The study of some newly collected material from the West Indies may justify a fourth paper on Caribbean Tenebrionidae in these “Studies”. Thanks to dr. P. WAGENAAR HUMMELINCK’S collecting work, the Tenebrionid fauna of the Antilles and the adjacent South American mainland shores may be considered to be pretty well known — at least as far as the Melasomes are concerned. Thus zoogeographical conclusions — though not differing essentially from those published in 1962 — appear to have a rather solid basis. Unfortunately much less is known about planticolous Tenebrionids, which anyhow are relatively less interesting for zoogeographical purposes, than the geophilous ones. We also had the privilege of consulting the collections of the I.N.R.A. at Guadeloupe (see MARCUZZI & D’AGUILAR 1971) which considerably increased our knowledge of the Tenebrionid fauna of that and neighbouring islands. Several specimens on hand at the Institute of Marine Biology, Mayagüez, proved extremely useful for obtaining a better knowledge of the Tenebrionid fauna of the old, sedimentary island of Puerto Rico. In a few single cases material from other sources (British Museum, Museum G. Frey and the private collection of the author) has been used.