There can be no doubt this shell is the _Unio nasutus_ of Say, who refers to the figure of Lister. The _Unio nasuta_ however of Lamarck I apprehend will be found different, as he seems to think; his shell also is purple inside with short thick teeth; indeed so much uncertainty hangs on the shells of this genus, that the species can only be fixed by ample descriptions and very correct figures. The figure is from a shell in the Linnaean Society's cabinet. Mr. Say says it is common in the Delaware River, North America. * * * * * Pl. 58 [Illustration] ACHATINA crenata. _Green hair-streaked Achatina._ * * * * * GENERIC CHARACTER.--See Pl. 30. * * * * * SPECIFIC CHARACTER. _A. (Div. 2.) testa alba, fasciis viridibus capillaribus; spira elongata, subattenuata, anfractibus 6 convexis, labio exteriore crenato; basi subtruncata._ Shell white, with capillary green bands; spire elongated, sub-attenuated, of six convex volutions; outer lip crenated; base slightly truncate. * * * * * A few specimens of this most delicate and beautiful shell were found by my brother, Mr. J. T. Swainson, jun. in the island of Cuba; nor am I aware of its having by any other means reached our cabinets, excepting a distinct variety which occurred in Mrs. Angus's, and is now (together with a young one of the same) in Mr. Dubois's collection. This has, in addition to the green bands on the spire, a row of bead-like cinereous spots at the base of the first and second spiral whorl; and others of a longitudinal square form on those whorls nearest the tip, which, with the inner lip, is slightly tinged with pink. The form of the shell also is shorter; but the general contour, and particularly the crenated mouth, common to both, clearly proves it can be considered only as a distinct variety. The specimen we have figured agrees with all those sent at the same time, in having not the slightest appearance of spots, though in a perfect state of preservation. The little notches on the margin of the lip are always placed at the commencement of each of the green lines; the base of the column is straight, and slightly truncated before it joins the outer lip. * * * * * Pl. 59 [Illustration] PSITTACUS Barrabandii. _Red-collared Parakeet._ * * * * * GENERIC CHARACTER.--See Pl. 1. * * * * * SPECIFIC CHARACTER. _P. viridis, sincipite gulaque flavis; torque coccineo circa medium cervicem extendente; rostro rubro; alis spuriis caerulescentibus._ Green, fore-part of the head and throat yellow; round the middle of the neck in front an orange-red collar; bill red; spurious wings blueish. * * * * *