BY THE REV. .1. E. TENISON-WOODS. 
1077 
FEESHWATER MOLLUSCA. 
Sub-order OPISOPHTHALMA. 
Family TRUNCATELLID^. 
These animals have a distinct bi-lobed muzzle with flat sub- 
ti’iangular tentacles, and a sub-spiral horny operculum. 
1. Truncatella, Risso, Hi.st. Nat. de I’Europe, IV. p. 121. 
Shell solid, cylindi'ical 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. 
There 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; Kiist. 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, Borneo ; Malacca. 
Tr. aurantia, Gould, Exp. Sh. 1846, p. 39, Ed. 1851, pi. 8, 
fig. 125 ; Pfr. Mon. Pneuraon. Suppl. I. p. 6. 
Mangsi Island, Borneo. 
Tr. 8CALAR0IDKS, von Mart. Monatsber. Berl. Ak. 25 Febr. 
1864; Pfr. Mon. Pneumon. Suppl. If. p. 7. 
Anjboyna. 
