24 



B. H. BUXTON 



In regard to group II, since the large abdominal ganglion of 

 the Solifugae is a single, solid mass, without any e\'idence of 

 neuromeres, nothing definite can be said about it. It may 

 represent a fusion of all the original abdominal ganglia, or it 

 may be composed of one or more of the original ganglia which 

 have suppressed and taken over the functions of others. The 

 same may be said of the three abdominal ganglia of the Palpi- 



Diagram 8 From Brauer. Development of the tail of the scorpion. Be- 

 tween segments XIV (last abdominal), and XV (first post abdominal), there is no 

 evidence of segmentation. Segment XIV seems to double over on itself to form 

 the base of the tail. In the tail itself only three out of the five segments have 

 been cut out at this stage. 



grades. In neither of these two orders can any relation between 

 the abdominal segments and ganglia be determined. In this 

 respect they differ again from group I; and a still further differ- 

 ence between the two groups can be pointed out; in each of 

 these two orders of group II there are nine post-genital seg- 

 ments instead of ten, as is probable in all the orders composing 

 group 1. 



