304 



THE INVERTEBRATA 



n. ch 



St. ar 



Fig. 214. A semidiagrammatic view of central nervous system of Astacus. 

 From Borradaile. ab. 1, ah. 6, the first and sixth abdominal ganglia; cer. 

 cerebral ganglion (brain); c.oe^. circumoesophageal commissure; I.e. longi- 

 tudinal commissures of ventral cord; n.ab.l. nerves to abdominal limbs; 

 n.an.' nerve to antennule; n.an." nerve to antenna; n.ch. nerve to cheliped; 

 n.m. nerves to limbs adjoining the mouth; opt.n. optic nerve; s.oes. sub- 

 oesophageal ganglion ; 5i.«r. sternal artery; th.i, th.6, first and sixth thoracic 

 ganglia; vis.n. nerve to proventriculus ; vis.n.' nerve to hind gut. 



