Phylum Pyrrhophyta [103 



Class Peridineae Wettstein Handb. syst. Bot. 1: 71 (1901). 



Division Dinoflagellata Engler Syllab. ed. 3: 8 (1903). 



Dinophyceae and Dinoflagellatae Pascher in Ber. deutschen bot. Gess. 32: 158 



(1914). 

 Order Diniferidea and tribe [group of families] Peridinioidae Kofoid and Swezy 



in Mem. Univ. California 5 : 106, 107 ( 1921 ) . 

 Order Dinoflagellida Calkins Biol. Prot. 267 (1926). 

 Division Dinophyceae, Class Dinoflagellatae, and order Peridiniales Pascher in 



Beih. bot. Centralbl. 48. Abt. 2: 326(1931). 

 Suborder Peridinina Hall Protozoology 144 (1953). 

 This order is very close to the preceding; its members are distinguished only by 

 the presence, while the cells are in the flagellate condition, of cell walls, consisting in 

 most examples of separable plates. The name Cilioflagellata is evidence of an early 

 error of observation: the circumferential flagellum was mistaken for a whorl of 

 cilia. This name and most of its synonyms were published as applying both to the 

 preceding order and this. For almost all of these names the type or obvious standard 

 example is Peridinium, with the effect that the names belong to the present order. 

 There are about five hundred species, prevalently marine. Five families may be 

 recognized. 



Family 1. Peridinaea Ehrenberg Infusionsthierchen 249 (1838). Family Peridin- 

 idae Kent Man. Inf. 1: 441 (1880). Family Peridiniaceae Schiitt in Engler and 

 Prantl Nat. Pflanzenfam. I Teil, Abt. lb: 9 (1896). Ceratiidae Kofoid in Bull. Mus. 

 Comp. Zool. Harvard 50: 164 (1907). The typical dinoflagellates, of numerous 

 genera and species. The distinctions among them are largely matters of the detailed 

 arrangement of the plates making up the walls. Glenodinium, the plates scarcely 

 distinguishable. Peridinium, Goniodoma, Goniaulax, Ceratium, Oxytocum, etc. The 

 cells of certain species in various genera are ornamented with prominent horns; in 

 Ceratium especially the epitheca is drawn out into one long horn, and the hypotheca 

 into one, two, or three. Goniaulax becomes abundant at certain seasons, is eaten by 

 shellfish, and renders them poisonous. 



The neuromotor apparatus (much as in Menoidium) and the process of nuclear 

 and cell division in Ceratium Hirundinella were described by Entz (1921) and Hall 

 (1925). Many nuclei lack the endosome; if present, it disappears during mitosis, as 

 does also the nuclear membrane. The daughter centrosomes lie at the sides of the 

 blunt-ended mitotic figure. When nuclear division is complete, the protoplast ex- 

 pands and then becomes constricted in such fashion that each daughter cell receives 

 certain plates of the wall; each daughter cell then secretes the plates which it lacks. 

 Zederbauer (1904) reported conjugation in Ceratium. He saw an elongate proto- 

 plast with each of its ends covered by a complete cell wall. Dividing cells are of 

 quite different appearance. 



Families Ptychodiscida, Cladopyxida, and Amphilothida of Kofoid (1907, the 

 names in the feminine; explicitly made families by Poche, 1913) are minor segregates 

 from Peridinaea. 



Family 5. Dinophysida (Bergh) Biitschli in Bronn Kl. u. Ord. Thierreichs 1: 

 1009 (1885). Subfamily Dinophysida Bergh in Morph. Jahrb. 7: 273 (1882). The 

 limits of the plates obscure; girdle near the anterior end; sulcus and girdle bordered 

 by prominent flanges. Strictly marine, mostly in warmer oceans. Dinophysis, Oxyphy- 

 sis, Amphisolenia, Triposolenia, etc. 



