— 63 — 



5. MONOCONDYLUS EXILIS. 



T. ovata, elongata, subœquilateralis, antice rotundata , 

 postice ovaliSj lamelloso-striata et distanter transversim 

 riigata, hrunnea ; margo dorsalis arcuatus, compressus ; 

 umbones late decorticati, depressi; dens cardinalis in 

 valva dextra major, in utraque compressus^ obtusus, lœvi- 

 gatus ; margarita cœrulescens, sub umbonibus salmonea, 

 ad margines iridescens. Altit. 30, latit. 57, diam. 

 i8 mill. 



Habit, cumprœcedente. 



4. Unio venustus. 



T. ovata, tumidula, elongatula, subœquilateralis, an- 

 tice attenuato-rotunda^ postice paulo magis dilatata, cari- 

 nata, medio leviter contracta, solidula, dense capillaceo- 

 striata, fulva, rugis viridibus, zigzag formibus vel angu- 

 laribus undique peculiariter insignita ; area compressa; 

 umbones depressiusculi, incurvi, fere integri, corrugati; 

 dens cardinalis compressus, elongatus, minute crenulatus, 

 in utraque valva duplex; lateralis lamelliformis, subsi- 

 nuosus, duplicatus; margarita argentea, ad margines cœru- 

 lescens, sub umbonibus lutescens. — Altit. 18, latit. 37 , 

 diam. 14 mill. 



Habit» cum prœcedente. 



5. Unio micropterus. 



T. compressa, alata, tenuis, olivacea vel viridi-fusca, 

 striatula, passim rugulosa ; margo anterior rotundatus, 

 brevis ; posterior ovato-attenuatus; superior ascendens ; 

 area in alam brevem, obtuse triangularem dilatata; um- 

 bones epidermide destituti, depressi ; dens cardinalis in 

 valva dextra bifidus, in utraque tenuis, lamelliformis ; 

 dens lateralis elongatus, breviter arcuatus, in valva 



