postabdomen (post-ab'-do-men). (a) The slender, attenuated posterior part of the abdomen of a scorpion, composed of five segments and a telson modified as a poison gland; the narrow posterior part of the abdomen of a merostome. (b) The telson of a crustacean. (c) A joint succeeding the third segment (abdomen) of the shell of a nassellarian radiolarian.
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anthill (ant'-hill). A common term for termitarium.
clastic dike . A sedimentary dike consisting of a variety of clastic materials derived from underlying or overlying beds; esp. a sandstone dike or a pebble dike.
syngenite (syn'-ge-nite). A colorless, white, or pale yellow monoclinic mineral: K2Ca(SO4)2•H2O . It is the K analogue of koktaite.
glimmerite (glim'-mer-ite). biotite rock.
ice cliff . Any vertical wall of ice; e.g. a very steep surface bounding a glacier or a mass of shelf ice. Less recommended syn: ice front; ice wall. Syn: ice face.
eurygeographic (eu''-ry-ge''-o-graph'-ic). Said of plant or animal species with wide geographic ranges. Cf: stenogeographic.
zero-order basin . An unchannelized upland valley that serves as a sediment storage site and may be important for debris-flow initiation. Cf: hollow; stream order.
delta diversity . The change in taxon diversity from geographic region to geographic region, arising from biotic provinciality. It is typically calculated as the ratio of epsilon to gamma diversity (Whittaker, 1972).
barrier [ecol] . A condition, such as a topographic feature or physical quality, that tends to prevent the free movement and mixing of populations or individuals.