466 



H. L. WIEMAN 





'i^S^ 



The figures were outlined at table level by means of a camera lucida at the mag- 

 nification obtained by using a 2 mm. apochromatic objective and compensating 

 ocular IS (Zeiss); while the details were drawn at a lower magnification. Figure 

 10 was later enlarged two diameters; all the figures were reduced 5 off in 

 reproduction. 



