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This study was carried out on a comprehensive collection of tongues of Pan troglodytes. Material of tongues of Tupaia glis, Microcebus murinus, Chirogaleus major, Lemur catta, Galago crassicaudatus, Cebus apella, and Macaca mulatta were used for comparison of the different stages of the development of the papilla foliata. The tongue of Pan exhibits longitudinal growth correlated with the growth of length of the jaws and individual age. A typical foramen caecum as it occurs in man was gross anatomically not recognizable. Seldom a small circular depression appeared in the midline close to the papilla circumvallata centralis which could be the remnant of the foramen caecum. There is a remarkable accumulation of papillae filiformes and fungiformes at the apex linguae; the same seems to be true for other genera of primates. It is self-explanatory that the accumulation of papillae makes the tip of the tongue a particularly sensitive area; this has been found to be true even in man. One specimen of the prenatal age just before term was studied. It exhibited remarkably elongated, thread-like papillae, their function is unknown as yet. They are no longer present in a newborn specimen of 4 d of age. In the aboral part of the dorsum linguae, a special kind of papillae occur; they are flat lobes which carry moderately elongated, tiny processes at their free margin. The function of these papillae is unknown; taste buds are absent.