NERVOUS SYSTEM OF SCORPION. 



49 



FIG. 8. Median sagittal section of an embryo of the 

 seventh stage, X 45 > ft '> oesophagus ; omo, neck of 

 median eye sacs ; n 1 ' 20 , cross commissures of first to 

 twentieth neuromeres ; r, rostrum ; R, rostral nerve ; si, 

 semilunar lobe. 



FIG. 9. Eighth stage of same, X 4 '> a > anus 5 a & 2 > 

 second abdominal appendage ; ch, cheiiceral articulat- 

 ion ; 15 ~ 20 , fifteenth to twentieth neuromeres ; s/, semi- 

 lunar lobe ; 15-20, fifteenth to twentieth body segments. 



Stage 6. (Fig. 6.) The median-eye 

 sacs have come together in the mid-line. 

 In this stage I have worked out the nerves 

 of the first thirteen neuromeres. Typically 

 there are two pairs of nerves to each neu- 

 romere : an anterior pair ("haemal " of Pat- 









. ' '' '' 



15 . 



^nis 



\ . 

 lb\ 



55 .- 



