The first part of the Catalogue of the osteological specimens in the museum of the College which, as already said, is devoted to man alone, is a most laborious, accurate, and valuable work, dealing first with the general osteology of man, then with his dentition, and, thirdly, with the special characters of the osteology and dentition of the different races of the human species—a line of study which had formed the subject of several of his lectures as Hunterian Professor. Nor is this by any means all, for the introduction to this volume forms a valuable compendium of the principles and rules of the science of craniology; the remarks on the mode of measuring skulls, and the method of calculating from such measurements “indices,” whereby skulls of different types can be compared with one another with exactness, being models of accuracy and clearness, and rendered the more valuable from the tables by which they are accompanied. For measuring the cubic contents of skulls, Flower was convinced that mustard-seed formed the best and most accurate medium. In addition to its value as a summary of the contents of that portion of the museum of which it treats, and as a _précis_ of its chief author’s views at that time as to the classification of mammals, the second part of the Catalogue is of special importance on account of containing an expression of opinion on the subject of zoological nomenclature—a subject on which Flower had previously spoken in no uncertain tones in his Presidential Address to the Zoological section of the British Association at the meeting held in Dublin in 1878, which is republished in _Essays on Museums_. The keynote of Flower’s introduction to his Catalogue was the urgent need of uniformity of nomenclature among zoologists; and on this, and the subject generally, he expressed himself as follows:—