Biting mandibles; second maxillae incompletely fused.
The variability in form and function of the second maxillae is sufficiently shown by the fact that G.
The Hemiptera, with their piercing mandibles and first maxillae and with their second maxillae fused to form a jointed beak, stand far apart from them.
The maxillae of the first pair (fig.
The maxillae are not piercing organs, and their function is to protect the mandibles and labrum and separate the hairs or feathers of the host.
Muller, our leading authority, adopts the confusing plan of calling them second maxillae in the Cypridinidae (including Asteropidae), maxillipeds in the Halocypridae and Cyprididae, and first legs in the Bairdiidae, Cytheridae, Polycopidae and Cytherellidae, so that in his fine monograph he uses the term first leg in two quite different senses.
This second pair of maxillae (or labium) form then the hinder or lower boundary of the mouth.
In their typical state of development, the first maxillae offer a striking contrast to the mandibles, being composed of a two-segmented basal piece (cardo and stipes, fig.
All these orders agree in the possession of biting mandibles, while their second maxillae have the inner and outer lobes usually distinct.
E, First maxilla; a, cardo; b, stipes; c, galea; d, lacinia; e, palp. B, Second maxillae (Labium); a, mentum; b, ligula (between the two galeae); c, c, palps.