298 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



closely apposed granules, which take chromatic stains 

 very easily. Close underneath the capsule, again, are a 

 number of smaller, more closely aggregated collections of 

 similar granules, usually spherical, or nearly so, in shape, 

 and staining less deeply than the reticula just described. 



Most of the structures above described are to be seen 

 in the remarkable sporozoan, Lymphocystis johnstonei, 

 described by Woodcock,* and it is difficult not to identify 

 the two parasitic structures as the same organism. The 

 mode of occurrence of the structures — on the skin and 

 fins — is the same, and despite the difference in size I 

 regard it as probable that in the case just described we 

 have to deal with an invasion of Lymphocystis individuals, 

 and that the nature of the host and, particularly perhaps, 

 the nature of the skin of the sole — where we find strongly 

 ctenoid scales, instead of the comparatively soft cycloid 

 structures found in the flounder — is the reason of the 

 difference in size. The difference in diameter, 0"32 mm. 

 and 1 to 1*5 mm. in the sole and flounder respectively, 

 may easily be explained by such considerations, and cne 

 may, indeed, find many examples of analogous differences 

 in size in identical parasitic species living on somewhat 

 different hosts. 



IV.— DERMAL CATARRH IN SALMON AND DAB. 



Two cases of pathological changes in the skin of 

 fishes have been observed which do not appear to be 

 referable to parasitic invasions of any kind. In 

 September, 1904, Mr. R. Okell sent me some salmon pan- 

 caught in a stream near Douglas which appeared to be 

 suffering from some obscure skin disease, obviously not 

 due to Saprolegnia. Fish thus infected were quite 



* In An. Eept. Lancashire Sea Fish. Laby. for 1903, pp. 63-72. 

 pi. III. 



