bundles. 



Fig. 1". Horizontal section through the lower level. The pars temporalis 

 is readily observed but it is difficult to determine whether the anterior 

 branch of the anterior commissure really represents the pars olfac- 

 toria. 



Fig. 18. Horizontal section through the upper level showing the fibres of the 

 callosal bundles in cross section and the posterior bundle caV, extend- 

 ing along the posterior horn of the lateral ventricle. The position 

 of the foramen is indicated by arrows. 



Fig. 19. Vertical section of the brain ofEmys Europaea. The corpus cal- 

 losum and anterior commissure are united in the median plane. 

 ' There is no intervening septum as in the batrachia and mammalia. 



Five folds [mf] may be observed at the sides of the fourth ventricle 

 as in the batrachia (fig. 2, text). 



