344 MESSRS. V. B. BEDDABD k^D P. CHALMERS MITCHELL [May 7, 



in a stout pericardium of an elastic nature. The pericardium 

 ensheathes the origins of the large vessels, and the point of the 

 ventricles is bound to the posterior end of the pericardiuui by 

 a stout gubernaculum. as in many Lizards but not in Birds. 



I. Ml 



Heart of Alligator. 



A, B, C. Scvlioiig through the hidbns at different hori~ons. 



C. In the region of the aortic valves the communication between the aortoe is 

 shown. B. In the largest part of the bulb ; A very narrow window 

 separates the aortse in one region. A. At the summit of the bulb. Pul 

 Common pulmonary trunk on ventral side : P.R., P.L. Right and left 

 pulmonaries. L.A. Left aorta arishig from right ventricle ; R.A. Right 

 aorta. R.sub. Right subclavian : Tr.An. Truncus anonymus. 



E. Dorsal aspect of heart. 



L.A. Left auricle. R.A. Right auricle. The letters Pul. arc placed upon the 

 base of the arterial bulb : the ventricles, with the guberuaoulum attached 

 to the apex, form the lower part of the figure. Ptil. Right pulmonary 

 vein ; I. Pul. Left pulmonary vein, which is closely attached externally to 

 the left anterior vena cava, l.a.c. The right anterior vena cava opens 

 into the sinus opposite l.a.c. The large median vessel is the post-caval. 



The accompanying drawing (E) illustrates the dorsal aspect of 

 the heart with the sinus venosus overlying it ; the sinus venosus 

 is a very small but distinct thin- walled cavity, in position and 



