79 



10. O. nigripes (Zettersledt). 

 Tab. IX. 



Larva: Head rounded; wider than long, a notch at insertion of antenna-; 

 front margin arcuate. Antenna? short; antennal tuft small, with only a few hairs; 

 on apex four hairs, one long, and a digit. Anteantennal tuft multiple; lower 

 and upper frontal tuft both consisting of one single feeble hair. Eyes large. Thorax 

 subquadratic, angled at hair-tufts; hair- formula of frontal border: 3231441323; hair 

 one after tuft four very short. Lateral hairs in multiple tufts and some single strong 

 hairs. Abdominal segments broad; the first of them much shorter than the last. 

 Lateral hairs on the first segment four; on the second three, on the third to seventh 

 two. On fourth to seventh segment subdorsal hairs single in two series. Tufts of 

 eighth segment in common arrangement; lateral comb consisting of about twenty 

 scales arranged over a little triangular area; scales formed as sharp strong thorns 

 without any lateral thorns or hairs. Sipho short, straight, tapering at front only 

 about two and a half times longer than broad. Pecten long consisting of about 

 fifteen thorns; the last of them out of line at greater distance from each other; 

 most of them with a short basal tooth. A tuft of hairs between end of pecten and 

 apex. Anal segment broader than long ringed by the dorsal plate; dorsal tuft rather 

 feeble but with two strong hairs; ventral brush consisting of about eighteen rays, 

 every ray carrying from seven to ten hairs; no hair-tufts before the barred area; 

 anal gills extremely long, acute and equal. 



Lateral tufts of labium short but dense; the inner part with a crown of comb- 

 hairs; palatum large, covered with long soft hairs. Mandibles quadrangular with 

 two strong spines, before collar a row of rather long cilia from a collar. About 

 eight thorn-like bristles from margin. Dentition: four acute teeth, before them a 

 long acute thorn; long cilia below thorns; Process below indistinctly furcate with 

 hair-tufts on both tips, a group of hairs at base. Maxilla 1 very broad, almost qua- 

 dratic with a brush of rather short hairs at apex and a seta; near the inner edge a 

 coating of long soft hairs; stronger dense haircovering along margin. Palpe thick, 

 high with four small digits at apex. Mentuni triangular with inconspicuous apical 

 tooth and many small almost equal lateral ones. 



Geographical distribution: Greenland; most probably circumpolar. 



11. O. punctor (Kirby). 



0. sylvw Theobald. 

 Tab. X. 



Description: Imago: Very similar to 0. communis. Scales of head and 

 thorax mostly yellowish-brown, brighter than in O. communis. Thorax with a more 

 or less commonly well-defined median stripe of dark brown scales on mesonotum. 

 The white bands of abdomen with a creamy tinge, not white as in 0. communis: 

 most of the bands at least them on segments 5 — 7 contracted or even interrupted 

 in the middle so that the bands are almost changed into creamy, yellowish, tri- 



