fircb- 



dors, vea 



retr.mue 



FIG. 74. Tetrastemma. General view of the internal organs, an. anus ; ac. st. 

 accessory stylet ; cer<g. brain ; cil. gr. ciliated groove ; dors, ves. dorsal vessel ; 

 lat.ne. lateral nerve; lat.ves. lateral vessel; neph. nephridium ; op. neph. 

 nephridial aperture ; profr-. eversible part of proboscis ; profi 2 . non-eversible part 

 of proboscis ; prob. ap. aperture for the protrusion of the proboscis ; retr. mus. 

 retractor muscle of the proboscis ; st. stylet. (From Hatschek's Lehrbuch.} 



L 2 



