The areas left and right of the axis, called pleura (or in plural pleurae) are without furrows.
The pleurae are sometimes abbreviated or extended to form long spines.
Extrapleural pneumonectomy is a more extensive operation that involves resection of the parietal and visceral pleurae, underlying lung, ipsilateral diaphragm, and ipsilateral pericardium.
The thorax axis is moderately convex and sharply defined, while the areas lateral of the axis (or pleurae) are nearly flat with distinct grooves.
The pleurae are clearly wider than the axis.
The side lobes of the thorax (or pleurae, singular pleura) have rounded ends.
The thorax and pygidium are very regularly divided into up to 23 rather narrow segments, without a furrow within each of the pleurae.
Its major characteristics are a large forward-reaching glabella, pointed pleurae or pleurae with very short spines, and a medium pygidium with well-impressed furrows.
