90 Part I11.—Twenty-sizth Annual Report 
of the larve greatly enlarged, while figure 6, Plate VI., represents a small 
portion of the viscera crowded with the parasites and figure 7 on the same 
plate shows a few of them separated out ; both of these figures are from 
photographs enlarged about twice the natural size, 
Like most of the Entozoa mentioned in the preceding notes, these 
parasites of the Porpoise are in their early stages probably migrants, but 
little or nothing appears to be known concerning their life-history. In 
Dr. Cobbold’s opinion “it is highly probable that the embryos enter the 
bodies of various fishes before they acauire sexual maturity. Thence they 
will be passively transferred to the stomachs of cetacea, whence they bore 
their way through the tissues to the bronchi and pulmonary vessels,” and 
thus reach the goal of all their wanderings—an environment where they 
can accomplish the purpose of their life, viz., the development of young, 
on which in their turn will devolve the responsibility for their continuance 
of the species. 
(3) ON THE INgURIoUS Errects or Parasites oN FISHES INFESTED 
BY THEM. 
In the many cases of parasitism that have come under my observation, 
I have usually been unable to notice any very serious results produced by 
the presence of such unbidden and, perchance, unwelcome guests. 
Occasionally evidence of injury apparently caused by them has been 
obtained. 
Whitings and other Gadoids have been captured reduced almost to skin 
and bone, having one or more large worm-like ZLernwa hanging at their 
gills full of the red blood they had extracted therefrom. Yet, even in cases 
like these, it may be a moot point whether the emaciation is caused by the 
Lernea, or that their presence is simply owing to the emaciated condition 
of the fish—the emaciation itself being due to other causes—which by 
reducing the fishes’ vitality has left it more exposed to the attacks of 
these parasites. But though there may be no direct proof that- the 
emaciated condition referred to was caused by these crustacean parasites, 
their presence doubtless tended to aggravate the trouble, and the same 
may be said about the attacks of parasites in other directions. The next 
example of parasitism to which I have to refer shows how these vermin 
(fishermen have a more suggestive name for them) may be injurious to 
fishes in other ways. Figure 5, Plate VI., reproduced from a photograph, 
represents the pectoral fins of a flounder infested with crustacean parasites, 
Lepeophtheirus pectoralis. They are so numerous that a large portion of 
both fins is covered by them. ‘The soft tissues of the fins, more especially 
round the edges and between the spiny rays, was extensively lacerated, 
and this with the added encumbrance of so many beasts hanging on to 
them must have interfered greatly with their movements. These parasites 
are usually found adhering to the underside of the fins, and in this position 
they are more sheltered and less likely to be rubbed off, and the irritation 
they may produce will be the more exasperating. 
A careful scrutiny of the photograph shows considerably over a hundred 
specimens of the Lepeophtheirus adhering to the pair of fins ; they are so 
crowded towards the outer edges of the fins that they overlap each other 
two or three deep, and the delicate margin of the fins has been destroyed. 
