The passage I quoted was in a long paragraph that began: "Several eminent naturalists have of late published their belief that a multitude of reputed species in each genus are not real species; but that other species are real, that is, have been independently created. This seems to me to be a strange conclusion to arrive at. ///" He is ridiculing the idea of theistic creation. -I'm looking at the first edition as quoted in the final pages of Steve Jones' "Almost Like a Whale". I can't find the earlier pasage you cite, but on the very next page there is a paragraph that reads: "Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. /// Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed."-Obviously in later editions he made alterations to appease his religious critics.