_Spire_ of the shell lengthened, conic, the tip acute: inner lip not thickened, outer lip straight: base of the pillar curved inwards, and marked by 2 strong plaits; upper plaits evanescent, or entirely wanting. _Aperture_ effuse, and closed by an operculum? _Nobis._ ---- SPECIFIC CHARACTER. _Shell whiteish, with a very acute spire, nearly as long as the aperture; middle of the body whorl marked by angulated brown lines: suture with spots and fascicles of longitudinal stripes: basal belt very broad: aperture purple._ Oliva biplicata? _Sow. Tank. Cat. No. 2332. p. 33._ ---- This shell maybe considered as typical of a small group of Olives, which we suspect are peculiar to the American seas; they offer many points of difference from those of the Indian Ocean. We recollect to have seen another species, in some cabinet, with a small operculum. We have been fearful of pronouncing this to be the _O. biplicata_, as the judicious Conchologist will perceive the two descriptions do not exactly agree; and we have another to which the characters given of _biplicata_ will equally well apply. The perpendicular line indicates the natural size. ---- OLIVA eburnea. _Ivory Olive._ _Shell entirely white, or marked by two bands of angulated purplish spots; pillar about 8-9 plaited: basal belt and spire always white; the former single._ Oliva eburnea. _Lam. Syst. 7. 1. p. 438._ ---- This is the very common little Olive, sent in such abundance in the West India boxes of shells; we figure it, because it is seldom rightly named in collections, being confounded with _conoidalis_, _oryza_, and several others of an equally diminutive size: the plaits are sharp, short, well defined, and nearly all of equal size; although the base of the pillar forms an internal elevation. * * * * * * [Illustration: MARIUS _Thetys_.] MARIUS Thetys. ---- Order Lepidoptera. Sub-order Papilionides. (Thrysanuriform Stirps.--Horsf.) GENERIC CHARACTER. See Pl. 45. ---- SPECIFIC CHARACTER. _Wings horizontally lengthened, above bright rufous, transversely banded, with blackish stripes; beneath marbled with brown: lower part of the head, body, abdominal margin of the inferior icings, and feet, cream colour._ Papilio Petreus, _Cramer, Pl. 87, D. E._ ---- Thetys. _Fabricius._ Mant. Ins. 2, p.47. Eus. Syst. 3, 1, 77. ---- We frequently captured this Butterfly on the skirts of the Brazilian forests: its flight is bold and powerful, but it loves to bask on those leafy spots, where the sun, darting through a small opening of the dense foliage, illuminates a little space with sparkling brightness. The poor and somewhat inaccurate figure of this insect in Cramer's work, is the only representation yet published. We have not had leisure to investigate its scientific relations, further than to ascertain its close affinity with _Marius_; of which group it appears on aberrant species.