21. There is a well-marked dark median line on the abdomen. 22. There is also a median line of grey scales. 23. The mouth is small and the external lip is divided behind on the median line . 24. The hindwings are white with an ochreous base and a blackish subbasal and median line . 25. The yellow colour along the costa is a shade paler than below the median line . 26. Sometimes the dark spots turn the median line inconspicuous, especially when the animal is contracted. 27. The thorax is dark grey, contrasting with the dark brown edges and the median line . 28. Thorax and tegulae shining greyish brown with reddish gloss, thorax with a white median line . 29. It straddles the median line between the British and Norwegian sectors of the North Sea. 30. The forewings are pale gray with a narrow dentate median line and numerous scattered brown scales.
