Stemmata (singular stemma) are a class of simple eyes. These stemmata are arranged in a semicircle. Some insect larvae, e.g., caterpillars, have a different type of simple eye known as stemmata. The eyes consist of twelve stemmata, which are rather more rounded in early instars. These first-instar larvae have stemmata (simple, single-lens eyes). On each side of the head there are usually six stemmata just above the mandibles. Below the stemmata there is a small pair of antennae, one on each side. In the pupal stage, such stemmata develop into fully fledged compound eyes. However, the genus "Scutigera" has secondarily re-evolved a compound eye composed of repeated stemmata. They should not be confused with the lateral ocelli of some insect larvae (see stemmata). EP Shirley, "The Sherley Brothers" (1848), and the same writer's "Stemmata Shirleiana" (1841, again 1873).