the vena cava inferior of the right heart, and the vena cava superior of the left heart

28. Vena cava superior, terminating in the right auricle of the left heart.

29. A trunk formed by the left subclavian vein, and the jugular veins of the left side of the left head.

30. A trunk formed by the jugular veins of the right side of the left head.

31. A trunk formed by the jugular veins of the left side of the right head.

32. A trunk formed by the right subclavian vein, and the jugular veins of the right side of the right head.

EXPLANATION OF PLATE IV.

Posterior View of the Hearts and Arteries.

1. Left heart.

2. Right heart.

3. Ductus arteriosus of the left heart.

4. Ductus arteriosus of the right heart.

5. The arch of the aorta of the right heart, where it receives the ductus arteriosus.

6. A trunk, from which the vertebral and inferior thyroid arteries, with the left axillary artery, arose from the aorta.

7.

The left vertebral artery of the right head, arising from the arch of the aorta, just as it receives the ductus arteriosus.

8. A trunk arising from the ductus arteriosus, which supplied the right vertebral, the right axillary, and the inferior thy

roid arteries.