1902-1903.| Duzstribution of the Smaller Crustacea. 9 
Hucheia norvegica, 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 G. 8. 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 Java, 
an ostracod discovered in this loch many years ago by the 
Rev. 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 bidiscalis, 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 Lernwenicus sprattce (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 
Lerneenicus, which is buried deep in the substance of the eye, 
