154 ^ CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



The following arrangement is a synthesis of the systems of Pascher (1931) 

 and Pringsheim (1944). Pringsheim has pointed to certain weaknesses in the 

 classification of Pascher and more recently Skuja (1948) has added to the class 

 the new family Senniaceae and has removed the Nephroselmidaceae to the Vol- 

 voeales in the green algae. 



Class Cryptophyceae (Pascher) Fritsch, in West (1927, p. 387) 



Non Cryptophyceae Thuret, m Le Jolis (1863, pp. 13, 25), nomen nudum 

 Order CRYPTOMONADALES Senn, in Engler (1903, p. 7) 



Syn.: Phaeochrysidales Pascher (1910, p. 9); Phaeocapsales Pascher (1912a, p. 

 196); Cryptocapsales Pascher (1931, p. 325) 



Family Cryptochrysidaceae (Pascher) Pascher (1931, p. 325) 



Family Cryptomonadaceae Ehrenberg orth. mut. Senn, in Engler (1903, 



p. 7) 



Syn.: Phaeocapsaceae De Ton! (1895, p. 591) ; Phaeoplakaceae Pascher 

 (1931, p. 325); Chiiomonadaceae Lemmermaun (1908, p. 473) 

 Family Cyathomonadaceae Pringsheim (1944, p. 149) 

 Family Kathablepharidaceae Skuja (1939b, p. 96) 

 Family Senniaceae Skuja (1948, p. 367) 

 Order CRYPTOCOCCALES Pascher (1914, p. 150) 



Family Cryptococcaceae Pascher (1931, p. 325) 



See the figures of Tetragonidium by Thompson in Smith (1950, p. 636). 



CLASS CHLOROMONADOPHYCEAE 



Characterization: This class embraces a few highly specialized unicellular, anteriorly 

 biflagellate genera (excepting Monomastix, which is uniflagellate, and Mer atrichia, which 

 is laterally biflagellate). The cells are naked, provided with a delicate periplast, meta- 

 bolic, flattened, dorsiventral, ovoid or pear-shaped, and usually possess a longitudinal 

 groove on the ventral surface. The flagella issue from a slight depression — one is directed 

 forwards and the other trails behind along the ventral surface. They are of the same 

 length, except in Thaumatomastix and Yacuolaria viridis, in v/hich the trailing flagellum 

 is longer than the other, and in Gonyostomum, in which it may be shorter or longer than 

 the other. The majority of the forms are green and are provided with numerous discoid 

 chromatophores containing a preponderance of xanthophylls. Nothing is known about the 

 composition of the pigment complex. Two of the genera {Reckertia, Thaumatomastix) 

 are colorless and presumably holozoic. Food is stored as oil. An eye-spot is lacking. 

 Contractile vacuoles are present. Some forms (e.g., Trentonia, Gonyostomum) are pro- 

 vided with an anterior cavity connected by a duct to the exterior and some (e. g., Mero- 

 trichia, Gonyostomum) possess trichocysts. Reproduction is by longitudinal division of 

 the cell. Cysts with a firm gelatinous wall may be produced. 



History: This small class of only seven genera was first established as an 

 autonomous group (Chloromonadina) by Klebs (1892, pp. 292, 391-394) who 

 referred to it the genus Yacuolaria Cienkowski (1870) and forms belonging to 

 Gonyostomum Diesing (1866) and Merotricliia Mereschkowsky (1879) as cur- 

 rently delimited. The first species to have been described sufficiently well to 

 be recognized by later workers is Gonyostomum semen which was described 

 by Ehrenberg (1853) as Monasf semen. Blitschli (1884, p. 819) placed the 

 members known at the time of his writing together with a variety of unrelated 

 genera in his family Coelomonadina. 



Formal recognition of the Chloromonadina as a group of plants begins with 

 Engler (1898, p. 8) and Luther (1899, p. 19) who independently erected for them 

 an order Chloromonadales. Luther placed the order in his class Heterokontae. 



