Sentence:  Often he wrote good ones on casual slips and fancied them his; names like Trevellyan or Montressor or Delancey, with musical prefixes; or a good, short, beautiful, but dignified name like "Gordon <WSD>Dane</WSD>". He liked that one. It suggested something. 
Meaning of the word marked with <WSD> tags:  (dot=) for someone who came from Denmark, also a variant of Dean.