On a new variety of Ampullaria crassa Swainson from French Guyana

The Gonini-Expedition, that explored in 1903 and 1904 some of the rivers, giving origin to the Marowijne or Maroni, as it is called by the French (see sketch of Surinam on p. 2 of this volume), made also a little excursion on French territory, and explored a part of Mount Cottica on the right bank of the Lawa. Here, at an altitude of 450 M., were collected some specimens of Doryssa hohenackeri Phil., of which species, although recorded from Surinam in general, no well-stated locality in our colony is known (see p. 35), and also three specimens of an Ampullaria, which apparently is related to the A. crassa Swains. from the Lawa, mentioned in my paper on the non-marine molluscs of Surinam (this volume pp. 1—46). With Mr. Sowerby, who had he kindness to compare it, I am agreeing in taking it for a variety of this species.