Pterygotus

Pterygotus anglicus is an extinct Eurypterid, related to arachnids (the spider family) and commonly called "sea scorpions." It lived in the Silurian and Devonian periods.
Fossils have been found in North America, South America, Europe and Australia. It is related to the larger "Jaekelopterus". It is similar to the freshwater "Slimonia".
"Pterygotus" could reach a body length of . It had a pair of large compound eyes. It also had another pair of smaller eyes in the center of its head. It had 4 pairs of walking legs. A fifth pair of legs were swimming paddles. It also had a pair of large pincers.