I have not a well defined dissection to appeal to. I have so often, as I remark above, seen the mouth far posterior to the organs referred to, that I had hardly doubted the relation I have suggested until you expressed your opinion about it.—2 I was not aware of the objectionable character of the terms Kingdom & Subkingdom as I have used them in my Chapter on Dist. of Crustacea,3 until I read your inferences from them.
The Study of Crustacea had led me to regard the two American Coasts Eastern & Western, as having a nearer relation to one another than to other coasts or Seas;4 and also Western Africa & the Pacific as having in general resemblance in the range of Species. On this account, or to exhibit this relation, I divided the earth into three meridional Sections, the Occidental, Africo European & Oriental, which I unfortunately named Kingdoms. All the earlier half of my Chapter had exhibited the fact that the several zones of temperature, the torrid, temperate & frigid, and even the subzones were very different in species from one another, and that the species of the same zone over the world were more closely related than species of different zones on any coast. In using the term Occidental Kingdom, I did not mean to imply that the species of the temperate zone had any close resemblance or any resemblance at all to those of the Torrid zone in this Kingdom: But only that the range of species as a whole from North to South differed strikingly from the range of species in the Africo-European Section: So in Subdividing the Oriental Kingdom, I did not mean to imply that the species of Temperate New Holland were allied to those of the East Indies, more than to those of New Zealand; for this would be contrary to the Grand law of distribution based on temperature.5 In fact New Zealand and Southern Australia, & especially Tasmania, have quite close relations in species, though not as close, as far as I have studied the Species as between New Zealand & western S. America from Chili to Tierra del Fuego. I should say however that the species of Tasmania have not yet been particularly described or Catalogued and it is possible that a stronger resemblance may be made out than we now know of.— (On our own coast Cape Cod off Massachusetts is a very remarkable boundary both for species of Mollusca and Crustacea).—
I regret that I did not use the term Section in place of Kingdom.6 But the species seemed to me to be so different, between the Sections—that is the temperate of one from the temperate of the other &c &c that I chose the stronger term—looking at the three Kingdoms as in a certain Sense an independent Kingdom of Species in Creation—a difference due still in a large degree to the different sea temperatures along the coasts. But I will not detain you longer. I would give much to have the pleasure of talking over the subject with you.— Please mention to Mr Lubbock that his letter and his valued paper7 came to hand safely. I am greatly interested in all his labors and gratified with them.
I am out of patience that my plates are not yet out—8 They are all engraved and almost ready. But I cannot hurry the person who has charge of them, and so ⟨they⟩ linger. I am always delighted to hear from you and of ⟨ ⟩
Very sincerely ⟨yours⟩ | James D. Dana
Please cite as “DCP-LETT-1544,” in Ɛpsilon: The Charles Darwin Collection accessed on