530 PROTOZOOLOGY 



Family 4 Myxobolidae Thelohan 



One, 2, or 4 polar capsules grouped at anterior end; sporo plasm 

 with iodinophilous vacuole. 



Genus Myxobolus Biitschli. Spores ovoidal or ellipsoidal, flat- 

 tened; 2 polar capsules at anterior end; sporoplasm with an iodin- 

 ophilous vacuole; sometimes with a posterior prolongation of shell; 

 exclusively histozoic in freshwater fish or amphibians. Numerous 

 species. 



^- pfeifferi Thelohan (Fig. 253, e,f). In the muscle and connective 

 tissue of body and various organs of Barhus barhus, B. fluviatilis, 

 and B. plebejus; tumor up to a diameter of 7 cm; most of infected 

 fish die from the effect (Keysselitz) ; spores 12-12.5^ by 10-10. 5/i. 



M. orbiculatus Kudo (Fig. 253, g-i). In muscle of Notropis gilberti; 

 spores 9-10m in diameter by 6.5-7m thick. 



M. conspicuus K. (Fig. 253, j, k). In corium of head of Moxostoma 

 breviceps; tumors 1/2-4 mm.; spores 9-11. 5m by 6.5-8ju. 



M. intestinalis K. (Fig. 1, a). In the intestinal wall of Pomoxis 

 sparoides; (fixed unstained) spores, 12-13m by 10-12.5m; the his- 

 tological changes brought about by this protozoan have been men- 

 tioned elsewhere (p. 27). 



M. squamosus K. (Fig. 253, l-o). In connective tissue below scales 

 of Hybopsis kentuckiensis; spore circular in front view, 8-9m in 

 diameter, 4.5-5iu thick. 



Genus Thelohanellus Kudo. Pyi'iform spores, each with one polar 

 capsule; sporoplasm with an iodinophilous vacuole; histozoic in 

 freshwater fish. 11 species. 



T. notatus (Mavor) (Figs, 1, 6; 253, c, d). In subdermal connective 

 tissue of Pimephales notatus, Cliola vigilax, Notropis cornutus, N. 

 blennius, and Leuciscus rutilus; tumor up to 7 mm, in diameter; 

 spores 17-18m by 7.5-10m; host tissue surrounding the organism be- 

 comes so greatly changed that it appears as an epithelium (p. 27). 



Genus Henneguya Thelohan. Spore circular or ovoidal in front 

 view; flattened; 2 polar capsules at anterior end; each shell-valve 

 prolonged posteriorly into a long process; sporoplasm with an iodino- 

 philous vacuole; mostly histozoic in freshwater fish. Numerous spec- 

 ies. 



H. psorospermica T. (Fig. 253, p). In gills of Esox and Perca; cyst 

 formation; total length of spores 35-40m. 



H. exilis Kudo (Figs. 246; 253, q-s). In gills and integument of 

 Ictalurus punctatus; cysts up to 3 mm. in diameter, conspicuous; 

 spores, total length 60-70^, spore proper 18-20ju long by 4-5/^ wide 

 by 3-3.5ju thick. 



