PLATE 6 

 FIG. PAGE 



ACTINOCYCLUS 



1 Actinocyclus barkleyi var. aggregata Rattr 27 



2 Actinocyclus moniliformis Ralfs 27 



BIDDULPHIA 



3 Biddulphia antediluviana (Ehr.) V. H 32 



5 Biddulphia reticulum (Ehr.) 33 



6 Biddulphia favus (Ehr.) V. H 31 



7-8 Biddulphia alternans (Bail.) V. H 33 



TRINACRIA 



9 Trinacria pileolus (Ehr.) Grun 30 



DITYLUM 



4 Ditylum intricatum (West) Grun 30 



TERPSINOE 



10 Terpsinoe americana (Bail.) Ralfs 34 



11 Terpsinoe novae-ciesareiB Boyer 34 



