the Genus Crassicauda. 



413 



Atkinson place tlie constriction at 3 mm. from the extremity, 

 but this is clearly an uiiderstatemeiit, as in some ot" the ' Terra 

 Novii* 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 len^^th. 



Nearly ventral views of iho tail of the male, (A) of C. boopis, (R) of 

 C, trunsiaiuda, drawn to the same scale ni' iija''i)iticatioii. 



The writer has failed, as did Leiper and Atkinson, to 

 discover any spicules in the 'Terra Nova' malos. The 

 remote possibility that they mi;^r|it have been left in the 

 vagina of the females after copulation was thought of, but 



