Pomona Collejje, ClaiciiKint, California 39 



size of the radial shields is especially noticeable in a series of spec- 

 imens. One of the interesting features of this species is the great 

 range of color variation found. This is true both in young and 

 adults. 



Conclusions : 



1. A rational system in the brittle-stars is lacking. Such a 

 system may result in part at least, from a complete study of growth- 

 stages. 



2. Jackson's law of localized stages repeating phylogenetic his- 

 tory seems to be well vindicated in this and other studies. 



3. The groups examined seem to bear certain relationships to 

 each other, as indicated above. 



Literature 



Bell, F. J. Contribution to the Classification of the Ophiuroids. 

 1892. Pro. Zool. Soc. London, pp. 175-183. 



Clark, H. L. Growth-Changes in Brittle-Stars. 1914 



Papers from the Tortugas Lab. of the Carnegie Inst. Was. vol. 

 5. pp. 93-125. 



Jackson. R. T. Localized Stages in development in plants and ani- 

 mals. 1899. Bost. Soc. Nat. Hist., vol. 5, pp. 89-153. 



Ludwig. H. Zur. Entwicklung.-geschichte de'^ Ophiurenskelettes. 



1881. Zeit. f. w. Zool., vol. 34, pp. 333-365. 

 . Jugendformen von Ophiuren. 1899 



Sit. d. K. Preuss. Akad. der Wiss. Berlin, vol. 14, pp. 210-200. 



