Nearly two years ago (www.ashbreure.nl / Snailblog 7 and 11 May 2009), I published some observations on dangling snails. This week, Mike Rutherford from the University of West Indies at Trinidad, draw my attention to some early papers on this topic. R.J.L. Guppy (1866) seems to earn the credits for the first publication about this phenomenon, when he described his Adamsiella aripensis. Tryon was the first to publish a figure, in his Monograph of American molluscs (1868), depicting a Chondropoma dentata Say, 1825 dangling on a leaf.
All the known occurrences are related to Annulariidae and Cyclophoridae.
Many thanks Mike for helping me with the literature search!
Guppy, R.J.L., 1866. On the terrestrial and fluviatile Mollusca of Trinidad. Annals and Magazine of Natural History (3) 17: 42-56.
Tryon, G.W., 1868. Monograph of the terrestrial Mollusca of the United States (concluded). American Journal of Conchology 4: 5-22.