$ 235. THE CEPHALOPODA. 253 
covered by its anterior border.® The sea-water, which enters into the inte- 
rior of the mantle, passes, with its various contents, into this funnel, and is 
thence expelled through its anterior orifice. 
Many Cephalopoda have, on the dorsal wall of this organ directly behind 
the anterior orifice, a tongue-shaped valve, which prevents the reflux of the 
water.” 
With the Loligina, the sides of the trunk have variously-shaped cutaneous 
lobes, which these animals use as fins. The Octopoda, on the other hand, 
swim by rowing with their arms, which are bound together at their base by 
a kind of natatory membrane, whose extremities have, each, a broader or 
narrower cutaneous dilatation.” 
§ 235. 
The mantle of many of the Cephalopoda secretes a shell, which may 
be either external or internal. 
1. An external shell is found with Argonauta and the Nautilina. That 
of the Paper-Nautilus is very thin and flexible, — and, in its composition, 
the organic base predominates above the calcareous matter, which consists 
of thickly-set, small, round masses. The substance of the shell, which, with 
Argonauta, is nowhere attached to the animal it encloses, is secreted prin- 
cipally by the two large cutaneous lobes of the two median dorsal arms, 
which lie upon the external surface of the shell. On this account, the 
structure of the two surfaces of these lobes is different ; — the external sur- 
face is quite smooth and has many chromatic cells; while the internal has 
searce any of these last, but is covered with numerous reticulated, project- 
ing lines, which become the more prominent when the lobes are contracted, 
and between which, cell-like depressions are formed.” 
With the Nautilina, the shell has a very complicated structure ; its walls 
are composed of two distinct layers, clearly separate, the internal of which 
has a beautiful mother-of-pearl aspect. The cavity of the shell is divided, 
even to the last spiral turns, by numerous transverse septa, which are all 
perforated. With Nautilus,” a tube traverses the septa, while with 
1 With Nautilus, the funnel is composed of two 
pretty large, cutaneous lobes, placed upon both sides 
of the throat, and reciprocally covering each other 
on the ventral surface in a cornet-like manner 5 
see Owen, Un the Nautilus, p. 10, Pl. I. or Isis. p. 
10, or Ann. d. Sc. Nat. loc. cit. p. 93, Pl. I. ILL. 
and Valenciennes loc. cit. p. 263, Pl. X. fig. 1. 
2 This is so with Sepia, Sepiola, Loligo, Se- 
pioteuthis, Onychoteuthis, and Nautilus. For 
this last, see Owen, loc. cit. Pl. I. fig. 2, e., and 
Valenciennes, loc. cit. Pl. XI. fig. 4, 2. I have 
sought for it in vain with Argonauta, Eledone, 
and T'remoctopus. It is also wanting with Loli- 
gopsis and Cranchia ; with Octopus, there exists 
in its place, that is, on the ventral surlace of the 
funnel, a transverse ridge. 
& With Sepia, and Sepioteuthis, both sides of 
the body are bordered their entire length with a 
cutaneous lobe. With Loligo, and Onychoteuthis, 
the two fins are triangular and inserted on the 
posterior extremity of the body ; they are round 
and short with Sepiola, Loligopsis, and Cranch- 
ia; in the first of these genera, they are situated 
on the middle of the sides of the body, and in the 
last two, upon its extremity. 
4 These interbranchial natatory membranes ex- 
ist with Octopus, Eledone, and Tremoctopus ; 
* they are particularly developed in this last genus, 
between the two pairs of dorsal arms. 
In this same genus, as also with Argonauta, the 
two dorsal arms are terminated by a very large 
cutaneous lobe, and are used not only as locomo- 
tive organs, but also for keeping the shell ia place 
by being applied on its external surface; see F'é- 
russac, loc. cit. Argonauta, PI. L. fig. 5, 6, Pl. VI. 
fig. 2, and in the Mem. de la Soc. d’Hist. Nat. de 
Paris, II. 1825, p. 160, Pl. VI. fig. 2, or Isis, 1832, 
p. 460, ‘Taf. V. fig. 2; Rang, Docum. pour servir 
a PHist. nat. des Cephalopodes, in the Magaz. 
de Zool. 1837, Livr. IV. p. 19, Pl. LXXXV1.— 
LXXXVIIL., or Ann. d. Sc. Nat, VIL. 1837, p. 
176 ; and Delle Chiaje, Descriz. loc. cit. Tav. VIL. 
i ds 2s 
1 It has been attested by several observers, that 
these two cutaneous lobes furnish the substance of 
the shell, and that, also, with which the animal re- 
pairs accidental lesions; see Rang, Mayaz. de 
Zool. loc. cit.; Jeanette Power, in the Atti dell’ 
Acad. di Scienz. Nat. di Catania, XII. 1839. 
or Isis. 1845 p. 606, or in Wiegmann’s Arch. 
1845, I. p. 369 ; and, Further experiments and ob- 
serv. on the Argonauta Argo, in the Reports of 
the Brit. Assoc. 1844, Notices and Communic. p. 
74. For the non-parasitism of the animal, see, 
moreover, Van Beneden, hoc. cit. p. 4, and F’érus- 
sac, loc. cit. p. 114. 
2 De Blainville, in the Nouv. Ann.du Museum 
@Hist. Nat. III. 1834, p. 3, Pl. I. I. 
