Some observations upon the structure of two new species of hectocotyle, parasitic upon Tremoctopus violaceus, D. Ch., and Argonauta argo, Linn. : with an exposition of the hypothesis that these Hectocotylae are the males of the Cephalopoda upon which they are found / by A. Kölliker ; communicated by Robert Brown ; read April 15 and May 6, 1845