. The Bermuda islands. An account of their scenery, climate, productions, physiography, natural history and geology, with sketches of their discovery and early history, and the changes in their flora and fauna due to man. Natural history. Figures 67a, 67&.—Pcecilozonites circumfirmatus; x2'^. Figures 68, a, &.—Thy- sanophora hypolejjta ; x 10. Figure 69.—Helicina convexa ; x 2. 67, 69, by A. H. v.; 68, by Pilsbry. are extinct. (See Part IV.) Two other species of snails are also supposed to be endemic, viz., Tliysano2^hoTa hypolepta Pilsb. (fig. 68), and Helicina convexa Pfr. (fig. 69),
. The Bermuda islands. An account of their scenery, climate, productions, physiography, natural history and geology, with sketches of their discovery and early history, and the changes in their flora and fauna due to man. Natural history. Figures 67a, 67&.—Pcecilozonites circumfirmatus; x2'^. Figures 68, a, &.—Thy- sanophora hypolejjta ; x 10. Figure 69.—Helicina convexa ; x 2. 67, 69, by A. H. v.; 68, by Pilsbry. are extinct. (See Part IV.) Two other species of snails are also supposed to be endemic, viz., Tliysano2^hoTa hypolepta Pilsb. (fig. 68), and Helicina convexa Pfr. (fig. 69), but these are closely allied to West Indian forms. The large slug (Veronicella SchivelycB Pilsb., fig. 84), known only from Bermuda, in its habits and local- ized distribution appears like an introduced species, but if so its origin is still unknown. The following native species of West Indian origin are supposed to have been introduced independently of human agency : Thysanophora vortex (Pfr.); Greater Antilles; Bahamas; South- ern Florida. Figs. 70, a, h. * TMs genus is the most interesting one. Its largest species (P. Nelsoni) is extinct, but it occurs abundantly in the older cave-conglomerates and aeolian limestones, sometimes in strata exposed only at low tide, thus showing that it lived on the islands before their partial submergence, and indicating the com- paratively great antiquity of the genus. Its nearest allies are now found in the eastern United States. The three living species are P. Bermudensis ; P. Reinia- nus; P. circumfirmatus (fig. 67a, 676). A vaiiety of the first is abundant as a fossil in the later and softer limestones, often retaining very distinct bands of brown color. The fossil variety {zonata V., nov.) is rather larger with a thicker and firmer shell, larger umbilicus, and thicker callus than the living form. Both varieties vary considerably in height of spire, size of umbilicus, and color. For two series of comparative figures, see Part IV, G
Size: 1226px × 2038px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectnatural, bookyear1902
