22 



B. H. BUXTON 



Turning now to the abdomen we find twelve segments, of 

 which the first is the genital, but there remain only eleven gan- 

 glia to supply them since we have already disposed of seven 

 ganglia (segments I to VII) (VII being transitory). The gan- 

 glia of the genital organ (VIII), pectens (IX) and first lung (X) 

 are fusedj^with the subo esophageal ganglion. Next comes a 



Diagram 7 Sagittal view of the su'ooesophageal ganglion of the scorpion, 

 showing nine neuromeres, the destination of the nerves proceeding from them, 

 and the ventral nerve mass secondarily supplying the pectens. It is under- 

 stood that all these structures can not be seen in one section. The neuromeres 

 can only be distinguished in sections through the median line, whereas the 

 nerves running to the appendages and the secondary nerve mass for the pectens 

 are paired structures which appear in sections on either side of the median line. 



series of three single ganglia for lungs 2, 3 and 4 (XI, XII, XIII), 

 posterior to which is the last abdominal segment (XIV). In 

 the post-abdomen there are five segments and four ganglia, of 

 which the last, situated in the fourth segment, is double (hav- 

 ing two neuromeres) and clearly suppUes segments 4 and 5. 

 The last segment in the abdomen, therefore, appears to be with- 

 out a ganglion. The first ganglion of the post-abdomen is cer- 



