| 释义 |
‖ pygidium Zool.|paɪˈdʒɪdɪəm, paɪˈgɪdɪəm|
[mod.L., f. Gr. πῡγή rump + dim. suff. -ίδιον.]
The posterior part of the body in certain invertebrates, chiefly insects, crustaceans, and worms, when forming a distinct segment or division; the caudal or pygal segment.
1849Murchison Siluria App. L. 545 Pygidium, or tail of some minute entomostraca. 1862Dana Man. Geol. 188 note, The posterior [segment of a trilobite] when shield-shaped and combining two or more segments [is] the pygidium. 1872Nicholson Palæont. 161 The crust exhibits three regions.—1, a cephalic shield; 2, a variable number of movable ‘body-rings’ or thoracic segments; and 3, a caudal shield or pygidium. 1899D. Sharp in Cambr. Nat. Hist. VI. 187 The last of such exposed dorsal plates [in Beetles] is termed pygidium.
Hence pyˈgidial a., of or pertaining to the pygidium.
1877Huxley Anat. Inv. Anim. v. 234 The hindermost segment of the body..divided at the end into two supports for the pygidial cirri. |