The word hippocampus comes from late Latin: hippocampus, derived from the Greek words for a horse+sea monster. In mythology it was a sea horse, having two forefeet, with the body ending in a dolphin's or fish's tail, represented as drawing the vehicle of Neptune the sea God. The earliest use (Oxford English Dictionary) was in 1606, cited as “Drummond of Hawthornden” Let. Wks. (1711) 232. “Stately pageants. that of Cheapside was of Neptune on a hippocampus, with his Tritons and Nêreides”.

Neurologists recognise it as each …