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Show 72 DR. A. GUNTHER ON THE ZOOLOGICAL [Feb. 6, 18. ARCA, sp. Two small shells, probably the young of a a larger species, seem most nearly allied to A. gradata, Brod. & Sowb. ; they are rather more finely reticulated than is usual with that species, but in form, and the position of the umbones, they agree very well. B. Terrestrial Species. 19. B U L I M U S N U X , Broderip. The specimens of this species collected by Commander Cookson are very coarsely striated, and much darker in colour than those described by Broderip. The)* are striped longitudinally with a mixture of slate-colour and brown, with here and there some pale streaks; and some specimens have a distinct pale band around the middle of the body-whorl; and the four apical whorls are bluish black. This species is considerably variable in form, some examples being much more elongate than others. The following measurements show how great is the variation in length. One shell is 20 millims. long and 10 in diameter, and another very short one has a length of only 16 millims. and yet is the same width as the longer specimen. 20. BULIMUS UNIFASCIATUS, Sowerby. 21. BULIMUS ESCHARIFERUS, Sowerby. This species is quoted by Reeve as having been found at Chatham Island by Darwin. The Charles-Island shells are considerably larger than those from the above locality, and also coarser in sculpture, some of them displaying spiral granoseor rugose striation as in B. rugulosus of Sowerby, from the same islands ; and, indeed, they appear to be an intermediate variety or connecting link between the two species, both as regards size and sculpture. The largest specimen measures 19 millims. in length, and 7\ in width. 22. SUCCINEA BETTII, sp. nov. (Plate XI. fig. 8.) Testa ovata, superne aliquanto acuta, tenuissima, diaphana, flavo-cornea, versus apicem rubescens, irregulariter arcualim striatula, nitens ; anfractus 3, penultimus parvus convexus, ultimus maximus, inflatus; apertura ovata, superne angustata vix obliqua; columella obliqua, parum arcuata, tenuissime callosa; peristoma simplex regulariter arcuatum. Long. 13 millim., diam. maxima 8, aperturae longit. 10 millim., diam. 5f. Var. Testa brevior. This species is most nearly allied to S. rubicunda Pfeiffer, which was described as coming from the island of Masafuera, off the coast of Chili. From it the present species differs in consisting of half a whorl more. This difference is quite apparent when the spires of the two species are regarded with the mouth of the shell towards the eye. The penultimate and apical whorls of the Galapagos species |