60 Zoological Society. 



compressiusculd, tenui, lcevigatd,pallescente, lineis brunneis non- 

 nidlis, per paria dispositis, cinctd ; spird subelatd, anfractibus 

 quinque, quorum duobus primis nigricantibus, tertio quart oque 

 pallidis, brunneo-unifasciatis, ultimo magno, postice gibbo, infra 

 planulato ; aperturd axi parallel d, auriformi ; peristomate late 

 expanso, albo, margine dextro producto, rotundato-subangulato ; 

 aperturd intus lamellis senis instructd, duobus in pariete aper- 

 turaliy quarum posticd compositd, tribus in margine basalt, una 

 compositd postice fur cat d antice bifida in margine dextro. 

 This is the largest species of this genus we remember to have seen ; 

 for which reason we have named it T. principalis. It is of a some- 

 what triangular form, rounded at the angles, and rather compressed, 

 not being nearly so globular as the remaining three species. The 

 substance of the shell is rather thin, it is smooth and of a pale colour 

 with several brown transverse lines disposed in pairs ; the spire is 

 rather elevated, consisting of five volutions, of which the first and 

 second are small and very dark-coloured, the. third and fourth are 

 pale with a brown band, and the fifth is large, and gibbose posteriorly, 

 its anterior margin white, and it is flattish and brown anteriorly ; the 

 aperture is parallel to the axis, ear-shaped, with a broadly expanded 

 white peristome, whose right margin is produced and forms a rounded 

 angle ; the aperture is furnished within with six lamellar teeth, two 

 on the columellar side, of which the posterior is compound, three 

 within the basal margin ; and a single compound plate which is fur- 

 cate posteriorly and bipartite anteriorly within the right hand margin. 

 In Mr. Cuming's collection. 

 From Pernambuco. 



2. Description of two newly discovered species of 

 Cyclostoma. By G. B. Sowerby, F.L.S. 



1. Cyclostoma formosum. Cycl. testa suborbiculari, subdepres- 

 sd, tenuiusculd, spiraliter striatd, tricarinatd,fidvo-rufescente; 

 spird brevi, acuminata, anfractibus quinis rapide crescentibus, 

 rotundatis, carinis duabus validis, albicantibus castaneo-arti- 

 culatis ; antice striis subobsoletis, gradatim majusculis, cari- 

 ndque tertid umbilicum circumferente ; suturd validd, Icevi; 

 aperturd magna, fere* circulari, postice paululum acuminata, 

 peritremate latiusculo refiexo, incisuris parvis tribus, ad carinas 

 externas idoneis ; umbilico magno, profundo, spiraliter striato, 

 striis exterioribus gradatim majusculis. 

 This very handsome Cyclostoma bears a general resemblance to 

 C. Cuvierianum, though easily distinguishable by having three distinct 

 keels, by having a more acuminated apex, and by the latter having 

 the spiral striae decussated by other sharp striae parallel with the 

 lines of growth. The C. formosum is nearly orbicular, though some- 

 what depressed ; it is rather thin and smooth, and of a reddish fulvous 

 or brown colour : its spire is rather short, but acuminated, consisting 

 of five volutions which are of a roundish form and increase rapidly, 

 and are ornamented with two keels which are of a pale colour, spotted 

 with chestnut brown : anteriorly the striae are rather indistinct, but 



