Note that Street Wraith wears bells that dangle from its cloak. If you look closely, you can see that the bells are very sinister in shape and origin. Mouse over the image below to enhance the detail of one of the wraith's bells.
As you can see in the full art, Street Wraith bears many of these skull-bells. They were an invention of the artist, Cyril Van Der Haegen, and really serve to add depth and menace to the wraith's character. Nice work, Cyril!