454 EMBKYOLOGY OF THE LOWER VERTEBRATES OH.VH 



the hind end of the body continuing to sprout out past and dorsal to 

 the anal opening. It is of course conceival le that in phylogeny the 

 tail arose similarly as an outgrowth of the body dorsal to the anus 

 hut this seems in every way less probable than the method of 

 evolution sketched above. 



LITERATURE 



Agar. Anat. Anzeiger, xxxiii, 1908. 



Balfour. Monograph on the Development of Elasmobranch Fishes. London, 1878. 



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Caldwell. Jouru. Proc. Roy. Soc. New South Wales, xviii, 1884. 



Dean, Bashford. Kupffers Festschrift. Jena, 1899. 



Ekman. Morph. Jahrb., xlvii, 1913. 



Gegenbaur. Untersuchungen zur vergl. Anat. der Wirbelthiere, iii. Leipzig, 1872. 



Goodrich. Quart. Journ. Micr. Sci., 1, 1906. 



Kerr, Graham. Phil. Trans. Roy. Soc. London, B, cxcii, 1900. 



Kerr, Graham. The Work of J. S. Budgett. Cambridge, 1907. 



Kerr, Graham. Keibels Normentafeln, iii. Jena, 1909. 



Rabl. Morph. Jahrb., xix, 1893. 



Semon. Zoologische Forschungsreisen, i. Jena, 1893-1913. 



Semon. Keibels Normentafeln, iii. Jena, 1901*. 



Taylor. Quart. Journ. Micr. Sci., lix, 1914. 



