JOURN. R. M1CR. SOC. 1905. PI. IV. 



FIG. I. 



A BCDEF 



FIG. 3. ,'' 



^rtv 





\ Slit to Bar 

 1\ I to I 



FIG. 2. 



FIG. 7 



FIG. 4. A 



X Slit to Bar 

 \ I to 2 



B 



\ Slit to Bar 

 2 to I 



1ST ^-w. 1ST 



2*P^' 



FIG. 6 



FIG. 9. 



FIG. 10. 



FIG. 11. 



