738 BIBLIOGRAPHY. 



Confining our attention to the Invertebrata it appears to me fairly clear 

 that Hatschek is justified in holding the provisional trochosphere excretory 

 organs of Polygordius, Echiurus and the Mollusca to be homologous. The 

 atrophy of all these larval organs may perhaps be due to the presence of a 

 well-developed trunk region in the adult (absent in the larva), in which 

 excretory organs, probably serially homologous with those present in the 

 anterior part of the larva, became developed. The excretory organs in the 

 trunk were probably more conveniently situated than those in the head, 

 and the atrophy of the latter in the adult state was therefore brought about, 

 while the trunk organs became sufficiently enlarged to serve as the sole 

 excretory organs. 



BIBLIOGRAPHY OF THE EXCRETORY ORGANS. 

 Invertebrata. 



(512) H. Eisig. " Die Segmentalorgane d. Capitelliden." Mitth. a. d. zool. 

 Staf. s. Neapd, Vol. I. 1879. 



(513) J. Fraipont. " Recherches s. 1'appareil excreteur des Trematodes et d. 

 Cestoides." Archives de Biologic, Vol. I. 1880. 



(514) B. Hatschek. "Studien lib. Entwick. cl. Anneliden." Arbeit, a. it. 

 zool. I nst it. IVien, Vol. I. 1878. 



(515) B. Hatschek. "Ueber Entwick. von Echiurus," etc. Arbeit, a. d. 

 zool. Instil. Wien, Vol. III. 1880. 



EXCRETORY ORGANS OF VERTEBRATA. 

 General. 



(516) F. M. Balfour. "On the origin and history of the urinogenital organs of 

 Vertebrates." Journal of Anat. and Phys., Vol. x. 1876. 



(517) Max. Fiirbringer 1 . "Zur vergleichenden Anat. u. Entwick. d. Excre- 

 tionsorgane d. Vertebraten." Morphol. Jahrbuch, Vol. iv. 1878. 



(518) H. Meek el. Znr Morphol. d. Ham- u. Geschlechtswerkz. d. Wirbelthiere, 

 etc. Halle, 1848. 



(519) Job. Miiller. Bilditngsgeschichte d. Genitalien, etc. Diisseklorf, 1830. 



(520) H. Rathke. "Beobachtungen u. Betrachtungen u. d. Entwicklung d. 

 Geschlechtswerkzeuge bei den Wirbelthieren." N. Schriften d. natttrf. Gesell. in 

 Dantzig, Bd. I. 1825. 



(521) C. Semper 1 . "Das Urogenitalsystem cl. Plagiostomen u. seine Bedeu- 

 tung f. d. iibrigen Wirbelthiere." Arb. a. d. zool.-zoot. Instit. Wiirzburg, Vol. n. 



1875- 



(522) W. Waldeyer 1 . Eierstock u. Ei. Leipzig, 1870. 



1 The papers of Fiirbringer, Semper and Waldeyer contain full references to the 

 literature of the Vertebrate excretory organs. 



