CNIDOSPORIDIA, MYXOSPORIDIA 



529 



M. cerehralis (Hofer) (Fig. 253, a). In the cartilage and perichon- 

 drium of salmonoid fish; young fish are especially affected by in- 

 fection, the disease being known as the "twist-disease" (Dreh- 

 krankheit); spores 6-10m in diameter. 



Fig. 253. a, Myxosoma cerehralis, X800 (Plehn); b, Agarella gracilis, 

 X1660 (Dunkerley); c, d, Thelohanellus notatus, X1530 (Kudo); e, f, 

 Myxobolus pfeifferi (e, section of a cyst; f, spore treated with Lugol, 

 X17S0) (Keysselitz) ; g-i, M. orbiculatus (g, infected muscle, X600; h, a 

 fresh spore; i, Lugol-treated spore, XlOOO) (Kudo); j, k, M. conspicuus, 

 X1530 (Kudo); l-o, M. squamosus (1, a cyst under a scale, X6.5) 

 (Kudo); p, Henneguya psorospermica, X1330 (Th^lohan); q-s, H. exilis, 

 X1530 (Kudo). 



Genus Agarella Dunkerly. Spore elongate oval; 4 polar capsules 

 at anterior end; shell prolonged posteriorly into long processes. One 

 species. 



A . gracilis D. (Fig. 253, h). In the testis of South American lung- 

 fish, Lepidosiren paradoxa. 



