1904-1905-] Copepoda living as Parasites or Messmates. 201 



to refer to, was discovered amongst some material dredged near 

 the Bass Eock in 1893, and was described by my son and 

 myself in the ' Annals and Magazine of Natural History ' for 

 February 1894. By our examination of it we were convinced 

 that it was not a free-living Copepod, but it was not till 1895 

 that we knew its habitat. During the summer of that year 

 the Fishery Board for Scotland ' carried out some line-fishing 

 experiments, when various things were found hanging to the 

 hooks every time the lines were hauled up. One of the 

 things most frequently thus found was the common five- 

 finger star-fish (Asterias ruhens), so I took the opportunity to 

 put a number of these into a large bottle containing fairly 

 strong methylated spirit. After the star-fishes had been vigor- 

 ously shaken to wash off anything adhering to them, the sedi- 

 ment in the jar was carefully examined, when close on a 

 hundred specimens of this new copepod were obtained, and 

 very little else. Later on other star-fishes of the same kind 

 were treated in a similar way, and gave like results, sometimes 

 even more successful than at first. The subsequent examina- 

 tion of numerous examples of Asterias ruhens has shown me 

 that one is more likely to obtain specimens of the copepod on 

 star-fishes brought up on fishermen's lines than on those taken 

 in the trawl-net. Those captured by the trawl are usually 

 considerably knocked about, and the copepods seem to get 

 shaken off. A considerable number of those obtained were 

 adult specimens, and several of the females carried ovisacs. 

 The adult specimens are nearly globular, and are of a brick- 

 red colour on the back, which harmonises so well with the 

 colour and the rough skin of the star-fish that it is difiicult to 

 detect the parasites unless they happen to move about. 



When my son and I described this species we placed it 

 provisionally in the Genus Dermatomyzon Glaus, but as it 

 differed somewhat from the characters of that genus, Dr 

 Giesbrecht instituted a new one — Scottomyzon — for its recep- 

 tion. The species is now known to have a fairly extensive 

 distribution. 



Parartotrogus Richardi T. and A. Scott, a curious little 

 copepod, was first observed in 1889 but not described till 

 1893, as previous to that year we had seen no specimens that 

 appeared to be fully adult, and we were therefore doubtful of 



