There should be noticed (1) the increase in the flexure of the brain 

 accompanying a rectification of the cranial axis ; (2) the elongated 

 pineal gland, and (3) the structure of the optic thalamus. 



Fig. 6 «, 6 ?>, 6 c. Views from the side, from above, and from below, of 

 a brain of Scyllium stellare during a slightly later stage than Q. 



Fig. *1 a and 7 &. Two longitudinal sections through the brain of a 

 Scyllium embryo during stage Q. Zeiss a, ocul. 2} 



7a cuts the hind part of the brain nearly through the middle line; while 

 7 b cuts the cerebral hemispheres and pineal gland through the middle. 



In 7 a the infundibulum (1), cerebellum (2), the passage of the resti- 

 form tracts (r t) into the cerebellum (3), and the rudiments of the tela 

 vasculosa (4) are shewn. In 7 & the septum between the two lobes of the 

 cerebral hemispheres (1), the pineal gland (2), and the relations of the optic 

 thalami (3) are shewn. 



Fig. 8a, 8b, 8c, 8 d. Four transverse sections of the brain of an 

 embryo slightly older than Q. Zeiss a, ocul. 1. 



8 « passes through the cerebral hemispheres at their junction with the 

 olfactory lobes. On the right side is seen the olfactory nerve coming off 

 from the olfactory lobe. At the dorsal side of the hemispheres is seen the 

 pineal gland (jyti). 



8 b passes through the mid-brain now slightly bilobed, and the opening 

 into the infundibulum (i«). At the base of the section are seen the oj^tic 

 nerves and their chiasma. 



8 c passes through the opening from the ventricle of the mid-brain into 

 that of the cerebellum. Below the optic lobes is seen the infundibulum 

 with the rudiments of the sacci vasculosi. 



8 d passes through the front end of the medulla, and shews the roots 

 of the seventh pair of nerves, and the overlapping of the medulla by the 

 cerebellum. 



1 Owing to a mistake of the engravers the references to the pituitary body 

 are ^r inT a and jpn iu 76. Tliey should be lit iu both cases. 



