250 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



On removing the pallium, it will be noted that there are 

 no lateral ventricles, but a large single median prosocoele. 

 In the floor of this are raised up the large corpora striata 

 separated dorsally by a wide fissure, but connected below 

 by the anterior commissure, and constituting the solid 

 cerebral hemispheres of older authors. These are con- 

 siderably smaller than the optic lobes, and the dorsal 

 surface of each is marked by a somewhat complex furrow 

 (" sulcus " of former authors — see fig. 30). In front of 

 and below the striata are the olfactory bulbs, from which 

 the olfactory nerves originate. The left is smaller than 

 the right. 



On the ventral surface of the brain the most notice- 

 able structures are the appendages of the 'tween-brain. 

 The lobi inferiores are a pair of large bean-shaped bodies 

 opposed by their median surfaces. In the middle line 

 immediately in front of these is the spherical pituitary 

 body. The apposition of the pituitary body and lobi 

 inferiores is not complete, and a triangular space is left 

 by which there emerges on to the ventral surface of the 

 brain the red thin-walled saccus vasculosus. This is at 

 its origin a very narrow tube, but it expands and passes 

 straight backwards in the middle line over the opposed lobi 

 inferiores. It is dilated behind, and ends blindly slightly 

 posterior to the hinder border of the lobi inferiores. In 

 the adult the pituitary body (hypophysis cerebri) and 

 saccus vasculosus are essentially glandular organs receiv- 

 ing a marked nervous supply from the infuiidibulum. 

 According to most recent authors the saccus at least 

 " probably forms part of a mechanism for secreting, or 

 otherwise controlling the pressure of, the cerebro-spinal 

 fluid. It m.aj affect the heart beat and blood pressure by 

 way of the vagus " (J. 13. Johnston). 



The crossing of the optic nerves is very obvious in the 



