164* 



191. Cyclostoma Deshayesianum (Tab. Suppl. xxxi. b, f. 

 326, 327), Petit, Kuster, I. 19. t. 25. f. 8-10. Cycl. gratum, 

 Ferussac, MS. 



C. testa suborbiculari, depressa, subdiscoidea, spiraliter lirata, 

 fulvescente ; spira brevissima, obtusa ; anfractibus quatuor, rotun- 

 datis, spiraliter liratis, postice pleriunque liris acutis, lineis incre- 

 meiiti decussatis, antice striatis, striis plus minusve validis ; 

 sutura subdistiucta ; apertura circulari, intus aurantiaca, peritre- 

 mate duplici, interno albo, incrassato, ad ultimum anfractum iu- 

 terrupto, externo lamellari, extenso, latiusculo ; umbilico maximo, 

 intiis spiraliter striate. 



Shell nearly orbicular, depressed, subdiscoid, of a light fulvous 

 colour ; spire very short, obtuse ; volutions four, rounded, with 

 distinct, elevated, sharp-edged spiral lines, which are decussated by 

 indistinct lines of gTOwth, particularly on the posterior part of the 

 shell ; the shell is also spirally striated anteriorly, the striae being 

 more or less prominent ; suture rather indistinct ; aperture circu- 

 lar, orange-coloured within, with a double peritreme, the inner of 

 wliich is tliick, prominent, and wliite, and interrupted at its junc- 

 tion with the last volution ; the outer is lamellar, broad, and 

 spread out; the umbilicus is very large and internally spirally 

 striated. 



In Mr. Cuming's collection are two specimens which appear to 

 belong to two distinct varieties : the one with an indistinct suture 

 and very slender spiral striae anteriorly ; the other with a distinct 

 suture and strongly marked spiral hues anteriorly. 



192. Cyclostoma bituberculatum (Tab. Suppl. xxxi. a, f. 

 290, 291), nobis. 



C. testa oblongo-pyramidali, ventricosiuscula, crassa, albicante, 

 spirse apice decollate, obtuso ; anfractibus quinque, Isevibus, 

 transversim subundulatim obsolete striatis ; apertura circulari, 

 peritremate externo iucrassato, extiis revoluto, postice contra ulti- 

 mum anfractum in uodulum desinente, delude imibilicum versus 

 angusto, demiim supra mnbihcum nodulum alterum formante ; 

 umbilico fere clauso, margine angulato. 



Shell oblong, pyramidal, rather ventricose, tliick, of a dull 

 whitish colour, apex of the spire decollated, obtuse; volutions 

 five, smooth, with nearly obsolete, shghtly undulated, transverse 

 strise ; aperture circular, with a light-coloured, very much 

 thickened external peritreme, revolute outwards, posteriorly 

 against the last volution forming a small lobe, then narrow to- 



