161* 



184. Cyclostoma subdiscoideum (Tab. vSuppl. xxxi. h, f. 

 304, 305), noUs. 



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

 zona interrupta, pallide fusca, ornata ; spira depresso-conica, ob- 

 tusa ; anfractibus quatuor, rotundatis ; sutura subcaualiculata ; 

 apertura circulari; peritremate teuui, albido, paululiiin reilexo; 

 umbilico maximo, aufractibus quatuor distinctis. 



Shell suborbicular, rather discoid, spirally grooved, whitish, 

 with an interrupted zone of a pale brownish colour ; spire de- 

 pressedly conical, obtuse ; volutions four, rounded ; suture very 

 slightly channeled ; aperture circular ; peritreme thin, whitish, 

 slightly reflected, and spreading a little posteriorly over the last 

 volution ; umbilicus very large, showing the four volutions 

 within. 



185. Cyclostoma depeessum (Tab. Suppl. xxxi. h, f. 306, 

 307), nobis. 



C. testa suborbiculari, albida ; spira depressa, apice prominulo, 

 obtuso; anfractibus quatuor, rotundatis, lajvibus, superne spi- 

 raliter striatis, mediane subcarinatis ; sutura, distincta ; apertura 

 fere circulari, peritremate tenui, subreflexo, supra ultimum anfrac- 

 tum paululi^im extenso ; umbilico maximo, intiis Isevi. 



Shell suborbicular, whitish, slightly clouded with very pale 

 brown; spire depressed, its apex somewhat prominent, obtuse; 

 volutions four, rounded, smooth, their upper half spirally striated, 

 shghtly keeled near the middle ; sutui-e distinct ; aperture nearly 

 circular, with a tliin, white, shghtly reflected peritreme, which is 

 slightly extended over the last volution ; umbilicus very large ; 

 smooth inside. 



Nearest to C. LitJndion, but easily distinguished by its flat spire 

 with an elevated apex. 



186. Cyclostoma subrugosum (Tab. Suppl. xxxi. h, f. 308, 

 309), nobis. 



C. testa suborbiculari, depressa, rugulosa, alba ; spira depressa, 

 obtusa, apice prominulo ; anfractibus quatuor, rotundatis, ])ostice 

 depressiuscuhs ; sutura distincta, linea obsoleta subsuturali no- 

 tata ; apertura fere circulari ; peritremate postice subinci'assato, 

 intiis propc umbilicmn tenui, ab ultimum anfractum disjuncto ; 

 umbilico magno, antice carinato. 



Shell suborbicular, depressed, slightly corrugated, white ; spire 



b*% 



