EXPLANATION TO PLATE XVII. 



Fi<i. 1. X,-rtiit<ir<-tli< i-i.i/nxii ( Linn.Tus). Part of branching colony (enlarged). 



L'. Si'i-liilnri'llii i-ii'/iixn. Colony with gonosoine (enlarged). (After Nutting. ) 



:'.. Sfrtnlnnllii riKjnxii. Three hyclrotlH-cn- (greatly enlarged). (After Nutting. ) 



4. Hfrlnliiri'ttii i-iii/nnn. Single hyilrothecii (greatly enlarged). (After Nutting.) 



, r >. Sirliilni-i-llii i-iii/nmi. Top of gonangium, slmwing teeth (enlarged). (After Nutting. ) 



it. \i-hiliir</ln uri'i/i Nutting. Part of colony (enlarged). 



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