1910]. 199 



SPECIAL DESCEIPTION OF PLATES III— VL 



Plate III (from photographs). 



Fi'^. 1. — Me'jhelophoriis aquidiciis, dorsal, aedeagus protruded from hist 

 abdominal segment. X 31. 



,, 2. — M. aqiiaticus, ventral, encasement and aedeagtis. X 31. 



3. — „ „ „ „ separated. X 31. 



,, 4. — „ ,, dorsal, tegmen. X 31. 



„ 5. — „ „ „ median lobe and ejaculatory duct. X 31. 



„ 6. — Mcijcmpleurus rugosus, aedeagus, dorsal aspect. X 'l'^. 



„ 7. — „ porculus, „ „ „ X -l'^- 



„ 8. — EnqAcurus nuhilus, „ and duct, dorsal aspect. X ^^^ 



„ 9. — „ his]}anicus, „ dorsal aspect. X 29. 



„ 10. — „ nuhilus, one of the lateral lobes is broken. X 29. 



„ 11. — Meghelophorus acqualis, aedeagus, dorsal. X 24. 



„ 12. — „ „ var., aedeagus, dorsal. X 36. 



,, 13. — ,, frigidus, „ ,, 



„ 14. — Triclicloplwrus altcrnans, „ „ X 36. 



„ 15. — ,, mauriianicus, ,, „ 



PLATES IV, V, AND VI (from camera lucida drawings). 



The magnification of the aedeagus is about X 60 ; broken lines indicate 

 internal parts. 



Figs. 16-21 are anatomical diagrams to explain the anatomy and mori^ho- 

 logy of the male genital tube of Helophorini ; they are all founded on 31. 

 arjuaticus, and the lettering is uniform. 



Fig. 16 : dorsal aspect of the genital tube and encasement, a, gut ; h, en- 

 casement = last body-segment ; c, membranous part of the tube connecting 

 encasement and aedeagvis ; d, basal piece ; c, ejaculatory duct, lying under the 

 alimentary canal, and shown therefore by fine dots ; /, lateral lobe ; g, median 

 lobe ; h, strut of median lobe. 



Fig. 17 : In figs. 17-21 the chitinous, or hard, parts are shown dotted ; 

 letters a-h as above ; fig. 17, tegmen dorsal ; fig. 18, tegmen ventral ; fig. 19, 

 median lobe dorsal ; fig. 20, median lobe ventral ; fig. 21, median lobe in pro- 

 file with the orifice fully open : i, dorsal rod ; k, ventral rod ; I, torn membrane, 

 making the continiiity of tegmen and median lobe : this membrane is really 

 less extensive than the diagrams show ; o, orifice. 



Figs. 22-70 are drawings made with camera Ivicida of the dorsal aspect of 

 the aedeagus of various species of HelopJiorini ; the magnification is in all 



