1 64* 



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, spiraKter lirata, 

 1'ulvescente ; spira brevissima, obtusa ; anfractibus quatuor, rotun- 

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

 menti decussatis, antice striatis, striis plus minusve validis ; 

 sutura subdistincta ; apertura circulari, intus aurantiaca, peritre- 

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

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

 intus spiraliter striato. 



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 growth, particularly on the posterior part of the 

 ishell ; the shell is also spirally striated anteriorly, the striaj being 

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

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

 which is thick, prominent, and white, 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 lines anteriorly. 



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

 290, 291), nobis. 



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

 spirse apice decollate, obtuso ; anfractibus quiuque, laivibus, 

 transversim subundulatim obsolete striatis ; apertura circulari, 

 peritreinate externo incrassato, extus revoluto, postice contra ulti- 

 mum anfractum in nodulum desinente, deinde umbilicum versus 

 angusto, demmn supra umbilicum nodulum alterum formante ; 

 umbilico fere clauso, margine angulato. 



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

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

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

 striae ; 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- 



