290 THE CEPHALOPODA. ^ 253. 



CHAPTER VIII. 



RESPIRATORY ORGANS. 



§ 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.'^' Nautihtshns, on each side, two 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, 

 g, 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.'^' 



i li\a.ve foxintlsach wilh Hectocotylus tremoc- 4 The number of the branchial lamellae and 



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



Argonauta lias also brancliiae. branchia is composed of a dou!)le row of forty-eight 



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

 Cuvier (Mem. p. 20, PI. II. fig. 3, PI. III. fig. 1, row also, composed of si.xty to ninety lamellae. 

 A.) and other zootomista as a muscular stripe; With Se/)ia, there are thirty pairs ; and with the 

 while Mayer (Analekten, &c., p. 5(5, Taf. V. fig. Octopoda, the number of branchial arches is still 

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

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

 ijiany musculai- 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 Hepia, see Tilesius, De Respirat. Se- 

 holds some special relations with the venous system, piae officinalis, Tab. I. II. 



3 See Otocn, On the Nautilus, p. 30, PI. VI. fig. fi 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- 

 Ser. II. PI. XXI. XXII. (He.pia) ; Treviranus, mens by my friend H. Koch at Trieste, although 

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

 fig. 52-54 -, Grant, Transact, of theZool. Soc. I. PI. it. 



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

 p. 20, PI. II. III.; Delle Chiaje, Descriz. Tav. enkorst, Tergestina, p. 1, and fVagner, in the 

 XIX. fig. 1-5 {Octopus); and Firussac, loc. cil. Isis, 1S33, p. 159. 



