ABSTRACT
The British fauna includes three species of Arenicola. The most abundant is the common lugworm, A. marina L., which Uves in great numbers on tidal sand flats and mud flats. The other two, A. ecaudata Johnston and A. branchialis Aud. & Edw. (=A. grubii Claparède), are found, usually together, in. coarse, rather foul, sandy material, between stones and rocks.
In a series of seventeen brainless isolated extroverts of branchialis, set up exactly as described for ecaudata, the great majority failed to give satisfactory tracings. The lever strokes were feeble or absent, even in the case of preparations which had been seen to contract vigorously and rhythmically in a bowl of sea water before they were mounted on the apparatus. Only two good records were obtained. One was like a typical ecaudata tracing (e.g. E. 30 in Fig. 1). The other—the most vigorous of the series—gave a quite exceptional record, like one obtained from an atypical marina oesophagus by Wells (1937, fig-3, lower half). The available specimens of branchialis were rather smaller than those of ecaudata-, partly for this reason, and partly because of our unsatisfactory experience with the extroverts, we made no attempt to set up more complicated preparations of branchialis.
