[Observe the powerful gnathobases of the sixth pair of prosomatic limbs and the median plates behind m.
5), and that the gnathobases of the chelae which act as the first pair of hemignaths are carried by the third somite.
The five pairs of appendages of the post-oral somites of the head or prosoma thus constituted all primitively carry gnathobasic projections on their coxal joints, which act as hemignaths: in the more specialized forms the mandibular gnathobases cease to develop.
In the more primitive forms the appendage of every post-oral somite has a gnathobase and two rami; in higher specialized forms the gnathobases may be atrophied in every appendage, even in the first post-oral.
How would you define gnathobases? Add your definition here.