270 THE CEPHALOPODA. $$ 231, 232. 
ADDITIONAL BIBLIOGRAPHY. 
Reinhardt and Prasch. Om Sciadephorus Miilleri en Nudersdgelse. 
Kjobenhavn, 1846, mit 5 Tafeln. 
Prasch. Nogle nye Cephalopoder, beskrevne og anatomisk undersdgte. 
(From the Mem. of the Danish Academy 5th ser. I.) Kjébenhavn, 1847. 
Milne Edwards. Régne animal, éd. illustr. Mollusques, Pl. 1*. 1°. 1. 
44, 1s. 1. (Octopus). — Ep. 
CHAPTER I. 
INTERNAL SKELETON. 
§ 231. 
The Cephalopoda have many cartilages, which, serving as points of inser- 
tion for muscles, and surrounding the nervous centres, may therefore 
be regarded as the rudiments of an internal skeleton. 
Their texture is essentially the same as that of the true cartilages of the 
vertebrata. There is a homogeneous, usually yellowish base, having the 
aspect of ground glass, in which are scattered numerous dark-colored mole- 
cules. This base contains, moreover, the proper cartilage cavities, which 
enclose a mass of granules, and each a more or less distinct nucleus. These 
cavities are more or less numerous, and are often partitioned each into two 
by a thin septum. 
§ 232. 
These rudiments of an internal skeleton may be divided into the 
cephalic, dorsal, articular, branchial, and pinnate cartilages.” 
1. The Cephalic cartilage is concave in front and convex behind. It 
is perforated in the centre by the cesophagus and by two lateral conchoidal 
prolongations. At its upper part there is a deep excavation for the 
reception of the brain; and, at the inferior part, an enlargement containing 
the auditive organs. It is, moreover, traversed by canals of different sizes 
for the passage of nerves. The two lateral prolongations cover, by their 
anterior and concave surface, the ocular bulbs, and are thus the analogues 
of a kind of orbits. With Loligo, and Sepia, there are, beside, two lanceo- 
late, cartilaginous lamellae, which join with the anterior and inferior parts 
of the cartilage, covering the ocular bulb in front, and thus completing the 
orbit. Nautilus differs very much from the other Cephalopoda in this 
respect. The lateral prolongations are wanting, and the body, which is 
incomplete above, is much developed below, and has two prolongations 
extending in front in a forked manner and concealing the auditory 
organs.” 
1 For the different cartilages, see Schultze, in 
XXIX.; and Van Beneden, loc. cit. Pl. I. (Argo- 
Mecket’s deutsch. Arch. IV. p. 334, Taf. IV, fig. 
nauta). 
1, A-G; Spix, Cephalogenesis, p. 33, Taf. V. fig. 
15-17 ; Mecked, Syst. d. vergleich. Anat. IT. Abth. 
1. p. 125; Brandt, Medizin Zool. I. p. 303, Tab. 
XXXIL 3 Owen, Cyclop. Anat. and Phys. I. p. 
524, fig 212, A-D; Wagner, Icon. zoot. Tab. 
2 See Owen, On the Nautilus, p. 16, Pl. VIII. fig. 
1, or Isis. 1835, p. 14, or Ann. d. Sc. Nat. XX VII 
p, 102, Pl. IV. fig. 1, and Valenciennes, loc. cite 
p. 271, Pl. LX. fig. 4-6. 
