15 



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. 



(Mollusca, PL II. figs. 4, 5, 8, 9.) 



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

 sd, temdusculd, spiraliter striatd, tricarinatd,fulvo-rvfescente; 

 spird brevi, acuminata, anfractibus quinis rapide crescentibus, 

 rotundatis, cari7iis duabus validis, albicantibus castaneo-arti- 

 cidatis ; antice striis subobsoletis, gradatim majusculis, cari- 

 ndque tertid umbilicum circumferente ; suturd validd, Icevi ; 

 aperturd magna, fere circulari, postice paululam acuminatd, 

 peritretnate latiusculo reflexo, incisuris parvis tribus, ad carinas 

 externas idoneis ; iimbilico magno, profunda, spiraliter striata, 

 striis exterioribus gradatim majusculis. 



This very handsome Cyclostoma bears a general resemblance to 

 C. Cuvierianiim, though easily distinguishable by having three distinct 

 keels, by ha\Tng a more acuminated apex, and by the latter having 

 the spiral strife 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 romidish 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 

 larger ; and there is a thick keel surrounding the umbilicus ; the 

 suture is distinct and smooth, but belted posteriorly by the middle 

 keel ; the aperture is large, nearly circular, slightly acuminated poste- 

 riorly, with a rather broad reflected peritreme, in which are three 

 little cuts answering to the ends of the external keels ; the umbilicus 

 is large and deep, spirally striated within ; the outer striae being the 

 larger. 



From Madagascar, in the collections of A. L. Gubba, Esq., Havre, 

 and Mr. Cuming. 



2. Cyclostoma aplustre. Cycl. testd suborbiculari, tenuius- 

 culd, Icevi, albicante,fasciis nonmdlis posticis, angustis, castaneis, 

 subinterruptis, striisque teymissimis spiralibus, ornatd ; spird le- 

 vatiusculd, subacuminatd, apice obtuso; anfractibus quinis rotun- 

 datis, creberrime transversim striatis, striis posticis fortioribus, 

 anticis fere obsoletis ; umbilico magno, intus spiraliter striata, 

 striis tenuissimis ; aperturd fere circulari, postice paululum 



