Note 11 — Class—CRUSTACEA. Sub-Class—CIRRIPEDIA.

M. Dujardin has lately (‘Comptes Rendus,’ Feb. 5, 1850, as cited in ‘Annals of Nat. History,’ vol. v, p. 318,) discovered that the “Hypopi are Acari with eight feet, without either mouth or intestine, and which, being deprived of all means of alimentation, fix themselves at will, so as to undergo a final metamorphosis, and they become Gamasi or Uropodi.” Here, then, we have an almost exactly analogous case. M. Dujardin asks—“Ought, therefore, the Hypopi to be called larvæ, when, under that denomination, have hitherto been comprised animals capable of nourishing themselves?”