60 Zoological Society. 
compressiusculd, tenui, levigatd, pallescente, lineis brunneis non- 
nullis, per paria dispositis, cinctd; spird subelatd, anfractibus 
quinque, quorum duobus primis nigricantibus, tertio quartoque 
pallidis, brunneo-unifasciatis, ultimo magno, posticée gibbo, infra 
planulato ; aperturd axi paralleld, auriformi ; peristomate late 
expanso, albo, margine dextro producto, rotundato-subangulato ; 
aperturd intus lamellis senis instructd, duabus in pariete aper- 
turali, quarum posticd compositd, tribus in margine basalt, und 
compositd postice furcatd anticé bifidd in margine dextro. 
This is the largest species of this genus we remember to have seen ; 
for which reason we have named it 7’. 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 
Cyctostroma. By G. B. Sowersy, F.L.S. 
1. Cycitosroma rormosum. Cycl. testd suborbiculari, subdepres- 
sd, tenuiusculd, spiraliter striatd, tricarinatd, fulvo-rufescente ; 
spird brevi, acuminatd, anfractibus quinis rapide crescentibus, 
rotundatis, carinis duabus validis, allicantibus castaneo-arti- 
culatis ; anticé striis subobsoletis, gradatim majusculis, cari- 
nique tertid umbilicum circumferente; suturd validd, levi ; 
aperturd magnd, fere circulari, postice paululim acuminatd, 
peritremate latiusculo reflexo, 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 strise decussated by other sharp striz 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 striee are rather indistinct, but 
