392 REPTILIA. 



animal : it is somewhat contorted, passes up before the oesophagus, and 

 soon dilates into a cavity of nearly the same size as the ventricle. 



This enlargement is somewhat grooved, so as to look as if made up of 

 different vessels ; but, on examination, it appeared to be one bag. It 

 terminates in two branches, which are much smaller than the bag from 

 which they arise, and continue diminishing as they pass towards the 

 head : near their origins and posterior surfaces, arise two arteries, one 

 on each side, which are reflected downwards to the lungs, and enter 

 them at their upper end. The two trunks diverge a little from one 

 another, as it were, winding round the oesophagus ; after which each 

 divides into two branches of nearly equal size. These two branches on 

 one side, for instance the left, pass outwards to the gills, and there 

 wind round and between the cartilages of those parts, approaching 

 towards the back ; then, beginning to converge round tbe posterior 

 surface of the oesophagus, they continue their course to the back-bone, 

 where both branches unite into one trunk. The single trunk thus 

 formed, runs down on the same side of the back-bone, attended by a 

 similar trunk on the other side, which has passed through exactly the 

 same course. These two, still converging, having rim a little way 

 down on the opposite sides of the back-bone, and having given off 

 branches to different parts, unite upon that bone into one principal 

 trunk, similar to that of fish, which, from this point, may be called the 

 descending aorta ; this passes down the back, abdomen, and tail, giving 

 in its way vessels to the different parts. 



The inferior vena cava, which collects all the blood from the parts 

 below the heart, is pretty large, and runs through the whole length of 

 the abdomen. At the lower end it lies between the two kidneys ; but, 

 after this, it is very loose, running upon the right of the mesentery, to 

 which it is attached by a thin membrane, as also to the back in the 

 same manner. Being got to the lower end of the liver it enters that 

 viscus, passes on and emerges at the upper end near the heart ; then, 

 after proceeding a little way, it enters the posterior part of the auricle, 

 having first received the vena cava hepatica, and the veins from the 

 head; so that there is but one vein entering the auricle. 



The gills are composed of three cartilages, which are placed in the 

 same manner as gills in fish; but these cartilages have neither the 

 pectinated part, nor the mushroom partition, which the gills of fish 

 have : their ends are articulated together, and the whole is joined to 

 the extremity of the same bone as that of the tongue. 



From the fauces there is an opening outwards, between the two 

 inferior cartilages of the gills, for the water to pass. In this opening, 

 which is oblong, is placed a structure composed of two valves, which 



