Prosobranchia was a large taxonomic subclass of sea snails, land snails and freshwater snails. This taxon of gastropods dates back to the 1920s. It has however been proven to be polyphyletic (consisting of more than one lineage of descent).

前鳃亚纲（學名： Prosobranchia ）是腹足纲之下的一個棄用生物分類，其物種現時已散落到其他分類。 本亞綱的物種從 海螺 、 蝸牛 及 淡水螺 均有。 「前鳃亚纲」這名稱的出現可追遡至1920年代，取名於本物種「 鰓 在 心臟 的前方」，與 後鰓亞綱 相對。

Prosobranch, any snail of the subclass Prosobranchia, class Gastropoda. Most of these roughly 20,000 snail species are marine; a few live on land or in fresh water. Many prosobranchs breathe by means of gills, which are located in the mantle cavity in front of the heart; some have a special

前鳃亚纲（Prosobranchia），腹足纲中最大的亚纲，贝壳发达，多为螺旋形。 神经系统的侧、脏神经连结交叉成8字形,因而又称扭神经亚纲。 多数种类有厣，本亚纲的种类多为海生，从潮间带的高潮区直到深海都有分布。

Nowadays the classification of Gastropoda undergoes considerable reorganization in the attempt to bring it as close as possible to a changing phylogenetic hypothesis of the class. There is compelling evidence that Prosobranchia as classically understood is a paraphyletic taxon, and as a consequence it is being progressively abandoned.

Nowadays the classification of Gastropoda undergoes considerable reorganization in the attempt to bring it as close as possible to a changing phylogenetic hypothesis of the class. There is compelling evidence that Prosobranchia as classically understood is a paraphyletic taxon, and as a consequence it is being progressively abandoned.

腹足纲(Gastropoda) 前鳃亚纲 (Prosobranchia)马蹄螺科(Trochidae)海生 软体动物 ，矮圆锥形的壳一端平截。 虽然分布范围从 潮间带 到深海，但从 赤道 到高纬度地区的岩岸浅海中种类最多，大西洋沿岸温带地区常见的有驼峰螺属(Gibbula)、 单齿螺 属(Monodonta)和 丽口螺 属 ...

前鳃亚纲（Prosobranchia）是腹足纲中最大的一个亚纲，生存种超过55000种。外套腔位于身体前端，鳃1～2个位于心耳之前，壳通常有板、侧脏神经索扭成"8"字形，因此又称为“扭神经类”。

Prosobranchia was a large taxonomic subclass of sea snails, land snails and freshwater snails. This taxon of gastropods dates back to the 1920s. It has however been proven to be polyphyletic (consisting of more than one lineage of descent).

Shell 35 mm high, white but usually covered with crustose coralline algae. Apex tall & centrally placed. Common but inconspicuous, often concealed under mats of geniculate coralline algae. Feeds on crustose corallines. Geogr. Range: Aleutian Islands to Baja.