OCR Text |
Show 344 MESSRS. V. E. BEDDAED AND 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 pericardium by a stout gubernaculum, as in many Lizards but not in Birds. HEART OP ALLIGATOR. A, B, C. Sections through the bulbus at different horizons. C. In the region of the aortic valves the communication between the aortas is shown. B. In the largest part of the bulb; A very narrow window separates the aortas in one region. A. At the summit of the bulb. Pul. C o m m o n pulmonary trunk on ventral side: P.R., P.L. Right and left pulmonaries. L.A. Left aorta arising from right ventricle ; R.A Right aorta. E.sub. Right subclavian: Tr.An. Truncus anonymus. E. Dorsal aspect of heart. L.A. Left auricle. R.A. Right auricle. The letters Pul. are placed upon the base of the arterial bulb: the ventricles, with the gubernaculum attached to the apex, form the lower part of the figure. Pul. Right pulmonary vein ; l.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 |