Abstract   The endostyle is a glandular and ciliated groove lining the pharyngeal floor of tunicates. This paper describes the histological structure of this organ in two new species of doliolid-like animals, Doliopsis bahamensis and Paradoliopsis harbisoni, and compares it with that of Doliolum nationalis. The results confirm the distinction between the Doliolida and the other Thaliacea.