(Vogt, 1854)
Trunk compact, up to 1.4 mm long (Oikopleura longicauda). Postcardial caecum pointing dorsally, adjoining the genital wall of the esophagus. A long velum (often torn) extending dorsally over the oral part of the trunk. Rectum extending scarcely beyond the oral wall of the stomach. Gonads adjoining the coil of the gut, and embracing it laterally when ripe. Tail musculature broad.