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Show 1875.] MAJOR H. H. GODWIN-AUSTEN ON HELICIDAE. 43 shortly to make them public. They are no doubt valid ; and conclude by observing that this ** Relation ' accordingly offers no evidence of the later existence of the Solitaire and other extinct birds of Rodriguez than we already had from the journal of Pingre kept in 1761. 5. Supplementary Notes on the Species of Helicidce of the Subgenus Plectopylis. B y Major H . H . G O D W I N - A U S T E N , F.R.G.S., F.Z.S., & c , Deputy Superintendent, Topographical Survey of India. [Eeceived January 11, 1875.] Since I have been at Calcutta, I have looked over the specimens of Plectopylis in the Museum, and find some additional notes to add to m y former paper, as well as a new species, which I now proceed to describe. HELIX (PLECTOPYLIS) TRILAMELLARIS, n. sp. Shell sinistral, widely and openly umbilicated, discoid, flat above; apex slightly raised, solid, covered with a brown epidermis, roughly and obliquely striated. Whorls 7, sides well rounded. Aperture oblique, widely lunate. Peristome white, much reflected and thickened, the margins united by a strong high ridge, reflected slightly forward, a slight notch separating it from the lower margin of the peristome. A single simple parietal vertical lamina is situated nearly one half of the circumference from the aperture, giving off from its lower end a long horizontal lamella, which extends halfway to the aperture; the usual median horizontal lamella is not united to the vertical lamina, but extends up to, and is united to the apertural parietal ridge, and is strongly developed. A third, thread-like free lamella extends also up to the aperture, having its origin just below the vertical lamina. The palatal plicse are simple, six in number, the first and upper very short, the second very long, and the rest moderate and equal. inch. Major diam 0*65 Minor diam 0*55 Alt. axis 0*22 Hab. Burmah. Exact locality unknown; collected by Mr. Theobald, jun., of the Geological Survey of India. In the collection of the Indian Museum, Calcutta. On an examination, kindly assisted by Mr. G. Nevill, of the Indian Museum, Calcutta, of all the species of this genus, the above form turned up. It differs so much from P. perarcta, with which it is closelv allied, that I do not hesitate to describe it as new. From that shell it differs internally in the upper horizontal lamella being |