Reviewing the enormous amount of literature concerning Cerion, one may wonder whether it makes sense to write another article on this genus not dealing with a fundamental problem. However — in the author’s opinion — the state of affairs is such that it may still be useful to publish a number of new data, hoping that this important animal-group will be included in modern taxonomical and ecological research to a greater extent as has been the case until now. The representatives of the genus Cerion have a remarkable distribution: a large area in the northern part of the Caribbean region — with three centres of speciation, in Cuba, the Bahamas and the Cayman Islands — yielding many dozens of species and subspecies, and a small area in the southern part, confined to the islands of Curaçao, Aruba and Bonaire, harbouring only one single species. The uniformity of the Cerion population of the three islands of the Leeward Group is most striking, compared to the pluriformity of the populations on several much younger and much less diversified Bahamian islands.