Therefore it need not be doubted that the two little folds of skin, which originally served as ovigerous frena, but which, likewise, very slightly aided in the act of respiration, have been gradually converted by natural selection into branchiae, simply through an increase in their size and the obliteration of their adhesive glands.
Horregatik ez dago dudan jarri beharrik larruazalaren tolestura txiki biak, hasieran galga obigerotzat balio zutenak, baina ziurrenik aranasa egiteko ere pittin bat laguntzen zutenak, hautespen naturalaren eraginez zakatz bilakatu zirela, tamainuz handituz eta guruin itsaskorrak besterik gabe enulduz.