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byIn the digestive system of some fishes the teeth may be found on the jaws, palatine, vomer, tongue, pharyngeal bones or gill arches, etc. There is a rare species of fish which have teeth in their esophagus. A part of the esophagus of these fishes contains a sac and there are tiny teeth (so-called esophageal teeth) in the inner wall of the sac. The sac is called an esophageal or a pharyngeal [1] sac, and KOSAKAI [2], one of present authors, reported that the sac was like a diverticulum of the esophagus. The gross anatomy and histology of the sacs and the teeth in only a few of these fishes have been described by GILCHRIST [3], BUHLER [1], BERNARD [4] and KOSAKAI [2]. How ever, these authors could not obtain many kinds of fishes of this type and their histological investigations of the esophageal sacs and the teeth were not always adaquate. This paper will contribute some additional morphologic observations about nine species of fish with esophageal sacs. Recently KOSAKAI [2] published in a Japanese language journal a paper on the esophageal teeth. Some parts of his study will also be included. in this paper. Materials and MethodsThe materials of this study consisted of nine fishes as follows : 1. Psenopsis anornala (Psenopsis) 2. Ocycrius japonicus (Ocycrius) 3. Icticus pellucidus (Icticus) 4. Ariomma lurida (Ariomma) 5. Pampus argenteus (P. arg.) 6. Pampus echinogaster (P. ech.) 7. Nomeus albula (Nomeus) 8. Tetragonurus cuvieri (T. cuv.) 9. Tetragonurus atlanticus (T. atl.) These fish names as abbreviated in the parentheses above were used in this paper. The first six fishes listed were the same as those investigated by KOSAKAI but the last three are described for the first time by the authors of this paper.Unaided, visual and stereoscopic microscopical dissections were used to examine the esophageal sacs and included teeth. It was noteworthly that an antiformin # method

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