3 (2). Antennae filiform in the basal part ... .3. C. insolutus McL. (p. 518' 



4 (l). Gills present on abdominal segments 1 — 6 



2. C. trimaculatus Curt. (p. 517; 



1. Cyrnus flavidus McLachlan 



Siltala, 1903c:7-10, Figure 2; 1905:132-134. - Ulmer, 1909:229, 296, 

 Figure 354.- Lestage, 1921 :503— 509, Figures 167—170.- Lepneva, 1940: 

 201, 205, Figures 152, 6. - MacDonald, 1950:22-24, Figures 5-8. 



Full-grown larva. Length 14— 16 mm. Anal legs extended posteriorly 

 (Figure 654). Head (Figure 655) light -yellowish brown, with chestnut brown 

 pattern; eyes situated on a white background; margin of occipital foramen 

 narrow, reddish brown. Frontoclypeus mainly dark; a light area in the 

 middle and a curved row of dark dots in the posterior part; less distinct 

 dots anterior to the light area form an irregular anterior arc; posterior 

 angle of sclerite light; 3 indistinct large dots and a small dot laterally near 

 the anterior margin. A short median seta and a long intermediate seta near 

 the dots; lateral anterior-margin seta curved and light. Anterior seta of the 



3 frontal setae short, thin, situated near the angle; middle seta similar; 

 posterior seta long and dark. Clypangulus narrow, dark brown; antennae 

 situated near the anterior margin, together with 3 setae, middle seta much 

 larger than the others. Indistinct chestnut brown dorsal stripes, which 

 converge lateral to the frontal sutures, near the bifurcation; area near 



452 curvature of frontal sutures light; large and small dots in the posterior part 

 along the dorsal stripes, lateral to the coronal suture and at the place of the 

 lateral stripes. Ventral side of head light, with indistinct dots near occipital 

 margin. Seta 9 is the longest seta of the head; seta 11 situated at a distance 

 from it, short, dark; seta 7 situated near margin, much shorter than seta 9; 

 seta 10 small and light; dark long seta 12 situated laterally, posterior to the 

 eye; thin, short seta 13 near it, slightly more dorsally; large seta 14 

 situated near the dorsal stripe; a pit and setae 15 and 16 situated posterior 

 to it; they are short and thin but distinct; similar seta 17 situated near the 

 suture near the posterior frontal seta. Short seta 8 situated ventrally, at 

 the anterior margin; seta 18 small and setuliform. 



Labrum with shallow median depression covered with straight, reddish 

 yellow, short, fine spinules; anterior angles rounded; dorsal sclerite 

 brownish; posterior -angle sclerites reddish brown; membranous anterior 

 margin narrow, with thin light hairs; seta 1 light, recumbent on the median 

 depression; seta 4 situated lateral to the depression, dark and strong; setae 2 

 and 5 thin, dark, situated near the anterior margin; seta 6 situated posterior 

 to them more medially; seta 3 situated laterally, near the margin, darker, 

 longer and thicker than the others. 



Left mandible with 3 teeth on the upper blade; middle tooth projecting 

 and large; lower blade with 3 short, blunt teeth; median depression with 



4 straight, light, strong, feathered chetoids in the penicillus. Upper blade 

 of right mandible with 2 strong, projecting teeth; lower blade with a large 

 tooth and 2 small teeth, which are fused. Outer setae of mandibles light 

 and long. 



511 



