Of a brownish ash colour, the hairs on upper part of body short and deep brown, on the sides and under parts long and grey; prothorax varied with black, in front, two large patches covered with grey hairs, mixed with longer; elytra spotted and varied with brown, wings clear, somewhat ferruginous at the base. Expanse of wings 3 inches 4 lines. Hab. Australia. * * * * * DESCRIPTION OF TWO NEW INVERTEBRATED ANIMALS FROM AUSTRALIA, BY J. E. GRAY, ESQ., F.R.S. Lamarck separated the mother-of-pearls shell (MARGARITA) from the swallow-tail muscles (AVICULA) on account of its more orbicular shape. Other Conchologists have been inclined to unite them, as some of the species of AVICULA approach to the shape of the other genus. The new one just received from Australia, which I am now about to describe, in this respect more resembles the Margarita than any before noticed; yet I am inclined to think that the pearl-shells deserved to be kept separate, as the cardinal teeth are quite obliterated in the adult shells, which is not the case with any AVICULAE I am acquainted with; and the young pearl-shells are furnished with a broad serrated distant leafy fringe, while the AVICULAE are only covered with very closely applied short concentric slightly raised minutely denticulated lamina, forming an epidermal coat on the surface. 1. AVICULA LATA, pl. 6. f. 1. Shell dark brown; half ovate; broad obliquely truncated, and scarcely notched behind; covered with close regular very thin denticulated concentric lamina, forming a paler external coat. The front ear rather produced, with a distant inferior notch; internally pearly, with a broad brown margin on the lower-edge. Inhab. North and West coasts of Australia. 2. SPATANGUS ELONGATUS, pl. 6. f. 2. Body elongate, cordate, with a deep anterior grove and notch; covered above with minute hair-like spines, with scattered very elongated tubular minutely striated spines on the sides; the anterior groves and circumference of the vent with larger equal hair-like spines on each side; the under surface with a triangular disk of similar spines beneath the vent, and with elongated larger tubular spines. Inhab. Western Australia. Having only a single specimen completely covered with spines, it is impossible to describe the form of the ambulacra or the disposition of the tubercles. The lower figures represent the mouth and vent of the animal in detail. * * * * * DESCRIPTION OF SOME NEW AUSTRALIAN LEPIDOPTEROUS INSECTS BY EDWARD DOUBLEDAY, ESQ., F.L.S., etc. THYRIDOPTERYX NIGRESCENS, pl. 5. f. 1. Head densely clothed with long whitish hairs; thorax and abdomen with black hairs; wings hyaline, the nervures and nervules brown, with a few black scales: base of the anterior and abdominal fold of the posterior more or less covered with black hairs; antennae and legs fuscous brown. Exp. 10--12 lines.