468 PROTOZOOLOGY 



Genus Merocystis Dakin. Spoiogony in the kidney of the whelk, 

 Buccinum; schizogon}- unknown, in another host (possibh- a crab); 

 microgametocj^tes produce first cytomeres which in turn form 

 microgametes ; anisogamy gives rise to zygotes, zygote forms many 

 sporoblasts, each developing into a spore; spore spherical, with 2 

 sporozoites. One species. 



M. kathae D. (Fig. 218, a, h). In the kidney of Buccinum un- 

 datum; spores spherical, about 14/i in diameter. Patten (1935) 

 studied its life cycle and found that during microgametogenesis and 

 sporogony, 6 chromovsomes occur. She added that meiosis occurs in 

 the zygote which is the only diploid stage as in Aggregata eberthi. 



Genus Pseudoklossia Leger and Duboscq. Anisogamy and spo- 

 rogony in the kidney of marine mussels; oocyst or zygote produces 

 numerous spores; spore with 2 sporozoites; no residual body; schi- 

 zogony unknown, in another host. 



P. pectinis L. and D. (Fig. 218, c). In kidney of Pecten maximus 

 in France; association of 2 sporozoites which are 3.5m in diameter. 



Genus Caryotropha Siedlecki. Both schizogony and sporogony 

 take place in a host. One species. 



C. mesnili S. In coelom (in floating bundles of spermatogonia) of 

 the polychaete, Polymnia nebulosa; schizogony in bundle of sper- 

 matogonia, in which cytomeres with 10-16 nuclei and then mero- 

 zoites are formed; schizogony repeated; gametocytes undergo de- 

 velopment also in the same host cells; microgametes become set 

 free in coelom, where union with macrogametes takes place; each 

 oocyst forms about 16 spores; spore with usually 12 sporozoites; 

 cysts are extruded with the reproductive cells of the host worm. 



Genus Myriospora Lermantoff. Anisogamy and sporogony in 

 marine snails; schizogony unknown; oocyst forms numerous spores 

 each with 2 sporozoites. One species. 



M. trophoniae L. In the polychaete, Trophonia plufnosa; macro- 

 gametes, vermiform, up to 800/x long, later ovoid; microgameto- 

 cyte forms first about 100 cytomeres, each with some 20 nuclei; 

 microgametes comma-shaped; anisogamy; ooc3^st with several hun- 

 dred spores, each with about 24 sporozoites. 



Genus Hyaloklossia Labbe. Schizogony unknown; sporogony in 

 the kidne.v of marine mussels; oocyst in the organ-cavity; spherical 

 spores of 2 kinds: smaller one with 2 spirally coiled sporozoites and 

 the other with 4-6 sporozoites. One species. 



H. pelsenecri Leger. Spherical oocysts 75-80/^ in diameter; spores 

 8m and 11-12^ in diameter; in kidney of Tellina sp. and Donax sp. 



