CRUSTACEA 



341 



n. ch 



st.ar. 



v%8,n.' ■ 



Fig. 225. A semidiagrammatic view of central nervous system of Astacus. 

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

 cerebral ganglion (brain); c.oes. 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; st.ar. sternal artery; th. i, th. 6, first and sixth thoracic 

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



