The main subgross anatomical features of the lungs of various mammals are presented. A tabulation of these features permits the lungs to be grouped into three distinctive subgross types. Type 1, is represented by the cow, sheep, and pig; type 2,, by the dog, cat, and monkey; type 3,, by the horse. Lobularity is extremely well developed in type 1,; absent in type 2,; imperfectly developed in type 3,. The pleura and interlobular septa are thick in types 1, and 3,. The pleura is extremely thin in type 2, and septa are absent. Arterial supply to the pleura in types 1, and 3, is provided by the bronchial artery, and in type 2,, by the pulmonary artery. In types 1,, 2, and 3, the bronchial artery terminates in a capillary bed shared in common with the pulmonary artery at the level of the distal bronchiole. In type 3, the bronchial artery also provides blood directly to the alveolar capillary bed. True terminal bronchioles comprise the most frequent form taken by the distal airways in types 1, and 3,, although small numbers of poorly developed respiratory bronchioles are present. Well developed respiratory bronchioles, on the other hand, appear to be the only form taken by the distal airways in type 2,. In type 1, the pulmonary vein closely follows the course of the bronchus and the pulmonary artery from the periphery to the hilum. This maybe due to the heavy interlobular connective tissue barriers present. In type 3, this general relationship is maintained peripherally but not centrally where the pulmonary vein follows a more independent path to the hilum as is the case throughout the lung in type 2,.