BREVIORA Mmseiiioi of Comparative Zoology Cambridge, Mass. Jaxiary 16, 1963 Xtmber 179 THE HOLOTHURIANS OF CLIPPERTON ISLAND IN THE EASTERN TROPICAL PACIFIC By Elisabeth Deichmann Museum of Comparative Zoology Cambridge, Massachusetts In 1902 H. L. Clark listed two typical Iiido-West-Pacific aspidochirote holothurians from Clipperton Island, though at that time he considered one of them a new species. Later expe-ditions brought no holothurian material from this island. It was not until 1958 that Deichmann was able to include in her Hancock report some material of a third species, collected by the Scripps Institution's expedition a few years before. Finally, in 1958, the University of California Clipperton Expedition, which used more refined methods, with diving, etc., brought back four species, two of which had never been reported from any locality in the eastern tropical Pacific. Of the five species now known from Clipperton Island, only one, Microtliele difficilis (Semper) appears to be well established on the mainland of the Pacific coast of America. Two other spe-cies had previously been listed from some of the outlying islands, Semperothuria atra (Jaeger) and Mertensiothuria leucospilota (Brandt). Of the remaining two forms, Stichopus korrens Selenka represents a typical Hawaiian form, while Sempero-thuria flavomaculata (Semper) is considered rare; it was orig-inally described from Samoa and later listed from Tahiti, and (?)Batavia in the East Indies. The conclusions one can draw from this short list are that more Indo-West-Pacific forms are able to cross, at least inter-mittently, the ' ' Ekman Barrier ' ' than hitherto assumed, and that some of these forms may have escaped notice because they are living at a greater depth here than that in which they normally live in the more favorable localities of the Indo-West-Pacific.