INTERIOR 459 
ventrally on the right wall of the atrium and reticulum to end at the reticulo- 
omasal orifice. It is about seven or eight inches (ca. 18-20 cm.) in length. Its 
axial direction is chiefly dorso-ventral, but it inclines forward to a variable extent 
and somewhat medially in its ventral part; the ventral end, which is at the reticulo- 
omasal orifice, is about an inch (ca. 2.5 cm.) in front of the plane of the cardia and 
to the right of the median plane. The groove is twisted in a spiral fashion, so that 
its thickened edges or lips project first backward, then to the left, and finally for- 
ward. The twist involves chiefly the left lip, and the relative position of the lips 
is reversed at the ventral end. The mucous membrane on the lips of the cesoph- 
ageal groove is brown and wrinkled, like that of the atrium; in the bottom of the 
Dorsal 
Anterior 
Fre. 391.—OmasuM oF Ox, Sacirrat Section; Ricut View. 
1, 2,3, 4, Laminew of various orders; 5, muscular pillar; 6, neck connecting with reticulum; 7, connection with 
abomasum. 
groove it is pale, like that of the cesophagus, marked by longitudinal folds, and pre- 
sents pomted, horny papille on its ventral part. 
In the reticulum the mucous membrane is raised into folds about half an inch 
high, which enclose four-, five-, or six-sided spaces or cells (Cellule reticuli); this 
peculiar arrangement suggested the scientific name and also the popular term 
“honey-comb.” These cells are subdivided by smaller folds, and the bottoms are 
studded with pointed, horny papille. The cells grow smaller and gradually dis- 
appear near the cesophageal groove and the edge of the rumino-reticular fold; an 
inch or two from the latter the mucous membrane has the papillary arrangement 
of the rumen. At the reticulo-omasal orifice there are peculiar horny papille, 
which are curved and resemble the claws of a small bird; hence they are termed 
unguliform (Papillze unguliformes). The reticulo-omasal orifice (Ostium reticulo- 
1Tt might better be termed the sulcus reticuli. 
