4 THE HUMAN BODY. 



nected with the blood-flow and is often called the hcemal 

 cavity. 



Upon the ventral side of the head is the mouth-opening 

 leading' into a tube, the alimentary canal, /', which passes 

 back through the neck and trunk and opens again on the 

 outside at the posterior part of the latter. In its passage 

 through the trunk-region -this canal lies in the ventral cavity. 



The Mammalia. In many vertebrate animals the ven- 

 tral cavity is not subdivided, but in the Mammalia it is; a 



FIG. 1. The Body opened from the front to show the contents off its ventral 

 cavity, lu, lungs; h, heart, partly covered by other things; le, le', right and left 

 liver-lobes respectively ; ma, stomach ; we, the great omentum, a membrane con- 

 taining fat which hangs down from the posterior border of the stomach and covers 

 the intestines. 



membranous transverse partition, the midriff or diaphragm 

 (Fig. ], z), separating it into an anterior chest or thoracic 



