Family Limacinidae Gray, 1847
Limacinidae consists of one genus Limacina.
The shell microstructure is either prismatic, or cross-lamellar or both simultaneously (Rampal, 1977). The shell is sinistrally coiled, transparent with a high or low spire. The shell may show a faint hue of brown or purple, only L. helicoides is clearly dark brown. Limacina inflata is coiled in one plane. Usually an umbilicus is present. The operculum, always present in young specimens, may be lost in adults. The shell shows few or no sculpture. Growth lines are always present. The aperture borders are not thickened and the columella is small. The protoconch is distinct from the teleoconch but the difference is small. The foot is transformed into two large laterally projecting wings used in swimming and a posterior footlobe, mainly used in feeding. The lips are in between the wings and mouth. The buccal mass contains a radula with one row of median teeth and at each side one row of lateral teeth, and a jaw. The body is surrounded by a mantle, ctenidia are absent. In the mantle a large mantle gland is found with several bands of different cell types. The ganglia are concentrated around the oesophagus near the buccal mass. The green to purple liver, and dark apical gonad tissues are clearly seen, as well as, the intestine encircling the body.
[1 genus]