of graminivorous and carnivorous Animals. 147 
not detected in the rabbit till they had been seen in the 
hare, but then were readily distinguished. Vide Plate V. 
fig. 4 and 5. 
No. IV. The Beaver. 
The stomach of the beaver is divided by a muscular con- 
traction into two portions ; the cardiac, which is of an oval 
form, may be called the descending portion ; the pyloric, 
which is much smaller, and bent upwards, may be called the 
ascending portion : the contraction between them is suffici- 
ently strong to bear the force necessary to distend the stomach, 
without yielding to it. The cuticular lining of the oesophagus 
terminates at the orifice of the stomach. Just within that 
orifice, upon the upper or small curvature is a large oval 
glandular structure, subdivided into three prominent ridges, 
placed in the direction of the stomach, and projecting into 
its cavity, one in the middle line, and one on each side of it : 
in the middle ridge there are nine large openings through 
the internal membrane, capable of contracting so as to shut up 
the orifices, or of dilating so as to expose three inner orifices 
leading to the gland ; each of these is continued into five or 
six processes, whose length is proportioned to the thickness of 
the glandular mass, extending nearly to its external surface. 
In each of the lateral ridges there are seven orifices. The 
•internal membrane of the descending portion of the stomach, 
into which these excretory ducts open, is uniformly smooth in 
every other part of it ; but the lining of the smaller ascending 
portion has a villous appearance, subdivided by slight fissures: 
this however is only to be seen when minutely examined. 
The part next the pylorus has a strong muscular covering 
