in the Cephalopoda. 109 



This summary furnishes a very striking evidence that there 

 must be something natural in D'Orbigny's division of the Deca- 

 pod Cephalopoda into the two principal groups, " Myopsides '* 

 and " Oigopsides/^ although no great inclination to adopt them 

 has hitherto been shown. The difference in the conditions of 

 reproduction shows especially that the genus Ommatostrephes, 

 D'Orb., is still more entitled to be removed far from the genus 

 LoligOy with which even modern malacologists, such as Verany 

 and Troschel, persist in placing it. D'Orbigny repeatedly points 

 out that his genus Philonexis or Tremoctopus is essentially 

 distinct from Octopus^ under which genus its species were 

 formerly arranged, and closely approaches Argonauta ; and the 

 above-mentioned conditions of reproduction also show this com- 

 pletely ; and in reference to this, it is very interesting to observe 

 that the supposed Octopus y in which Verany has described the 

 complete flec^oco/yZws-development, namely O. Carence, Ver., has 

 proved to be a Philonexis or Tremoctopus. If, therefore, D'Or- 

 bigny^s division into great groups finds much confirmation in 

 the above- described peculiarities, these should also furnish many 

 hints for a probably more natural limitation of the particular 

 families, and this applies especially to the collocation of the 

 genus Sepia with Rossia and Sepiola, which, however, has ap- 

 peared less natural to many. The negative characters which 

 united these three genera in opposition to the other Myopsidce, 

 have already lost something of their strength, as the want of the 

 muscular cords on the funnel has been detected in the small 



of the axis of the arm ; but even a single sucker or a group of suckers, 

 which their enemies may have bitten from the sides or the base of the arm, 

 is reproduced with the greatest facility. 



I have already called attention to the misinterpretations of Aristotle, 

 where he has been understood as if, in his representations of the circum- 

 stances of reproduction in his Polypus, he had in his eye a Hectocotylus- 

 formation, such as we are now acquainted with in Argonauta and Tremoc- 

 topus. This appears to me to be the place to clear up, as far as possible, an- 

 other misconception which stands in connexion with the preceding. Roulin 

 (Ann. des Sc. Nat. xvii. p. 189), namely, supposes that it is the observation 

 of male Octopods from which the Hectocotylus had separated, and which 

 therefore had lost one arm, that gave rise to the story referred to by Ari- 

 stotle, that at certain times, especially in winter, when the Octopus retracts 

 itself more into its cavities, it bites off its own arms, and to Aristotle's 

 view — by which he endeavours to explain the origin of the story — that it 

 is the voracious eels that bite off the arms of the animal. The foundation of 

 both the story and its explanation is of course neither more nor less than the 

 frequent and striking injuries and renovations in the common Octopus, and 

 Aristotle's explanation is correct, as the stomachs oHhe MurcencB are found 

 filled with fragments of the arms. " Ego vero," says the excellent Belon, 

 " cum apud Epidaurum semel Muraenas secarem, earum ventriculos cirrhis 

 polyporum refertos comperi." (P. Bellonii de Aquatilibus, libri duo. Paris, 

 1563, p. 331.) 



