360 Papers from the Department of Marine Biology. 



stricted lumen. In most mammals and in man such mechanism is 

 functionally superfluous, and consequently absent except in slight and 

 variable degree. As such it may persist or become accentuated, and 

 produce congenital atresia or stenosis of the esophagus. The relatively 

 frequent embryonic and congenital occlusions of the duodenum just cau- 

 dal to the pancreatic anlages may perhaps hkewise find their explana- 

 tion in terms of a phylogenetic protective device against yolk invasion. 



LITERATURE. 



Balfour, Francis M. 1878. A monograph on the development of elasmobranch fishes. 



. 1880. Comparative embryology. 



Dean, Bashford. 1896. On the larval development of Amia calva. Quart. Jour. Micr. 



Sci., vol. 38. 

 KoLLMANN, J. 1898. Lehrbuch der Entwichlungsgeschichte des Menschen, pp. 340-341. 

 Kretjter, Erwin. 1903. Solide Oesophagus den Selachier. Diss. Anat. Inst. d. Univ. 



Miinchen. Erlangen. 

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in Lichte der Entwicklungsgeschicte. Deutsche Zeitschrift ftir Chirurgie, 



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 Lewis, Frederick T. 1912. The development of the esophagus. Keibel and Mall's 



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 LiLLiE, F. 1908. The development of the chick, p. 312. 

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seanc. de I'Acad. d. science, T. 102. 

 Oppel, Albert. 1891. Vergleichung des Entwicklungsgrades der Organe zu verschiede- 



nen Entwicklungszeiten bei Wirbeltieren. 



