"So far from such work being a loss of time, I believe it would have been well worth his while, had it been practicable, to have supplemented it by a special study of embryology and physiology. His hands would have been greatly strengthened thereby when he came to write out sundry chapters of the 'Origin of Species.' But of course in those days it was almost impossible for him to find facilities for such work." No one can look a the two volumes on the recent Cirripedes, of 399 and 684 pages respectively (not to speak of the volumes on the fossil species), without being struck by the immense amount of detailed work which they contain. The forty plates, some of them with thirty figures, and the fourteen pages of index in the two volumes together, give some rough idea of the labour spent on the work. (The reader unacquainted with Zoology will find some account of the more interesting results in Mr. Romanes' article on "Charles Darwin" ('Nature' Series, 1882).) The state of knowledge, as regards the Cirripedes, was most unsatisfactory at the time that my father began to work at them. As an illustration of this fact, it may be mentioned that he had even to re-organise the nomenclature of the group, or, as he expressed it, he "unwillingly found it indispensable to give names to several valves, and to some few of the softer parts of Cirripedes." (Vol. i. page 3.) It is interesting to learn from his diary the amount of time which he gave to different genera. Thus the genus Chthamalus, the description of which occupies twenty-two pages, occupied him for thirty-six days; Coronula took nineteen days, and is described in twenty-seven pages. Writing to Fitz-Roy, he speaks of being "for the last half-month daily hard at work in dissecting a little animal about the size of a pin's head, from the Chonos archipelago, and I could spend another month, and daily see more beautiful structure."