Sentence:  It is strange that, long as the College of Physicians and its regulations have been before the medical world, so little should be known as to the history and qualifications of the class called Extra-Licentiates. ... [M]any imagine that these physicians are <WSD>supernumerary</WSD>, over and above a certain number assigned to the Licentiates. 
Meaning of the word marked with <WSD> tags:  Beyond the prescribed or standard amount or number; excess, extra.