126 ^ CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



(Kurssanov and Schemakhanova, 1927) and that Apiococcus consociatus is 

 diploid (Korshikov, 1926). 



Among the more remarkable discoveries of recent times are those showing 

 that even the Volvocales include forms exhibiting an alternation of generations. 

 Thus it has been shown by Strehlow (1929) and Belilau (1935) that ChJoro- 

 brachis gracilUma is the diploid motile stage of Pyrohotrys gracilis. Two other 

 species of Pyrobotrys likewise have a motile zygote (Behlau, 1935). Behlau 

 (1939) has also shown that Carteria ovata is the diploid motile stage of Chlamy- 

 domonas variabilis. 



Judged by their morphology, especially that of the motile cell, the Chloro- 

 phyeophyta show affinities only with the Charophycophyta. The possession by 

 the Euglenophycophyta of chlorophyll a and chlorophyll b suggests that this 

 phylum is related to other green plants. Morphologically the euglenid cell is 

 very different, however, from the motile cell of the green algae, and whatever 

 relationship there may be between these two groups probably is extremely re- 

 mote. Fossil Chlorophycophyta are known from the Ordovician onward. 



The following synoptic outline of the Chlorophycophyta is adapted largely 

 from Fritsch (1935), Smith (1950), and Egerod (1952). 



Phylum CHLOROPHYCOPHYTA Papenfuss (1946, p. 218) 



Syn.: Chlorophyta Pascher (1914, p. 158); Glaucophyta Skuja (1948, p. 63) 

 Class Chloropiiyceae Kiitzing (1843, p. 118) 



Syn.: Chlorospermeae Harvey (1836, p. 163); Glaucophyceae Bohlin (1901, p. 16); 

 Chlorophyllaceae Rabenhorst (1863, p. 117) ; Chlorophyllophyceae Rabenhorst (1868, 

 p. 1) ; Zygophyceae Rabenhorst (1868, pp. 1, 101) ; Isokontae Blackman et Tansley 

 (1902, p. 20) ; Akontae Blackman et Tansley (1902, p. 168) ; Stephanokontae Black- 

 man et Tansley (1902, p. 166); Prasinophyclnees Chadefaud (1950b, p. 988); Eu- 

 chlorophycin^es Chadefaud (1950b, p. 988); Pocillophycinees Chadefaud (1950a, 

 p. 788) 



Order VOLVOCALES Oltmanns (1904, p. 133) 



Syn.: Chlamydomonadales Fritsch, in West (1927, p. 67); Chlorodendrales 

 Fritsch, in West (1927, p. 67) ; Pyramidomonadales Chadefaud (1950b, p. 988) ; 

 Tetrasporales Lemmermann (1915, p. 21) 

 Suborder Volvocineae West (1916, p. 161) 



Syn.: Chlamydomonadineae Fritsch (1935, p. 78) 

 Family Polyblepharidaceae (Blackman et Tansley) Oltmanns (1904, p. 135) 

 Syn.: Polytomellaceae (Blackman et Tansley) Skuja (1930, p. 158) 

 Family Pedinomonadaceae Korschikov (1938; not seen, cited from 

 Skuja, 1939b) 

 Family Nephroselmidaceae Pascher (1913b, p. 110) 



(See Skuja, 1948, pp. 65, 66, 367) 

 Family Chlorovittaceae Schiller (1925b, p. 104) 



Family Chlamydomonadaceae Stein orth. mut. G. M. Smith (1920, p. 90) 

 Syn.: Carteriaceae G. M. Smith (1920, p. 92); Sphaerellaceae 

 (Schmidle) West (1916, p. 166) 

 Family Haematococcaceae (Trevisan) Marchand orth. mut. G. M. Smith 

 (1950, p. 109) 

 Syn.: Protococcaceae (Endlicher) Hassell orth. mut. Nageli (1847, p. 

 153; as to type only cf. Silva and Starr, 1953) 

 Family Spondylomoraceae (Ehrenberg) Korschikov (1923, p. 178) 

 Family Astrephomenaceae Pocock (1954, p. 126) 



Family Volvocaceae Ehrenberg orth. mut. Cohn (1856, p. 323, as Volvo- 

 cin^es) 



Syn.: Pandorinaceae Luerssen orth. mut. Eichler (1880, p. 4) 



