98 Maddox, on Parasites of the Common Haddock. 
found a codfish that measured two feet; and in the latter 
were the skeletons of two whitings, within which again were 
other small fish.” As similar parasites, as previously noticed, 
are found in the cod, haddock, and whiting, it is possible 
that in the angler the Distoma neuronaia Monroii finds its 
perfect habitat, unless again through the angler it still passes 
to some larger predatory fish — I hardly think to the seal or 
birds. The food of the haddock is chiefly shell-fish. Couch 
recommends naturalists to search in them for interesting 
species — he having found twelve separate species among a mul- 
titude of univalve and bivalve shells. Perhaps here begins the 
earliest stage of the parasite, so imperfectly noticed in this 
article, but which I hope to have shown presents much 
interesting matter for future research. 
Note. — From Dr. Sharpey’s letter to Mr. Goodsir, as pub- 
lished in the f Anatomical and Pathological Observations 
i( When in Berlin some years ago, the late Professor Ru- 
dolphi remarked to me in conversation, that he thought it 
not unlikely the little bodies discovered by Dr. Monro (second) 
on the nerves of the cod, haddock, and other allied fish, 
would turn out on examination to be entozoa : and he su£t 
gested that I should take an opportunity of inquiring into 
the point, on my return to Scotland. Accordingly, in the 
autumn of 1836, I examined these bodies in the haddock or 
whiting, I really forget which, but I think it was the former, 
and found that each of them was a little cyst, containing a 
distoma, which could be easily turned out from its enclosure 
aliveJ The specimens I examined were from the membranes 
of the brain. This observation was made in Edinburgh, and, on 
going to London soon after, I mentioned the fact to Mr. 
Owen ; and I have been accustomed to take notice of it in 
my lectures ever since, suggesting at the same time that it 
would be well to search for these or for analogous parasites 
in the nerves of other animals, as it was not likely that the 
Gadus tribe of fishes should be the only example.” * * * * 
“ Rudolphi, as far as I know, never examined the structure 
of the spheroidal bodies of Monro ; and the only notice of 
them I have met with in his writings (to which he did not 
refer me) is in his f Historia Naturalis Entozoorum, 5 vol. ii. 
Part 2, page 227 , where, under the head of “ Dubious En- 
tozoa, 5 ’ he enumerates an object described and figured by 
J. Rathke, under the name of “ Hydatula Gadorum,” which 
that observer found in the pia mater of the Gadus morrhua 
and G. virens, often in great numbers, and wRich appeared 
to be a vesicle containing a worm. The nature of the para- 
