Nos. 618-619] RESTOCKING INLAND WATERS 343 



taken in Lake Clear were attached to either the dorsal or 

 anal fin. The gills of these fish were examined but no 

 fish-lice noticed upon them. This seems strange as 

 Fasten (1911-12) reports them as especially abundant 

 upon the gills. They were found on trout ranging from 

 four inches in length to those fourteen inches long, which 

 were caught in Trout Brook, in the lake near the mouth 

 of this inlet, station 1, and in the bay near station 5. 

 They were taken upon both large and small fish in each 

 of these locations. My specimens were collected during 

 July, August and September. The last specimens were 

 on a nine-inch male caught in Big St. Germain Bay, Sep- 

 tember 28, 1916. The egg-sacs were full of embryos. 



This common " fish-louse" is easily recognized. From 

 the main part of the body two large egg-sacs are sus- 

 pended. With an ordinary hand lens, the numerous 

 small embryos can be noted, and the small beak which 

 attaches the parasite to its host. Fasten has recently 

 worked out the life history and the habits of this inter- 

 esting parasite, which undergoes an extensive degenera- 

 tion after becoming parasitic. 



These parasites are widespread in the United States in 

 the native trout streams, and in Canada and Europe. 

 The first scientific record of this particular parasite is by 

 Linnaeus in 1761. It seems strange that an animal could 

 be known for so long and its habits not be understood 

 until within the past five years. The fact that it is so 

 widespread and has been known for so long indicates that 

 it is not a serious pest except under very favorable 

 living conditions. These are best found in the hatcheries 

 or stock ponds, where many fish live in a small enclosure. 

 The numerous parasitic larvae then have little trouble in 

 finding a host. In the streams and ponds of this state, 

 we need not fear that the trout will be killed by them. 

 The chief reason is that the trout are few in numbers in 

 any given place, so that when the embryo parasites make 

 their escape, there is small chance of their ever becoming 

 attached to a trout. The result is that each trout in a 



