8 
MAMMALIAN ANATOMY 
The drawing as a whole should be accurately labeled and dated; 
and each part drawn should be labeled, if only tentatively, as 
soon as drawn, the temporary labels to be replaced by permanent 
ones in the final finishing of the drawing. Usually the most 
convenient method of permanent labeling is that of a set of neatly 
dotted, ruled, leading lines, which places the names of the parts at 
one side where they can be neatly written or printed. 
Order of Procedure in Dissecting. —Use strong forceps, scis¬ 
sors, and scalpels, the latter kept in a well sharpened condition 
during the dissection by frequent honing. Moisten the prepara¬ 
tion frequently, or in case a very small mammal is used, dissect 
under water. 
Remove the skin from the entire body, except from the feet and 
from the regions immediately surrounding the ears, eyes, nose, 
mouth, and the anal and urogenital orifices, 
i. The Coelomic Cavity, and Its Contents in situ. 
After a brief review of the superficial bony landmarks and 
general distribution of the muscles, open the abdominal cavity by 
a midventral incision from the posterior end of the sternum to the 
symphysis pubis, and make a transverse incision through the wall 
upon each side of the midline, sufficiently extensive to allow the 
ventral abdominal wall to be turned back in four flaps to expose 
the abdominal viscera in situ. 
Note that the anteribr boundary of the cavity is formed by 
the dome-shaped muscular partition, the diaphragm, which in 
the mammal subdivides the coelomic cavity transversely into the 
thoracic and the abdominal cavities. Posterior to the level of the 
pubic arch the coelom narrows and becomes the pelvic cavity. 
Note the smooth, moist serous membrane, known in the 
abdominal cavity as the peritoneum, the parietal portion of which 
lines the cavity throughout while the visceral portion, as will be 
seen more clearly later, invests and supports the contained organs. 
Identify the viscera so far as you are able without disarranging 
them. Most conspicuous of all is the voluminous coiled intestine. 
Anterior to this intestinal mass and partly hidden in the concavity 
of the diaphragm, are the stomach and the liver, the latter lying 
more on the right side, while the spleen which is located to the left 
of the stomach, may often be seen. 
