462 PHYSIOLOGICAL SERIES. 



The form of calcarine sulcus is somewhat unusual, for it 

 appears to be prolonged into an extraordinarily precocious 

 parieto-occipital sulcus. 



The cerebellum is now well-fissured. 0. C. 1341 F. 



Presented by John Hilton, Esq. 



D. 681. The right hemisphere of the brain of a seven months' 

 female foetus, hardened in chromic acid. 



On the mesial surface of this hemisphere the vestiges of the 

 ropra-oallosal hippocampus (vide account of Marsupial 

 brain) are very clearly seen in the callosal sulcus, especially 

 near the splenium of the corpus callosum. The calcarine 

 and parieto-occipital sulci appear to be united to form a 



Fig. 263. (x.) 



SULC. RECT. 



SULC.ORB. 



SULC.'FR. ORB. 



Y-shaped figure ; but, as we have seen in the Apes, so also 

 in the developing human brain the parieto-occipital sulcus 

 is usually quite independent of and altogether subsidiary to 

 the calcarine sulcus. The retrocalcarine sulcus the cross 

 of the T is widely separated from the calcarine. The 

 collateral sulcus is represented by very faintly-marked 

 depressions, but the occipito-temporal sulcus is present as 

 two deep sulci. The calloso-marginal and rostral sulci are 

 well developed. 



The orbital sulcus is fully formed. 



The Sylvian fissure is in an interesting stage of develop- 

 ment. The fronto-parietal, temporal and orbital opercula 

 surround a triangular Sylvian fossa. [Unfortunately the 

 anterior part of the specimen is damaged so that the frontal 



