| 释义 |
placo-|ˈplækəʊ|
before a vowel plac-, combining form of Gr. πλάξ, πλακ- a flat plate, tablet, entering into various scientific words. placoˈbranchid |-kɪd| [Gr. βράγχια gills], one of the Placobranchia, a division of nudibranchiate gastropods having lamellar gills covering the upper surface of the lobes and back; so placoˈbranchoid |-kɔɪd| a., resembling or akin to the Placobranchia. ˈplacoderm [Gr. δέρµα skin] a., having the skin encased in broad flat bony plates, as certain fossil fishes; of or belonging to the Placodermata or Placodermi, an order of Palæozoic fishes having the head and pectoral region thus protected; n. one of the Placodermata; so placoˈdermal, placoˈdermatous adjs.; placoˈdermoid a., resembling the placoderms in form or structure. ˈplacodont [Gr. ὀδούς tooth] a., of or belonging to the Placodontia, a division of fossil saurians having thickly-set short flat palatal teeth; n. (also placoˈdontid), a reptile belonging to the Placodontia; so placoˈdontoid a., resembling the placodonts in form or structure. placoˈganoid [ganoid] a., of or pertaining to the Placoganoidei, a division of fossil Devonian fishes, having the head and part of the body protected by large ganoid plates; n., a fish of the Placoganoidei; also placogaˈnoidean a. and n. plaˈcophoran [Gr. -ϕόρος bearing] a., of or pertaining to the Placophora, a sub-order of molluscs, sometimes made a primary division, comprising only the chitons (Polyplacophora); n., one of the Placophora, a chiton; so plaˈcophorous a.
1859–65Page Geol. Terms (ed. 2), *Placoderms,..Dr. Pander's term for the bony-plated or bone-encased fishes of the Old Red Sandstone. 1886A. Winchell Walks Geol. Field 239 The placoderm was destined to disappear with the Devonian period.
1889Nicholson & Lydekker Palæont. (ed. 3) II. 1001 Points in which the Siluroids resemble the *Placodermatous Ganoids.
Ibid. 921 It has..been suggested..that the *Placodermoid Ganoids were closely related to the Ascidian Invertebrates.
1859Owen in Encycl. Brit. (ed. 8) XVII. 124/2 The *placoganoid and ganoid, heterocercal and notochordal fishes of the Devonian. 1862Dana Man. Geol. vii. 276 Placoganoids, having the body covered with plates instead of scales. 1872W. S. Symonds Rec. Rocks vii. 254 During the latter part of the Silurian epoch the..Placoganoids make their appearance. |
