1865.] MR. F. MOORE ON BENGALESE LEPIDOPTERA. 755 Thyella pulchra, H. Adams. T. testa mibcequilatei'ali, antice long'wre, Candida, valvarum super-ficie costis tenuibus radiantibus et Uris excentricis decussata ; um-bonibus parvis, subrecurvis ; margine dorsali excavato ; sinu pal-liali profunda. Long. 13, alt. 11, lat. 7 mill. Hab. Singapore (^Coll. Cuming.). This genus appears to have most affinity with Semele, but differs in the absence of lateral teeth, in its more ventricose form, and in the position of the internal ligament. The surface of the valves of the species described is decussately sculptured by radiating ribs and thin concentric lirse. I avail myself of this opportunity to state that the genus Leu-conyx, some time since described by my brother and myself, must be cancelled, as we have recently had an opportunity of proving that it is founded upon the internal spathulate appendage of Pholas costata. The name Plectostoma also, which I gave lately to a very peculiar form of Helix from Labuan, must be considered a synonynt of Opisthostoma. Blanford, which was established to receive a small shell from India, much more Pupa-shaped than the type of Plec-tostoma, but, I think, belonging to the same group, and which has hitherto been supposed to be furnished with an operculum, and to be allied to Diplonimatina. 12. On the Lepidopterous Insects of Bengal. By Frederic Moore. (Plates XLI., XLII., XLIII.) Excepting a brief list of Lepidopterous Insects from the N.W. Himalaya, compiled by KoUar and published in Hijgel's ' Kaschmir,' and another by myself, printed in the ' Proceedings ' of this Society for the present year, of a collection of Diurnal Lepidoptera recently made in nearly the same districts by Capt. A. M. Lang, no record has appeared of the many very interesting " local " Indian collections that have so frequently been formed. In the following pages a list is given of the species contained in a very extensive collection made in the Province of Bengal by Mr. A. E. Russell, of the Bengal Civil SerA ice, who has kindly placed them in my hands for this purpose, and of others collected in the same Province by Mr. W. S. Atkinson and the late Capt. J. Lind Sherwill. Sect. I. RHOPALOCERA. Tribe 1. Papiliones. Fam. PapilionidjE. Ornithoptera rhadamanthus, Boisd. Spec. Gen. Le'p. i. p. 180.