290 



THE CEPHALOPODA. 



^253. 



CHAPTER VIII. 



RESPIKATORY ORGANS. 



§ 253. 



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

 ated in the cavity of the mantle, separated from the other viscei'a, 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.*^' Nautilushas, 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 mantlfe 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 I have found such with Hextocotylus trenioc- 

 topodis ; according to Äö/ttAer (loc. cit.) that of 

 Argonauta has also brancliiae. 



2 This ^'landular body has been regarded by 

 Cwmcr (Mem. p. 20, PI. II. tig. 3, PI. 111. fig. 1, 

 A.) and otlier zootomists as a muscular stripe; 

 while Mayer (Analekten, &c., p. 56, Taf. V. fig. 

 1, No. 14), from its cellulo-vascular te.xture, has 

 taken it for a sjjleen. I liave been unable to find in 

 it any muscular fibres, but oidy numerous cells, and 

 I am of the ojiinion that this enigmatical organ 

 holds some special relations with the venous system. 



3 See Owen, On the Nautilus, p. 30, PI. VI. fig. 



I, 2, or lais, p. 26, Taf. IV., or Ann. d. Sc. Nat. p. 

 124, PI. 111. fig. 2, 3, and yalencie?ines, loc. cit. 

 p. 281, PI. IX. X. i The Catalog, of the Physiol. 

 Ser. II. PI. XXI. XXII. (liepia) ; Treviranim, 

 Beobacht. aus. d. Zoot. u. Physiol, p. 37, Taf. VIU. 

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



II. XI. (Loliaoimis and Sepiota) ; Cuvier, Mem. 

 V. 20, PI. II. 111.; VeUe Chiaje, Descriz. Tav. 



\1X. tig. 1-b {Octopus); and Firussac, loc. cit. 



i The number of the branchial lamellae and 

 arches varies very much. With Nautilus, each 

 branchia is composed of a double row of forty-eight 

 lamellae ; the long-bodied Loliginu have a double 

 row also, composed of si.\ty to ninety lamellae. 

 With Sepia, tliere are thirty pairs ; and with the 

 Octopoda, the number of branchial arches is still 

 less ; there are only fifteen pairs witli Argonauta, 

 and twelve alone with Octopus, and Eledone. 



5 For the distribution of the blood-vessels ni the 

 branchiae of Sepia, see Ttlesius, Be Respirat. Se- 

 piae officinalis. Tab. I. II. 



fi That, with the Cephalopoda, which are In gen- 

 eral so poor in cilia, tliere should be no ciliated 

 epithelium on the branchiae, is so remarkable a 

 fact, that I have had it confirmed from fresh speci- 

 mens by my friend M. hoch at Trieste, although 

 Sharpey (Cyclop. I. p. 619) had already spoken of 

 it. 



" For these respiratory movements, see Grav- 

 enhorst, Tergeslina, p. 1, and fVagner, in tho 

 Isis, 1833, p. 159. 



