NOTES ON THE EEEE-LIVING NEMATODES. 



449 



sometimes distinguished by extreme variability of the 

 secondary sexual characters. In such specific characters as 

 size aud proportions of various parts the males are fairly 

 constant, but the arrangement of the papilla? supporting the 

 copulatory bursa aud the shape of the accessory piece of 

 the copulatoi-y spicules show wide differences. When 

 Diplogaster maupasi was first obtained from various 



Text-fig. 4. 



samples of soil round Sutton Broad, the differences existing 

 between the males found in separate cultures made me 

 conclude that I was dealing with a number of nearly related 

 species. It soon became clear that distinct types of male 

 were not characteristic of each culture, but that even 

 brothers from the same family often exhibited wide 

 differences. 



The typical arrangement of the bursal papillas in Diplo- 



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