@Simpleton They were two separate people. Darwin was a contemporary acquaintance of Miss Bird's, but he did not ever visit Japan. Charles Dallas Esq. was the author of the paper "Notes Collected in the Okitama Ken" that was published in the journal Transactions of the Asiatic Society of Japan vol 3 issue 10. I managed to track down a digitized pdf (horribly boring stuff, do not recommend) in order to see if the content matched up (it didn't).
@toriaezu Yea, I gathered as much from the different names and from the explanation you gave. XD
I just meant that in the manga they might have been combined into the fictional character of "Charles Darwin, incidentally doing stuff that he didn't do in real life, but which should rather be ascribed to Mr. Dallas." :)
@toriaezu Yes, you are completely correct. It clearly separates the two. This has all been just me having managed to confuse myself in a manner suitable to my name. As you were, and sorry about wasting your time.
(Edit to clarify, the above is not sarcasm. I finally trawled through the chapter again and found the reference I had managed to overlook. And I truly am sorry.)