— 159 — 

 erosa , anfr. 4 superne planati, deinde convext, iiîtimus 

 permagnus, leviler depressus, sutura sulco lenui margi- 

 nala ; umbilicus parvus, plerumque aperlus, pervius ; 

 apertura acute ovalis, intus cœrulescens ; perisloma sim- 

 pleXy reclum, tenue^ marginibus callo junclis. — AUit. 

 20, diam. 21 mill. 



Habitat in lacu Ebrie Senegahnsi. 



IV. COCHINCHINE. 



12. UmO MEGAPTERUS. 



T. oblonga, subcompressa, antice in rostrum aculum 

 producta, postice attenuata, carinata, epidermide viridi 

 transversim slriata induta; umbones compressi; area, in 

 alam triangularem acuminatam, plicis verlicalibus fim- 

 briatam, ligamentum celontem et poster in s hiantem, dila- 

 tala ; lamellœ horizontales, acutœ, tenues ,• dentés cardi- 

 nales lamelliformes; margarita cœruleo-opalina. — Alt. 

 58, lalit. 80 , diam. 19 mill. 



Habitat in Cochinchina. 



13. Unio mandarinds. 



T. ovalis, inœquilatera, depressa, solidula, antice bre- 

 viter rotundata, postice magis dilatata, attenuata, rugis 

 eminentibus viridibus, zigzag formibus, peculiariter exa- 

 rata, inter rugas pallide fulva ; umbones depressi, extre- 

 mitati anteriori approximatif area compressa j ligamen- 

 tum terminale ; lamellœ médiocres , arcuatœ j dentés cardi- 

 nales compressi, crenulati; margarita argentea. — Alt. 

 20 , latit. 57, diam. 13 mill. 



Habitat cumprœcedenle. A. M. 



