224 VERTEBRATES. 



creas opens, and also the duct from the gall bladder, which 

 is attached beneath the edge of one lobe of the liver. 



Posteriorly the intestine opens into a widened terminal 

 portion of the canal (the cloaca). Near the end of the 

 intestine are two little lateral side branches, which end 

 blindly, and are called cceca (or diverticulce). 



Cut off the esophagus near its anterior end, and the 

 intestine near its posterior end. Dissect out the inter- 

 vening part of the alimentary canal, liver, and pancreas, 

 noting the dark-red spleen lying near the stomach, the 

 mesentery looping up the intestine, and the blood vessels 

 distributed to all the parts. 



IV. The Heart. Slit open the pericardium. Expose 

 and examine the heart. Note its conical shape, and the 

 firmer texture of its more muscular posterior end. The 

 auricles (right and left) at the anterior end are distin- 

 guishable from the ventricles by their darker color, and 

 by being marked off from the ventricles and from each 

 other by delicate yellowish lines of fat. Prick a hole in 

 each auricle, insert a pipette, and inflate to see their extent. 



That there are two ventricles also (right and left), is 

 not evident from the exterior. Snip off the posterior end 

 of the heart with sharp scissors, and look at the cut sur- 

 face. The cavities of the two ventricles will be at once 

 apparent, that of the left ventricle circular, and sur- 

 rounded by very thick, muscular walls ; that of the right 

 ventricle, crescent-shaped, and with thinner walls. Dis- 

 sect out the heart and its connecting blood vessels, 

 and fully expose the lungs. 



V. The Lungs. Pass a bristle into one of the lungs 

 through its bronchus, and probe to find the openings 

 by which the lungs communicate with the air sacs. 

 Lay open the bronchus with fine scissors, and see how 

 it is branched, and how its branches are distributed 

 through the lung. Dissect out the lungs, and note how 



