Note 20 — Chapter VI · THE DISTRIBUTION AND THE ÆTIOLOGY OF THE CRAYFISHES.
Reading edition
According to strict zoological usage the names should be written A. fluviatilis (var. torrentium) and A. fluviatilis (var. nobilis) on the hypothesis that the stone crayfish and the noble crayfish are varieties; and A. torrentium and A. fluviatilis on the hypothesis that they are species; but as I neither wish to prejudge the species question, nor to employ cumbrously long names, I take a third course.