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.


KEY TO MARINE GENERA OF DINOPHYSIDÆ.

Diagnostic characters: The cross-furrow is above the center of the
body, and its edges, as well as the left edge of the longitudinal