— 226 — 



basi rotundata : perist. tenue y rectum, niargine dextro 

 arcuato. — Altit. M, diam. 7 mill. 

 Cochinchina. 



4. Hélix dic^la. 



T. umbilicata, subdiscoidea, utrinqiie concava, tenuis, 

 sublœvigata, nitidissima, corneo-rufa ; spira leviter im- 

 mersa; anfr. 5-5 hj'^parum convexi, sutura marginata 

 juncti, priores angusti, ultimus dilatatiis, angiilatus, su- 

 perne convexus, subtus plamdatus, circa umbilicum per- 

 spectivum excavatus, breviter descendens ; apertura obli- 

 qua, depressa, ovato-limaris ; perist. simplex, acutum, 

 rectum. •— Diam. max. 5, min. 4, altit. 2 mill. 



Siam. 



5. Hydrocena marginata. 



T. subimperforata, globoso-conica, solidula, corneo-ru- 

 bella vel fulvastra; spira variabilis, apice intégra; su- 

 tura late et pallide marginata ; anfr. 6 convexiusculi; 

 ultimus spiram valde superans, inflatus, subglobulosus ; 

 apertura subverticalis, semi-ovalis ; perist. rectum, mar- 

 gine columellari calloso, appresso. Operculum paucispi- 

 rwn, rufum. — Long. 6-8, diam. 4-5 1/3 mill. 



Siam. 



G. Hyurocena tdrbinata. 



T. parvula, imper for ata, ovato-conica^ tenuis, glabra, 

 nitidula, cerea, fulva; spira exserta, acutiuscula : sutura 

 nigro marginata ; anfr. 5, supremi plant, ultimus ventro- 

 sus, subangulatus, carina filari periomphalum cingente et 

 aperturam paulo superante munitus; apertura subsemilu- 

 naris; perist. rectum, margine columellari calloso, ap- 

 presso. — Long. 3, diam. fere 2 mill. 



Cochinchina. 



