provided those properties are important, and the objects contained in each genus or family resemble each other more than they resemble anything which is excluded from the genus or family. After the recognition and definition, then, of the _infimæ species_, the next step is to arrange those _infimæ species_ into larger groups: making these groups correspond to Kinds wherever it is possible, but in most cases without any such guidance. And in doing this it is true that we are naturally and properly guided, in most cases at least, by resemblance to a type. We form our groups round certain selected Kinds, each of which serves as a sort of exemplar of its group. But though the groups are suggested by types, I cannot think that a group when formed is _determined_ by the type; that in deciding whether a species belongs to the group, a reference is made to the type, and not to the characters; that the characters "cannot be expressed in words." This assertion is inconsistent with Dr. Whewell's own statement of the fundamental principle of classification, namely, that "general assertions shall be possible." If the class did not possess any characters in common, what general assertions would be possible respecting it? Except that they all resemble each other more than they resemble anything else, nothing whatever could be predicated of the class. The truth is, on the contrary, that every genus or family is framed with distinct reference to certain characters, and is composed, first and principally, of species which agree in possessing all those characters. To these are added, as a sort of appendix, such other species, generally in small number, as possess _nearly_ all the properties selected; wanting some of them one property, some another, and which, while they agree with the rest _almost_ as much as these agree with one another, do not resemble in an equal degree any other group. Our conception of the class continues to be grounded on the characters; and the class might be defined, those things which _either_ possess that set of characters, _or_ resemble the things that do so, more than they resemble anything else.