161* 



184. Cyclostoma subvuscoideum (Tab. Suppl. xxxi. b, f. 

 304, 305), nobis. 



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

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

 tusa ; anfractibus quatuor, rotundatis ; sutura subcanaliculata ; 

 apertura circulari ; peritremate tenui, albido, paululmn reflexo ; 

 umbilico maximo, anfractibus 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. b, f. 306, 

 307), nobis. 



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

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

 raliter striatis, mediane subcarinatis ; sutura distincta ; apertura 

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

 tum paululurn extenso ; umbilico maximo, intiis lasvi. 



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, 

 slightly keeled near the middle ; suture distinct ; aperture, nearly 

 circular, with a thin, white, slightly reflected peritreme, which is 

 slightly extended over the last volution ; umbilicus very large ; 

 smooth inside. 



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

 with an elevated apex. 



186. Cyclostoma subkugosum (Tab. Suppl. xxxi. b, f. 308, 

 309), nobis. 



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

 obtusa, apice prominulo ; anfractibus quatuor, rotundatis, postice 

 depressiusculis ; sutura distincta, linea, obsoletft subsuturali no- 

 tata ; apertura fere circulari ; peritremate postice subincrassato, 

 intus prope umbilicmn tenui, ab ultimum anfractum disjuncto ; 

 umbilico magno, antice carinato. 



Shell suborbicular, depressed, slightly corrugated, white; spire 



b* 2 



