Note 18 — CLASS—CRUSTACEA. Sub-Class—CIRRIPEDIA.

In my volume on the Lepadidæ (p. 200) in searching for analogies for the permanently epizoic and rudimentary condition of the male Cirripedes, I quoted two cases, which I believe are now known not to be analogous; namely, the Syngamus trachealis of Von Siebold, and the worm-like Hectocotyle, which latter was quite lately supposed to be a male Cephalopod, but has now been ascertained to be only one of the arms of the male wonderfully adapted and organised as a sperm-receptacle. The Asplanchna, the mouthless male of a Rotifer, (p. 292) alone remains for me.