ON COPEPODS LIVING IN THE NOSTRILS OF FISHES 155 



species belonging to the Ergasilidae noticed in this paper is 

 twenty -two, and thirteen of them belong to the genus 

 Bomolochus. On referring to the habitats of the various 

 species, not- only of Bomolochus but also of those belonging 

 to the other two genera, we find that in no case are any of 

 them described as occurring in fishes' nostrils. This is the 

 more remarkable from the fact that Bomolochus does not 

 seem to be at all rare, especially in the nostrils of the Cod. 

 Moreover, the Copepods are not limited in their distribution 

 to the Cod-fishes of the north-east of Scotland, for my son 

 informs me that quite recently he has found them in the 

 nostrils of Cod caught in the Irish Sea. As a matter of fact, 

 they are found in the nostrils of most of the Cod-fishes I 

 examine ; frequently several, and occasionally a considerable 

 number of, specimens are found in the nostrils of a single 

 fish. In the nostrils of a moderately large Cod from the 

 Moray Firth I found as many as twenty-nine specimens of 

 Bomoloclms. They included males, females (carrying ovisacs), 

 and young. In the nostrils of another Cod caught in the 

 salmon-nets in the Bay of Nigg, near Aberdeen, twenty-four 

 specimens were obtained ; several of these, when removed 

 from the mucus with which they were surrounded and put 

 into clean water, were very lively and very pretty. In 

 seeking for them, the method I adopt is very simple. With 

 the edge of my knife I press gently but steadily on the skin 

 behind the nostrils till the mucus is forced out of the 

 openings, when the Copeods, if they be present, usually appear 

 as whitish specks amongst the mucus ; but as some may be 

 more transparent than others, it is better to transfer the 

 mucus into some water in a shallow glass vessel placed on 

 a sheet of black paper, or other dark -coloured substance. 

 The mucus can then be spread out with a camel's-hair pencil, 

 when the Copepods will come clearly into view, and especially 

 if the eyes be assisted with a hand-lens. 



The fact that the same species of Bomolochus should be 

 found in the nostrils of such distinctly different fishes as the 

 Lumpsucker, the Cod, and the Plaice, is of interest as showing 

 a greater adaptability than would seem to be the case with 

 some other of our parasitic Copepods affecting fishes. 



