The insects of this genus are usually brown, with dark or paler shadings, and eye-like spots on their upper or under wings. They principally inhabit the woods of tropical regions, and the hedge sides and lanes of European countries; this circumstance probably induced Latreille to change their name from _Hipparchia_ (Fabricius) to _Satyrus_; which, although an innovation on the rules of nomenclature, may in this instance be allowed. * * * * * Pl. 160 [Illustration] ANODON purpurascens, _Purple Anodon, or Horse Mussel._ * * * * * GENERIC CHARACTER.--See Pl. 96. * * * * * SPECIFIC CHARACTER. _A. testa transversim oblonga, crassa, depressa, intus purpurascente, lamina cardinali crassa, truncata, dente lamellari in utraque valva supposito; umbonibus retusis._ Shell transversely oblong, thick, depressed, within purple; hinge plate thick, truncate, with an obsolete lamellar tooth in each valve; umbones retuse. * * * * * This is an entirely new and very rare shell, remarkable for its shape and internal colour; it is also highly interesting, as exhibiting the generic characters of _Anodon_, blended (in some degree) with those of _Unio_: according to the principles of Lamarck, it might therefore be made into a genus; but I feel convinced too much importance has already been attached by that naturalist and his followers to the hinge of bivalve shells; and that the nomenclature of the science is burthened with genera, trivial in themselves, bewildering to the scientific, and unintelligible to the student. From having paid some attention to the Fluviatile Bivalves, and possessing a most extensive collection of specimens, I am clearly of opinion that no permanent characters will be found sufficient to retain either the genera _Dipsas_ (Leach), _Hyria_ (Lamarck), or _Alasmodonta_ of Say, much less that of _Damaris_ (Leach), and another, whose name I forget, made by Dr. Turton from the same shell as Leach's _Damaris_, viz. Mya Margaritifera of Linnaeus. In fact, the line of demarcation between Unio and Anodon appears to rest on the first possessing cardinal teeth, and the latter having none. I have several valves (in different stages of growth), and one perfect specimen of this shell; they were sent to me from the back settlements of North America. * * * * * Pl. 161 [Illustration] VOLUTA punctata, _Red-dotted Volute._ * * * * * GENERIC CHARACTER. _Testa ovata. Spira apertura brevior, apice papillari. Basis truncata, emarginata. Columella plicata, plicis inferioribus majoribus._ Shell ovate. Spire shorter than the aperture, the tip papillary. Base truncated, emarginate. Pillar plaited, the inferior plaits generally largest. Generic Types. _Volutae Olla_, _Imperialis_, _Pacifica_, _&c._