290 THE CEPHALOPODA. "§. 253. 



CHAPTER VIII, 



RESPIRATORY OKGANS. 



§ 253. 



All the Cephalopoda respire by means of Branchiae. These are situ- 

 ated in the cavity of the mantle, separated from the other viscera, and out- 

 side of the peritoneum. Hectocotylus forms the only exception in this 

 respect, — its branchiae being free, and placed along the sides of the ante- 

 rior half of the body under the form of numerous oblong, thin, thickly- 

 set lamellae.*^* Nautihis has, on each side, tvro branchiae, while the other 

 Cephalopoda have only one. 



These organs have a more or less oblong, pyramidal form, and are 

 attached, at one of their borders, to the external surface of the mantle by 

 a thin cutaneous fold, — leaving their extremity to extend freely in front. 

 The adherent edge is bordered by the trunk of the branchial artery, and by 

 a large glandular band,'-' while the free border is occupied, from its base 

 to the top, by the principal branchial vein. With Nautilus, and the Loli- 

 gina, there are, between these vessels, numerous, triangular, branchial lam- 

 ellae lying upon each other, and plicated upon both surfaces. But with 

 the Octopoda, these lamellae are replaced by arches, which, on each side, 

 pass from one vascular trunk to another, and have, upon their convex edge, 

 a multi-plicated membranous band.*'" The branchial vessels extend from 

 the branchial artery to the branchial vein through the lamellae and the 

 branchial arches;'*' and in this passage, the venous is changed to arterial 

 blood. '^' As there is no ciliated epithelium on the surface of the branch- 

 iae, the water is renewed exclusively by the rhythmical respiratory move- 

 ments.'®' It enters, from both sides of the funnel, into the interior of the 

 mantle when its borders are open, and is ejected through the funnel by the 

 contractions of the mantle when its borders are closed. "^^ 



1 Ihuve foandsach with Hectocoti/lus tremoc- 4 The number of the branchial lamellae and 

 topodis ; according to KoUiker (loc. cit.) that of arches varies very much. With Nautilus, each 

 Argonauta has also branchiae. bi'anchia is composed of a doul)le row of forty-eight 



2 This glandular body has been regarded by lamellae ; the long-bodied Loligina have a double 

 Cuvie.r (Mem. p. 20, PI. II. fig. 3, PI. III. fig. 1, row also, composed of sixty to ninety lamellae. 

 A.) and other zootomists as a muscular stripe; With Sepia, there are thirty pairs ; and with the 

 while Mayer (Analekten, &c., p. 56, Taf. V. fig. Octopoda, the number of branchial arches is still 

 1, No. 14), from its cellulo-vascular te.xture, has less ; there are only fifteen pairs with Argonauta, 

 taken it for a sijleen. I have been unable to find in and twelve alone with Octopus, and Eledone. 



it any muscular fibres, but only numerous cells, and 5 For the distribution of the blood-vessels in the 



I am of the opinion that this enigmatical organ branchiae of Sepia, see Tilesius, De llespirat. Se- 



holds some special relatiDns with the venous system, piae olBcinalis, Tal). I. II. 



3 See Owen, On the Nautilus, p. 30, PI. VI. fig. •> That, with the Cephalopoda, which are in gen- 



I, 2, or Isis, p. 26, Taf. IV., or Ann. d. Sc. Nat. p. eral so poor in cilia, there should be no ciliated 

 124, PI. III. fig. 2, 3, and Valenciennes, loc. cit. epithelium on the branchiae, is so remarkable a 

 p. 281, PI. IX. X. ; The Catalog, of the Physiol, fact, that I have had it confirmed from fresh speci- 

 8er. II. PI. XXI. XXII. (J^epia) ; Treviranus, mens by my friend /f. A'ocA at Trieste, although 

 Beobacht. aus. d. Zoot. u. Physiol, p. 37, Taf. VIII. Sharpey (Cyclop. I. p. 619) had already spoken of 

 fig. 52-54 ; Grant, Transact, of the Zool. Soc. I. PI. it. 



II. XI. (Loligopsis and Sepioln) ; Cuvier, Miin. " For these respiratory movements, see Grav- 

 p. 20, PI. II. III.; Del/e Vhiaje, Descriz. Tav. enkorst, Tergestina, p. 1, and Ifagner, in the 

 XIX. fig. 1-h {Octopus); and Firussac, loc. cit. Isis, 1833, p. 159. 



