SEA-FISHERIES LABORATORY. 295 



impossible to avoid associating the presence of the 

 infusorian with the death of the fish, as no other cause 

 was apparent which would account for the large mortality 

 experienced. It is just possible that the infusorian kills 

 the fish by forming a toxine which is absorbed through 

 the delicate epithelium of the gills, or at the abraded 

 surface of parts of the latter structures. 



Associated with the Ichthyo'phthirii in some of the 

 fishes were infusorians belonging apparently to the genus 

 Trichodina. This is the well-known ciliate found on the 

 common Hydra. The number of specimens found were, 

 however, few, and in such bad condition that the certain 

 determination of the species was not possible. 



Lymphocystis johnstonei, Woodcock. 



A small sole was sent to the Laboratory in April last 

 by Dr. Masterman, H.M. Inspector at the Board of 

 Agriculture and Fisheries. The fish was captured off 

 the East coast of England by a steam trawler, and sent to 

 the officials of the Board in a sample box of various 

 fishes. The fish is an immature female about 7^ inches 

 in total length, and was apparently healthy and in good 

 condition. But the greater part of the surface of the 

 skin was covered over by very small, white, and spherical 

 opaque bodies which were evidently parasites of some 

 kind. They were densely scattered over the ocular side 

 of the fish particularly on the dorsal and ventral regions 

 of the body. On either side of the lateral line the skin 

 was very nearly free from them, but, towards the dorsal 

 and anal fins they became more densely aggregated 

 together. On the fins they were most abundant, par- 

 ticularly on the dorsal fin near the head and on the tip 

 of the pectoral fin. Here they formed dense clusters 

 seated on most of the fin-rays. The skin of the head was 



