–Museum three—one from D^r. Richardson who is well known there having worked much in the collection; one from M^r Yarrell & one from M^r. Bowerbank—¹

I will make it a point to borrow Whewell’s book² from Owen & to read it the moment he returns— As regards Classification of animals some conclusions I have come to are as follows—³

That species of animals belonging to the same genus may have an affinity to each other; genera of the same family may have a mutual affinity; relationship of affinity may likewise exist between orders of the same class, but the degree of affinity is different in the different cases— The affinity between species of the same genus may be called an affinity of the first degree; that of genera to genera, of the same family, of the second, or more remote, degree; and, that of families of the third degree & so on— Then species of one family have affinity with species of other families of the same order an affinity of the third degree only, and species of different orders of the fourth degree only— That some such feeling as this is impressed upon Naturalists may be inferred from the pains that is taken to place prominently the points of resemblance between animals of different groups of high value—as in the case of the affinity of the ornithrhynchus, or the Echidna, to the Reptiles— the differences here I do not find are dwelt upon with the same ‘gout’ as the points of resemblance— The affinity of the Ornithorhynchus to the Echidna in very much closer than that of either of these animals to the Classes Reptilia, or Aves,—& of a different nature as I will undertake to show— That other, and closer links between the Classes may hereafter be found would be stupid to deny, but as a matter of feeling —reasoning from analogies—I do not expect it. There is much to be said on this subject which I will trouble you with hereafter—

I have been hard at work at brains for some time past & immensely interested with my studies because in some respects I find the result so very different from what I expected. The Whales for instance are placed by Cuvier & many Naturalists at the end of the Class Mammalia, & yet they have a most highly organized brain— I have puzzled myself much about this matter, for although from all I can learn of the Whales they appear to enjoy a considerable stock of intelligence it does not at all come up to what would be inferred from the consideration of the brain alone—and, it has occurred to me that as the brain is a thing to be educated from without it does not follow that what would be termed a highly organized brain is necessarily followed by corresponding intelligence in the animal— The whales have many of them no olfactory nerves & in the others they are in a most rudimentary condition— Their organ of vision does not appear to be particularly good— Of legs they have none & their hands & most unfitted for touch—and yet this animal has to suckle its young &c— he ought to have a good brain to recompense him for the imperfections of the educatory media— Among the Carnivora, the brain of the seal is perhaps one of the highest & this poor brute is likewise in a bad school— I mention this as having connexion with “The physiological importance to life of different structures”—& I may add that in animals of the same group (in the Quadrumana for instance) there is immense difference in the structure of the brain— species of many groups have a much higher brain than the lowest Quadrumana but none have so good a brain as the highest of that order— as a general rule each group begins as it were lower than its predecessor (beginning at the bottom) & terminates higher— each at the same time seems to perfect something—in the organs of respiration, circulation & locomotion the bird is higher than Man—

Having had my bit of chat I will go to bed—so good night | Always sincerely yours | Geo. R. Waterhouse