BY THE REV. J. E. TENISON-WOODS. 1077 



FRESHWATER MOLLUSCA. 



Sub-order OPISOPHTHALMA. 



Family TRUNCATELLID^. 



These animals have a distinct bi-lobed muzzle with flat sub- 

 triangular tentacles, and a sub-spiral horny operculum. 



1. TnuxcATELLA, Risso, Hist. Nat. de I'Europe, IV. p. 121. 



Shell solid, cylindrical in its young state, truncated in the adult ; 

 whorls rounded ; mouth oval ; peristome complete, reflected ; 

 operculum horny, thin, with a lateral nucleus. 



Animal furnished with a retractile bifid muzzle proboscis-shaped. 

 Thei^e are about 15 species, tropical or sub-tropical, found in salt 

 and fresh water. 



Truncatella valida, Pfr. Mon. Auric, p. 184 ; Zeitschr. f. 

 Malak. 1846, p 182, No. 1; Kust. Mon. p. 11, No. 7, pi. 2, 

 tigs. 7, 8, 19, 21, 23. 



Philippines, Baclayon, Capul, New Caledonia, and Malay 

 Peninsula. 



Tr. marginata, Kiist. Mon. p. 12, No. 8, pi. 2, figs. 24-26 ; 

 Pfr. Mon. Auric, p. 186. 

 Labuan, Boi-neo ; Malacca. 



Tr. aurantia, Gould, Exp. Sh. 1846, p. 39, Ed. 1851, pi. 8, 

 fig. 125 ; Pfr. Mon. Pneumon. Suppl. I. p. 6. 

 Maagsi Island, Borneo. 



Tr. scalaroides, von Mart. Monatsber. Berl. Ak. 25 Febr. 

 1864; Pfr. Mon. Pneumon. Suppl. II. p. 7. 

 Amboyna. 



