5 (5) Somatic spines on mid posterior border of 

 somatic plate II present; 2 cusps only along 

 margin of cephalic plate Stygarctus bradypus 



5 (3) Somatic spines on somatic plate II absent; 4 cusps 



along margin of cephalic plate Stygarctus granulatus 



6 (2) Cephalic appendages absent 7 



6 (2) Cephalic appendages present 9 



7 {6) First pharyngeal macroplacoid 

 longer than second; inner diam- 

 eter of pharyngeal tube 3 (im 8 



7 {6) First macroplacoid shorter than second; inner diameter of pharyngeal tube 1.5 fim 



Hypsibius stenostomus 



