I have little doubt that this shell is a smooth variety of the _Pinna bullata_ of Gmelin, and the _P. marginata_ of Lamarck; both these authors refer to the same figure in Gualtieri, but both also have overlooked that of Chemnitz, above quoted, as well as Knorr's, which latter, although it represents the shell nearly smooth (similar to that here figured), I apprehend is only a variety. No doubt therefore having existed as to Gmelin's _bullata_, M. Lamarck had no plea for altering its specific name to _marginata_. I have consequently recorded it under Gmelin's name. The Pinnae are rather numerous, although many of the species remain in obscurity; they attach themselves to rocks, deep in the sea, by a silky _byssus_. It has been commonly stated, that gloves and stockings are fabricated in the Mediterranean from this byssus, as articles of commerce; such, however, is not now the case; though articles, so fabricated, are sometimes shown in Naples and Sicily as subjects of curiosity. Pinna bullata is, I believe, found in the West Indies. The vaulted spires on this and other species, easily fall off; and become, therefore, a very uncertain specific character. * * * * * Pl. 159 [Illustration] SATYRUS argenteus. * * * * * GENERIC CHARACTER. _Antennae mediocres, clavo elongato, gracili. Palpi porrecti, compressi, vix recurvi, remoti, pilis ciliatis, longis, hirsutissimi; articulo ultimo elongato, nudo, gracili, acuto. Alae posticae orbiculares, integrae, raro dentatae._ Antennae moderate, the club lengthened and slender. Palpi porrected, compressed, slightly recurved, remote, with long ciliated hairs; the last joints long, naked, slender, acute. Posterior wings orbicular, entire, rarely dentated. Generic Types. _Pap. Hyperanthus_, _Galathea_, _Semele_, _&c._ Lin. * * * * * SPECIFIC CHARACTER. _S. alis fuscis; posticarum disco supra flavescente, maculis 2 fuscis fucato, infra albente, margine postico fulvo, maculis 2 atris guttisque 7-8 argenteis ornato._ Wings brown; posterior above with a yellowish disk and two brown spots, beneath whitish, the hind margin fulvous, with two black spots and 7-8 silver dots. * * * * * Without being ornamented by rich or vivid colouring, this is, nevertheless, one of the most chastely beautiful little butterflies found in Brazil. I met with it very plentifully in a small wood not far distant from Cashoera, on the western extremity of St. Salvador's bay: to this particular spot it seemed confined, for I never saw a single specimen in any other part of Brazil. No colouring can imitate the richness of the silvery spots on the under wings, which appear embossed, or as if solid drops of silver had fallen on the insect when it first emerged into life. The two sexes are perfectly similar.