278 



THE CEPHALOPODA. 



^241. 



»back of the mantle.''^ With Sepia, this inferior portion has several swell- 

 ings ; from the two anterior of these, which are the largest, arise the nerves 

 of the arms ; while the two lateral posterior send oflf the two optic nerves.'^' 

 With Nautilus, this same portion is divided into an anterior and a pos- 

 terior transverse band, ^"' which maybe compared, to a certain extent, to 

 the semi-circle of ganglia upon the inferior surface of the oesophagus with, 

 certain Gasteropoda. 



§ 241. 



Among the Peripheric nerves, those of the arms and mantle should b& 

 specially mentioned. 



The Brachial nerves enter into the axial canals of the arms at the base of 

 these last, and extend even to their extremity after intercommunicating, each, 

 by a transverse anastomosis with the two neighboring nerves.'^* In their 

 course through this canal, they give off numerous filaments to the muscular 

 substance of the arms and to the suckers. With the Octopoda, these nerves 

 are composed of two parallel cords, each one of which has, alternately right 

 and left, ganglionic enlargements.^^* 



The two Pallial nerves, which are easily seen from their size, pass, at 

 first, between the cervical muscles, and, having reached the internal sur- 

 face of the back of the mantle, terminate in two very large ganglia {Gan- 

 glion stellatuvi) from the external border of which pass off numerous nerv- 

 ous filaments, which enter, ray-like, the fleshy portion of the mantle.® With 

 those Loligina, which have fins, the pallial nerves, before terminating in 

 the star-like ganglia, send off a large branch, which, at a short distance from 

 its origin, is joined by another large branch from the pallial ganglion, and 

 is then distributed to the muscles of the fin.'^* With the long-bodied spe- 

 cies of this family, this nerve pursues a long course by the side of the me- 



1 The nervous system of the Cephalopoda has 

 been carefully described by Cuvier, Mem. p. 34, 

 PI. I. fig. 4 (Octopus); Brandt, Mediz. Zool. p. 

 308, Taf. XXXII. fig. 23 (Sepia); Owen, and Fa- 

 lenciennex, loc. cit. (Nautilus) ; aud by Kara Be- 

 neden, loc. cit. (Argonauta) ; see, moreover, the 

 figures given by Owen, of that of Sepia (On the 

 Nautilus, PI. VII. fig. 3, or Isis, 1835, Taf. IV. 7, 

 fig. 3, or in the Ann. d. Sc. Nat. XXVIII. PI. III. 

 fig. 5, and Cyclop. I. p. 549, fig. 23'2), and those of 

 Loligo, Sepia, and Octopus, in Delle Chiaje, 

 Memor. &c. Tav. XCV. C.-CH., and Descriz. Tav. 

 XXV. XXIX.-XXXI.* 



2 Brandt, loc. cit. 



3 Owen, On the Nautilus, p. 36, PI. VII. fig. 1, 

 or, Isis, 1835, p. 30, Taf. IV. 7, fig. 1, or, Ann. d. 

 Sc. Nat. XXVIII. p. 134, PI. III. fig. 4, and Va- 

 lenciennes, loc. cit. p. 287, PI. VIII. fig. %A. 



1 Cuvier, M^m. p. 36, PI. I. fig. 4, (Octopus); 

 Delle Chiaje, loc. cit. Tav. CII. (29), C. (31), (Oc- 

 topus and Sepia) ; Firussac, loc. cit. Pi. P, fig. 

 1, and Van Beneden, loc. cit. p. 15, PI. II. fig. 2, 

 and PI. IV. (Argonauta).\ 



*[§ 240, note 1.] See especially the excellent 

 illustrations of Milne Edwards, R^gne anim, loc. 

 cit. PI. I*". See, for a very detailed description 

 of this system with Ommastrephes, Hancock 

 (Ann. Nat. llist. X. 1852, p. 1), who has sought to 



2 Van Beneden, loc. cit. p. 14, PI. II. fig. 3-5, 

 PI. III. fig. 4, and PI. IV. (Argonauta). I have 

 found the same organization with Octopus, and 

 Tremoctopits. In this last genus, the ganglia 

 may, from their reddish color, be very clearly sepa- 

 rated from the white nervous substance. Both the 

 smooth and the nodulated cords send off nerve-fila- 

 ments, but with the last, they arise exclusively from 

 the ganglionic swellings. 



I have been unable to decide if the smooth cords 

 send off filaments only to the muscles, and the nod- 

 ulated ones to the suckers ; or if the first contain 

 only motory fibres, and the second sensitive fibres. 

 I should add that in the axis of Hectocotylus 

 tremoctopodis I have also found a highly-devel- 

 0])ed, nodulated trunk, the number of swellings of 

 which corresponded with that of the suckers. 



3 See the figures of Van Beneden, Delle Chi- 

 aje, Brandt, loc. cit., and of Owen, in the Cyclop. 

 I. tig. 232 (Argonauta, Octopus, Loligo, and 

 Sepia). 



4 See the figures of Delle Chiaje, and Owen, 

 loc. cit. (Lotigo and Sepia). 



point out the homologies of the Cephalopoda with 

 the Mollusca. — Ed. 



t [ § 241, note 1.] See also the lUustrationB of 

 Milne Edwards, K^gne animal, loc. cit. PI. I. fig. 

 3, f. f. (Argonauta). — Ed. 



