102 BRITISH SERPENTS. 



shown on pp. 101, 103.) The gullet is shown dis- 

 tended with an ordinary blowpipe, and then ligatured 

 at the entrance, and again below the stomach end. 

 Incidentally the illustration shows the double row of 

 scales on the under surface of the tail and the shape of 

 tail in a male. The next dissection (p. 105) shows them 

 even better, and it is distinct enough to count them. 



Heart and liver. — Tbe heart is found to lie 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 lies 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 produces 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 



