§ 233. 271 
2. The Dorsal cartilages are found only with Sepia and Loligo. They 
‘are two in number ; the inferior is situated in the neck, and the superior 
in the mantle at the anterior extremity of the internal shell. The cervical 
cartilage of Loligo is very long, rhomboid, and pretty massive ; while that 
of Sepa consists of a thin, semilunar plate, with the cavity directed back- 
wards. In both genera, its median line has a longitudinal groove; and in 
both also, the superior cartilage is only a thin semi-lunar lamella, both 
extremities of which are extended backwards by a long prolongation. 
3. Those are called Articular cartilages, which, with Argonauta, and 
the Loligina, are found on each side of the base of the funnel, in the form 
of long cupels whose cavities receive, when the mantle is closed, the two 
cartilaginous prominences of its (the mantle’s) internal surface. 
4. The Brachial cartilage is found only with Sepia. It is a narrow 
plate, transversely situated directly in front of the superior border of the 
cephalic cartilage. It has, anteriorly, three short apophyses for the support 
of the base of the arms. With the Loligina, there is found in the mantle, 
at the base of the lateral fins of the body, two other narrow lamellae, — 
the Fin-cartilages; these serve as points of insertion of the muscles of the 
fins, and extend more or less along the sides of the body, taking the form 
of the fins. 
THE CEPHALOPODA. 
CHAPTER II. 
CUTANEOUS ENVELOPE. 
§ 233. 
The Cephalopoda are distinguished from the other Mollusca by a wholly 
peculiar structure of their skin. The skin is easily detached from the sub- 
jacent muscular layer, to which it is united by a loose cellular tissue, the 
fibres of which are interlaced in every direction, The extremely thin 
epithelium of the skin is lamellated, but never ciliated, with the adult indi- 
viduals. The Corium is composed of a contractile fibrous tissue, in the 
meshes of which are contained the remarkable contractile Chromatophoric 
cells.” These consist of flattened, contractile cavities surrounded by a very 
8 See the figures of Férussac, loc. cit. (Sepia, 
Sepiola, and Argonauta). With Argonauta, the 
Cyclop. &c. fig. 212, D. D.), but very short with 
Sepiola. é 
tivo projections of the mantle are round tubercles, 
while with Loligo, Onychoteuthis, and Sepiola, 
they are two very long longitudinal ridges, to 
which corresponds a groove-like excavation in the 
two oppositely situated cartilages of the funnel. 
By means of these articular cartilages, together 
with the two dorsal, when present, the collar-like 
border of the mantle is exactly fitted about the neck 
of the Cephalopoda. 
4 The cartilages of the fins are very long with 
Sepia (Schultze, loc. cit. fig. C. D., and Owen, 
* [ § 233, note 1.] Ihave made some careful ob- 
servations with the microscope upon the chromatic 
1 For the chromatic cells, see San Giovanni, in 
the Giornale enciclopedico di Napoli Ann. XIIL 
No. 9, or Froriep’s Not. V. 1823, p. 215, or Ann. 
d. Sc. Nat. XVI. 1829, p. 308; Frenage, Observ. 
sur la mohilité des taches que ’on remarque sur la 
peau des Calmars, &c., Paris, 1823 ; Delle Chiaje, 
Memor. &c.-IV. 1829, p. 63, and Descriz. I. 1841, 
p. 14; Wagner, Isis, 1833, p. 159, in Wiegmann’s 
Arch. 1841, I. p. 35, and Icon. zoot. Tab. XXIX. 
fig. 8-13, and Harless, in Wiegmann’s Arch. 
1846, I. p. 34, Taf. I.* 
my subject the common Squid (Logligo illicebrosa). 
My results differ somewhat from those of Harless 
relations of the skin »f the Cephalopoda, for 
abi d. I found only one kind of pig- 
