The characters of _Malurus_, together with a few observations on the birds composing it, I have already given at plate 170 of this work. Yet as the species are scattered in several distinct genera of the Linnaean school, I have here represented that which may be termed the type of the genus, as instituted by Professor Temminck, and as modified by myself. On comparing the characters of _Timalia_ (a new genus of Dr. Horsfield's) with those of _Malurus_, they will be found to designate one and the same group of birds. Indeed, the minute and interesting details, which Dr. Horsfield has given, put the question almost beyond doubt, and lead me to conclude, that the Doctor was not aware, at the time, that his genus was already recorded. This bird is not uncommon at the Cape of Good Hope. The notes of the male (according to M. Le Vaillant) are soft and agreeable, much resembling those of a flute; the shortness of the wings renders its flight very low. The figure is of the natural size; and the bird has been so well described by Brisson and Latham, that it is needless to repeat what they have said; the figures both of Le Vaillant and Brisson are by no means accurate. The tail feathers are delicate and transparent; and those of the whole body very soft, with detached webs or _radii_, similar to Dr. Horsfield's _Timalia pileata_, and _gularis_. * * * * * Pl. 171 [Illustration] UNIO fragilis. _Fragile River Mussel._ * * * * * GENERIC CHARACTER.--See Pl. 58. * * * * * SPECIFIC CHARACTER. _U. testa transversim ovata, tenui, intus purpurascente; dentibus cardinalibus tuberculatis, sub-obsoletis._ Shell transversely oval, thin, within purple; cardinal teeth tuberculated, nearly obsolete. * * * * * Most fresh water bivalves are remarkably destitute of that variety of colouring, which diversifies the exterior of marine shells, and renders their distinction comparatively easy. A uniform olive green, or brown tint, pervades all the fluviatile genera; their specific distinctions rest on characters which frequently require long and perplexing descriptions, but which can be explained by the artist with ease and precision. It follows, therefore, that accurate figures of these shells are more particularly wanted; for, although Lamarck has described so many, the short descriptions which he has given, and the want of figures to elucidate them, render it impossible to determine accurately one half of the species which he has enumerated.