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Show 452 MR. HARPER PEASE ON POLYNESIAN LAND-SHELLS. [May 2, occur, represented by H. bursatella, Gld. They differ from the type in being angulate at the periphery, with the spire more elevated, and the whorls more plain. Their greatest peculiarity, and one by which they may be easily recognized, is the shape of the umbilicus, which becomes at maturity partly covered over by the base of the last whorl, thus becoming cavernous. Two species have been described from Tahiti and the Hervey Islands, viz. jacquinoti, Pfr., and fratercula, Pse., which evidently belong to the above group, but are depressed and carinate at the periphery, corresponding in their variation to stellula, Gld., at the Hawaiian Islands. I add the following remarks on the synonymy of the species. PITYS BURSATELLA, Gld. Of this variable species I have had an opportunity of examining several hundred specimens, and have also received a full series selected from the collections of the American exploring expedition, and from the late Mr. Cuming's type specimens of H. jacquinoti, Pfr. The synonymy, as determined by Dr. Gould on the labels of distribution issued by the Smithsonian Institution, and adopted in the following catalogue, is correct, with the exception of H. oceanica, Guill., and H. cavernula, Jacq. Of the synonyms determined as above, II. excavata, Jacq., and H. coarctata, Pfr., are pure synonyms of the type ; H. streptaxon, Roe, is an abnormal form, and II. turricula, Jacq., identically the same; II. oceanica, Guill., which I exclude from the synonymy, is described as being concavely depressed on its base ; and no mention is made of the laminae in its aperture, which are distinct and could not have escaped notice. Should the determination by Dr. Gould prove to be correct, //. oceanica, Guill., should have precedence over H. bursatella, Gld., having been described four years previously. H. jacquinoti, Pfr. (cavernula, Jacq.), differs from P. bursatella, Gld., or any of its varieties, in being more depressed, acutely carinate at the periphery, without epidermis (surface somewhat shining), its ribs solid, more prominent, extending over the edge of the whorls in a serrated manner, and all the whorls depressedly grooved concentrically at their middle. I have met with no species of its type in collections from the Marquesas, and refer it therefore to Tahiti with a doubt. The only other species of its peculiar form is P. fratercula, Pse., inhabiting the Hervey Islands. PITYS JUGOSA, Migh. Helix jugosa, Migh. Proc. Boston Soc. 1845, p. 19. Helix rubiginosa, Gld. Proc. Boston Soc. 1846, p. 171 • A m E X D Ex. 1852, p. 50, fig. 49. ' ' V' The above species ranges over all parts of the island of Kauai; it varies in being more or less openly umbilicate, and in the colour being either wholly reddish brown or tessellated with a dusky yellowish colour. |
