Polyommatus Artaxerxes, or the Scotch Argus, is an insect not only of great local interest, but has attracted, and continues to attract, the notice of entomologists all over the world. Among the English, and still more among the foreign students, who annually throng our University, there are always a considerable number who arrive in Edinburgh anxious to see “the rare butterfly from Arthur's Seat,” or who are commissioned by entomological friends to obtain it. Besides, there are the still more destructive emissaries from the London and provincial dealers in insects, who infest the hill during the season in which it is found. But although the situation in which this insect is principally taken is extremely circumscribed, I am not aware that its numbers are materially diminished by this continuous drain upon them.