PLATE LXIX. 



Balcenoptera borealis. 



Fig. 1. Tongue, pharynx and larynx. 2| X natural size. 



Fig. 2. Base and diaphragmatic surface of heart. 2f X natural size. 



Fig. 3. Cavities of the atria. 2f X natural size. 



1. Tongue. 15. 



2. Nasopharynx. 16. 



3. Ridge of velum corresponding to margin of tensor palati. 17. 



4. Free edge of velum and arcus palatopharyngeus. 18. 



5. Concavity of dorsum of velum palati. 19. 



6. Epiglottis. 20. 



7. Arytenoid cartilage. 21. 



8. Muscular ridge. 22. 



9. Oropharynx into which opens the faucial canal. 23. 



10. Middle constrictor. 24. 



11. Inferior constrictor. 25. 



12. Thyroid cartilage. 26. 



13. (Esophagus. 27. 



14. Trachea. 



Depression of floor of mouth between the tongue and fauces. 



Aorta. 



Pulmonary artery. 



Precava. 



Postcava. 



Coronary sinus. 



Left pulmonary veins. 



Right pulmonary veins. 



Groove of right pulmonary artery. 



Reflection of serous pericardium. 



Interventricular furrow. 



Atrioventricular furrow. 



Valve of the foramen ovale. 



