440 



F. A. PO'I'TS. 



and jiliiiost colourless; accessory piece small, in lateral view 

 generally a right-angled triangle, but frequent departures 

 from this type by the rounding of the angles. Numljer and 

 arrangement of the bursal papillte strikingly variable. 



Text-hg. 1. 



B. 



dors. 



vent. 



It wns at fir.^t thought that the shape of the buccal cavity 

 was distinctive of species. The accompanying diagram of 

 D. maupasi shows liow greath^ the state of contraction of 

 the mouth aifects the buccal cavity. 



Text-fig. 2. 



Cxes^ov^ fi£os 



■Tf" 



D. linstowi s}\n. (Text-Hg. 2). 



