in the Cephalopoda. 103 



Guided by this remarkable form and metamorphosis, in the 

 males of Octopus and Eledone, of exactly the same arm which, 

 in the male individuals of the genera Aryonauta and Tremocto- 

 pus, becomes developed into a separable and deciduous transferer 

 of semen, and by the unmistakeable concordance which occurs 

 again between the development of the arm in Octopus and Ele- 

 done, and the peculiarity which I have above described in the male 

 Decapoda*, I no longer regard it as doubtful that all these de- 

 velopments belong to one category, and all have essentially the 

 same object, namely the transference of the spermatophora, or 

 of the seminal masses contained in these peculiar capsules, to 

 the female, or perhaps to the eggs. Nor do I doubt that, pro- 

 vided this supposition be correct, the peculiar transitions pre- 

 sented by each genus have their determinate purpose, and give 

 rise to many different modes of fecundation ; but what the 

 details of these may be, must be left to be decided by observa- 

 tions on the animals in a state of nature. For the guidance 

 of subsequent investigators, I shall take leave at a future 

 meeting of the Society to bring forward the indications which 

 have been furnished to me by spirit specimens, as in these we 

 certainly see that the transfer of the spermatophora takes place 

 in very different ways, and that the actual fecundation of the 

 ova must be effected in many cases in an unexpected and very 

 remarkable fashion. 



Before passing to some general remarks to which these ob- 

 servations lead, I shall give an exact description of a very per- 

 fect Hectocotylus, or of an arm which is destined not merely 

 to transfer the semen, but also to become detached and to fasten 

 itself with the entire mass of semen upon the female ; and I do 

 this the rather, as hitherto the formation of Hectocotyli is only 

 known in the larger species of Tremoctopus ( T. violaceus and T. 

 Carena) which live in deep water, but not in the smaller oceanic 

 species of the genus living nearer the surface, for which we may 

 perhaps provisionally retain D'Orbigny's name of Philonexis ; 

 and it is exactly one of these small oceanic species, namely P. 

 Quoyanus, D^Orb.f, of which I have had the opportunity of 

 examining the Hectocotylus. 



In Philonexis Quoyanus the development of the Hectocotylus 

 differs from the w^ell-knowu process in T. Carena, in that it is 

 not formed in a pedunculated membranous bladder, but in a 



* In one of my males of Rossia I found two soft envelopes of seminal 

 capsules between the cutaneous folds of the arm. 



t Should it turn out hereafter that P. semipalmatus, Owen, is not 

 S)'nonymous with D'Orbigny's species, my species will probably be nearest 

 to semipalmatus, accordin;^ to Owen's figures. A male was captured with 

 three females, bv Professor Remhardt, under 2-T 4' N. lat. and 24" 4(1' W. 

 long. 



