protegulumn.
/prə(ʊ)ˈtɛɡjᵿləm/, U.S. /proʊˈtɛɡjəl(ə)m/ Zoology.
In brachiopods: the initial or embryonic form of the shell, or of each valve of the shell.
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the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > phylum Brachiopoda > [noun] > member of > parts of
periosteum1758
periostracum1833
pallium1834
mantle cavity1853
adjustor1857
jugum1888
protegulum1891
1891 C. E. Beecher in Amer. Jrnl. Sci. 41 344 All brachiopods, so far as studied by the writer, have a common form of embryonic shell, which may be termed the protegulum.
1935 W. H. Twenhofel & R. R. Shrock Invertebr. Paleontol. viii. 269 Growth proceeds around the protegulum, mainly along the anterior and lateral margins of the two valves.
1959 L. H. Hyman Invertebrates V. xxi. 531 Each valve begins as a minute plate, the protegulum, presumably composed of periostracum.
1993 E. N. K. Clarkson Invertebr. Palaeontol. & Evol. (ed. 3) vii. 174/2 Shell secretion then begins on the now reversed outer surface of the mantle, but the brachial and pedicle valve protegula are separate from the beginning.
This entry has been updated (OED Third Edition, June 2007; most recently modified version published online March 2022).
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n.1891