bo 
-T 
-I 
TRUNCATELLIDA. 
Lanistes, Montfort. 
Distr.—Hast Africa. L. Bolteniana, Chemn. (Ixxiv, 19). 
Shell sinistral, depressed; umbilicated ; peristome simple, 
Sharp. Operculum horny. 
MELADOMUS, Swainson. Shell sinistral, oval-conic, not umbili- 
cated. Africa. L.olivacea, Sowb. (Ixxiv, 20). 
Marisa, Gray. 
Syn.—Ceratodes, Guilding. 
Distr.—A few species. So. America, West Indies. MM. cornu- 
arvetis, Linn. (Ixxiv, 21). M. Chiquitensis, d’Orb. (Ixxiv, 23). 
Shell flattened or planorbiform, spire depressed or very 
slightly elevated; widely umbilicated; aperture expanded. 
Operculum horny. 
Famity TRUNCATELLID&. 
Shell subeylindrical or turbinate, with elevated spire, apex 
obtuse or truncate ; aperture oval, entire, peristome continuous. 
Operculum subspiral. 
Animal with short, diverging triangular tentacles, and eyes 
at their bases. Amphibious, inhabiting usually margins of 
streams, salt marshes, damp places, ete. The relationship of 
these mollusks with the Rissoids and Assiminiz is very close, 
so that they may be considered as terrestial Rissoide ; on the 
other hand, they connect with the typical operculated land-shells, 
the Cyclostome. 
TRUNCATELLA, Risso. 
Looping snail. Syn.—Choristoma, Crist. and Jan. Erpeto- 
metra, Lowe. 
Distr,—62 sp. World-wide, mostly tropical. Fossil. Eocene; 
Paris basin. 1. truncatula, Drap. (Ixxv, 24). 
Shell minute, cylindrical, truncated; whorls striated trans- 
versely ; aperture oval, entire; peristome continuous. Opercu- 
Jum corneous, subspiral. 
Animal with short, diverging, triangular tentacles; eyes 
centrally behind; head bilobed; foot short, rounded at each 
end.— ForBes. 
The Truncatellz are found on stones and sea-weeds between 
tide-marks, and survive many weeks out of the water.—Lowe. 
They walk by contracting the space between their lips and foot, 
like the geometric caterpillars.—Gray. They are found semi- 
fossil along with the human skeletons in the modern limestone 
of Guadaloupe. 
TAHEITEA, H. and A. Ad. Operculum calcareous, radiately 
lamellate. Aperture usually more or less separated from the 
preceding whorl. Polynesia. TT. Vitiana, Pease. Viti Isles. 
