Since the first illustration of this elegant species appeared, at plate 74 of this work, I have had the means of ascertaining a very extraordinary circumstance which takes place in the progressive growth of the young shell to the adult state; and that is the change effected in the form and termination of the pillar or columella. In the noble collection of shells formed by the late Earl of Tankerville, there is a numerous series of this species; from these I have ascertained, that in the young shells the base of the columella unites with the termination of the outer lip, making the aperture entire, similar to the lengthened Helices; but, as the shell advances in growth, the base of the columella becomes thick, detached, as it were, from the marginal rim, so as to produce an intervening notch, and thus gives the old and the young shell not only an appearance of being distinct species, but of belonging to separate genera. From these facts, I have drawn the conclusion, that _Achatina pallida_ (pl. 41), is but the young shell (having the margin of the aperture as yet entire) of _Achatina fasciata_; and the three additional varieties now figured, will, I hope, prove an interesting addition to the history of this species. * * * * * Pl. 163 [Illustration] HEMIPODIUS nivosus, _White-spotted Turnix._ * * * * * GENERIC CHARACTER. _Rostrum mediocre, gracile, rectum, valde compressum culmine levato, ad apicem sub-incurvo. Nares laterales, lineares, sulcatae, membrana convexa cornea vix tectae, apertura fissa, elongata. Pedes longi, digitis tribus anticis divisis. Halluce caret. Cauda brevissima tectricibus obtecta. Alae mediocres._ Bill moderate, slender, straight, much compressed, culmen elevated, towards the tip slightly incurved. Nostrils lateral, linear, sulcated, partially covered by a convex horny membrane, the aperture narrow and elongated; legs long, with three toes before, divided at their base. Hind toe none. Tail very short, concealed by the covers. Wings moderate. Generic Type. _Perdix nigricollis._ Lath. * * * * * SPECIFIC CHARACTER. _H. supra ferrugineo varius; mento albescente; jugulo pectoreque pallide ferrugineis, maculis albis, nitidis, ornatis; corpore albo; uropygio caudaeque tectricibus superioribus rufis, immaculatis._ Above varied with ferruginous; chin whitish; throat and breast pale ferruginous, with white shining spots; body white; rump and upper tail-covers rufous, unspotted. H. nivosus. _Swainson, in Tilloch's Phil. Magazine_, _vol._ 60. _p._ 353. * * * * *