ANATOMY OF THE TURTLE. 509 
mesentery, and contains three oval eggs, one of which is 
lettered Hg. The oviduct can be followed to its anterior 
end which is much pigmented and has a terminal opening. 
The cut-end of the left oviduct (evd) shows the folds of the 
lining mucous membrane. 
The ovary (0) is likewise suspended by a thin membrane, 
the mesovarium, and is equally developed on both sides in a 
complete specimen. It is easily recognized by the numerous 
bulging yellow spheres, of all sizes, which are the egg-yolks 
in various stages of development. 
The heart of the turtle (Fig. 447) will repay careful dis- 
section. A small round body lies just in front of it; this is 
usually considered the equivalent of the thyroid gland, 
through its real nature is still un- 
certain. The heart itself (Fig. 447) 
consists of two auricles and one 
ventricle (ven), with an imper- 
fect internal septum. It receives 
the veins upon its dorsal surface, 
and gives off the arterial trunks 
from its ventral side. The two 
auricles are equal in size ; together 
they a little more than equal the 
ventricle. The arterial vessels arise 
together a little to the right, and 
are most conveniently described as 
three in number: Ist. The right 
aorta (# Ao) arising on the left ; 
2d. The left aorta on the right Fig. f47-— Ventral surface of 
(Z Ao); the two cross near their as itis, Dlssccked aad drier 
origin and curve upwards and back- >Y © & Minot. 
wards, to reunite posteriorly just in front of the retractor 
muscles, their union forming the single median descending 
aorta; 3d. The pulmonary aorta (pa), which soon divides 
into a branch for each lung. The left aorta gives off a 
branch (d@) which persists as a mere cord, the remnant of the 
ductus arteriosus, which originally united the aorta with the 
pulmonary artery. The right aorta gives off an innominate 
branch, that soon divides, and from each division springs 
