but in the several species of one genus, Pyrgoma, these valves present a marvellous amount of diversification; the homologous valves in the different species being sometimes wholly unlike in shape; and the amount of variation in the individuals of the same species is so great that it is no exaggeration to state that the varieties of the same species differ more from each other in the characters derived from these important organs, than do the species belonging to other distinct genera.
baina genero baten, Pyrgomaren, espezie ezberdinetan, plaka hauek ezberdintasun miresgarria aurkezten dute; izan ere, espezie ezberdinetako plaka homologoak batzuetan formaz zeharo ezberdinak dira, eta espezie bereko banakoek hain aldakuntza kopuru handia dutenez gero, ez da gehiegikeria esatea espezie bereko aldakiak elkarrengandik ezberdinagoak direla organo inportante hauetatik eratorririko ezaugarrietan, beste genero bateko espezieak diren baino.