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SPOROZOA. 



I. Order MYXOSPORIDIA Biitschli, 



1881. 



The Myxosporidia are distinguished by their characteristic 

 spores, which are of various shapes and dimensions. Each 

 spore is covered by a bivalved chitinous membrane called the 

 spore -membrane, the two valves of which are united in a 

 sutural plane, which may be more or less straight or irregularly 



E F G 



Fig. 164. — Some characteristic forms of spores of various Myxosporidia. 

 A, Ceratomyxa truncata Thelohan ; B, Ghloromyxum 

 ■ leydigi Mingazzini ; C, Sphserospora rostrata Thelohan ; 

 D, Myxidium procerum Auerbach ; E, Zschokkella acheilo- 

 gnathi Kudo ; F, Myxoholus carassii Klokacewa ; G, Henne- 

 guya gurleyi Kudo. ( X 1500.) (After Kudo.) 



curved . The surface of the valves may be smooth or marked 

 with ridges, and the form of the spore depends upon the shape 

 of the valves and the presence of accessory appendages. 



Within the shell are polar capsules, which may be one, 

 two or four in number and are usually situated at what is 

 described as the anterior end of the spore. In the family 

 Myxidiidse there are two polar capsules, one near each pole 

 of the spore. Each polar capsule contains a coiled filament, 

 which can be extruded through its pore. The substance 

 contained in the spore, apart from the polar capsules, is 

 designated the sporoplasm. It usually contains two nuclei. 



