I had considered both C. severata and C. subrectaria and had gone fore the 2nd as it has a narrower strip of strong (like on forewing) patterning on the hindwing. Looking again now - is their faint scalloping of the outer margin suggesting C. severata ? Also the middle image on CD p. 2/3, Moths of Vic., Part 3. Comparing C. arachnitis - little strong patterning on hindwing (yes), strong dark medial line on hindwings (no), scalloped outer wing margins (yes), strong white band on abdomen (not so clear in all MoVic examples) (no), all live moths Illustrated in MoVic are largely shades of grey while above specimen is worn brown ( the > 100yo pinned specimens have changed colour (browned) I suspect)