150 The Mastigophora 



Family 2. Blastodiniidae. This group (36) includes intestinal parasites 

 of copepods and sessile polychaetes; ectoparasites of copepods, annelids, 

 and salpids; intracellular parasites of Siphonophora, tintinnioid ciliates, 

 Radiolarida, and eggs of copepods; and parasites of the body cavity in 

 copepods. Amyloodinium (Fig. 4. 19, A-C) parasitizes the gills of marine 

 fish (26, 199), and Oodinium limneticum (118) has been described from 

 the same location in fresh-water fish. Chromatophores are present in some 

 Blastodiniidae and absent in others. 



In a representative life-cycle (Fig. 4. 25, D-F), the young parasite divides 

 into two cells, a "trophocyte" and a "gonocyte." The latter undergoes a 

 number of divisions to produce "sporocytes" which develop into gymno- 

 dinioid flagellates. In the meantime, the trophocyte may divide into a 

 second gonocyte and a trophocyte. The second gonocyte produces another 

 generation of sporocytes, and the procedure may be repeated several 

 times. This pattern is not followed in Amyloodinium, which apparently 

 does not produce differentiated trophocytes and gonocytes. 



The family includes Amyloodinium Hovasse and Brown (115; Fig. 4. 19, A-C), 

 Apodinium Chatton (36), Atelodinium Chatton (36), Blastodinium Chatton (36; Fig. 4. 

 25, A-C), Chytriodinium Chatton (36), Duboscquella Chatton (36), Endodinium Hovasse 

 (111), Haplozoon Dogiel (258; Fig. 4. 25, D-G), Merodinium Chatton (37) from Radio- 

 larida, Oodinium Chatton (36, 112), Paradinium Chatton (37), Protoodinium Hovasse 

 (112), Syndi7iium Chatton (36), and Trypanoditiium Chatton (36). Coccodiuium Chat- 

 ton and Biecheler (Fig. 4. 25, H-L), parasitic in other dinoflagellates, possibly should 

 be referred to this family. 



Family 3. Ellohiopsidae. These ectoparasites of Crustacea resemble the 

 Blastodiniidae in their parasitic stages, but the known free-living stages 

 show no obvious relationships to dinoflagellates. Therefore, the tax- 

 onomic position of the group is uncertain. Ellobiopsis Caullery (32) is 

 the type genus. 



Order 5. Phytomonadida 



These flagellates are mostly ovoid to spherical, but various spindle- 

 shaped, hemispherical, flattened, and spirally twisted types are known. 

 Medusochloris phi ale, one of the more unusual forms, is a medusa-like 

 flagellate which swims mainly by contractions of the body (204). Except 

 in the Polyblepharidae, the body is enclosed in a distinct membrane, com- 

 posed at least partly of cellulose. In the Phacotidae the membrane is im- 

 pregnated with calcium salts to form a "shell." One to eight, but usually 

 two or four flagella are present. The flagella of membrane-covered species 

 may emerge through one opening or through individual flagellar pores 

 (Fig. 4. 26, A-C). In the first case the flagella may or may not arise from a 

 cytoplasmic papilla. Contractile vacuoles vary in number and position, 

 but there are often two near the bases of the flagella. A single large green 

 chromatophore is typical, although two or more smaller ones occur in 



