Reading: Fetal Pig Dissection | Biology II Laboratory Manual Obtain a fetal pig and identify the structures listed in figure 1. ... Circulatory System Figures 29 and 30 summarize the circulatory system of a mammal. Figure 29. Circulatory system. ... This diagram shows that the ductus arteriosus connects the pulmonary artery to the aorta and diverts blood that would otherwise go to the lungs.