口 前触角 前触角神经 口锥 三叶日块 头巾 后触角 口锥神经表皮神经 视神经脑 5唾液腺 食道 消化腺 肠 幅膜 两性膝
Classification with shell, head indistinct, one pair tentacles . Suborder Thecosomata被壳亚目 with one left-handed spiral or straight calcified shell . Euthecosomata真壳部 left handed spiral shell.Limacinidae 虎螺科 straight or some what backward bending shell .Cavoliniidae龟螺科 typical form with one cartilaginous inner shell . Pseudothecosomata假壳部 without shell, head distinct, two pairs tentacles .Suborder Gymnosomata裸体亚目
Classification with shell, head indistinct, one pair tentacles . Suborder Thecosomata被壳亚目 with one left-handed spiral or straight calcified shell . Euthecosomata真壳部 left handed spiral shell.Limacinidae 虎螺科 straight or some what backward bending shell .Cavoliniidae龟螺科 typical form with one cartilaginous inner shell . Pseudothecosomata假壳部 without shell, head distinct, two pairs tentacles .Suborder Gymnosomata裸体亚目
Limacinidae 螺科 small, thin, fragile lefthanded spiral shell mantle cavity on dorsal side single lobed fin Limacina Limacina helicina
Limacinidae 螺科 small, thin, fragile lefthanded spiral shell mantle cavity on dorsal side single lobed fin Limacina Limacina helicina
Cavoliniidae龟螺科 Shells are straight or slightly curved. transverse section circular smooth shell surface.Creseis笔帽螺属 transverse section flat aperture oval, shell with ring-like constriction .Hyalocylix玻杯螺属 aperture constricted elongated aperture without thickenned margin, small posterior foot lobe. Cavolinia龟螺属
Cavoliniidae龟螺科 Shells are straight or slightly curved. transverse section circular smooth shell surface.Creseis笔帽螺属 transverse section flat aperture oval, shell with ring-like constriction .Hyalocylix玻杯螺属 aperture constricted elongated aperture without thickenned margin, small posterior foot lobe. Cavolinia龟螺属