102 BRITISH SERPENTS. 
shown on pp. 101, 103.) The gullet is shown dis- 
tended with an ordinary blowpipe, and then hgatured 
at the entrance, and again below the stomach end. 
Incidentally the illustration shows the double row of 
seales on the under surface of the tail and the shape of 
tailina male. The next dissection (p. 105) shows them 
even better, and it is distinct enough to count them. 
Heart and liver.—The heart is found to he just 
about the junction of the gullet with the stomach. It 
is three-quarters of an inch in length and half an 
inch thick. Immediately behind it is the liver, the 
thick end of which hes in contact with the apex of the 
heart, and the rest of the liver tapers away down the 
abdominal cavity for 5 inches or so. The respective 
positions of the two organs are seen in fig. 27. The 
ophidian heart is three-chambered, consisting of a 
right and left auricle and a single ventricle. The 
partition in the ventricle being incomplete, the cir- 
culation is necessarily an imperfect one, as far as 
keeping the pure from the impure blood is concerned. 
The heart does its best to drive the pure blood to one 
aortic arch and the impure to the lung for aeration, 
the mixed blood going into the left aortic arch. Snakes 
are, of course, cold-blooded, 
The liver is a large one, and prodaces a powerful 
secretion for digestion. There is a gall-bladder, and 
also a pancreas. 
The dissection on p. 107 shows the heart, lung (dis- 
tended with a blowpipe), and liver separated from the 
