KEY TO FAMILIES OF DINOFLAGELLIDIA.
1. No crossfurrow; two free flagella Family Prorocentridae
2. One or more cross-furrows 3
3. Cross-furrow nearly central
to Family Dinophysidae
Several cross-furrows Family Polydinidae and flagella (One genus, Polykrikos.)
KEY TO MARINE GENERA OF PROROCENTRIDAE.
Diagnostic characters: The transverse furrow is absent and the two flagella arise from the anterior end of the body. The shell may be bivalved.
1. No tooth-like process dorsal
to the flagellum
2. With tooth-like process
dorsal Genus Prorocentrum
to the flagellum
* Presence at Woods Hole indicated by asterisk.
KEY TO MARINE GENERA OF PERIDINIDAE.
Diagnostic characters: The cross-furrow is nearly central (see, however, Oxytoxum); the body may or may not have a shell; the shell may or may not be composed of distinct plates; the plates are distinguished as equatorial (i.e., bordering the cross-furrow), apical, and antapical, while still another, the “rhombic plate”, may be present, extending from the cross-furrow to the apex.
1. Without distinct shell Genus *_Gymnodinium_
With a distinct shell 2
2. Shell not composed of definite
Shell composed of definite plates 4
3. Cross-furrow replaced by
defined; Genus Protoceratium
reticulate markings raised
defined; Genus *_Glenodinium_
4. Two parts of shell equal
Two parts of shell very unequal 11
5. With transverse flagellum
a distinct furrow
not in a 10
6. With horns, or with wing-like
Without processes of any kind 9
7. Processes small, wing-like,
Processes horn-like 8
8. Anterior part with 7 equatorial
and 1 rhombic plates
with 5 equatorial Genus Gonyaulax
and no rhombic plates