Cephalic Canal System

Head canal with a single canal between the eyes. Pores C and D are generally represented by a single pore and designated C(s) and D(s) according to Akihito's terminology

Head canal with a double canal between the eyes. Pores C and D and represented by two pores each and designated C and D by Akihito's terminology.

Confused by the different systems used to name pores? Click here for a chart comparing the systems.