Between 1930 and 1973 PIETER WAGENAAR HUMMELINCK of the Zoölogisch Laboratorium of the State University of Utrecht made nine collecting trips to the Caribbean. While most collecting was undertaken in the territories of the Netherlands Antilles, visits were also made to several other West Indian islands and to Southern Florida. Dr. HUMMELINCK was particularly interested in the biology of coastal lagoons and salt ponds so that his collections are representative of these environments but do not contain much material from other important marine environments such as coral reefs and open water sea grass beds. At the invitation of Dr. HUMMELINCK I have examined all of the Ascidiacea (Tunicata) in these collections containing several thousand animals. A high proportion of the material came from two lagoons in Curaçao and Bonaire and I have reported separately on this material (GOODBODY, 1984) as it provides an opportunity to compare the ascidian fauna of two contrasting environments. The remaning material comes from fifty different localities in nineteen territories in the West Indies and Florida. The ascidian fauna of the Caribbean is well known as a result of the work of VAN NAME (1921, 1924, 1930, 1945), MILLAR (1962), VAN DER SLOOT (1969), MILLAR & GOODBODY (1974) and a recent series of papers on the ascidians of Guadeloupe by CLAUDE MONNIOT (1983) and FRANÇOISE MONNIOT (1983). The material from HUMMELINCK’s collections presents no taxonomic problems and is all referable to well known species. It is of interest as a contribution to our knowledge of the distribution and ecology of ascidians in the Caribbean. Dr WAGENAAR HUMMELINCK was meticulous in describing the localities from which specimens were collected and this information has been separately published (1977). We thus have information not only on the regional distribution of ascidians but also on the type of environment in which each species may be found. The information contained here is by itself insufficient on which to base positive conclusions but is necessary source material on which to draw later for discussion of the habitat distribution of Caribbean ascidians. For this reason it is presented here solely as tabular material without further discussion.