BOOK ELEVENTH. 



CEPHALOPODA 



CLASSIFICATION. 



§ 230. 



The Cephalopoda present, in their organization both internal and 

 external, so many peculiarities which distinguish them from all the other 

 Mollusca, that it is necessary to consider them in a class by themselves, 

 although their genera are not numerous. 



It is, moreover, necessary to state why we here regard the different forms 

 of Hectocot ylus which hitherto have been considered as parasites of these ani- 

 mals, as the males of certain Octopoda.^^' The researches o{ KöUiker have 

 led us to make this change. This naturalist founds his opinion upon the 

 following convincing reasons:'-' The specimens of Hectocotylus have bran- 

 chiae, and a heart with arteries and veins, and they cannot, therefore, be 

 regarded as Heliuinthes. On the other hand, they have, in common with the 

 Cephalopoda, the contractile chromatophoric cells of the skin, and the same 

 kind of spermatic particles and suckers ; and the muscular substance of 

 their body is arranged exactly like that of the arms of the Cephalopoda. 

 All of them are males, and the Cephalopoda, with which they are connected, 

 are all females; finally, the embryos found in the eggs of certain Octopoda 

 exactly resemble them. Whoever has had the opportunity of examining the 

 species yet known, viz : Heciocotylus argonaictae, octopodis, and tremoctopo- 



1 At present there are knovra two or three species XVIII. 1829, p. 147, PI. XI. A. fig. 1 5, or Fro- 



of these singular beings resembling the torn-off riep^s Not. XXVII. 1830, p. 6, fig. 16-19, or Isis, 



arms of the Octopoda, and which Uve in the cavity 1832, p. 559, Taf. IX. ftg. 1-5) should be found in 



of the mantle of certain Octopoda, attached by the cavity of the mantle of Octopu.i s;ranuliitus 



the means of suckers. Hector.otyliis anronautae {Lamarck). It is probably identical with Octopus 



was first described quite imperfectly by Delle Chi- tutierculatus of Delle Chiaje {Octopus Verany, 



aje (Memor. &c. II. p. 225, Tav. ,XVI. fig. 1, 2, Warner), which lives in the Mediterranean Sea, 



and Isis, 1832, Taf. X. fig. 12, a. b.) under and perhaps, also, with Tremoctopus violaceus. 



the name of Trichocephalus acetabularis. An- If this last is not so, there is then a third species 



other description by Costa (Ann. de Sc. Nat. of Hectocoti/lus, viz : the male of Tremoctopus 



XVI. 1841, p. 18t, Fl. .XIII. fig. 2, a.-c.)ha3 not violaceus. 



added nmch to our knowledge of the real nature of 2 Sae Kölliker, On the Hectoeotylus of Tre- 



this animal. knoÜxüT »\KQ\iii, Hectoeotylus onto- moctopus violaceus, and Arf^onauta argo, la 



podis, established by Cuvier (Ann. d. Sc. Nat. the Ann. of Nat. Hist. XVI. 1845, p. 414. 



