198 ILLINOIS BIOLOGICAL MONOGRAPHS [436 



four out of nine host fish examined; in two cases in the kidney only, in one 

 case only in the gall-bladder, and in one instance in both gall-bladder and 

 kidney. Cysts were found in the kidney, while only spores were recognized 

 in the gall-bladder. 



Vegetative form: The cysts which could only be detected in sections, 

 lie in the connective tissues of kidney. They are of minute size, ranging 

 somewhat widely from 36m in diameter to 144 by 100/i. According to the 

 authors no definite structure could be found. 



Spore: Rounded oval. It bears quite a close resemblance to that of 

 Myxobolus hylae (page 153), which is slightly longer, and which has a longer 

 polar filament than the present form. The vacuole, however, is apparently 

 not iodinophilous(?). Average dimensions: length 10 to 12ju, breadth 7 to 

 8/x, polar capsules 5 by 2^, length of polar filament 30 to 40^. 



HENNEGUYA AUSTRALIS Johnston et Bancroft 

 1919 Henneguya australis Johnston and Bancroft 1919 : 523-524 



Habitat: In the branchiae of Plectroplites amhiguus; Thomson River 

 at Longreach, Australia. The parasite was detected in four out of nine host 

 fish examined. The infection was extremely light in all cases. 



Vegetative form: The parasites form cysts. They lie embedded in the 

 spongy mass of the gill filament, and in many cases occupy a relatively 

 large area of the section. Cysts showed two layers in section; the outer- 

 most clear ectoplasm and inner endoplasm with developing spores, the 

 central portion of which being filled with mature spores. The spores appear 

 to lie in a definite manner, the long axis of the spore commonly being at 

 right angles to the boundary of the cyst, the anterior end of the spore 

 pointing outwards. 



Spore : Elongated ovoidal. Anterior end pointed, posterior end drawn 

 out into a tail. The tail appears single when the spore is removed from the 

 cyst but separates soon afterward into two halves which usually diverge 

 widely. Two polar capsules parallel to each other are quite frequently of 

 different length. The sporoplasm contains two nuclei and a small vacuole 

 (iodinophilous?). Average dimensions: length 11 to IS/x, breadth 3 to 5/i, 

 thickness 3 to 4/z, polar capsules 5 to 6^ by 1 to 2jli, length of tail about 20/Lt. 



HENNEGUYA GRACILIS Johnston et Bancroft 

 1919 Henneguya gracilis Johnston and Bancroft 1919 : 524-526 



Habitat: In the gill filament of Therapon hillii; Thomson River at 

 Longreach, Australia. Out of thirteen specimens examined, eight were 

 infected. Heavy infection was recognized only in one case. 



Vegetative form: The cyst is of definite, narrow, pear-shaped form, and 

 lie transversely, i.e., at right angles to the long axis of the gill filament. 



