Abstract
Interambulacral sections of live test from Echinus esculentus, pieces of dead test, and settlement slates coated with various echinoid and barnacle extracts were made available to settling cypris larvae of Balanus balanoides. These cyprids appear unable to settle on live healthy test preparations of the sea‐urchin. The test of E. esculentus itself is not physically unsuitable for the settlement of cypri'ds, and there is no repulsion due to chemicals in the epithelium or the pedicellariae. However, cyprids do not appear able to settle when the pedicellariae and spines are active.
Notes
Present address: Department of Zoology and Comparative Physiology, Queen Mary College, University of London, Mile End Road, London El 4NS, U.K.