0100,0100,0100 Hammerhead Sharks/Balance Fish. Bill Butcher, in his notes to his translation of 20k leagues under the seas, has drawn attention to the fact that Verne is sometimes a bit shaky on marine biology.This is confirmed in Les enfants de Capitaine de Capitaine Grant where the crucial event of the description of a message in the stomach of a Balance Fish (Hammerhead Shark) captured in the Clyde Estuary in effect launches the story. The Hammerhead is a sub- tropical fish and I have never been aware of it migrating as far North as the Clyde. I checked this with Geoff. Swinney, Curator of the fish section of the National Museum of Scotland and a specialist in sharks. In an extremely erudite reply he tells me that only one species of shark with expanded vane-like protuberances on the head is the smooth hammerhead, Sphyrna zygaena (Linnaeus,1758) occurs in the northern part of the North-eastern Atlantic. In the case of the British Isles, this has been recorded as"rare" in the English Channel and not recorded north of the Bristol Channel, some 500 kilometers south of the Clyde. In spite of the warm North Atlantic Drift (Gulf Stream), the Clyde would be well North of the shark's natural range, so as usual, Verne is not one to spoil a good story by insisting on biological accuracy. Ian Thompson.