THE DEVELOPMENT OF ASTEEINA GIBBOSA. 281 



I hope in a future paper to be able to show that the 

 Trochophore larva is also related, though much more distantly, 

 to the Dipleurula. 



Zoological Laboratory, 



March 8th, 1895, Cambridge. 



[Postscript. — With reference to the point discussed on 

 p. 275, viz. the existence of a fixed Echinoderm in which the 

 tentacles were directed towards the substratum, it is of interest 

 to note that in the fossil Crinoid Cheirocrinus the calyx 

 was sharply beut on the stalk, so that the arms were directed 

 downwards towards the substratum.] 



List or Works referred to in this Memoir. 



1. Bury, H. — "The Early Stages in the Development of Antedon 



rosacea," 'Phil. Trans. Roy. Soc.,' 1888. 



2. BtJUY, H. — " Studies in the Embryology of Echinoderms," ' Quart. 



Journ. Micr. Sci.,' 1889. 



3. CuENOT, L. — " Contributions a I'liitude anatomique des Asterides," 



'Arch, pour Zool. Exp.,' 2me series, tome v bis. 



4. CoENOT, L. — " ;^tudes morpliologiques sur les Echinoderms," ' Arch, de 



Biol.,' tome xi, fascicles 1 and 2. 



5. Field.—" The Larva of Asterias," ' Quart. Journ. Micr. Sci.,' 1892. 



6. Gakstang, W. — "Oq some Bipinnarise from the English Ciiannel," 



' Quart. Journ. Micr. Sci.,' 1894. 



7. Hamann, Otto v. — "Die Wandernden Urkeimzellen und ihre Reifungs- 



statte bei den Echinodermen," ' Zeitsch. fiir wiss. Zool.,' 1880. 



8. Hamann, Otto v. — 'Beitrage zur Histologic der Echinodermen,' 4 



Hefte, Jena, 1889. 



9. Leipoldt, H. — " Das angebliche Excretiensorgan der Seeigel," ' Zeitsch. 



fiir wiss. Zool.,' 1893. 



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fur wiss. Zool.,' Bd. xxxiv, 1880. 



12. LuDWiG, H. — " Entwickelungsgeschichte der Asterina 'gibbosa, 



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