Observations on the anatomy of the respiratory system of the river otter, sea otter, and harp seal. I. The topography, weight, and measurements of the lungs.

The lungs of the river otter and sea otter are triangular in outline, with the apex directed cranially. Lungs of the harp seal are oval in outline. The lung shapes correspond closely to the shape of the thoracic cage of each species. The hilus is located more cranially in the harp seal than in the river otter and sea otter. The ratio of total lung weight/100 g body weight is 1.39 in the river otter, 3.86 in the sea otter, and 1.31 in the harp seal. In the river otter and sea otter the right lung has four lobes (compared with two in the left) and is always the larger and heavier. In the harp seal each lung has three lobes and are topographically more similar to each other, with the left lung being the larger and heavier.