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620 WILSON. 



PLATE XXIX. 



[Figs. 1-3, from living specimens ; the others from preparations ; 270 diameters.] 



Figs. 1-3. First and second cleavages. 

 Figs. 4-7. Third cleavage ; pure radial form. 

 Figs. 8-10. The same ; spiral form. 

 Fig. II. Mixed form ; from lower pole. 

 Fig. 12. Bilateral form. 



