THE MYXOSPORIDIA, OR PSOROSPEUMS OF FISHES. 107 



Liver (exclusive of gall bladder and ducts). But two species are 

 known here, and these are the two wliich have the widest organal 

 range, viz; Myxobolus elUpsoides and Myxoholus sp. 51. 



Kidney. — In only a few instances has any distinction been made 

 between the stroma of the kidney and the tubules. It seems, however, 

 not improbable that, as regards organal distribution, a distinction 

 should be made, and the tubules be regarded as a part of the hollow 

 fluid-filled urinary tract, the stroma forming a solid connective tissue 

 seat. The following occur here: 



"Kidney": M. piriformis, M. brachycysfis, 3f. milUeri, Myxoholus sp. 

 51, 31. ? sp. Go, M. diplurus. 



Kenal tubules: Myxobolus brevis, M. medius, Ghloromyxum (S.) elegans, 

 C. (S.) ohhnacheri. 



Spleen.— This organ ha,s furnished: Myxobolus piriformis, M. brachy- 

 cysfis, M. EUipsoides, M. sp. 51. 



Ovary.— From this are known: Myxobolus miilleri, M. sp. 51, M. 

 brevis (2 hosts), M. medius (2 hosts), M. ef. creplini, Ghloromyxum (S.) 

 elegans (2 hosts), G. sp. 91. 



Excretory tract.— Fov purposes of organal distribution, the gall and 

 urinary bladders should be considered together, as they present prac- 

 tically identical environmental conditions, both being internal (which 

 means a uniform temperature) and both being fluid-filled. To these 

 cavities may perhaps be added, as exhibiting similar conditions, the 

 bile-ducts and the renal tubules. 



If, now, we consider this tract as a whole, we find that its rich and 

 peculiar fauna stands in strong contrast to the species inhabiting the 

 remaining organs. For we find absolutely confined to it the following: 

 The Ghloromyxidw except only Ghloromyxum dujardini, the Gystodiscidw, 

 except the insecticolous Gystodisctis f ? diploxys, and the Myxidiidce. 

 Besides these, only the following species occur in this tract: 



{a) In the gall bladder: Genus incert. sp. 9, '^Myxosporidium^^ congri,^ 

 Myxobolus ? merlucii.^ 



(6) In the renal tubules : Myxobolus brevis, Myxobolus medius. 

 In the following table all the species— 47 in number— whose generic 

 references are fairly certain and whose seats are known, are compared 

 as regards their organal distribution. The unit adopted is the occur- 

 rence of 1 myxosporidian species in 1 organ of 1 host. The number of 

 such "occurrences" is shown for each species by the Eoman, and for 

 each genus by the Arabic numerals. 



' Spore unknown (genus f See pp. 110, 182). 



« Generic reference, in the almost entire absence of a description, by no means 



certaio. 



