| 释义 |
‖ placula Biol.|ˈplækjʊlə|
[mod.L., dim. from Gr. πλάξ, πλάκ- tablet, plate.]
Name for the embryo of Calcispongiæ at that stage in its development when it has the form of a plate or disc. Hence ˈplacular, ˈplaculate adjs., having the form of a placula.
1884A. Hyatt in Proc. Boston Soc. Nat. Hist. XXIII. 89 The primitive differentiation of the placula into two layers is established in what we have designated the diploplacula. Ibid. 97 The embryo of Calcispongiæ is also a placula until the same stage. Ibid. 150 A full-grown, primitive, placulate form. 1895Syd. Soc. Lex., Placular,..Placulate. |