Which part lacking in stomach of camel

The part lacking in the stomach of camel is Omasum.
Camels have a three-chambered stomach, lacking the separation of omasum and abomasum; the rumen and reticulum are equipped with glandular pockets separated by muscular walls having sphincters and glands.
The omasum is a globe-shaped structure containing leaves of tissue (like pages in a book). It absorbs water and other substances from digestive contents.