XI.—The Condition of the Mantle Cavity in Two Pulmonate Snails living in Loch Lomond

Abstract

Synopsis A survey has been made of the condition of the mantle cavity in populations of Lymnœa (Radix) peregra (Müller) and Physa fontinalis (L.) living in a range of depths and habitats in Loch Lomond. In many populations, including some in relatively shallow water, the mantle cavity remains water-filled throughout life. Where the cavity contains a gas-bubble, micro-gas-analysis (using a modification of Krogh's methods) has revealed that in some cases the gas composition is such that the bubble could be used as a physical gill, while in others such use is unlikely. Other observations on respiratory behaviour of the two species are reported, and growth-changes are noted in the surfaces available for cutaneous respiration. The study is discussed in relation to previous work on the respiration and ecology of freshwater pulmonate snails.