the 3 setae of anteclypeus long and one short, but not as short as in 

 Plectrocnemia; 2 long setae of labrum shorter than setae of anteclypeus; 

 other setae small. Mandibles sickle -shaped, blunt; outer setae very short; 

 right mandible situated above the left at rest. 



Wing sheaths reaching segments 4—5. First four segments of tarsi of 

 fore and midlegs with natatorial setae. 



Gills present on abdominal segments 2—7; gill of segment 2 consisting 

 of one dorsal filament, gills of segments 3—6 of 2 filaments; a dorsal and 

 a ventral; gill of segment 7 consisting of one ventral filament; if a dorsal 

 filament is present it is short. 



Plates of holding apparatus present on segments 3—8; small pointed 

 spinules present among the large blunt spinules; number of spinules as 

 follows: 111:6-10; IV:5-10; V:5-9+ 7-11; VI:7-10; VII:5-8; VIII:6-8. 



End of body with 2 short rounded lobes with numerous strong dark setae. 

 Sheath of outer lobes of male genitalia broad and rounded; penis sheath 

 divided at the end; segment 8 of female pupa with a broad, conical process 

 ventrally. 



Pupal case 10—12 mm long; walls of case made of loose tissue covered 

 with plant fragments, sand grains or fragments of shells; pupa lying in a 

 grayish brown cocoon. 



Mode of life and habitats. Predacious, building capturing nets; 

 stagnant and slowly running water; on the bottom and in plant thickets. 



Distribution. European USSR: Western Siberia. In addition, Europe. 



456 2. Cyrnus trimaculatus Curtis 



Siltala, 1905:129-130, Figure 34. - Ulmer, 1909:229, 296. - Lestage, 

 1921:504-510, Figures 168-169. 



Full-grown larva. * Length 10—11 mm. Sclerites light yellow, with 

 distinct punctate and shaded pattern. Frontoclypeus mainly yellow; margin 

 of anterior part and middle dark; sclerite with 3 small dots on both sides 

 anteriorly; 1 dot and 2 dots on the stripes posterior to them; posterior 

 part with a transverse curved row of dark, large dots. Short, dark, broad 

 dorsal stripes extending also along the coronal suture lateral to the frontal 

 sutures, beginning in the middle of the sclerite; large dots on the stripes 

 and lateral to them; similar dots present instead of lateral stripes. 



Teeth of right mandible blunt; middle tooth of lower blade larger than 

 the others. 



Pronotum with distinct dots, slightly darker posteriorly; 2 dots near 

 the median suture; a longitudinal curved row of dots in the middle of each 

 half; anterior angles of sclerite with 2 or 3 dots. 



Propleuron with dark dots in the episternal part; hornlike process 

 brownish. 



Pupa. Length 6—8 mm. Antennae moniliform, reaching abdominal 

 segments 7—8. Fore and mid-tarsi with natatorial setae. Number of 

 spinules on plates of holding apparatus as follows: 111:3—7; IV: 5— 8; 

 V:4-6 + 7-13; VI:7-10; VII:6; VIII:5-6. Gills less numerous than in the 

 other species: gill of segment 2 with one dorsal filament; gill of segment 3 

 with a dorsal and ventral filament; gills of segment 4—5 sometimes with 



* Larva little known. 



517 



