8. Anterior part with 7 equatorial Genus *_Peridinium_
and 1 rhombic plates
Anterior part with 5 equatorial Genus _Gonyaulax_
and no rhombic plates
Anterior part with 3 equatorial Genus *_Ceratium_
and no rhombic plates
9. Anterior part with 14 equatorial Genus _Pyrophacus_
and 1 rhombic plates
Anterior part with 7 equatorial Genus _Goniodoma_
plates
Anterior part with 4 equatorial Genus _Amphidoma_
plates
10. Apical extremity drawn out Genus _Podolampas_
into a tube
Apical extremity not drawn out Genus _Blepharocysta_
into a tube
11. Cross-furrow deep, with great Genus _Ceratocorys_
ledge-like walls
Cross-furrow wide, no ledge-like Genus _Oxytoxum_
walls
* Presence at Woods Hole indicated by asterisk.