282 THE CEPHALOPODA. § 247. 
The auditory organs of Nawtilus are somewhat different. They are 
widely separated from each other, and situated in the prolongations of the 
cephalic cartilage which extend in front; they consist of a very long, nar- 
row labyrinthian cavity containing a homogeneous, thick liquid without 
otolites.© 
§ 247. : 
The Eyes of the Cephalopoda are very highly developed and dispro- 
portionately large.” Although resembling very much those of the Verte- 
brata, yet they differ from them in many respects.” With the Octopoda, 
and Loligina, each eye has an ocular Bulb and a Capsule. 
The capsule is formed by the cartilaginous orbit, and by a fibrous mem- 
brane attached to the borders of this last, and is blended externally with 
the cutaneous envelope. This envelope, in the form of a circular swelling, 
covers the eye, and, being thin and transparent, takes the place of a Cornea, 
—a part which, properly, does not exist with the Cephalopoda. 
The circular swelling often has, above and below, a semilunar fold of 
skin containing muscular fibres, which, upon contraction, cover the con- 
vexity of the eye like an upper and under lid. The ocular bulb, contained 
in this capsule, is round and a little flattened in front; and, as it is not ad- 
herent to its capsule in front nor upon the sides, there is a free space, 
which, from the absence of a cornea, would coincide with the anterior 
chamber of the eye.” In most cases, this space contains a transparent 
liquid, and is lined by a serous membrane covering not only the posterior 
surface of the anterior part of the capsule, but also the anterior surface of 
the bulb. It is remarkable that this same space, which contains in part 
the anterior chamber, communicates, externally, by a circular orifice which, 
with the Octopoda, is covered by the upper lid, and with the Loligina, is 
situated upon the anterior border of the cutaneous fold which takes the 
place of the cornea. Internally, this space can be closed by a kind of fold 
disc, concave on one side, and very convex and 
sometimes even conical, on the other Scarpa, loc. 
cit. Tab. IV..fig. 9, and Weber, De Aure et Audi- 
tu, p. 11, Tab. Il. fig, 8, (Octopus); also Delle 
Chiaje, Memor. Tay. LVIIL., and Descriz. &c. Tav. 
XII. fig. 15, 19, 23, 24, (Octopus and Eledone). 
With Octopus, they have a crystalline structure 3 
but with Eledone, where they are very flat and 
_ colored brown on one of their surfaces, they con- 
sist of a soft limeless substance, — often rendering 
in vain the search for themin specimens long pre- 
served in alcohol. 
The irregular otolites of the Loligina, which ap- 
pear bristling with points and serratures (Scarpa, 
loc. cit. Tab. LV. fig. 8, and Delle Chiaje, loc. 
cit. Tav. LVIII. (12) fig. 18, 14, 16, 25, 26, (Se- 
pia and Loligo),), have the aspect, under the mi 
croscope, of an aggregation of very fine, acute 
prisms, the points of which turn inwards (Carus, 
Lehrb. d. vergleich Zoot. I. p. 358). 
5 See Valenciennes, loc. cit. p. 291, Pl. VIII. 
fig. 2, No. 3, and Pl. IX. fig. 4,5, «. He has 
seen it supplied with nerves coming directly from 
the brain. Owen (Qn the Cephalop. with cham- 
bered shells, p. 10) took them for venous sinuses, 
and could not admit that they were auditive or- 
gans, since they contained no otolites. But it 
might be argued that these otolites are limeless like 
those of E/edone, and may, therefore, dissolve and 
entirely disappear after death. 
1 The largest eyes are found with the Loligina ; 
the smallest with the Octopoda. 
2 For the structure of the eyes of Cephalopoda, 
see, beside Cuvier, Mém. p. 37, Pl. II. fig. 5, and Pl. 
III, fig. 7, and Owen, Cyclop. I. p. 551, fig. 234, 
—Massalien, Descript. oculorum Scombri Thynni 
and Sepiz, Diss. Berol, 1815, p. 10; Soemmer- 
ring, De Oculorum hominis animaliumque sectione 
horizontali, p. 76, Tab. III.; De Blainville, Princ. 
d’Anat. comp. p. 441; Mayer, Analekt. f. vergleich. 
Anat. Hft. I. p.52; Krohn, Nov. Act. Acad. Leop. 
Carol. XVII. Pt. I. p. 339, Tab. XXVI., and XIX. 
Pt. IL. p. 43; Wharton Jones, Lond. and Edinb. 
Philos. Mag. 1836, Jan’y, or Froriep’s Notiz. 
XLVIII. p. 2, fig. 1-3; Delle Chiaje, Descriz. 
&c. I. p. 70, Tay. XIX. and XXIX. alse Osservaz. 
Anatom. su locchio umano 1838, Tav. IX. fig. 1- 
11; Valentin’s ideal section of an eye of a Cepha- 
lopod, in Wagner’s Icon. zoot. Tab. XXIX. fig. 
42; and John Power, Dublin Jour. of Med. Sci- 
ence, XXII. 1843, p. 350. 
8 Krohn, Valentin, and others, admit the exist- 
ence of a particular horny substance situated be- 
tween the cutaneous layers of the anterior part of 
the ocular capsule. 
4 Treviranus (Vermischte Schrift. III. p. 1545 
says he has observed a thin, transparent, but solid 
membrane, placed directly in front of the lens, and 
continuous with the conjunctiva (Argentea), thus 
forming a completely-closed anterior chamber ; but 
this statement requires confirmation, 
