250 THE CANADIAN ENTOMOLOGIST 



Structurally the nymph is very similar to that of S. alternatus 

 except that the lateral abdominal spines are shorter. The setae 

 are but once banded and there is a very pronounced brownish band 

 at the apical end of each tarsus. 



The nymphs show the same U-shaped ventral abdominal brown 

 markings as the adults. 



Siphlonurus triangularis sp. nov. 



Male suhimago. — Length 12-13 mm. Head mostly deep brown, 

 varied with whitish and yellowish irregular markings. Lower part 

 of face transparent whitish. Thorax above deep brown; sides and 

 ventral surface brown with white areas. Legs uniform light brown, 

 but with darker markings on coxae and trochanters at joints. 

 Wings rather dull with light brown venation and without clouded 

 areas. Dorsal surface of abdomen deep brown with a pair of 

 lateral light areas on segments 2-7. Ventral surface of abdomen 

 light brown with deep brown triangular areas, See PI. IX., fig. 10. 

 Lateral setae 11-12 mm. long, the middle one rudimentary, showing 

 4-5 segments. 



Female suhimago. — Length 14-15 mm. Similar to male in 

 coloration. 



Female imago. — Length 15 mm; setae 15 mm.; fore leg 8 mm. 

 Middle and hind legs 6.5 mm. Very similar in coloration to the 

 male subimago, but lighter and ventral markings of alxlomen 

 more pronounced. Wings clear, light brown venation, no clouded 

 areas. 



Nymph. — Length (mature) 12-15 mm.; setae 5-6 mm.; leg 

 5 mm. General colour brown and white. Mouth-parts, see PI. 

 X, fig. 11-15. Thorax darker on upper surface. Legs whitish,, 

 banded with brown as follows: Femur with a basal brown band 

 and another on apical fifth; tibia with a basal band, tarsus with 

 basal and apical bands. Legs covered with numerous small spines 

 and hairs; claws long, slightly curved and very pointed. Each 

 segment of abdomen dorsally, except 1 and 10, usually light coloured 

 in middle with brown band across basal margin from which project 

 caudad two brown streaks. Each segment brownish toward the 

 lateral margins, but with light areas in both anterior and posterior 

 margins. A pair of very dark dots at posterior margin of each 



