ith those
Cryptomonadine Flagellates which possess two unequal flagella; the
zoospores or young of the Cystoflagellates are practically colourless
Dinoflagellates.

1. _Gymnodiniaceae_: body naked, or with a simple cellulose or
gelatinous envelope; both grooves present. _Pyrocystis_ (Murray),
often encysted, spherical or crescentic, becoming free within cyst
wall, and escaping whole or after brood-divisions as a form like
_Gymnodinium_; _Gymnodinium_ (Stein); _Hemidinium_ (Stein);
_Pouchetia_ (Schutt) (fig. 2, 7) with complex eye-spot; to this group
we may refer _Polykrikos_ (Butschli) (fig. 2, 9), with its metameric
transverse grooves and flagella.

2. _Prorocentraceae_ (Schutt) ( = the Adinida of Bergh); body
surrounded by a firm shell of two valves without a girdle band;
transverse groove absent; transverse flagellum coiled round base of
longitudinal. _Exuviaeella_ (Cienk.) (fig. 2, 3); _Prorocentrum_
(Ehrb.) (fig. 2, 4).

3. _Peridiniaceae_ (Schutt); body with a shell of plates, a girdle
band along the transverse groove, in which the transverse flagellum
lies. Genera, _Peridinium_ (Ehrb.) (fig. 1), fresh-water and marine;
_Ceratium_ (Schrank) (fig. 2, 5, 6), fresh-water and marine;
_Citharistes_ (Stein); _Ornithoceras_ (Claparede and Lachmann) (fig.
2, 1).

LITERATURE.--R. S. Bergh, "Der Organismusder Cilioflagellaten,"
_Morphol. Jahrbuch_, vii. (1881); F. von Stein, _Organismus der
Infusionsthiere_, Abth. 3, 2. Halfte; _Die Naturgeschichte der
arthrodelen Flagellaten_ (1883); Butschli, "Mastigophora" (in Bronn's
_Thierreich_, i. Abth. 2), 1881-1887; G. Pouchet, various observations
on Dinoflagellates, _Journal de l'anatomie et de la physiologie_
(1885, 1887, 1891); F. Schutt, "Die Peridineen der Plankton
Expedition" (_Ergebnisse d. Pl. Exed._ i. Th. vol. iv. 1895); and
"Peridiniales" in Engler and Prantl's _Pflanzenfamilien_, vol. i. Abt.
2 b. (1896); Zederbauer, _Berichte d. deutschen botanischen
Gesellschaft_, vol. xx. (1900); Delage and Herouard, _Traite de
zoologie concrete_, vol. i. _La Cellule et les protozoaires_ (1896).
(M. HA.)

DINOTHERIUM, an extinct mammal, fossil remains of which occur in the
Miocene beds of France, Germany, Greece and Northern India. These
consist chiefly of teeth and the bones of the head. An entire skull,
obtained from the Lower Pliocene beds of Eppelsheim, Hesse-Darmstadt, in
1836, measured 4-1/2 ft.