60 Zoological Society, 



compressiusculd, tenuis l€evigatd,pallescentey lineis brunneis non- 

 nullis, per paria dispositisy cinctd ; spird subelatd, anfractihus 

 quinqucy quorum duobus primis nigricantibuSy tertio quartoque 

 pallidisy brunneo-unifasciatisy ultimo magno, postich gibbo, infra 

 planulato ; aperturd axi paralleldy auriformi ; peristomate late 

 expanso, alboy margine dextro product Oy rotundato-subangulato ; 

 aperturd intus lamellis senis instructdy duubus in pariete aper- 

 turali, quarum posticd compositd, tribus in margine basaliy una 

 compositd postice furcatd antice bijidd 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 op 

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



1. Cyclostoma formosum. Cycl. testd suborbiculariy subdepres- 

 sd, tenuiusculdy spiraliter striatd, tricarinatdyfidvo-rufescente; 

 spird breviy acuminatdy anfractibus quinis rapide crescentibus, 

 rotundatiSy carinis duabus validisy albicantibus castaneo-arti- 

 culatis ; antice striis subobsoletis, gradatim majusculis, cari- 

 ndque tertid umbilicum circumferente ; suturd validdy Icevi; 

 aperturd magna, ferh circulari, postice paululum acuminatdy 

 peritremate latiusculo reJlexOy incisuris parvis tribuSy ad carinas 

 externas idoneis ; umbilico magno, profundoy spiraliter striatOy 

 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 



