THE BRAIN. 411 



face of the hemisphere, at first, in three separate parts, an an- 

 terior and a posterior temporal and an occipital part. Its middle 

 part is a total fissure, so is its anterior part sometimes. When 

 both are total they produce a long eminence in the inferior horn 

 of the lateral ventricle, external to the hippocampus and parallel 

 with it, hence its name, the eminentia collateralis. 



There are many tertiary sulci which do not appear until near 

 birth, some of them one or two years after birth. 



Transverse Fissure of the Cerebrum. Only the anterior part 



Fig. 121. Medial sagittal section through the brain of an embryo of three months, 

 showing the primitive fissures on the medial surface of the cerebral hemisphere. 

 (McMurrich after Mihalkovicz.} 



c. Calcarine fissure, ca. Anterior commissure, cc. Corpus callosum. cf. Chorioidal fis- 

 sure, dg. Dentate gyrus. fm. Foramen interventriculare (Monroi). h. Hippocampal fissure. 

 po. Occipito-parietal fissure. 



of this fissure, which is between the fomix and the inter-brain, 

 belongs wholly to the cerebrum; the posterior part separates 

 cerebrum from cerebellum. The anterior part of the transverse 

 fissure is produced by the backward growth of the united cere- 

 bral hemispheres over the free dorsal surface of the diencephalon, 

 the inter-brain. It is continuous laterally with the chorioidal 

 fissure in each hemisphere and contains the chorioid tela of the 

 third ventricle. 

 Cerebral Cortex and Medulla. As the gyri of the cerebrum 



