The front of the head is termed the _face_, the top the _crown_, the sides
are nearly entirely occupied by the compound eyes (Plate I., fig. 11, AA),
and the lower surface by the organs of the mouth.
The _Eyes_ consist of a very large number of simple lenses arranged in the
form of two hemispheres, one on each side of the head. The _ocelli_, or
simple eyes, are situated on the crown, and are usually almost entirely
covered by scales.
The _Antennæ_ are two jointed appendages attached to the top of the head
above the eyes. They vary very much in structure. The following are the
terms used in describing the different forms of antennæ in the
_Lepidoptera_:--
1. _Pectinated_, when the joints have long processes like the teeth of a
comb. If these are on one side only, the antennæ are _unipectinated_; if on
both sides, _bipectinated_. (Plate I., fig. 20, bipectinated antenna of
_Nyctemera annulata_.)