Development of Neopallium 127 



low in the zoological series as worms the effect 

 of exposure of their nervous system to an in- 

 crease in the complexity of the stimuli acting 

 on it, has tended to develop the growth and 

 organisation of its nerve cells. Under like 

 conditions the cerebral cortex of some bony 

 fishes is of a higher order than that possessed 

 by the lamprey ; in reptiles and birds it becomes 

 differentiated structurally and functionally. 

 The brain of some of the Marsupialia or pouch 

 bearing animals structurally consists of some- 

 thing between that of reptiles and the more 

 typical mammals. The " Tasmanian Devil " 

 affords us an example of this order of beings; 

 it possesses well-developed basal ganglia, into 

 which nerve fibres extend from the various sen- 

 sory organs; from the terminal cells of these 

 ganglia numerous fibres extend to a rudi- 

 mentary neopallium, from which lines of com- 

 munication pass to motor cells controlling the 

 action of the muscles of the animal's body and 

 limbs. The behaviour of this, one of the lowest 

 orders of mammals, is evidently governed by 

 instinct, its fierce nature, strenuous efforts for 

 self-preservation, and the fondness it shows for 



