AWATOMY OF TBE TURTLE. 



50£> 



mesentery, and contains three oval eggs, one of whicli is 

 lettered Eg. 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 {ovd) shows the folds of the 

 lining mucous membrane. 



The ovary (o) 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 : 1st. The right 

 aorta {R Ao) arising on the left ; 

 2d. The left aorta on the right 

 {L Ao) ; the two cross near their 

 origin and curve upwards and back- 

 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, wliich originally united the aorta with the 

 pulmonary artery. The right aorta gives off an innominate 

 branch, that soon divides, and from each division springs 



Fig, 447. — Ventral surface of 

 the heart of the Turtle, Gkryse- 

 mys picta. Dissected and drawn 

 by C. S. Minot. 



