PAPERS ON ZOOLOGY 301 



As to the effect of the parasites upon the host-body, 

 the writer has but little to state. In the ease of infection 

 of the gall-bladder or urinary bladder, the host fish did 

 not show any recognizable effect which may be attributed 

 to the myxosporidian infection. This has been true in 

 almost all cases of the so-called ''free" forms. In the 

 tissue-infecting species, however, some effect was 

 noticed. The heavy infection of Myxoholus discrepans 

 Kudo on the branchial lamellae, apparently reduced the 

 activity of the host, Carpiodes difformis, so that the host 

 fish was caught wdth a small net without much trouble, 

 and also seemed to have quickened the death of the host 

 which occurred shortly after its capture. 



It is noticable that even very young fish, Lepomis sp. 

 which were less than three centimeters in length har- 

 bored a few spores in their gall-bladder which fact must 

 be considered seriously when they are used as experiment 

 animals. It is also noticable that so far the writer has 

 not encountered any species which would produce cysts 

 in the subcutaneous tissues of the body or fins of the host. 



II. MICROSPOKIDIA* 



Little is known about North American Microsporidia. 

 In connection with M^^osporidia, the writer has also 

 been stud™g Microsporidia. The stud}^ has just begun, 

 yet the writer feels justified in stating that this group of 

 Cnidosporidia plays some role in certain aquatic arthro- 

 pods. 



The larvae of Culex pipiens and Anopheles punctipen- 

 nis and the npnphs of Baetis sp. (!), which were col- 

 lected in October from the drainage at Urbana, have 

 been found to be infected by three different Microsporidia 

 respectively. 



Out of 38 larvae of Cidex pipiens examined, six were 

 found to be infected by Thelohania magna Kudo. The 

 adipose tissue and body cavity were the seat of infec- 

 tion, other organs being so far free from the infection. 



* Full account of these Microsporidia will be published in the Journal 

 of Morphology. 



