1845.] Linnean Society. -237 



May 6. 



ITie Lord Bishop of Norwich, President, in the Chair. 



Benjamin Clark, Esq., was elected a Fellow ; and II Cavaliere 

 Giambattista Amici, M. G. P. Deshayes, and Prof. Karl Friedrich 

 von Ledebour, Foreign Members. 



Read the conclusion of Prof. KoUiker's memoir on the Hectocotyla 

 of TVemoctopus violacens and Argonauta Argo. 



In this paper Prof. Kolliker gives a detailed description of the 

 external form and anatomical structure of two remarkable parasites 

 referable from their characters to the genus Hectocotyle of Cuvier, 

 and bearing much resemblance to the Hect. Octopodis of that author. 

 Of one of these, that which is parasitic on the Argonaut, Delle Chiaje 

 has given an unsatisfactory account in his Memoirs on Comparative 

 Anatomy, under the name of Trichocephalus acetabularis ; and Costa 

 has endeavoured, in the sixteenth volume of the second series of the 

 ' Annales des Sciences Naturelles ' to prove that it is only a separated 

 portion of the animal on which it is found. But this opinion is, ac- 

 cording to Prof. Kolliker, quite erroneous, all its characters indica- 

 ting beyond a doubt that it is a distinct animal. The two species 

 described were found by Prof. Kolliker at Messina, and are severally 

 named by him Hect. Treinoctopodis and Hect. Argonautce, from the 

 animals on which they parasitically live. 



Prof, Kolliker enters into a particular statement of the reasons 

 which have induced him to believe that these Hectocotyla are in 

 reality the males of the Cephalopods on which they are found ; of 

 which reasons he gives the following summary : — 



1. The Hectocotyl(E have arteries and veins, a heart and branchiae ; 



and hence it is improbable that they should be Epizootic 

 Worms. 



2. Hect. Argonauta and Hect. Tremoctopodis bear a close relation to 



the Cephalopoda in general, and more especially to the genera 

 on which they are found ; inasmuch as they have — 



a. The same spermatozoa ; 



b. Contractile pigment-cells ; 



c. Similarly formed and similarly organized suckers ; 

 No. XXV. — Proceedings of the Linnean Society. 



