pygidlal

[Mod. Lat. pygidium; Eng. suff. -al.] Pertaining to the pygidium; caudal. py-gid-1-ŭm, s. [Gr. pygidion, dim in. from pygē =the rump.] Compar. Anat .: The caudal shield, or tail, of a Trilobite. It consists of anchylosed or amalgamated segments, and is usually trilobed like the thorax. There is an elevated axis, with a marginal limb. The extremity is sometimes rounded, but it may be prolonged into a spine, or the ends of the pleure may be extended into spine-like projections. The name is sometimes applied to the posterior segment of a flea.