PLATES 



All of the figures in plates 1 and 2 are microphotographs of permanent prepa- 

 rations (total mounts) stained with Delafield's hematoxylin and in most cases 

 counterstained with tetra-brom-fluorescic acid. The use of other counterstains 

 is denoted in the explanation of figures. The same magnification (525 diameters) 

 was used in all cases with the exception of figures 8, 15, 18, and 19, which are 

 magnified 375 diameters. 



