1 902-1903.] Distribution of the Smaller Crustacea. 31 



Euchceta normgica, Boeck,^— another of Sir John Murray's 

 additions to the British fauna. This copepod is found, some- 

 times in great abundance, in the deep water of Upper Loch 

 Fyne, so much so that a large drop-jar may be filled by a 

 single short haul with the tow-net. It is also got, but more 

 sparingly, in other parts of the Clyde area. Yet it is so 

 scarce in other parts of the British seas that there is no 

 mention of it in the excellent ' Monograph of the British 

 Copepoda,' by Professor Gr. S. Brady, published in 1878-80; 

 and I have never once met with it on the east coast of Scot- 

 land, and only occasionally off the Shetland Islands. There 

 are similar interesting examples among fresh-water species, 

 such as the occurrence in Duddingston Loch of Cyprois flava, 

 an ostracod discovered in this loch many years ago by the 

 Eev. A. M. Norman, and which I have occasionally found 

 there. On one of these occasions the species was moderately 

 common, yet it is doubtful if this ostracod is found living 

 anywhere else in Britain. Other examples might be given, 

 but I shall rather proceed to notice the curious habitats of 

 some of the parasitic species. 



Although a number of the parasitic crustaceans found on 

 fishes are not confined to one particular kind of fish, such, for 

 example, as Caligus rapax, — a species which seems to have a 

 kind of " roving commission," — the habitat of many of them 

 is limited to a particular kind of fish, and sometimes even to 

 a particular part of the fish. This is well shown in the case 

 of Lerneopoda Udiscalis, de Vismis Kane. This parasitic 

 copepod has hitherto only been found adhering to the ends of 

 the claspers of male specimens of the tope (or toper), — a large 

 kind of dog-fish. The ends of the claspers, where these 

 parasites adhere, are frequently lacerated and bleeding. 

 Whether the laceration is caused directly by the parasite, or 

 by the efforts of the fish to shake off its tormentors, is not 

 known. The LerncKenicus sprattoe (Sowerby), found on the eye 

 of the sprat, is another interesting example of limited distri- 

 bution, for not only is the species confined to the sprat, but it 

 is also confined to the eye of the fish. Another species of the 

 same genus is found on the eye of the herring, and a Lerneo- 

 poda on the eye of the Greenland shark. The head of the 

 Zernoeenims, which is buried deep in the substance of the eye, 



