$ 247. THE CEPHALOPOLA. 283 
or Pupil. The serous membrane just mentioned, which is spread over the 
ocular bulb even to the papillary border of the iris, contains a particular 
pigment of a silvery lustre, called the Argentea, and comparable to a Con- 
jJunctiva.© 
With Onychoteuthis, Loligopsis, and allied genera, the anterior wall of 
the ocular capsule is entirely wanting, and as there is also no cornea, the 
crystalline lens is in direct contact with the surrounding medium (the water 
of the sea)... In the first of these genera, the free border of the capsule has, 
in front, a deep fissure corresponding, perhaps, to a lachrymal canal. © 
The Jris is formed from the argentea, which is covered on its posterior 
surface by a black Uvea, while its anterior surface often has chromatic cells. 
The pupil is usually of a transverse, or semilunar, rarely of a circular 
form, and is.capable of being completely closed.” Under the Argentea 
extends a thin cartilaginous tunic — Sclerotica —which, behind, circum- 
scribes the ocular bulb, and, in front, penetrates a certain distance into the 
iris, It furnishes points of insertion for the muscles of the eye, and is crib- 
riform behind for the passage of numerous filaments of the optic nerve. 
The cavity of the bulb is filled with a transparent, watery liquid which 
takes the place of the vitreous body, and is contained in a very thin Hya- 
loidea. 
The Crystalline lens is spherical, and lodged in a deep depression of the 
vitreous body. It is of a brownish color, and its anterior surface projects 
through the pupil, so that the posterior chamber of the eye is only a small 
circular space. As with the Vertebrata, this organ is composed of numer- 
ous concentric layers, but has the remarkable peculiarity of being divisible 
into halves, the anterior of which is less convex than the posterior, but 
both are exactly joined together; the borders of these halves are quite 
bevelled, but are kept in place by the Ciliary body which arises from the 
sclerotica and iris, 
One part of this ciliary body embraces the borders of 
the lens, while the other penetrates between its halves as a thin, transparent 
septum, ® 
5 Zootomists are not agreed upon the interpreta- 
tion to be put on this membrane. Krohn, and 
Owen (loc. cit.), who regard the anterior part of 
the ocular capsule as a cornea covered by a con- 
junctiva, consider the cavity found behind it as a 
large anterior chamber, filled with a Humor aque- 
us. Cuvier, Wharton Jones (loc. cit.), and J. 
Muller (in his Arch. 1836, Jahresb. p. 91), re- 
gard the capsular cavity with its serous membrane, 
as a closed conjunctival sac; so that the transpa~ 
rent convexity of the capsule is not a cornea, but 
a continuous closed eyelid. Moreover, as there 
are often found two rudimentary eyelids in the 
eyes of Cephalopoda (Mayer, Analekt. f. vergleich. 
Anat. Hft. I. p. 52, Taf. LY. fig. 6-11), this trans- 
parent convexity may be regarded as a third lid 
or a nictitating membrane adherent throughout ex- 
cept at the point of the opening. Many anatomists, 
and especially Cuvier, and Owen, have not no- 
ticed this opening of the ocular capsule. But De 
Blainville (Princip. @’Anat. comp. I. p. 444, and 
Dict. d. Sc. Nat, XLVIII. p. 262) mentions it with 
Loligo, Octopus, and Sepia; and Wagner (Ana- 
lekt, &c. p. 53) has described it carefully. 
In the large work of Férussac, it is often fig- 
ured under the name of Orifice lacrymal; see 
oligo, Pl, XX. fig. 7, Pl. IL. fig. 5, a. 17, 
- * (§ 247, note 8.] The microscopic structure of 
this lens corresponds also with that of the Verte- 
brota — that is, composed of delicate tubes or fibres. 
Pl. XXIV. fig. 2, d, 145 and Sepioda, Pl. III. fig. 
5, 15. a, Pl. VI. fig. 2. a, Pl. IV. fig. 10. a. 
6 On account of this singular organization, D’Or- 
bigny (in Férussac, loc. cit. Introduct. p. 15) has 
separated, under the name Oigopsidés, the genera 
mentioned in the text from the other Loligina which 
he calls Myopsidés. The segment of the border of 
the capsule, and which is wanting with Loligopsis, 
is spoken of as a Sinus lacrymalis in Férussac, 
loc. cit. Onychoteuthis, Pl. IIL, fig, 1, Pl. III. tig. 
2, Pi. XII. fig. 4, 18, Pl. XIV. fig. 1; Ommastre- 
phes, Pl. I. fig. 15, Pl. II. fig. 3, 11. 
7 The pupil is not circular except with Onycho- 
teuthis, Ommastrephes, and Loligopsis. 
The upper papillary border, usually convex 
with the other Cephalopoda, is often prolonged as 
a Velum or Operculum pupillare. With Sepia, it 
is often bilobed after death ; see the figures of F'é- 
russac, loc. cit. and Delle Chiaje, Osservaz. anat. 
loc. cit. Tay. IX. fig. 1, 2, 3. . 
8 For the lens and the ciliary body, see Huschke, 
Comment. de pectine in oculo Avium, 1827, p. 9, 
fig. 11, and Delle Chiaje, Descriz. &c. Tav. V. fig. 
18, and Tav. XIX. fig. 6-8. Although Mayer 
(Analekt. loc. cit. p. 54)'declares that this lens has 
a capsule, yet I am undecided on this point, for the 
other anatamists are silent.* 
These fibres however are more than twice as small 
as those of any of the Vertebrata I have examined. 
—Eb. 
