Sentence:  Underside: ground-colour similar, both fore and hind wings with extensive <WSD>irroration</WSD> of black scale which varies considerably in amount: in some specimens it is very dense and gives a glackish tint to the ground-colour, especially on the hind wing. 
Meaning of the word marked with <WSD> tags:  Markings reminiscent of spots or (dew drops).