You appear to be correct. I have an old Bantam paperback which doesn't identify the edition, but there's a newer Penguin edition which is an abridgement of the original Journal of Researches published in 1839.
It has nothing so suggestively "evolutionary", but there is a corresponding passage referring to "The law of sucession of types" and suggesting that if Buffon had known of these fossils ( Megatherium etc. ) he would have said "... that the creative force in America had lost its vigour, rather than that it had never possessed such powers." - so there's the "C word".
My first hand knowledge of Darwin's correspondence and notebooks, such as it is, is consistent with Shermer's thesis: Darwin didn't become an evolutionist until after his return to England.
Well, the terms evoutionist and creationist are highly misleading in this context. Darwin refers to "creative force" evidently in a very general way. At the time of his voyage, he was deeply involved in Lyellian geology and was putting his observations in that context, so the general framework in which he was working is recognizable as a prototype of todays cosmic and terrestrial "evolutionism" .
But Lyell was (almost militantly) anti-evolutionist. Sure, he was a progressive creationist, but so were all (scientific) creationists of the time, as biological succession in the geological record was an established fact. The "creative force" explained (however vaugely) biological succession, but it was most definitely NOT evolutionary.