GASTEROPODA. 239 
Distribution, 111 species. West Indies, Mauritius, Australia. 
Fossil, 12 species. Chalk—. France, Britain. 
OpDosTomiA, Fleming, 1824. 
Etymology, odous, a tooth, and stoma, mouth. 
Wage, O. plicata. Pl. VIII., Fig. 12. 
Shell subulate or ovate, smooth; apex sinistral; aperture 
ovate; peristome not continuous; columella with a single 
tooth- like fold; lip thin; operculum horny, “ac ueL on the 
inner side. 
Distribution, Pspecies. Britain, Mediterranean, Red Sea, 
Australia. 
Fossil, 15 species? Eocene—. Britain, France. 
Very minute and smooth shells, having the habit of rissoe, 
and like them sometimes found in brackish water. They range 
from low water to 40 fathoms. The animal is undistinguishable 
from chemnitzia. 
CHEMNITZIA, D’Orbigny. 
Etymology, named in honour of Chemnitz, a distinguished 
conchologist of Nuremburg, who published seven volumes in 
continuation of Martini’s ‘‘ Conchylien-cabinet,”’ 1780-95. 
Synonyms, Turbonilla, Risso. Parthenia, Lowe. Pyramis and 
Jaminea, Br. Monoptigma, Lea, part. Amoura, Moller. 
Type, C.elegantissima. Pl. VIII., Fig. 13. 
Shell slender, elongated, many-whorled ; whorls plaited; 
apex sinistral; aperture simple; ovate; peristome incomplete ; 
operculum horny, sub-spiral. 
Animal head very short, furnished with a long, retractile 
proboscis; tentacles triangular; eyes immersed at the inner 
angles of the tentacles; foot truncated in front, with a distinct 
mentum. 
Distribution, 32 species. Britain (4 species), Norway, Medi- 
terranean. Probably world-wide. Range from low water to 
90 fathoms. 
Fossil, 240 species. Silurian—. Britain, France, &c. 
The ‘‘melaniz” of the secondary rocks are provisionally 
referred to this genus. Those of the paleozoic strata to 
loxonema. 
_ Sub-genera. Eulimella, Forbes. HE. scilleo, Scacchi. 4 British 
@pecies. Shell smooth and polished; columella simple; apex 
ginistral. 
Stylopsis (Adams, 1860) much resembles and is probably 
synonymous with this sub-genus. 
