The cephalon, thorax and pygidium are of approximately equal length. The thorax is a series of articulated segments that lie between the cephalon and pygidium. The elytra, which cover the wings, expose the pygidium. The pygidium is formed from a number of segments and the telson fused together. Its pygidium (caudal shield) was comparatively small. The posterior border of pygidium is longer medially than laterally. The thorax is usually much longer than the pygidium, which is usually small. The body is narrowed at the articulation between cephalon and pygidium. The cephalon is of approximately equal size as the pygidium (or isopygous). In insects, the pygidium is the dorsal tergite of the last external abdominal segment. Posterior margin of the pygidium has a long broad medial notch. However, Kobayashi's holotype consisted only of a badly preserved external mold of a fragmentary pygidium. The species "M. pectoralis" looks similar, but its pygidium is rounded. Along the margins of the pygidium are a pair of very small backward-pointing spines. These modifications, along with the "V" shaped pygidium give these trilobites a cartoon "fish-skeleton" appearance.