4 246. 



THE CEPHALOPODA. 



281 



With Nautilus, the two olfactory papillae are situated, directly beneath 

 the eyes, in a cavity which is surmounted by a wart-like swelling. <-' With 

 the Octopoda, the olfactory organs are concealed, behind the eyes, in the an- 

 ^le of insertion of the mouth upon the occiput. With Argonauta, and 

 Tre7)ioctopus, they consist of two naked papillae ; and with Octopus, and 

 Elcdone, of two menibi-anous cavities.'"* 



With the Loligina, these organs are situated behind and a little below 

 the eyes, and consist of fossae having narrow apertures ; but they are easily 

 seen from the elongated or round cutaneous swelling with which they are 

 surrounded.'^' 



§ 246. 



The Auditory organs of the Cephalopoda are situated in the lower mid- 

 dle portion of the cephalic cartilage, where they form two more or less 

 large, round cavities, separated by a cartilaginous septum, and without 

 any external communication.'^* With the Octopoda, the internal walls of 

 these cavities are smooth ;'-* but with the Loligina they have many tuber- 

 cles or papillae, which are sometimes quite prominent.^" This portion of 

 these organs may best be compared to the osseous Labyrinthus of the Verte- 

 brata. These cavities are filled with a liquid substance, and contain, also, 

 each, a small pyriform sac — membranous labyrinth — adhering to the car- 

 tilaginous labyrinth at the point where the auditory nerve enters it, and 

 upon which this nerve is spread out. This sac contains a single, white, 

 irregular otolite of a crystalline texture.''*' 



2 Valenciennes Ooc cit. p. 290, PI. VTII. fig. 

 •2, h. PI. IX. fig. 1, h. X., and fig. 3) in 1841, 

 and consequently before KiiUiker, described these 

 organs as olfactory with Nautilus. He found not 

 only the nerve which goes to the olfactory papilla, 

 but also an orifice at the base of this last, leading 

 into a cavity lined with a mucous membrane which 

 Jiad two regular rows of folds. Owen (On the Ceph- 

 alopods with chambered shells, p. 11) has regarded 

 these papillae, which he appears to have complete- 

 ly overlooked in his earlier memoir, as short hol- 

 low tentacles. On the other hand, he regards as 

 the olfactory organs a row of twenty membranous 

 lamellae arranged longitudinally at the entrance of 

 the mouth between the two internal labial prolon- 

 gations (On the Nautilus, p. 41, PI. IV. 1., PI. 

 VII. fig. 1, g. fig. 2, or Isis, p. 34, Taf. III. IV., 

 or Ann. d. Sc. Nat. p. 141, PI. II. fig. 1, 1., PI. III. 

 fig. 4, g. fig. 6); but it would appear to me that 

 these lamellae are tactile lobules, for they receive 

 numerous nerve-filaments from the ganglia of the 

 nerves of the internal labial prolongations {Owen, 

 loc. cit.). 



3 With Argonauta, and Tremoctopus, these ol- 

 factory nerves have a ganglion lying on the optic 

 nerve {KöUiker, Entwickel. d. Ceph. p. 168); this 

 was seen by Van Beneden (loc. cit. p. 13, PI. I. 

 fig. 5, 6, k.), but not explained. The olfactory 

 cavities of Octopus did not, indeed, escape the no- 

 tice of Rapp (Naturwiss. Abhandl., von einer Ge- 

 sellsch. in Wurtemberg, 1826, p. 69), and of Delle 

 Chiaje (Descriz. &c. Tav. VI. fig. 1. k. and Tav. 

 XVIII. fig. 1, y), but they did not in the least sus- 

 pect their nature. 



4 According to Owen's account accompanied 

 with a figure (On the Nautilus, pi. VII. fig. 3, No. 9, 

 or Isis, 1835, Taf. IV., or Ann. d. Sc. Nat. XXVIII. 

 PI. III. fig. 5, No. 9, and Cyclop. I. p. 549, fig. 

 232, k), the olfactory nerves of Sepia and Loligo 

 appear to arise from a special ganglion situated 



near the Ganglion opticum. The entrance, witK 

 its tumid borders, of the olfactory cavities, has 

 often been figured with the Loligina, by Ferussac 

 (loc. cit. Sepia, PI. XVII. fig. 2. c. PI. XVIII. fig. 

 3, b. PI. XXVII. fig. 1, 6 ; Loliso, PI. XX. fig. 

 7, PI. XXIII. fig. 5, 17, PI. XXIV. fig. 2, 14 ; 

 Sepioteuthis, PI. VI. fig. 2, b.; Sepiola, PI. III. 

 fig. 5, 15 b.). 



1 It has already been seen (§ 245) that the olfac- 

 tory organs of the Loligina have been taken by 

 some naturalists for an external ear. 



A very remarkable organ — a flexuous canal 

 lined with ciliated epithelium, has been seen by 

 Kollikcr (Entwick. d. Ceph. p. 105, fig. 60-63), 

 but, only with the embryos of Sepia and Loligo; 

 departing from the auditive vesicles, it ran in 

 front without opening either upon the surface of 

 the body, or into the oesophagus, so that it could 

 have been neither an external auditory duct, nor a 

 Tuba Eustachii. 



2 See Scarpa, Anat. disquis. de auditu et olfac- 

 tu, p. 3, Tab. IV. fig. l\(Octopus); Delle Chiaje, 

 Descriz. &c. Tav. XIV. fig. 1, d.; and Van Bene- 

 den, loc. cit. PI. I. fig. 3 {Argonauta). 



3 See Brandt, Mediz.Zool. p. 309, Taf. XXXIL 

 fig. 14 ; Wagner, Icon. zoot. Tab. X.KI.X. fig. 37- 

 39 ; Owen, Cyclop. I. p 554, fig. 235, and Trans- 

 act, of the Zool. Soc. II. PI. X.\:i. fig. 17 ; and 

 Delle Chiaje, Descriz. &c. I. p. 68, Tav. XII. fig. 

 12, 21 {Sepia and Loligo). This last-mentioned 

 author has compared some of these cartilaginous 

 prominences to the Ossicula of the ear ; but to me 

 they appear to represent rather the first traces of 

 semicircular canals, which, with the embryos of 

 fishes, appear to consist, likewise, of simple prom- 

 inences on the internal surface of the auditive vesi- 

 cle. 



4 These otolites are composed mostly of carbon- 

 ate of lime, and vary considerably in their forms. 

 With the Octopoda, they resemble, more or less, a 



