The anterior and lateral borders of the cephalothorax are smooth.

The anterior border is serrated for articulation with the frontal bone.

The anterior border is the longest and slopes downward and forward.

The anterior border is thin above, thicker below, and continuous with the oblique line.

The second through ninth segments each have a full set of spines as anterior borders.

It is much longer than the anterior border, and projects, below, into the phrenicocostal sinus.

Its anterior border attaches to the posterior edge of the buccinator.

The pygidium of B. forteyi is wider than long, with a straight anterior border.

However, most of its anterior border is covered by the pectoralis major.

The lobes have three different types: anterior, posterior and inferior borders.