urochordn.
/ˈjʊərə(ʊ)kɔːd/, /ˈjɔːrə(ʊ)kɔːd/, U.S. /ˈjʊrəˌkɔrd/ Zoology.
1. A notochord that is confined to or present in the tail region, esp. as characteristic of certain tunicates (urochordates). Now rare.Quot. 1890 is referring to the garpike ( Lepisosteus).
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the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > division Molluscoidea > [noun] > division Tunicata > notochord of
urochord1877
1877 T. H. Huxley Man. Anat. Invertebrated Animals x. 595 The appendage..may be termed the urochord.
1880 A. Wilson in Gentleman's Mag. Jan. 46 Among the sea-squirts, the ‘urochord’ persists throughout life.
1890 Amer. Naturalist 24 422 (caption) Lepidosteus, caudal skeleton.., adult; showing urochord more prolonged and attenuated than in the preceding.
1911 Encycl. Brit. XXVII. 389/1 The embryo..never shows the features characteristic of larval Ascidians, such as the urochord.
1995 C. Nielsen Animal Evol. li. 396 It appears clearer to use..the term urochord for the chorda in the tail of urochordate larva and adult larvaceans, and to restrict the term notochord to cover the structure along the whole dorsal side of cephalochordates and vertebrates.
2. = urochordate n. rare.
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the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > division Molluscoidea > [noun] > division Tunicata > member of
tunicary1835
tunicate1848
urochord1885
urochordate1895
1885 F. J. Bell Compar. Anat. & Physiol. ix. 313 Amphioxus has no external skeleton, nor have those Urochords that are tailed throughout life.
1951 Amer. Naturalist 85 270 The notochord in urochords also develops from endodermal cells intimately related to those giving rise to the digestive tract.
This entry has been updated (OED Third Edition, September 2009; most recently modified version published online December 2021).
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n.1877