PARASITIC DISEASE IN BATRACHIA AND SALMONIDAC. 3 77 
head, gills, throat, and heart, as, with the exception of the 
bit of gill sent, these organs seemed right.” 
On May 1st, and again on the 3rd, I submitted Mr. Simp¬ 
son’s specimens to microscopic, investigation, and although 
neither the long “ white body” in the muscles, nor a similar 
filamentous band two inches in length, and loose in the 
bottle, turned out to be tapeworms, it was soon perfectly 
clear that the mass of parasites from the “ flesh” were 
cestode worms. Some were in capsules, whilst others had 
been liberated, but all, whether encysted or free, were 
sexually immature. At first I thought they might be cap¬ 
suled Trisenophori, but, after soaking in glycerine (by which 
simple device their characters were better brought out), I 
became satisfied that they were very young examples of 
Ligula cligramma. Practically it is, perhaps, of little moment 
as to what species of adult cestode these larvae may be re¬ 
ferred, but I regard L. digramma as a synonym of L. sim- 
plicissima, both of these cestodes being sexually imperfect 
worms. 
Now, the beautiful researches of M. Duchamp have shown 
that the larval Ligula residing in the bodies of various fresh¬ 
water fishes are the young of the Ligula monogramma of 
water birds. Thus, by experiment, M. Duchamp succeeded in 
causing the larval forms which abound in the tench ( Tinea 
vulgaris) to become sexually mature in the common duck. 
He says: “ Cette evolution est extremement rapide : quatre 
jours suffisent pour que les ceufs soient aptes a la repro¬ 
duction.” 
I have examined a considerable number of Ligules from 
different fishes and birds. What has occurred in this in- 
« 
stance is probably as follows : The trout either captured and 
killed or found a dead water-bird, which it ate, together 
with the Lingulae it contained; or, possibly, it swallowed 
part of the strobile of a Ligula which had escaped a living 
bird per anum, as not unfrequently happens. The ingestion 
of the Ligulae set free the contained ciliated ova. The six- 
hooked scolices in their interior migrated from the intestine 
into the flesh beneath the peritoneal membrane, and there 
underwent the usual transformation into young Ligulte. 
These cestodes were so numerous as to seriously incon¬ 
venience the fish, thus giving rise to the disease which I 
call ligulosis. Here was a form of piscine epizooty which, 
though not hitherto so called, has already been recognised 
as capable of affecting fishes fatally. This, as M. Duchamp 
has pointed out, was the case with the trenches in the ponds 
of La Bresse, In the present instance I think Mr. Simpson’s 
