the Genus Crassicauda. 413 
Atkinson place the constriction at 3mm. from the extremity, 
but this is clearly an understatement, as in some of the ‘ Terra 
Nova’ females it is over 5 mm. from the tip of the tail. In 
the South Shetlands specimens the terminal knob measures 
only 1 mm. to 2°5 mm. in length, 
Fig. 2. 
Nearly ventral views of the tail of the male, (A) of C. boopis, (B) of 
CU. crassicauda, drawn to the same scale of magnification. 
The writer has failed, as did Leiper and Atkinson, to 
discover any spicules in the ‘Terra Nova’ males. . The 
remote possibility that they might have been left in the 
vagina of the females after copulation was thought of, but 
