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Show 596 MR. E. A. SMITH ON SHELLS [June 2, Pfeiffer, have the spire a trifle shorter, and the body-whorl the least more ventricose. In all the apex is reddish, and the lines of growth rather coarse. 25. CYCLOSTOMA (ADELOSTOMA) TRISTE, Tapparone Canefri, var. ? Hab. Faro and Shortland Islands and Choiseul Bay in Bougainville Straits and Santa Anna Island (Guppy) ; Guadalcanar (Mac-yillivray, in Brit. Mus.). Dr. Tapparone Canefri has kindly compared specimens from these islands with his C. triste, and is of opinion that they may be considered a variety of it; and observes that the New-Guinean form is a little smaller, its spire a little more slender, its surface more glossy, the colour redder, and the apex of the spire darker. The shells under examination are clothed with a very thin epidermis wdien in a fresh condition, exhibiting numerous very fine spiral thread-like lines, which entirely disappear in worn shells and can easily be rubbed off with a brush. For several species having a similar epidermis and an incomplete peristome, Dr. Tapparone Canefri has proposed the subgenus Adelostoma. The little shell Cyclostoma infans from Wild Island, Admiralty group, described from the 'Challenger' Collection (Proc. Zool. Soc. 1884, p. 226, pi. xxiii. fig. 8) belongs to the same section. 26. LEPTOPOMA JACQUINOTI, Pfeiffer. Hab. Rua Sura Island, off the north coast of Guadalcanar. This species does not appear to have been frequently met with by collectors, and is chiefly known (as Cyclostomapellucida) by Rousseau's description in the 'Voyage au Pole Sud,' and the diagnosis by Pfeiffer taken from the figure in the Atlas to that work. The three specimens collected by Mr. Guppy are uniformly semipellucid white, with the exception of the apex, which is pale reddish. The whorls are five in number, considerably convex, rapidly enlarge, and are sculptured throughout with very fine concentric striae besides the more prominent spiral lirce, which are most distinct uoon the body-whorl above the prominent carina at the periphery. The peristome is moderately and equally expanded all round except at the short interruption at the body-whorl and just under the umbilicus, where it is conspicuously emarginate. The operculum is thin, pale dirty yellowish, consists of about eight volutions which are separated by a raised revolving sutural line and sculptured with rather coarse cross-lines of growth. The largest of the three specimens from Rua Sura is 15 millims. high, 17 at its greatest diameter and 12| at its smallest. L. immaculatum, Chemnitz, is very like this species in some respects, but differs a little in form, having a taller and more conical spire, less rounded whorls, a more shallow suture, &c. 27. LEPTOPOMA VITREUM, Lesson. Hab. Santa Anna, Simbo, and Shortland Islands. |