[Lung structure of Sphenodon punctatus. A comparative anatomic study].

After a critical review of the literature, the authors describe the structure of the lung of Sphenodon, dealing with form, arteries, veins, and septation. The external form, circulatory pattern, degree of complication, height of the septa, vascular structure, and decrease in complication (?) are discussed from the standpoint of comparative anatomy. In an attempt to explain the unusual findings, the capacity for development of the central and subpleural type of differentiation is compared and contrasted. Obvious relations between the unusual lung structure and the phylogenetic age of the Sphenodon were sought, with the conclusion that the Sphenodon cannot be included in the Reptilian oders since its physical structure forms a class by itself.