Through a pocket lensNote 13 — Chapter II · ARTHROPODS AND THEIR CLASSES.—THE MARGINED WATER BEETLE; THE GREAT WATER BEETLE; THE COCKTAIL BEETLEReading editionZeitschrift f. wiss. Zoologie, Bd. xl. S. 481.◇Copy noteReturn to CHAPTER II ARTHROPODS AND THEIR CLASSES.—THE MARGINED WATER BEETLE; THE GREAT WATER BEETLE; THE COCKTAIL BEETLE