in the Cephalopoda. Ill 



"Lectures on Comparative Anatomy and Physiology, London, 

 1855/^ the celebrated English anatomist, Professor Owen, has 

 no peculiarity in the Octopoda and Decapoda to place beside the 

 sexual distinctions so often referred to in Argonauta and Tremoc- 

 topus, except the following : — " In the Calamary {Loligo vulgaris) 

 the gladius of the male is one-fourth shorter, but is broader than 

 that of the female. The sepium of the Cuttle {Sepia) shows a 

 similar, but not so much, sexual difference in its proportions,'' 

 p. 628 ; so that of such characters he is only acquainted with 

 the greater or less breadth of the gladius, according to the sexes. 

 Still less has Professor Leuckart to place beside this sexual 

 peculiarity in Argonauta and Tremoctopus. In his " Nachtrage 

 und Berichtigungen zu dem ersten Bande von J.Vander Hoeven's 

 Handbuch der Zoologie, Leipzig, 1856," which have just ap- 

 peared, I find that this author, so well known by his observa- 

 tions upon the sexes and reproduction of the sea animals, says, 

 in connexion with the above-mentioned two genera : "Amongst 

 the other MoUusca no instances of a sexual dimorphism have 

 yet been observed, for the difference in the formation of the 

 labial tentacles in the male Nautilus, pointed out by Van der 



Hoeven, and recently confirmed (according to his letters) 



can scarcely be placed beside the remarkable peculiarities of those 

 Cephalopoda.'' 



But the more these peculiarities have been overlooked, the more 

 does the question arise, how can they have escaped observation ? 

 and, as the answer to this, I must state that I suppose that they 

 must really have been frequently noticed by naturalists, but 

 that they must have regarded them as morbid developments or 

 accidental mutilations, of which the traces had not been effaced 

 by regeneration. I have already stated that D'Orbigny has 

 indicated as a disease, what in my opinion is a character of the 

 reproductive males in the genus Sepiola; and that the short, 

 hectocotylized arm of Octopus and Eledone has been regarded as 

 an injured or mutilated arm, the lost terminal portion of which 

 had not yet grown, appears to me to follow distinctly enough, 

 although indirectly, from the numerous figures of these animals 

 possessed by science. I have been unable to find a single one 

 of these with a male arm of this description ; and as it is incon- 

 ceivable that, especially amongst so many Octopods figured in 

 such different places and at such different periods, there should 

 not have been a single male (although these appear to me to be 

 at least as abundant as the females), the artists or naturalists 

 must, in order to complete the animal, have given it the sym- 

 metry which they supposed to belong to it. This applies also to 

 the form of the left arm in the male Loligines and Sepice, and the 

 more so as, according to the text and the lettering of the plates. 



