118 The Mastigophora 



form of the body, which often shows dorso- ventral differentiation; some 

 genera have an open ventral "pharyngeal" groove; in others the groove is 

 closed, posteriorly or throughout its length, to form a pouch; refractile 

 granules ("trichocysts") usually lie just beneath the wall of the groove 

 or pouch; there may be a single bilobed chromatophore or two or more 

 chromatophores which are usually brown, less commonly red, blue, blue- 

 green, or green; starch and lipids are stored. 



(4) Dinoflagellida: biflagellate forms, typically with two grooves, a 

 transverse girdle and a longitudinal sulcus in the body wall or theca; one 

 of the flagella typically lies in the girdle; chromatophores, when present, 

 are usually golden-brown to dark-brown, sometimes green or bluish-green; 

 starch and lipids are stored. 



(5) Phytomonadida: except in one family, there is a distinct membrane 

 of cellulose or pectins, or a test impregnated with calcium or iron salts; 

 usually two or four, sometimes eight flagella; there is often a single cup- 

 shaped chromatophore; one or more pyrenoids are usually present; chloro- 

 phyll typically is not masked by other pigments; starch and lipids are 

 stored; red haematochrome accumulates in some species. 



(6) Euglenida: relatively large forms, usually with one or two flagella 

 arising from an anterior reservoir ("gullet"); pellicle may be flexible or 

 relatively rigid; green chromatophores, usually numerous and equipped 

 with pyrenoids; reserves include paramylum and lipids; some species 

 accumulate red haematochrome. 



(7) Chloromonodida: typically biflagellate, one flagellum trailing; the 

 body is often flattened dorso-ventrally, with a shallow groove on the 

 ventral surface; presence of a cytopharynx, reported for some species, has 

 been denied (232); chromatophores, when present, are typically numerous 

 and grass-green (or "meadow-green"); no stigma is reported; lipids are 

 stored. 



Order 1. Chrysomonadida 



This group, represented by fossils from Upper Cretaceous to recent 

 deposits, is widely distributed in salt, brackish and fresh water. Although 

 chromatophores occur in the majority, colorless holozoic species are com- 

 mon and there is a marked trend toward holozoic nutrition in many pig- 

 mented types. Formation of pseudopodia is fairly common. Some species 

 possess delicate pseudopodia which superficially resemble the myxopodia 

 of Foraminiferida and capture food in comparable fashion. Others form 

 lobopodia. Non-flagellated amoeboid and palmella stages are not unusual 

 and have become the dominant phase in some life-cycles. Most species 

 measure less than 50[j, and the majority probably less than half as much, 

 although some fossils exceed 100[x. One, two, or three flagella may be 

 present; if two, they may be equal or unequal in length. Mastigonemes 



