A MANUAL OF ZOdLOGY 71 



Preserve the location of the arteries, and. veins by 

 putting bristles in them. How many arteries do you find? 

 Cut off the end of the ventricle of the heart. Is there 

 evidence of two chambers? Open the sinus and note the 

 manner in which it opens into the auricles. Is there an 

 opening from the sinus into each auricle? Are there valves 

 there? Put bristles into the stumps of the arteries leading 

 into the heart, and then dissect along them until you find 

 where they lead. Open tae ventricle and see if you can 

 find any evidences of a partition there. Is it complete? 

 Are there any valves between the auricles and the ventri- 

 cles? Sum up the differences between the heart of the 

 turtle and that of the frog. Are there any evidences of a 

 diaphragm in the turtle? Beneath and to the side of the 

 heart find the large liver. With bone forceps remove a 

 part of the carapace until the viscera is more accessible. 

 How many lobes has the liver? On which side is the gall 

 bladder? How does the liver compare in shape and in po- 

 sition with the other forms that you have studied? How 

 do you account for any differences? Begin at the edges 

 of the liver and carefully pick it away, noticing to what it 

 ^ is fastened, and also the large hepatic veins, one from 

 each lobe of the liver leading into the sinus. Remove 

 the sffin from the front part of the neck and find the 

 trachea. ,Down which side of the neck does it go? Work- 

 ing from the side and being careful not to cut veins and 

 arteries, trace it down a short distance. Does it branch? 

 Note the manner in which it enters the liings and the very 

 peculiar structure of the lung. Trace the ar- 

 teries leading from the heart. The one lying on the left 

 is the pulmonary artery. The one next to this is the 

 right aorta, and the one farthest to the right is the left 

 aorta. The two aortae cross one another a short distance 

 from the heart. The right aorta, close to the heart, gives 

 oft the innominate artery, which almost immediately gives 

 off the right and the left subclavians, and then" divides 

 into the carotids. These latter pass into the skull through 

 a foramen. Trace all these points out. Trace the right, 

 and the left aorta, noticing that they pass backward over 

 the right and left bronchi respectively and communicate 

 with one another. Fr,om this point they become the dorsal 



