466 



PROTOZOOLOGY 



Family 1 Selenococcidiidae Poche 



Vermiform body and gametic differentiation place this family 

 on the borderline between the Coccidia and Gregarinida. 



Genus Selenococcidium Leger and Duboscq. Nucleus of vermi- 

 form trophozoite divides 3 times, producing 8 nuclei; trophozoite 

 becomes rounded after entering gut-epithelium and divides into 

 8 schizonts; this is apparently repeated; schizonts develop into 

 gametocytes; microgametocyte produces numerous microgametes; 

 gametic union and sporogony (?). One species. 



Fig. 216. Selenococciduim intermedium, X550 (L^ger and Duboscq). 

 a, schizont in host gut; b, c, schizogony; d, microgametocyte; e, micro- 

 gametes; f, macrogametocyte; g, macrogamete; h, zygote (oocyst). 



S. intermedium L. and D. (Fig. 216). Octonucleate vermiform 

 schizont 60-IOOm long, and divides into vermicular merozoites in 

 gut cells; parasitic in gut lumen of European lobster. 



Family 2 Aggregatidae Labbe 



Anisogamy results in production of zygotes which become trans- 

 formed into many spores, each with 2-30 sporozoites; in schizogony 

 cytomeres first appear and then merozoites; alternation of genera- 

 tions and of hosts which are marine annelids, molluscs and crus- 

 taceans. 



Genus Aggregata Frenzel. Schizogony in a crustacean and sporo- 

 gony in a cephalopod; zygote produces many spores, each with 3 

 sporozoites. Many species. 



A. eherthi (Labbe) (Fig. 217). Schizogony in Portunus depura- 

 tor and sporogony in Sepia officinalis. Spores (a) germinate in the 

 crab gut, each liberating 3 sporozoites (6) which grow and produce 

 merozoites (lO/x by 2^) by schizogony in peri-intestinal connec- 

 tive tissue cells (6 chromosomes) (c-/) ; when host crab is eaten by 



