Speculations on the Immigration of the Barnacle Elminius modestus in France

The literature on the recent immigration of the Australian barnacle Elminius modestus to West European coasts is rather exhaustive. The present author has given details on the exact centre of immigration on the Dutch coast. The spreading from this centre has been followed in subsequent years (DEN HARTOG, 1953). From the French coast only few data are known. The localities where it first established itself are unknown. Speculative though it may be, therefore, it seems useful to try a reconstruction of the immigration of Elminius in France as exact data are still available. In July 1951 the author found Elminius on the Boulonnais coast (Pas de Calais: Le Portel, Boulogne sur Mer, Wimereux, Ambleteuse, Audreselles, Cap Gris Nez). On account of our findings on the Dutch and Belgian coasts, they seemed to us to belong to a population radiating from Holland. BISHOP’S (1954) observation however, in the same region, Wimereux, a year earlier (September 1950) did not exactly fit in with this supposition. Real doubt as to the Dutch descent of these specimens arose after finding Elminius in Brittany.