ffn.7- 





FiG. ^D.—Asiacus flHv\at\lis,—T\i'& central nervous system seen from 

 above (nat. size), a, vent ; an, antennary nerve ; a!n, antennulary 

 nerve; f, circumcesophageal commissures ; gn. 1, supraoosophageal 

 ganglion; gn. 2, infraoesophageal ganglion; gn. 6, fifth thoiacic 

 ganglion ; ^/i. 7, last thoracic ganglion ; gn. 13, last abdominal gang- 

 lion ; ces, oesophagus in cross section ; on, optic nerve; m, sternal 

 artery in cross section ; sgn, stomatogastric nerve. 



