The Mastigophora 149 



pattern. Urococcus Kiitzing, in which the pahnella shows a very thick and 

 stratified sheath, has been referred to the family (259). 



Suborder 5. Dinococcina. The dominant phase is a "pyrocystis" or a 

 "crescent-cyst" stage and the flagellate stages are typically gymnodinioid. 

 The non-flagellated stage, which may be floating or sessile, has a cellulose 

 membrane and is enclosed in a sheath composed of pectin. 



Family 1. Phytodiniidae. This group, as the most typical family, shows 

 the characteristics of the suborder. A number of American species have 

 been described by Thompson (270). 



The family includes: Cystodinedria Pascher (226); Cystodinium Klebs (11, 91, 205, 

 208, 225; Fig. 4. 24, A, B); Dinastridium Pascher (205); D'mopodiella Pascher (226; Fig. 

 4. 24, F, G); Dissodinium Klebs (205); Hylmodinhun Klebs (205; Fig. 4. 24, E); Phyto- 

 dinedria Pascher (226; Fig. 4. 24, J, K); Phytodinium Klebs (205); Rnciborskia Wolo- 

 szynska (219); Stylodinium Klebs (11, 205, 226; Fig. 4. 24, L); and Tetradinium Klebs 

 (91, 205; Fig. 4. 24, H, I). According to Baumeister (11), the flagellate stage of 

 "Stylodinium tarnuni" has a theca composed of discrete plates. 



Fig. 4. 25. A-C. Blastodinium spiuulosum Chatton; undivided parasitic 

 stage (A), x210; trophocyte and four small sporocytes (B), x2I0; flagellate 

 stage (C), X1840 (after C). D-F. Haplozoon dogieli, x325 (after Shumway); 

 young parasite (D), trophocyte and gonocvte (E), gonocytes and sporocytes 

 (F). G. Flagellate stage of Haplozoon clymenellae, xl520 (after Shumway). 

 FI-L. Coccodinium duboscqi Chatton and Biecheler, parasitic in Peridinium 

 sp.; growth and nuclear division preceding merogony (H-K); g>mnodinioid 

 stage (L); schematic (after C. & B.). 



