of the Ornithorhynchus paradoxus* 7 5 
The lungs are large in size, corresponding to the capacity of 
the chest. On the right side there are two lobes ; there is a 
small azygos lobe under the heart ; and in the left side only one. 
Instead of a portion of the lungs being above the heart, as in 
other animals, the heart may be said to be above the lungs ; for 
they only embrace its sides, and do not surround its upper sur- 
face, but extend downwards, into the more moveable part of the 
cavity of the chest. 
The diaphragm is very broad, and every where towards the 
circumference is muscular, having only a small central portion, 
which is tendinous, immediately under the heart. 
The oesophagus is extremely small, more particularly at its 
origin behind the larynx, where the fauces terminate in it. 
The stomach is a membranous bag, of an oval form, into 
which the oesophagus can hardly be said to enter, being rather 
continued along one end of the oval, till it forms the duodenum ; 
so that the stomach appears to be a lateral dilatation of a canal, 
which is the oesophagus where the dilatation is formed, and 
becomes the duodenum immediately afterwards, at which part 
the. coats are thickened, forming the valve of the pylorus. 
The stomach is smaller than in most other animals ; in this 
respect it is like the true stomach of birds. In the collapsed 
state it is only i-- inch long, and \ of an inch broad. This 
is exactly double the size of one of the pouches in the cheek. 
The duodenum makes a turn in the right side of the 
abdomen ; then crosses the spine, and becomes a loose intestine. 
The small intestines are strung upon a loose, broad, transparent 
mesentery. The origin of the colon is only to be distinguished 
by a small lateral appendage, i\ inch long, and of an inch in 
diameter, going off from the side of the intestine, which is not 
L 2 
