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Show 1878.] FROM JAPAN AND BORNEO. 499 kozoologie,' 1847, p. 44) for the reception of the curious shell figured by Martyn under the name of Lituus brevis.^ It only differs from Myxostoma in having the inner lip of the aperture sinuated above, and in the wing-like expansion of the outer rim not leaning upon the penultimate whorl. The canaliculate suture, I presume, is only a specific character. In all respects agreeing with this species are two others, Cyclostoma planorbulus, Lamarck, and Pterocyclos albersi, Pfr. The former has had several localities quoted as its home, among which are Senegal?, Philippine Islands, Bengal, Java, Borneo, Sumatra (in Mus. Cuming), and Pulo Condore Island. Which of these is the true habitat I cannot say with certainty, nor am I aware that it has ever been definitely settled; there is, however, some slight evidence to show that tbe last locality is the correct one. W e are also in the same state of uncertainty respecting Pt. albersi. Pfeiffer described the species not knowing its locality ; and Benson ('Annals of Nat. Hist.' 1857, vol. xix. p. 208) is wrong in attributing a shell found at Teria Ghat, Khasia hills, India, to this species ; for it was, as shown by Hanley ('Conchologia Indica,' p. 56), only a variety of Pt. parvus, Pearson. Here, then, is a small group of four species, all having a Pterocy-cloid expansion of the outer rim of the lip, and an operculum of precisely the same structure. Three of them have channelled sutures to the whorls, are of a depressed orbicular form, and have the inner lip sinuated at the termination of the sutural channel. The fourth (brevis) and the type of Myxostoma lacks the channelled suture, and has only the slightest trace of a sinus in the lip-both of which characters, especially the former, I consider more specific than generic. From Cyclophorus with its simple concentric thin horny operculum and simple lip to the aperture, the different operculum and expansion of the lip of Myxostoma warrant, at all events, a subgenerie separation. There are two or three Burmese species (Cyclophorus pinnulifer, Benson, C. calyx, Benson, and C. hispidulus, Blanford) which will also conveniently range under this genus. They are depressed sub-discoid shells with a double rim to the aperture, the outer lip with a small superior wing-like expansion, and the operculum thick, horny, with the outer margins of the whorls lamellated. For this group Blanford proposed the name Scabrina (Journ. Asiatic Soc. Bengal, 1863, p. 322). The museum is indebted to Mr. J. B. Sowerby for a single specimen of this interesting species. |
