It was Huxley who coined the terms "the new synthesis" and "evolutionary synthesis"; he also invented the term "cline" in 1938 to describe species whose members fall into a series of sub-species with continuous change in characters over a geographical area. The classic example of a cline is the circle of subspecies of the gull "Larus" round the Arctic zone. This cline is an example of a "ring species".<br>Some of Huxley's last contributions to the evolutionary synthesis were on the subject of ecological genetics. He noted how surprisingly widespread polymorphism is in nature, with visible morphism much more prevalent in some groups than others. The immense diversity of colour and pattern in small bivalve molluscs, brittlestars, sea anemones, tubicular polychaetes and various grasshoppers is perhaps maintained by making recognition by predators more difficult.