Maddox, on Parasites of the Common Haddock. 97 
On turning to Dr. Cobbold’s valuable work on Entozoa, 
at p. 36 is figured a Distoma, the “ Gasterostoma gracilescens 
(Wagener), from the intestines of the angler, Lophius pise a- 
torius, magnified 60 diam.,” very like the subject of the 
present article, in a more advanced condition. Indeed, I 
think, as we shall presently see, it is more than probable 
that this is one of the higher phases of Distoma neuronaia 
Monroii in its free state of Gasterostoma — Dr. Cobbold 
writes, “ In this singular genus the ventral sucker seems 
to have taken the position usually assigned to the oval 
opening, whilst the latter is placed lower down, towards the 
centre of the body. The digestive caeca also disappear, 
leaving only a short stomachal cavity, which reminds one of 
the same viscus in the imperfectly organised sporocysts or 
redke. The yelk-forming glands exhibit conspicuous, round, 
secreting cells, the testes also being largely developed. I 
have also noticed two other small bodies, one of which 
probably represents the ovary or germ stock, whilst the other 
may be referred to the receptaculum seminis, or posterior 
seminal vesicle of Yon Siebold. This connection between 
these several organs is not seen in this specimen, but their 
relative position is well shown. When the species first 
came under my observation I naturally followed Rudolphi, 
w T ho described this Trematode as a Distoma (. Distoma graci- 
lescens , Eudolphi). I remember seeking most diligently for 
the digestive tubes, being greatly puzzled, not merely by 
their absence, but also by the character and position of an 
organ which we now well know to be the sheath of the intro- 
mittent appendage. The uterus also terminates in its imme- 
diate vicinity, opening externally by a common outlet. The 
anatomy of this genus has been pretty fully illustrated by 
Yon Siebold. According to Molin, the excretory, water- 
vascular organ (or respiratory apparatus, as he interro- 
gatively puts it) consists (in Gasterostoma fimbriatum ) of a 
broad central tube, occupying the entire length of the body. 
In connection with this tube he did not discern any branches, 
but he represents it as a simple sac, opening externally at the 
caudal extremity.” 
Now, referring to Couch’s excellent work on ‘ Fishes,’ 
vol. ii, 1863, p. 129, art. “ Lophius piscatorius,” he says, 
the angler sometimes seeks its prey at mid-water, — a fisher- 
man had hooked a codfish, and while drawing it up he felt 
a heavier weight had attached itself to his line ; this proved 
to be an angler. How indiscriminately these fishes feed on 
each other appears from the fact that, in the stomach of an 
angler which measured two feet and a half in length, was 
