In his work on cirripedes [Cirripedia, vol. 1 Lepadidae (1851), pp. 53–5] CD described a particular organ as an "auditory-sac" although he was unable to trace the supposed nerve from it to any ganglion. August Krohn [in "Observations on the development of the Cirripedia", Ann. & Mag. Nat. Hist. 3d ser. 6 (1859): 423–8] concluded that the organ was ovarian. CD supposes that Krohn is correct, but gives further observations that suggest an auditory function. If someone could find ova within the curious organ it would confirm Krohn’s view.