THE HEART IN SAUROPSIDA. 



266 



two, a left and a right, at the time of the auricular systole. 

 The left portion becomes filled with arterial blood from the 

 left auricle, and is distinguished as the cavu7n arteriosum ^ 

 the right receives the venous blood from the right auricle, and 

 is the caviwi venosum. 



No arterial trunk arises from the cavum arteriosuni, but 

 two arterial trunks arise from the right-hand end of the cavum 

 ve)iosum / these are the two aortic arches. One of these 

 passes to the left and the other to the right side, and thev 



zZ>.A 



Jl.Ao. 



fio 92. — The Heart of a Turtle {OJielone midas). — A, a drawing: from nature: the ventral 

 face of the ventricle being laid open. J?, a diagram explanatory of the arrangement of 

 the cavities and vessels, i?. A., L. A., right and left auricles, w, a*, arrows placed in 

 the auriculo-ventricular apertures to indicate the course of the blood at the auricular 

 systole, -w, the right, and ^i, the left median auriculo-ventricular valves. C. v., cavum 

 veTiosum. C. p., cavurri' pulmonale, a, the incomplete septum which divides tha 

 cavum pulmonale from the rest of the cavity of the ventricle. P. A., pulmonary artery. 

 H. Ao., L. Ao., right and left aortae. s, arrow showing the course of the blood in th« 

 left aorta ; t, in the right aorta ; s, in the pulmonary artery ; % between the cavum 

 venosum and ca/vum pulmonale ; x. In the left, and w,in the right auriculo-ventriculai 

 aperture. 



12 



