The origin of the paired arteries from the PrGabp 1 ._.
- Diagrams of the development and adult structure of one of the paired central eyes of a scorpion.
Asp, Paired anterior process of the subneural arch.
DR, The paired dorsal ridges.
An important feature is the occurrence in some species (Ptychoderidae) of paired longitudinal pleural or lateral folds of the body which are mobile, and can be approximated at their free edges so as to close in the dorsal surface, embracing both the median dorsal nerve-tract and the branchial grooves with the gill-pores, so as to form a temporary peri-branchial and medullary tube, open behind where the folds cease.