The present writer was privileged to attend only one of these courses—on the general structure of the Mammalia—and is therefore not competent to speak from experience of these lectures as a whole. Nevertheless the one course was amply sufficient to convince him of the lecturer’s special qualifications for his task. Flower was indeed an ideal lecturer, endowed with a fine presence, a suave and yet penetrating voice, great power of expression, a slow and impressive delivery, and, above all, an absolute mastery of his subject (whatever it might be) down to the minutest and apparently most insignificant details. For him, every detail of structure, whether functional or rudimentary, had a significance and a meaning, and he would never rest satisfied till he had found out what that meaning was, and had laid the whole of the evidence on which he based his conclusions before his audience. That audience, which generally included a considerable number of the elder members of the medical profession, as well as many well-known zoologists and anatomists, invariably listened with rapt attention to the story told so admirably by the accomplished lecturer. Of these lectures, the first course, delivered in 1870 on the Osteology of the Mammalia, is perhaps the one which has rendered Flower most widely known among zoological students, since, as noticed below, it became the basis of a valuable little volume. His introductory lecture in February 1870 was largely devoted to the subject of plan, or “type,” in Nature, and to the evidence in favour of the transmutation of species and evolution of organised beings—a doctrine which was at that time by no means so widely accepted, even among scientific men, as it is at the present day. In this address the lecturer prefaced his remarks by explaining that since the main part of his anatomical knowledge was derived from the splendid series of specimens and preparations in the museum under his charge, so he intended to act as the mouth-piece of the specimens themselves. After this introductory lecture followed the regular course for the year, which was devoted to the Osteology of the Mammalia, and it is perhaps this series which has rendered the name of Flower most familiar to the ordinary students of scientific zoology and comparative anatomy, since it was published during the same year as a volume in Macmillan’s _Manuals for Students_, under the title of _An Introduction to the Osteology of the Mammalia: being the Substance of a Course of Lectures delivered at the Royal College of Surgeons of England_. Such was the success of this admirable little volume—which has ever since formed the recognised text-book on the subject of which it treats, that a second edition was called for in 1876, and a third in 1885. In expanding and revising the latter—in which, by the way, the second half of the original title was dropped—the author, owing to the pressure of official duties, called in the assistance of Dr. J. G.