152 ILLINOIS BIOLOGICAL MONOGRAPHS [390 



capsule, 6.5/x by 2n, polar filament 3 to 4 times the length of the spore 

 (42.9 to 57.2)Li). Polar filament coiled 10 to 14 times. Shell thin, almost 

 invisible. The spores found in the gill: length 12 to 13.4ju, breadth 6/i to 

 10.4ai. a vacuole is present in the sporoplasm. 



Remarks: Examination of Hahn's first paper suggested that he was 

 dealing with the present form as a new species tho he did not mention 

 at all Keysselitz who gave the name Myxoholus musculi Keysselitz to 

 the parasite of Barbus fiuviatilis from German riverg. I was informed by 

 Hahn that he gave the name, Myxoholus musculi, without knowing the 

 fact that it was preoccupied by Keysselitz (1908) (see page 148) and that 

 tho he became aware of it later, he can not determine differences by which 

 the two forms can be distinguished. A comparison of the descriptions 

 of Keysselitz and Hahn, however, shows that these two forms differ in 

 several respects. Hence the latter form is recorded here as a distinct 

 species under the new name. 



It is interesting to note that very similar forms, one without an iodino- 

 philous vacuole at any stage of spore-formation (Myxosoma funduli Kudo, 

 see page 125) and the other with a vacuole, occur in the same hosts 

 in the same locality. As mentioned above, the reader is requested to refer 

 to Hahn's original paper for further data. 



. MYXOBOLUS PLEURONECTIDAE Hahn 



[Fig. 477] 



1917 Myxoholus pleuronectidae Hahn 1917 : 160-161 



Habitat: Subcutaneous muscular tissue of Pseudopleuronectes ameri- 

 canus; Woods Hole. 



Vegetative form : Similar to that of Myxoholus f unduli. 



Spore: Hahn writes as follows: Shape and appearance resembles 

 Myxoholus pfeifferi. Dimensions: length 14.5/x, breadth 11.9ju, polar 

 capsules 6n by 3.7 fx. 



MYXOBOLUS CAPSULATUS Davis 



[Fig. 478] 

 1917 Myxoholus capsulatus Davis 1917 : 237 



Habitat: Visceral connective tissues of Cyprinodon variegatus; Beaufort. 



Vegetative form: Irregular form. In the state of diffuse infiltration. 

 Polysporous. 



Spore: Pyriform, flattened. Polar capsules large and pyriform, filling 

 almost entire cavity of the spore. Sporoplasm relatively small. lodino- 

 philous vacuole visible in living spore. Dimensions: length 16)li, breadth 

 10 to 1 Iju, polar capsules 1 1/x by 4/i, length of polar filament 84/i. 



