The head is extended from behind forwards, so that the crown (epicranium) is large, while the face (clypeus) is small.
Above is the crown (vertex or epicranium), on which or on the " front " may be seated three simple eyes (ocelli).
Riley (1904) the epicranium cord; M, mesodermal pouches.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.