306 HANDBOOK OF PROTOZOOLOGY 



Severe epidemic diseases of fishes are frequently found to 

 be due to myxosporidian infections. According^to Davis, the 

 "wormy" halibut of the Pacific coast of North America is due 

 to the myxosporidian, Unicapsula niuscularis, which invades 

 the muscular tissue of the host fish. The "boil disease" of the 

 barbel, Barhiis barbus and others, of European waters, is caused 

 by Myxoboliis pfeifferi. Lentospora cerebralis which attacks the 

 supporting tissues of salmonoid fish, is known to be responsible 

 for the so-called "twist disease," which is often fatal, especially 

 to young fishes and which occurs in an epidemic form.^ 



The Myxosporidia are divided into three suborders, as fol- 

 lows: 



The largest diameter of the spore at right angles to the sutural plane; 

 one polar capsule on each side of the plane; sporoplasm with- 

 out iodinophilous vacuole Suborder 1 Eurysporea 



The spore spherical or subspherical with one, two, or four polar capsules; 



sporoplasm without iodinophilous vacuole. Suborder 2 Sphaerosporea 



The sutural plane coincides with, or is at an acute angle to, the largest 

 diameter of the spore; one, two, or four polar capsules; sporo- 

 plasm with or without iodinophilous vacuole 



Suborder 3 Platysporea 



Suborder 1 Eurysporea Kudo 

 Family Ceratomyxidae Doflein 



Genus Ceratomyxa Thelohan. Shell-valves conical and hol- 

 low, attached on the bases; sporoplasm usually not filling the 

 intrasporal cavity. The majority in the gall-bladder of marine 

 fish. Numerous species. 



Ceratomyxa mesospora Davis (Fig. 130, a). In the gall 

 bladder of Cestracion zygaena. The dimensions of the spore: 

 Sutural diameter 8 microns, width 50 to 65 microns. 



Genus Leptotheca Thelohan. Shell-valves hemi-spherical. 

 The majority live in the gall bladder or urinary bladder of 

 marine fish and one in amphibians. Several species. 



Leptotheca ohlmacheri (Gurley) (Fig. 130, b-h). In the urini- 

 ferous tubules of the kidney of frogs and toads. Dimensions 

 of spore: Sutural diameter 9.5 to 12 microns; breadth 13 to 

 14.5 microns. 



Genus Myxoproteus Doflein. Spores pyramidal with or with- 



