ELEDONE. 598 
enclosed in their common envelope, lie wholly outside and 
ventral to the sinus (fig. 53, S,V.). The anterior aorta 
penetrates into the latter at the anterior end of the 
stomach, and runs therein, leaving it only after its 
anterior bifurcation. Several small infoldings of skin 
attach the stomach to the wall of the sinus, forming small 
mesenteries (fig. 53, J/es.). The two abdominal veins 
running from this cavity to the venae cavae, leave it 
dorsally, one at each side, towards the anterior end of 
the stomach (fig. 53, Abd.V.). Thus the blood from the 
sinus is drained off by these, and passes direct to the 
lateral venae cavae, and thence to the gills. 
3. ‘The posterior division contains the spiral caecum, 
which is attached to its wall by several small mesenteries. 
The anterior wall of this region is common to it and the 
middle division, but forms only an incomplete septum, 
allowing free passage of blood, as it is pierced dorsally and 
ventrally by a row of rather large holes (ffy. 53, Lac.). 
The intestine soon after its origin pierces the wall of the 
middle region, and then bending up over the ventral 
surface of the liver, lies wholly outside the sinus (fig. 53). 
The two hepatic ducts pierce the wall of the posterior 
region, and uniting inside this part of the sinus, enter the 
spiral caecum. Into the adjacent portions of the venous 
sinus open small veins from the buccal region, lips, 
surface of the brain, and the different organs of the 
alimentary canal which float freely in the sinus. 
RESPIRATORY SYSTEM. 
(1) Respiration. 
The respiration of Eledone appears to agitate the 
whole of the trunk. Water enters the mantle cavity by the 
anterior opening during the period of inspiration, when 
the sides of the body may be seen to swell outwards. At 
