The Cambridge natural history, Vol. 03 (of 10)Note 50 — Chapter II · LAND AND FRESH-WATER MOLLUSCA, THEIR HABITS AND GENERAL ECONOMYReading editionZeit. wiss. Zool. xlii. p. 203 f.◇Copy noteReturn to CHAPTER II LAND AND FRESH-WATER MOLLUSCA, THEIR HABITS AND GENERAL ECONOMY