RHETUS Cramerii. ---- GENERIC CHARACTER. _Larva_ and _Pupa_ unknown. _Wings_ triangular; the posterior lengthened and rather acutely tailed. _Antennæ_ with the club linear-fuciform. _Palpi_ cylindrical, elongate, porrect, incurved, remote, naked; the second joint remarkably long. _Anterior feet_ in the male short and very hairy; in the female longer, naked, and furnished with minute claws. _Wings_, when at rest, horizontal. _Types._--Pap. Rhetus. Periander.--(_Cramer._) ---- SPECIFIC CHARACTER. _Wings black, with two white subhyaline bands, both sides alike; posterior wings elongated, vivid blue, acutely tailed, with a transverse sub-lunular band at the anal angle._ Papilio Rhetus. _Cramer. pl. 63, f. c._ ---- This is one of the rarest and most splendid lepidopterous insects of Brazil. We were once fortunate in capturing six specimens, fluttering over a shrub in the early morning sun, during our encampment in the Forest of Urupeè, in the Province of Bahia: but we never again met with this charming creature. The perfect insect has been figured in the costly, but truly valuable, work of Cramer; yet as neither the larva or pupa are known, we cannot determine on its natural group. Its relations, as suggested by the perfect insect, appear to be these. We consider the analogy between the groups respectively containing _P. Podalirius_, and _Marius_ (Cr.), to be immediate and direct: the form of the last type, and much of its general structure, is seen in our insect; but the details will not admit of a further similitude. Among the _Ericinæ_ we again detect this form in _P. Corineus_ and _Dorylus_ (Cr.), and continuing the comparison, we see the _antennæ_, _palpi_, and feet (in one sex) of _Rhetus_, accurately represented in those of _P. imperialis_ (Cr.), among the _Thecladæ_. We therefore suspect, that the real affinities of our insect lie between the two last groups: It seems moreover to have a strong analogy with _Leilus_. The upper figure is of the male, the under of the female. * * * * * * [Illustration: ROSTELLARIA. P. 1 _R. curvirostris._] ROSTELLARIA curvirostris. _Short-beaked Spindle._ ---- Class Mollusca. Order Zoophaga.--(_Gasteropoda, Cuv. Pars._) Carnivorous Mollusca without jaws; the mouth formed into a retractile trunk: conveying nutriment by suction. Respiration aquatic: the water being conducted to the branchiæ by a projecting siphon. Family,? Strombidæ. (_Les Ailées. Lam._) ---- SYNOPSIS OF THE GENERA. Div. 1. _Outer lip with a sinus; distinct from the basal canal._ STROMBUS. _L._ Outer lip dilated, entire, basal canal short. _Stromb. gigas, auris-Diana, tridentatus, urceus, &c._ PTEROCERAS. _Lam._ Outer lip digitated; canal lengthened, arcuated. Div. 2. _Sinus simple; formed by the prolongation of the canal._ APORRHAIS. _Dacosta._ Outer lip dilated and digitated. _Strombus pes-pelecani. Auct._