ELEDONE. 508 
is quite near this point (figs. 17 and 18). In size the 
stomach is rather less than the crop, and lke the 
oesophagus is lined by an easily detachable layer of chitin. 
This lining is specially thick where 1t covers the grinding 
pads (figs. 18 and 19, ch,, pad.). Where it covers the 
posterior wall of the stomach, however, it is smooth and 
thin. At the exit of the spiral caecum and intestine the 
euticle ends, thus leaving a circular orifice through which 
food passes onwards from the stomach (PI. V, fig. 38, or.). 
The food is ground in the stomach, and also well mixed 
up with the digestive fluid which enters from the spiral 
caecum (Bourquelot), so that here digestion takes place. 
Spiral Caecum.— A narrow passage leading out from 
the stomach, soon bifurcates, and so gives rise to the spiral 
caecum on the one hand and the intestine on the other 
(Pl. V, fig. 38, Int. ap.). 
The spiral caecum is in reality a long narrow sac, 
e.g., caecum in Loligo, which in the Octopodidae and 
others becomes curled in a spiral of one and a half turns. 
It is thin walled, and the internal septa are seen faintly 
from outside (PI. LV, fig. 28). The columella of the spiral 
is on the side opposite to the intestine (fig. 38). On 
cutting open the caecum along the columellar edge, and 
pinning it out, it will be seen that there is a series of 
delicate folded valves, running transversely to its length 
(fig. 38, v., v,). Cuvier described a spiral valve running 
down the caecum in Octopus, but in Eledone there is a 
series of short transverse valves instead, closely set. They 
are widest centrally, and taper at their two ends, which 
are attached to the columellar region of the wall. Along 
this columellar region also runs a longitudinal fold, at 
the side of which enters the common hepatic duct, some 
distance from the anterior end of the caecum (fig. 38, 
h.ap.). Probably this fold guides the digestive secretion 
