DIGESTIVE SYSTEM. 333. 
other, and to retain them in their proper position. For 
this purpose, its duplicatures enclose all the digestive or- 
gans I have already enumerated ; and, from their peculiar 
position and contents, appear to serve some other end in 
the animal economy. 
The Omentum is the most remarkable sf these duplica- 
tures or processes, and belongs only to the mammalia. It 
arises from the peritoneal covering of the stomach, and forms 
a bag which hangs from the stomach and liver, the other 
end being free in the cavity of the abdomen. Where it is in 
connection with the liver, it has been termed omentum par- 
ovum or hepato-gastricum. The walls of this sac are re- 
markable for containing fatty bands, disposed in a reticu- 
lated form. The quantity of fat depends on the condition 
of the animal. It appears to be deposited here by the sys- 
tem, as a storehouse of nourishment, and is quickly ab- 
sorbed when food is scantily supplied. 'The omentum like- 
wise protects the intestines from friction against the walls 
of the abdomen ; and, according to some, contributes to re- 
tain their heat. 
The Mesentery, which exists in all.the vertebral animals, 
is the duplicature of peritoneum which invests the intestines, 
unites them to one another, and to the abdomen, and which 
serves as a support to the nerves, vessels, and glands which 
belong to them: That portion which is more intimately 
connected with the smaller intestines, is considered more 
particularly as the mesentery, while other portions. receive 
peculiar appellations, as Mesocolon, and Mesorectum, from 
the parts of the large guts with which they are united. 
Although the digestive organs furnish important and 
highly useful characters, in the discrimination of the habits: 
of the species of certain genera, they can seldom be em- 
ployed with advantage to distinguish any divisions of a 
higher kind. 
