The athecate hydroids Coryne pintneri Schneider and Thecocodium brieni Bouillon, previously unreported from British waters, have been found near Oban, western Scot-land. Descriptions and figures are given, with observations on behaviour in culture. It is considered that Coryne pintr.eri is specifically distinct from Coryne filiformis (Rees). The feeding response of Thecocodium brieni is described, and it is concluded that it ismediated chemically by diffusion of exudate from captured prey. Response to mechanical stimulation is also described: it evidently is transmitted through the stolonal network, but it is not known whether this is via nervous or non-nervous tissue. The occurrence in Scotland of thesetwo species, previously known only from north-west France and the Mediterranean, is attributedto their probable introduction on oysters from Brittany, France.