During a voyage to the West Indies undertaken in 1963-1964 Dr. P. WAGENAAR HUMMELINCK collected many specimens of marine organisms from Piscadera Baai, Curaçao, as a basis for the compilation of a preliminary list of the local fauna and flora. This paper deals with the styelid ascidians which dr. HUMMELINCK entrusted to me and whose study has formed the subject of a student’s nine-month practical course in taxonomy. Only three species, amongst the material collected from Piscadera Bay, seemed to be well enough characterized for them not to need revision. They are Styela partita (Stimpson), 1852, Polyandrocarpa (Eusynstyela) tincta (Van Name), 1902, and Symplegma viride Herdman, 1886. It has, therefore, been necessary to compare my material with earlier collections.