To begin with, 1 Though not relating exactly to our present theme, it would be improper to dismiss Nitzsch's name without reference to his extraordinary labours in investigating the insect and other external parasites of birds, a subject which as regards British species was subsequently elaborated by Denny in his Monographia Anoplurorum Britanniae (1842) and in his list of the specimens of British Anoplura in the collection of the British Museum.