1902-1903-] Distribution of the Smaller Crustacea. 35 



and for that matter, to any part of the fish ; but the adult is 

 never found anywhere except on the gills of the fish, and 

 usually on the gills of a Gadoid. It may be that only those 

 young Lerngea that happen to attach themselves to the gills 

 are able to survive and reach the adult stage, while those 

 which become fixed to other parts, finding an environment 

 unsuited to the kind of life they have to live, and food 

 differing from that which they require, necessarily perish. 

 But only a knowledge of the life-histories of these parasites 

 will throw light on some of the difficulties that have been 

 alluded to. 



Though the examples of restricted distribution I have 

 referred to are no doubt interesting, the next example I 

 would mention seems to me to be still more remarkable, 

 and a reference to it will, for the present, conclude these 

 observations. It is the occurrence of what appear to be 

 free-living copepods in the nostrils of the cod and of some 

 other teleostean fishes. My attention was first directed to 

 this peculiar habitat by observing a whitish coloured object 

 close to the outer edge of one of the nostrils of a lumpsucker 

 {Cycloptenis Itcmpus). This whitish object, on being carefully 

 examined, proved to be a Bomolockus, apparently identical with 

 Bomolochus solece, Claus, so named from its having been taken 

 by Claus on the back of the common sole (Solea vulgaris). 

 But though the Bomolochus happened to be first noticed in 

 the nostrils of the lumpsucker, it did not appear, from sub- 

 sequent examination, to be very common on that fish. I was, 

 however, not a little surprised to find that the lumpsucker was 

 not the only fish that harboured copepods in its nostrils, but 

 that they were also present in the nostrils of other kinds, and 

 especially in those of the cod-fish. I have examined a con- 

 siderable number of cod-fish since the copepods were first 

 observed, and find that they are moderately common in the 

 nostrils of that fish. My son has obtained them in the 

 nostrils of cod captured in the Irish Sea ; and Mr Lindsay 

 has also found them in the nostrils of cod he examined, and 

 which were caught near the Isle of May. Bomolockus solece 

 has now been got in the nostrils of at least six other 

 kinds of fishes besides the lumpsucker and the cod — viz., the 

 haddock, whiting, saithe (or coal-fish), ling, plaice, and flounder, 



