CHAP. IV. 



TANAIS DUB1US. 



21 



filaments, which stand in groups of from five to seven 



together. 



Figs. 3-6. 



1 Fig. 3. Head of the ordinary form of the male of Tanais dubius (?) 

 Kr. magn. 90 times. The terminal setae of the second pair of antennae 

 project between the cheliferous feet. Fig. 4. Buocal region of the same 

 from below ; A, labrum. Fig. 5. Head of the rarer form of the male, 

 magn. 25 times. Fig. 6. Flagellum of the same, with olfactory fila- 

 ments, magn. 90 times. 



