PAPENFUSS: CLASSIFICATION OF THE ALGAE 137 



Order EUGLENALES Engler (1898, p. 7, as "Reihe") 



Syn.: Euglenocapsales Pascher (1931, p. 326), 7wmc7i nudum, based on Eugleno- 

 cajisa Steinecke (1932); Euglenomonadales Chadefaud (1950a, p. 789) 

 Family Euglenaceae Stein ortli. mut. Klebs (1883, p. 296) 



Syn.: Eutreptiidae Hollande (1942, p. 168); Distigmidae Hollande 

 (1942, p. 168) ; Euglenocapsaceae Pascher (1931, p. 326), nomen nudum 

 Family Astasiaceae Ehrenberg orth. mut. Senn (1900, pp. 174, 177) 

 Family Peranemaceae Klebs orth. mut. Senn (1900, pp. 174, 178) 



Syn.: Menoidiidae Hollande (1942, p. 168) 

 Family Rhynchopodaceae Skuja (1948, p. 233) 

 Family Rhizaspidaceae Skuja (1948, p. 235) 

 Order COLACIALES G. M. Smith (1938, p. 148) 



Family Colaciaceae G. M. Smith (1933, p. 612) 



Phylum Chrysophycophyta 



This phylum (as Chrysophyta) was established by Pascher in 1914 (cf. also 

 Pascher, 1921) to encompass the three classes Xanthophyceae, Chrysophyceae, 

 and Bacillariophyceae. Although the Bacillariophyceae appear to be only re- 

 motely allied to either the Xanthophyceae or the Chrysophyceae, a good deal 

 of evidence is at hand that points to a close relationship between the latter two 

 classes (Pascher, 1911, 1921, 1932, 1937). 



The more important features of correspondence between the three classes 

 as stressed by Pascher (1914, 1921, 1924, 1937, pp. 155-173) and other authors 

 are: (1) storage of leucosin or oil as food reserves in members of all three 

 classes; (2) formation of a distinctive type of endoplasmatic spore (cyst) with 

 a usually silicified wall of two pieces; (3) possession by the vegetative cells of 

 some Xanthophyceae {OpJiiocytium, Tribonema) of a wall of two pieces com- 

 parable to that of the diatom frustule and that of the cysts of all three classes; 

 (4) growth in length of the. cell wall by the deposition of thimblelike segments 

 or intercalary bands in certain members of all three classes. 



Although the pigmented members of these three groups usually have yellow- 

 green or golden-brown chromatophores and it has consequently been assumed 

 that they possess similar pigment complexes, it is now known that there are some 

 significant differences (Strain, 1951, p. 253). The three classes are considered 

 separately below. 



CLASS XANTHOPHYCEAE 



Characterization: This class is comprised of forms which in the vegetative condition 

 are: (1) unicellular, naked, and terminally biflagellate, excepting Nephrocliloris which 

 appears to be uniflagellate; (2) unicellular and amoeboid; (3) unicellular, nonmotile, 

 and in the form of gelatinous aggregates of various shapes and sizes (palmelloid types) ; 

 (4) unicellular, nonmotile, provided with a firm cell wall, and usually attached by a short 

 mucilaginous stalk (coccoid types); (5) simple or branched septate filaments which may 

 or may not be attached; or (6) vesicles or nonseptate branched filaments. 



In the flagellated species and in the zoospores of the nonflagellated members of the 

 class, the two flagella are of unequal length and the longer flagellum is beset with cilia. 

 The majority of the species are pigmented, being yellow-green owing to a preponderance 

 of carotenoid pigments. Depending upon the species, the cells have one to many plastids 

 which are usually of a discoid shape. The pigment complex consists of chlorophyll a, 

 chlorophyll e (in Tribonema) , beta-carotene, and xanthophyll. Pyrenoids are only rarely 

 present and are of the naked type. Reserve food is stored as oil or leucosin. Rarely cer- 



