PLATE LXXIII. 



FIGS. 



1. Clathrulina elegans Cienk. x 300. 



2. Hedriocystis spinifera Brown. x 2400. 



3. H. spinifera, portion of test further enlarged. x 5000. 



4. H. spinifera, optical section showing portion of capsule 



and plasma with nucleus and contractile vacuole. 

 x 5000. 



Figs. 2-4 from drawings by J. M. Brown. 



