Some of those zoologists who look to Peripatus, or a similar worm-like form, as representing the direct ancestors of the Hexapoda have laid stress on a larva like the caterpillar of a moth or saw-fly as representing a primitive stage.
On the other hand, it has been argued that the presence of wings in a vast majority of the Hexapoda suggests their presence in the ancestors of the whole class.
On either view it may be believed that the Hexapoda arose with the allied classes from a primitive arthropod stock, while the relationships of the class are with the Crustacea, the Chilopoda and the Diplopoda, rather than with the Arachnida.
Further details of the geological history of the Hexapoda will be found in the special articles on the various orders.
Development of most Hexapoda is the formation of a protective These six divisions of the head are diverse in kind, and subsequently undergo so much change that the part each of them takes in the formation of the head-capsule is not finally determined.
The Orthoptera have been largely used for anatomical and embryological researches, the more important of which are mentioned under Hexapoda (q.v.).
Part by the yolk, and in part by those anterior and posterior rudiments Its composition has been the subject of prolonged difference of which usually form the mesenteron, but that in some Hexapoda opinion.
The study of the Hexapoda of oceanic islands is full of interest.
Polar bodies were first observed in the eggs of Hexapoda by F.
The mandibles of the Hexapoda are usually strong jaws with one or more teeth at the apex (fig.