156 PLEUROTOMIDA. 
Genus BELA (Leach), Gray, 1847. 
Shell usually thin and white, fusiform; spire elongated, 
turreted; canal short, straight, truncated below; columella 
simple, flattened ; lip thin, the sinus absent or barely indicated. 
Operculum oval, pyriform, with apical nucleus. 
Foot truncated or bilobed in front, drawn out behind; ten- 
tacles cylindrical, rather short, the eyes external at the middle 
or three-fourths of their length. Teeth straight (1-0-1); Plate 
33, figs. 55, 52. 
Distr.—Northern Seas. 
The following may be considered sections :— 
Section TYPHLOMANGILIA, Sars., 1878. Animal blind. 
Section HapropieurA, Monterosato, 1883. Shell not turricu- 
lated, with a few strong longitudinal ribs. Mediterranean. 
Section EtantontA, Desh., 1862. This eocene group is here 
included by Dr. Fischer. I have placed it in the family Aplus- 
tride (S. and S. Conch., ii, 362). 
Subgenus Benomitra, Fischer, 1882. 
Shell elongated, with mammillary apex; aperture oblong; 
lip sinuous, slightly concave towards the suture ; columellar lip 
with several small but strong plications; canal short. Operculum 
with apical nucleus. 
Genus LACHESIS, Risso, 1826. 
Shell small, strong, turreted, many-whorled, the last whorl 
not very large; surface sculptured by longitudinal ribs and 
revolving strive; apex mammillated ; aperture oval; canal very 
short, straight, not recurved ; outer lip slightly thickened exter- 
nally, crenated within, without apparent sinus. Operculum 
unguiculate. 
Animal with diverging tentacles, short siphon, and short ovate 
foot; the eyes on stalks connate with, and at half the length of 
the tentacles. 
I retain the above name, although previously used by Daudin 
in reptilia and by Savigny in arachnida. One of its synonyms, 
Neszea, Risso, was also used by Lamarck for a genus of Polyps, 
and by Leach in crustacea. On these accounts the group has 
