EXPLANATION OF THE FIGURES. 



Brain (supra-cesophageal ganglion) of an ant (Lasius fuliginosus), magnified 

 60 diameters, seen from above. 



Fig. W. Brain of the Worker. 



Fig. F. Brain of the Queen (Female) 



Fig. M. Brain of the Male. 



St. Brain trunk. L. op. =Lobus opticus (optic lobe). Z. olf. =Lobus olfac- 

 torius sive antennalis (olfactory lobe). N. = Facetted eye. N. olf. =Nervus olfac- 

 torius sive antennalis (olfactory nerve). O. =Ocelli, or simple eyes with their 

 nerves (present only in the male and queen). H. = Cellular brain cortex (developed 

 only in the worker and queen). C. $. = Corpora pedunculata, or fungiform bodies 

 (developed only in the worker and queen). R. =Rudimental cortex of male. 



The length of the whole ant is : 



in the worker 4.5 mm ; 

 in the queen 6.0 mm ; 

 in the male 4.5 mm. 



N. B. The striation of the corpora pedunculata and their stems is represented 

 diagrammatically, for the purpose of indicating rather coarsely their extremely 

 delicate fibrillar structure. 



