350 Mr. Wilson's Description of a 
ture, formed it in the same manner as it usually does ; sent 
off the vessels belonging to the head and upper extremities; 
descended before the vertebrae, and passed into the abdomen 
between the crura of the diaphragm. From the place where it 
began to form the arch, it was in no respect different from the 
aorta of any other infant, except that no bronchial artery was 
sent to the lungs, from it or any of its ramifications. 
The vessel which proved to be the pulmonary artery, almost 
immediately divided into two branches ; one going to the lungs 
of the left, the other to the lungs of the right side. Upon mea- 
suring accurately the circumference of the aorta, where it se- 
parated from the original trunk, it was found to be exactly one 
inch and a quarter. Upon measuring the circumference of the 
pulmonary artery, in the same manner, it was found to be 
fifteen sixteenths of an inch ; so that it was five sixteenths of 
an inch less than the aorta. 
The vena cava inferior, having been partly surrounded by 
the substance of the liver, entered the lower and back part of 
the auricle. The subclavian vein of the right side crossed over 
to the left of the mediastinum, where it joined the left subcla- 
vian, and formed the vena cava superior. This passed down on 
the left of the ascending, and before the descending, part of 
the aorta ; it was then joined by a trunk formed by two large 
veins, which came out of the lungs, and which were situated 
immediately behind the pulmonary arteries : the union of this 
trunk with the vena cava superior was continued into a large 
vessel, which gradually expanded itself into the auricle. The 
vena azygos ascended on the left side ; received some branches 
which passed under the aorta from the right, and then entered 
the upper and back part of the vena cava superior ; there were 
