Brain of Crayfish 77 



cerebral system, and thus over the behaviour of 



the animal. 



0.0. 



O.T. 



, ; 



CC. 



^ C.PC.L. 

 .. GL. 



.-:' '''. .-- GB - 



ffSJS&i 



sw. I! 



wI?*s;'* . -^i-?SiXvoxV''- -*.*%< 



'^ 

 *&V 



,' ' ''' "** re 



i'.;'K* /;-,/ --/^.- j^if* GB 



*-^"'^ > * ,* .",'".'''' >; . v^":-*/!f ; / ' 



[/"/{;'' ^iv';'-'''"'"'- GL. 



DC' / *vaa ''/: 



* * / * * 



C.'GB. ' ; VS|3 



T. c. 



FIG. n. Horizontal section through the brain of a crayfish, 

 x 40. C.C., corpus centrale ; C.GB., commissure of globuli ; 

 C.PC.L., commissures of protocerebral lobes; DC., mid-brain; 

 GB., globulus; GL., glomeruli ; G.N., ganglionic nuclei; O.D., 

 decussating bundle of optic tract ; O.T., optic tract ; PC.L., fore- 

 brain ; T.C., hind-brain. (Cat. Physl. Series, Museum Roy. Coll. 

 Surgeons, Vol. II., p. 22.) 



As a consequence of the more complex 

 structural arrangement and development of the 

 central nervous system, and sensory organs in 



