Madeiran Geomitra Snail (Geomitra delphinuloides)
The Madeiran Geomitra Snail, which was endemic to the island of Madeira, was discovered and apparently also described in 1860. It appears to be known exclusively from fresh but empty shells as well as from numerous subfossil and fossil specimens from both Pleistocene and Holocene deposits. [2]
The shells reached sizes of about 1,75 cm in diameter, they were rather this and fragile in substance, extremely roughened, perfectly opaque, flattened, rounded and planorbiform, with the spire greatly depressed and its umbilicus excessively wide and open, and of a uniform dull pale-brownish flesh-color varying into a chalky white. [1]
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The following citation is from T. Vernon Wollaston (1878) and tells a bit about the species.:
“This is not only one of the most anomalous of the Madeiran Helices, but by far the most remarkable one which has been brought to light of late years, – it having been discovered, by Mr. Lowe, so recently as in 1860. It was at an elevation of about 4000 feet [ca. 1219 m], in the Ribeira do Fayal, that Mr. Lowe met with it, and moreover in considerable abundance, -‘on the surface of the somewhat moist, loose, friable, black vegetable mould, amongst tufts of grasses, ferns, etc., on a steep, dry, sunny bank clothed with shrubs of Vaccinium and Heath, and mixed with a few scattered trees of Laurus, at the foot of perpendicular crags, along the new Levada called the Levada da Fajãa dos Vinhaticos [Levada da Fajã dos Vinháticos aka. Levadinha Joao de Deus].‘” [1]
The locality, mentioned in the citation above, could never be relocated.
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The species disappeared at around 1620 AD.. [2]
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References:
[1] T. Vernon Wollaston: Testacea Atlantica: or the Land and Freshwater Shells of the Azores, Madeiras, Salvages, Canaries, Cape Verdes, and Saint Helena. London: L. Reeve & Co. 1878
[2] Glenn A. Goodfriend; R. A. D. Cameron; L. M. Cook: Fossil evidence of recent human impact on the land snail fauna of Madeira. Journal of Biogeography 21: 309-320. 1994
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(public domain)
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edited: 16.06.2020