Whoever looks at the immensity of the animal kingdom, and observes how intelligibly and systematically it is arranged in these various divisions, will admit that, however imperfect, the scheme is a magnificent product of human ingenuity and labour. It is not an arbitrary arrangement, like the grouping of the stars in constellations; it expresses, though obscurely, the real order of Nature. All true Classification should be to forms what laws are to phenomena: the one reducing varieties to systematic order, as the other reduces phenomena to their relation of sequence. Now if it be true that the classification expresses the real order of nature, and not simply the order which we may find convenient, there will be something more than mere resemblance indicated in the various groups; or, rather let me say, this resemblance itself is the consequence of some community in the things compared, and will therefore be the mark of some deeper cause. What is this cause? Mr. Darwin holds that “propinquity of descent—the only known cause of the similarity of organic beings—is the bond, hidden as it is by various degrees of modification, which is partially revealed to us by our classifications”[10]—“that the characters which naturalists consider as showing true affinity between any two or more species are those which have been inherited from a common parent, and in so far all true classification is genealogical; that community of descent is the hidden bond which naturalists have been unconsciously seeking, and not some unknown plan of creation, or the enunciation of general propositions, and the mere putting together and separating objects more or less alike.”[11] Before proceeding to open the philosophical discussion which inevitably arises on the mention of Mr. Darwin’s book, I will here set down the chief groups, according to Cuvier’s classification, for the benefit of the tyro in natural history, who will easily remember them, and will find the knowledge constantly invoked. There are four Sub-kingdoms, or Branches:—1. Vertebrata. 2. Mollusca. 3. Articulata. 4. Radiata. The VERTEBRATA consist of four classes:—Mammalia, Birds, Reptiles, and Fishes. The MOLLUSCA consist of six classes:—Cephalopoda (cuttlefish), Pteropoda, Gasteropoda (snails, &c.), Acephala (oysters, &c.), Brachiopoda, and Cirrhopoda (barnacles).—N.B. This last class is now removed from the Molluscs and placed among the Crustaceans. The ARTICULATA are composed of four classes:—Annelids (worms), Crustacea (lobsters, crabs, &c.), Arachnida (spiders), and Insecta. The RADIATA embrace all the remaining forms; but this group has been so altered since Cuvier’s time, that I will not burden your memory just now with an enumeration of the details.