Family Volutidæ. Sub-family Mitriana. _Nob._ GENERIC CHARACTER. Shell smooth, polished, sub-fusiform, the base obtuse and effuse; the plaits of the pillar oblique, and extending far beyond the aperture; outer lip internally smooth, the margin entire. _Nobis._ Types of form. 1. _M. fissuella._ 2. _casta. bicolor._ 3. _Olivæformis._ ---- SPECIFIC CHARACTER. _Shell entirely brown, marked by bands of punctured dots; spire and aperture nearly equal._ ---- The natural situation of this group, in its own circle of affinity, has already been shewn; it connects, in the most satisfactory manner, the genus _Mitra_, as now restricted, with that of _Conohelix_, and opens at the same time a passage to the Olives. The species yet discovered are few, and hence we yet can only trace three types of form; the first evidently representing _Mitra_, and the third, probably, typifying _Conohelix_. _M. Olivaria_ Lam., which truly belongs to this genus, may, perhaps, be only a modification of the 2nd type, to which our present species strictly belongs. The representation of this group among the Volutes, will be found in _Voluta Zebra_ and its allies. _Mitrella fusca_ is small, and of great rarity; our own specimen, beautifully perfect, is the only one we have yet seen. ---- MITRELLA ocellata. _Shell whiteish, the lower half of the principal whorl brown, with a band of alternate rufous and white spots, and marked with reticulated white lines, and remote sulcated striæ, internally punctured; spire, and upper part of the body whorl, delicately plaited, the plates crossed by transverse lines of excavated dots._ ---- This species has probably been overlooked as a variety of _M. Fissurella_; its markings, indeed, are partially the same, but its sculpture, and even its form, proves it to be distinct. The alternate white and rufous spots bear a fanciful resemblance to eyes. The description of _M. Olivæformis_ has already been given at Pl. 48, in the first volume of our former Series. * * * * * * [Illustration: MARGARITADÆ Pl. 1 _Margarita crocata._] MARGARITA crocata. _Orange Pearl-Oyster._ ---- Order Acephala. Family Margaritadæ. _Nob._ MARGARITADÆ. _Animal_ byssiferous, attached to marine bodies by a fascicle of tendinous filaments. _Shell_ foliaceous, the centre internally pearly and iridescent: the form irregular; the margins fragile and transparent. _Nob._ GENERA. MARGARITA. MALLEUS. PERNA. PINNA. (VULSELLA?) _Lam._ Sub-genera? Avicula. Crenatula. Inoceramus. _Auct._ ---- GENERIC CHARACTER. Margarita. See Leach. Zool. Miss. 1. p.107. (1814.) (_Meleagrina. Lam. Syst. 1819._) ---- SPECIFIC CHARACTER. _Shell subquadrate, squamose, fulvous or yellow, the ear of the right valve dilated and scarcely sinuated, that of the left valve very small: inside silvery blue, hinge smooth._ ----